F04.42 - Biomaterials and Biomolecules for TEMPs

SIGNIFICANCE AND USE
4.1 Standard Structure—This standard has been organized according to a typical bioprinting operational workflow. In this way the standard has three main sections: pre-printing considerations, printing considerations, and post-printing considerations. There is also a section on bioprinting modalities and additional considerations of product release, containers, and transport. Certain processes will appear across multiple sections, for example cytocompatibility or crosslinking, as these issues have considerations that take place prior to printing, during the printing process, and following the printing process. Contents of main sections are listed below.    
Scope  
Section 1  
Referenced Documents  
Section 2  
Terminology  
Section 3  
Significance and Use  
Section 4  
Bioprinting Modalities  
Section 5  
Pre-Printing Considerations  
Section 6  
Printing Considerations  
Section 7  
Post-Printing Considerations  
Section 8  
Additional Considerations  
Section 9  
Keywords  
Section 10  
References  
4.1.1 Pre-Printing Considerations—Pre-printing considerations include: bioink common applications, support material, and bioink selection considerations. Bioink selection considerations include: formulation of bioinks, bioink properties, changes in properties resulting from formulations, sterility, cellular component, and fugitive element considerations. Within the bioink properties there are considerations related to the viscoelastic properties, chemical properties, structure of polymer and functional groups, purity of material, mechanism of crosslinking, and degradation considerations. Contents of the section on pre-printing considerations are listed below.    
Bioink Common Applications  
6.2  
Support Material Considerations  
6.3  
Bioink Selection  
6.4  
Formulation of Bioinks  
6.4.1  
Concentration of Components  
6.4.1.1  
  
...
SCOPE
1.1 This guide is a resource for bioprinting tissue-engineered medical products (TEMPs) with bioinks and biomaterial inks. There are existing standards that cover biomaterials and scaffolds in a more general fashion (Guide F2150, Guide F2027, ISO 10993 series). This guide focuses specifically on extrusion bioprinting utilizing bioinks and biomaterial inks with inherent or inducible fluidic properties with or without encapsulated cells used to construct TEMPs. For the remainder of this guide, both bioinks and biomaterial inks will be collectively referred to as bioinks.  
1.2 For the purposes of this guide, bioprinting is defined as the three-dimensional printing of materials (bioinks) to fabricate structured constructs for use in biological or medical applications.  
1.3 TEMPs may be produced by many different bioprinting modalities, including but not limited to the following: electrospinning, electrospray, extrusion-based, droplet-based, inkjet-based, and laser-assisted bioprinting. Extrusion-based bioprinting is the primary focus of this document since it is currently the most well-understood modality used to construct TEMPs, but other bioprinting modalities are also addressed.  
1.4 This guide will focus on bioinks and biomaterials used as inks with inherent or inducible fluidic properties. These inks may or may not contain encapsulated cells. Chemical properties of the inks and other factors that affect printability are addressed.  
1.5 Pre-printing and printing considerations are the focus of this guide, but considerations regarding post-printing product stabilization are also addressed.  
1.6 This guide will address assessments regarding the sterility and cytocompatibility of bioinks, including chemical and physical benchtop tests, as well as measures of post-printing cell viability.  
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsi...

SIGNIFICANCE AND USE
4.1 The term “surface texture” is used to describe the local deviations of a surface from an ideal shape. Surface texture usually consists of long wavelength repetitive features that occur as results of chatter, vibration, or heat treatments during the manufacture of implants. Short wavelength features superimposed on the long wavelength features of the surface, which may arise from polishing or etching of the implant, are referred to as roughness.  
4.2 This guide provides an overview of techniques that are available for measuring the surface in terms of Cartesian coordinates and the parameters used to describe surface texture. It is important to appreciate that it is not possible to measure surface texture per se, but to derive values for parameters that can be used to describe it. ISO has published a series of standards on surface texture measurements that may be consulted for more information (ISO 3274, ISO 4287, ISO 4288, ISO 5436-2, ISO 10993-19, ISO 12179, ISO 13565-1, ISO 19606, ISO 21920-1, ISO 21920-2, ISO 21920-3, ISO 25178-1, ISO 25178-2, ISO 25178-3, ISO 25178-6, ISO 25178-70, ISO 25178-71, ISO 25178-72, ISO 25178-73, ISO 25178-600, ISO 25178-601, ISO 25178-602, ISO 25178-603, ISO 25178-604, ISO 25178-605, ISO 25178-606, ISO 25178-607, ISO 25178-700, ISO 25178-701).
SCOPE
1.1 This guide describes some of the more common methods that are available for measuring the topographical features of a surface and provides an overview of the parameters that are used to quantify them. Being able to reliably derive a set of parameters that describe the texture of biomaterial surfaces is a key aspect in the manufacture of safe and effective implantable medical devices that have the potential to trigger an adverse biological reaction in situ.  
1.2 This guide is not intended to apply to porous structures with average pore dimensions in excess of approximately 50 nm (0.05 μm).  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
4.1 The objective of this document is to provide guidance in the production, characterization, testing, and standardization of: (1) polymerizable collagen starting materials; and (2) collagen polymeric materials produced with polymerizable collagen formulations, used for surgical implants, substrates for TEMPs, vehicles for therapeutic cells and molecules, and 3D in-vitro tissue systems for basic research, drug development, and toxicity testing. This guide can be used as an aid in the selection, characterization, and standardization of the appropriate polymerizable collagen starting formulations as well as collagen polymeric materials prepared from polymerizable collagens for a specific use. Not all tests or parameters are applicable to all uses of collagen and users are expected to select and justify a subset of the tests for characterization purposes.  
4.2 This guide can be used by the following types of users:  
4.2.1 Manufacturers of polymerizable collagens and collagen polymeric materials who wish to set specifications for their products or provide characterization data for customers or users. They may also use the terminology and characterization sections to specify and differentiate the properties of polymerizable collagens and collagen polymeric materials.  
4.2.2 Producers of collagen polymeric materials that use polymerizable collagen as starting materials. Producers may use this guide to evaluate and characterize multiple sources of polymerizable collagen. They may also use this guide to assist with evaluation and comparison of single or multiple sources of polymerizable collagen and collagen polymeric materials.  
4.2.3 Researchers may use this guide as a reference for properties and test methods that can be used to reproducibly evaluate polymerizable collagens and collagen polymeric materials.  
4.3 The collagen covered by this guide may be used in a broad range of applications, forms, or medical products, for example (but not limited to) wound an...
SCOPE
1.1 This guide is intended to provide characteristics, properties, test methods, and standardization approaches for evaluation and identification of specific polymerizable collagen formulations and collagen polymeric materials produced with these formulations.  
1.2 This guide focuses on characterization of purified polymerizable forms of type I collagen, which is the most abundant collagen in mammalian connective tissues and organs, including skin, bone, tendon, and blood vessels. Polymerizable type I collagen may be derived from a variety of sources including, but not limited to, animal or cadaveric tissues, cell culture, recombinant cell culture, and chemical synthesis.  
1.2.1 This guide covers evaluation of polymerizable collagens and collagen polymeric materials prepared from polymerizable collagens for use as a starting material for wound and hemostatic dressings, surgical implants, substrates for tissue-engineered medical products (TEMPs), delivery vehicles for therapeutic cells or molecules, and 3D in-vitro tissue systems for basic research, diagnostics, drug development, and toxicity testing. Most collagen products on the market today are regulated as devices since their primary intended purpose is not achieved through chemical action within or on the body. However, a medical product comprising polymerizable collagens or collagen polymeric materials may be regulated as a device, biologic, drug, or combination product depending on its intended use and primary mode of action.  
1.2.2 Polymerizable collagen or collagen self-assembly implies that the collagen composition exhibits spontaneous macromolecular assembly from its components without the addition of exogenous factors such as cross-linking agents. Polymerizable collagens may include but are not limited to: (1) tissue-derived monomeric collagens, including tropocollagen or atelocollagen, and oligomeric collagens; (2) collagen proteins and peptides produce...

SIGNIFICANCE AND USE
4.1 This document describes the basic principles that need to be followed to obtain a mean value of the Darcy permeability coefficient for structures that consist of a series of interconnected voids or pores. The coefficient is a measure of the permeability of the structure to fluid flowing through it that is driven by a pressure gradient created across it.  
4.2 The technique is not sensitive to the presence of closed or blind-end pores (Fig. 1).
FIG. 1 Schematic of the Different Pores Types Found in Tissue Scaffolds. Fluid Flow Through the Structure is via the Open Pores  
4.3 Values of the permeability coefficient can be used to compare the consistency of manufactured samples or to determine what the effect of changing one or more manufacturing settings has on permeability. They can also be used to assess the homogeneity and anisotropy of tissue scaffolds. Variability in the permeability coefficient can be also be indicative of:  
4.3.1 Internal damage within the sample, for example, cracking or permanent deformation.  
4.3.2 The presence of large voids, including trapped air bubbles, within the structure.  
4.3.3 Surface effects such as a skin formed during manufacture.  
4.3.4 Variable sample geometry.  
4.4 This test method is based on the assumption that the flow rate through a given sample subjected to an applied pressure gradient is constant with time.
Note 1: If a steady-state flow condition isn’t reached, then this could be due to structural damage (that is, crack formation or the porous structure deformed as a result of the force being placed upon it by the fluid flowing through it). Sample deformation in the form of stretching (bowing) can also occur for less resilient structures as a result of high fluid flow rates. This topic is discussed in more detail in Section 7.  
4.5 Care should be taken to ensure that hydrophobic materials are fully wetted out when using water or other aqueous-based liquids as permeants.  
4.6 Conventionally, the p...
SCOPE
1.1 This guide describes test methods suitable for determining the mean Darcy permeability coefficient for a porous tissue scaffold, which is a measure of the rate at which a fluid, typically air or water, flows through it in response to an applied pressure gradient. This information can be used to optimize the structure of tissue scaffolds, to develop a consistent manufacturing process, and for quality assurance purposes.  
1.2 The method is generally nondestructive and non-contaminating.  
1.3 The method is not suitable for structures that are easily deformed or damaged. Some experimentation is usually required to assess the suitability of permeability testing for a particular material/structure and to optimize the experimental conditions.  
1.4 Measures of permeability should not be considered as definitive metrics of the structure of porous tissue scaffolds and should complement measures obtained by other investigative techniques, for example, scanning electron microscopy, gas flow porometry, and micro-computer X-ray tomography (Guides F2450, F2603, and F3259).  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
4.1 Although the test method can be used for assessment of the bioactivity of crude preparations of rhBMP-2, it has only been validated for use with highly pure (>98 % by weight protein purity) preparations of rhBMP-2.
SCOPE
1.1 This test method describes the method used and the calculation of results for the determination of the in-vitro biological activity of rhBMP-2 using the mouse stromal cell line W-20 clone 17 (W-20-17). This clone was derived from bone marrow stromal cells of the W++ mouse strain.2  
1.2 This test method (assay) has been qualified and validated based upon the International Committee on Harmonization assay validation guidelines3 (with the exception of interlaboratory precision) for the assessment of the biological activity of rhBMP-2. The relevance of this in-vitro test method to in-vivo bone formation has also been studied. The measured response in the W-20 bioassay, alkaline phosphatase induction, has been correlated with the ectopic bone-forming capacity of rhBMP-2 in the in-vivo Use Test (UT). rhBMP-2 that was partially or fully inactivated by targeted peracetic acid oxidation of the two methionines was used as a tool to compare the activities. Oxidation of rhBMP-2 with peracetic acid was shown to be specifically targeted to the methionines by peptide mapping and mass spectrometry. These methionines reside in a hydrophobic receptor binding pocket on rhBMP-2. Oxidized samples were compared alongside an incubation control and a native control. The 62, 87, 98, and 100 % oxidized samples had W-20 activity levels of 62, 20, 7, and 5 %, respectively. The incubation and native control samples maintained 100 % activity. Samples were evaluated in the UT and showed a similar effect of inactivation on bone-forming activity. The samples with 62 % and 20 % activity in the W-20 assay demonstrated reduced levels of bone formation, similar in level with the reduction in W-20 specific activity, relative to the incubation control. Little or no ectopic bone was formed in the 7 and 5 % active rhBMP-2 implants.  
1.3 Thus, modifications to the rhBMP-2 molecule in the receptor binding site decrease the activity in both the W-20 and UT assays. These data suggest that a single receptor binding domain on rhBMP-2 is responsible for both in-vitro and in-vivo activity and that the W-20 bioassay is a relevant predictor of the bone-forming activity of rhBMP-2.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 The purpose of this guide is to provide guidance on characterization of the properties of porcine fibrinogen as a starting material for surgical implants and as a matrix for tissue-engineered medical products (TEMPs). This guide contains a set of physical and chemical parameters directly related to the function of porcine fibrinogen. This guide can be used to help select and characterize appropriate fibrinogen starting materials for specific purposes. Not all tests or parameters are suitable for all uses of fibrinogen.  
5.2 Fibrinogen described in this guide may be used in various types of medical products including, but not limited to, implants, tissue-engineered medical products (TEMPs), and cell, drug, or DNA delivery vectors. The recommendations in this guide shall not be construed to guarantee the successful clinical application of any tissue-engineered medical product.  
5.3 In determining whether fibrinogen meets the requirements for use in a TEMP, the relevant regulatory authorities or other appropriate guidelines relating to the production, regulation, and approval of TEMP products shall be taken into account (Guide E1298, Practice F981, Practice F1983).
SCOPE
1.1 This guide covers the evaluation of porcine fibrinogen suitable for use in biomedical or pharmaceutical applications including, but not limited to, tissue-engineered medical products (TEMPs).  
1.2 This guide addresses key parameters relevant for functionality, characterization, and purity of porcine fibrinogen.  
1.3 As with any material, some characteristics of porcine fibrinogen may be altered by processing techniques, such as electrospinning (1)2 and sterilization, required for the production of a specific formulation or device. Therefore, properties of fabricated forms of this protein should be evaluated using test methods that are appropriate to ensure safety and efficacy and are not addressed in this guide.  
1.4 The primary focus of this document is fibrinogen derived from porcine blood, which is similar to human fibrinogen. The biggest advantage that pigs have over other species (such as cattle, sheep, goats, elk, and deer) is that they are less likely to transmit transmissible spongiform encephalitis (TSE) (ISO 22442-1 Annex D; WHO Guidelines, 2003; WHO Guidelines, 2006; WHO Guidelines, 2010). The document may also discuss fibrinogen from other sources when useful information is available. Fibrin is also discussed in some sections.  
1.5 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 This guide is a guideline for the characterizing and testing of alginate foam scaffolds used in tissue-engineered medical products. Alginate foam scaffolds can be used in a number of tissue engineering and regenerative medicine applications such as anti-adhesion, internal wound healing, and guided tissue regeneration. In addition, alginate foam can be used as a matrix for cell-based cell therapies and for the release of bioactive agents.
SCOPE
1.1 Consistent functionality of scaffolds used in TEMPs can be made more predictable by monitoring relevant characteristics related to physical and biological properties. This guide may be used in the selection of suitable test methods of dried ionically gelled alginate foam scaffolds that may be a component of a medical device or considered a medical device itself.  
1.2 This guide provides information relevant for the physical testing of alginate foam scaffolds such as mechanical properties, hydration properties, pore structure, and scaffold degradation. In addition, issues related to biological properties such as elemental impurities, bacterial bioburden, bacterial endotoxins, sterility, and biocompatibility are outlined.  
1.3 This guide is intended to be used in conjunction with appropriate characterization and evaluation of any raw or starting materials utilized for fabrication of the alginate foam, such as described in Guides F2027 and F2064.  
1.4 This guide addresses alginate foam scaffolds with and without bioactive agents or biological activity. This guide does not address the characterization or release profiles of any biomolecules, cells, drugs, or bioactive agents that are used in combination with the scaffold.  
1.5 Only SI units are used in this standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 The test methods contained herein guide characterization of the structural, physical, chemical, mechanical, and biological properties of a fiber-based construct. Such properties may be important for the success of a TEMP, especially if they affect cell retention; activity and organization; tensile strength; the delivery of bioactive agents; or the biocompatibility and bioactivity of the construct.  
5.2 Tests described herein may be used for quality control during manufacturing or to assess how the product may perform its intended clinical function.  
5.3 Plans for product development, product characterization, and the regulatory pathway should be discussed with the appropriate regulatory body.
SCOPE
1.1 This guide is a resource for the characterization of fiber-based constructs intended for use in a tissue-engineered medical product (TEMP). There are existing standards that broadly cover scaffolds in a more generalized fashion (Guides F2150, F2450, F2900, F2902, ISO 21560). This guide focuses specifically on fiber-based constructs.  
1.2 Fiber-based constructs may be fabricated by many different methods including, but not limited to the following: electrospinning, forcespinning, meltspinning, pneumatospinning, blowspinning, melt-electrowriting, melt extrusion, wet extrusion, fused deposition, liquid crystal deposition, electrochemical alignment, drawing, spinning, knitting, weaving, braiding, powder bed fusion (laser sintering), vat photopolymerization (stereolithography), binder jetting, directed energy deposition, self-assembly (for example, fibrillogenesis), and hybrid approaches. This document is intended to address fibers made by any of these methods, although electrospun fibers are addressed in greater detail in some sections.  
1.3 This guide will focus on constructs made of fibers wherein the average fiber diameter is within the range of approximately 100 nm to 100 µm.  
1.4 For the purposes of this standard, a “fiber-based construct” is defined as a construct composed of slender, elongated filaments.  
1.5 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
4.1 The objective of this guide is to provide guidance in the characterization of Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs). This guide contains a listing of physical and chemical parameters that are directly related to the function of collagen. This guide can be used as an aid in the selection and characterization of the appropriate collagen starting material for the specific use. Not all tests or parameters are applicable to all uses of collagen.  
4.2 The collagen covered by this guide may be used in a broad range of applications, forms, or medical products, for example (but not limited to) medical devices, tissue engineered medical products (TEMPs) or cell, drug, or DNA delivery devices for implantation. The use of collagen in a practical application should be based, among other factors, on biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application.  
4.3 The following general areas should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs. These are source of collagen, chemical and physical characterization and testing, and impurities profile.  
4.4 The following documents or other appropriate guidances from appropriate regulatory bodies relating to the production, regulation, and regulatory approval of TEMPs products should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs:    
FDA CFR:  
21 CFR 3: Product Jurisdiction:  
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=3    
21 CFR 58: Good Laboratory Practice for Nonclinical Laboratory Studies:  
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=58    
FDA/CDRH CFR and Guidances:  
21 CFR Part 803: Medical Device ...
SCOPE
1.1 This guide for characterizing collagen-containing biomaterials is intended to provide characteristics, properties, and test methods for use by producers, manufacturers, and researchers to more clearly identify the specific collagen materials used. With greater than 20 types of collagen and the different properties of each, a single document would be cumbersome. This guide will focus on the characterization of Type I collagen, which is the most abundant collagen in mammals, especially in skin and bone. Collagen isolated from these sources may contain other types of collagen, for example, Type III and Type V. This guide does not provide specific parameters for any collagen product or mix of products or the acceptability of those products for the intended use. The collagen may be from any source including, but not limited to, animal or cadaveric sources, human cell culture, or recombinant sources. The biological, immunological, or toxicological properties of the collagen may vary, depending on the source material. The properties of the collagen prepared from each of the above sources must be thoroughly investigated, as the changes in the collagen properties as a function of source materials is not thoroughly understood. This guide is intended to focus on purified Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs); some methods may not be applicable for gelatin or tissue implants. This guide may serve as a template for characterization of other types of collagen.  
1.2 The biological response to collagen in soft tissue has been well documented by a history of clinical use (1, 2)2 and laboratory studies (3-6). Biocompatibility and appropriateness of use for a specific application(s) is the responsibility of the product manufacturer.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this...

SIGNIFICANCE AND USE
4.1 This document provides guidance for users who wish to obtain quantifiable data from images of tissue scaffolds manufactured from polymers that include both high water content gels and woven textiles.  
4.2 Information derived from tissue scaffold images can be used to optimize the structural characteristics of the matrix for a particular application, to develop better manufacturing procedures or to provide a measure of quality assurance and product traceability. Fig. 1 provides a summary of the key stages of image capture and analysis.
FIG. 1 Key Stages in Image Capture, Storage, and Analysis  
4.3 There is a synergy between the analysis of pores in tissue scaffolds and that of particles that is reflected in standards cited and in the analysis described in Section 9. Guide E1919 provides a compendium of standards for particle analysis that includes measurement techniques, data analytical and sampling methodologies.
SCOPE
1.1 This guide covers the factors that need to be considered in obtaining and interpreting images of tissue scaffolds including technique selection, instrument resolution and image quality, quantification and sample preparation.  
1.2 The information in this guide is intended to be applicable to porous polymer-based tissue scaffolds, including naturally derived materials such as collagen. However, some materials (both synthetic and natural) may require unique or varied sample preparation methods that are not specifically covered in this guide.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 Scaffolds potentially may be metallic, ceramic, polymeric, natural, or composite materials. Scaffolds are usually porous to some degree, but may be solid. Scaffolds can range from mechanically rigid to gelatinous and can be either absorbable/degradable or non-absorbable/non-degradable. The scaffold may or may not have a surface treatment. Because of this large breadth of possible starting materials and scaffold constructions, this guide cannot be considered as exhaustive in its listing of potentially applicable tests. A voluntary guidance for the development of tissue-engineered products can be found in Omstead, et al (1).15 Guide F2027 contains a listing of potentially applicable test methods specific to various starting materials. Guidance regarding the evaluation of absorbable polymeric materials and constructs can be found in Guide F2902. Guidance regarding the evaluation of collagen-based materials can be found in Guide F2212. Guidance regarding the evaluation of scaffolds composed of ceramic or mineral-based material is available in Guide F2883. Similarly, guidance for the assessment of unique aspects of scaffolds based on hydrogels (for example, gel kinetics, mechanical stability, and mass transport properties) may be found in Guide F2900.  
5.2 Each TEMP scaffold product is unique and may require testing not within the scope of this guide or other guidance documents. Users of this guide are encouraged to examine the references listed herein and pertinent FDA or other regulatory guidelines or practices, and conduct a literature search to identify other procedures particularly pertinent for evaluation of their specific scaffold material (2,3,4). It is the ultimate responsibility of the TEMP scaffold designer to determine the appropriate testing, whether or not it is described in this guide.  
5.3 A listing of potentially applicable tests for characterizing and analyzing the materials used to fabricate the scaffold may be found in Guide F2027. However, co...
SCOPE
1.1 This guide is a resource of currently available test methods for the characterization of the compositional and structural aspects of biomaterial scaffolds used in the development and manufacture of regenerative medicine and tissue-engineered medical products (TEMPs).  
1.2 The test methods contained herein guide characterization of the bulk physical, chemical, mechanical, and surface properties of a scaffold construct. Such properties may be important for the success of a TEMP, especially if the property affects cell retention, activity and organization, the delivery of bioactive agents, or the biocompatibility and bioactivity within the final product.  
1.3 This guide may be used in the selection of appropriate test methods for the generation of an original equipment manufacture (OEM) specification. This guide also may be used to characterize the scaffold component of a finished medical product.  
1.4 This guide is intended to be used in conjunction with appropriate characterization(s) and evaluation(s) of any raw or starting material(s) used in the fabrication of the scaffold, such as described in Guide F2027.  
1.5 This guide addresses natural, synthetic, or combination scaffold materials with or without bioactive agents or biological activity. This guide does not address the characterization or release profiles of any biomolecules, cells, drugs, or bioactive agents that are used in combination with the scaffold, but may be used to address the effects on other (e.g., structural) properties as a result of such release. A determination of the suitability of a particular starting material and/or finished scaffold structure to a specific cell type and/or tissue engineering application is essential, but will require additional  in vitro and/or in vivo evaluations considered to be outside the scope of this guide.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its...

SIGNIFICANCE AND USE
4.1 Decellularization is used in the preparation of medical products that make use of the native structure and/or composition of the extracellular matrix derived from a specific tissue source. Upon implantation or placement, the decellullarized product is commonly intended to undergo and/or induce constructive remodeling and incorporation into the native host tissue instead of being recognized as foreign material. Typically, immune system recognition of foreign material leads to encapsulation of the material and an aggressive inflammatory response, causing the ultimate rejection or other failure of the product.  
4.2 As described above, decellularization is a recognized technique which allows the use of ECM-derived products in medical treatments with a reduced risk of an adverse host immune response and immune rejection by disrupting and removing cells and/or cell contents while aiming to preserve significant features of the ECM structure and/or composition. More complete decellularization is often associated with a beneficial response (1, 2)6 but can also be associated with the loss of important ECM components and the loss of structural or biomechanical integrity from the tissue during the decellularization process (3, 4, 5, 6). Therefore, given the typical objective of producing a product that does not elicit an adverse immune response while maintaining the integrity of the tissue for its intended surgical application, this guide presents a standard approach to the evaluation of decellularization processes, including assessment of adequate decellularization to achieve this end.  
4.3 An ideal decellularization process would completely remove source tissue cells and associated cellular content from a tissue or organ, while minimizing unwanted effects on the remaining ECM. However, a more widely encountered and practical representation of an optimized decellularization process exhibits partial removal and/or disruption of resident cells and cellular material to le...
SCOPE
1.1 This document provides guidance on the characterization and evaluation of the decellularization processes used to produce decellularized extracellular matrix (dECM) materials which will be used as medical products in direct or indirect contact with the body. The decellularization process may be performed on tissue from human or other mammalian sources or produced in vitro from human or other mammalian cells. The dECM may or may not be recellularized prior to use. Decellularized ECM material derived from non-mammalian tissue or cells and decellularized ECM material used for non-medical purposes may follow the framework provided but may require additional considerations outside the scope of this document.  
1.2 Biological tissues are composed of a structural extracellular matrix (ECM) and embedded cells. The intent of a decellularization process is to disrupt and/or remove cells and cellular components from an ECM material while maintaining key structural and/or compositional properties of the material. Decellularization comprises process steps intended or expected to result or aid in the disruption of source tissue cells and/or removal of cellular content from the material undergoing decellularization. Actions that are intended to rinse or otherwise remove decellularization reagents or by-products should also be considered in that context as part of the decellularization process. Purifications or other isolations of specific ECM components are not considered decellularization and are outside the scope of this document.  
1.3 This document describes relevant parameters of decellularization processes used to prepare extracellular matrix materials as medical products.  
1.4 This document provides guidance on the measurement of specific and general properties of dECM. This includes both the analysis of cellular material as well as the assessment of the effects of decellularization on dECM properties such as composition...

SIGNIFICANCE AND USE
5.1 The ability to culture functional tissue to repair damaged or diseased tissues within the body offers a viable alternative to xenografts or heterografts. Using the patient’s own cells to produce the new tissue offers significant benefits by limiting rejection by the immune system. Typically, cells harvested from the intended recipient are cultured in vitro using a temporary housing or scaffold. The microstructure of the scaffold can be defined by the existence, type, size distribution, interconnectivity, and directionality of pores – all of which are critical for cell migration, growth, and proliferation (Appendix X1). Optimizing the design of tissue scaffolds is a complex task, given the range of available materials, different manufacturing routes, and processing conditions. All of these factors can, and will, affect the surface texture, surface chemistry, and microstructure of the resultant scaffolds. Surface texture, surface chemistry, and microstructure of the scaffolds may or may not be significant variables depending on the characteristics of a given cell type at any given time (that is, changes in cell behavior due to the number of passages, mechanical stimulation, and culture conditions).  
5.2 Tissue scaffolds are typically assessed using an overall value for scaffold porosity and a range of pore sizes, though the distribution of sizes is rarely quantified. Published mean pore sizes and distributions are usually obtained from electron microscopy images and quoted in the micrometer range. Tissue scaffolds are generally complex structures that are not easily interpreted in terms of pore shape and size, especially in three dimensions. Therefore, it is difficult to quantifiably assess the batch-to-batch variance in microstructure or to make a systematic investigation of the role that the mean pore size and pore size distribution has on influencing cell behavior based solely on electron micrographs (Tomlins et al,  (1)).4  
5.2.1 Fig. 1 gives an indication...
SCOPE
1.1 This guide covers an overview of test methods that may be used to obtain information relating to the dimensions of pores, the pore size distribution, the degree of porosity, interconnectivity, and measures of permeability for porous materials used as polymeric scaffolds in the development and manufacture of tissue-engineered medical products (TEMPs). This information is key to optimizing the structure for a particular application, developing robust manufacturing routes, and providing reliable quality control data.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
4.1 This guide contains a listing of those characterization parameters that are directly related to the functionality of chitosan. This guide can be used as an aid in the selection and characterization of the appropriate chitosan or chitosan salt for a particular application. This standard is intended to give guidance in the methods and types of testing necessary to properly characterize, assess, and ensure consistency in the performance of a particular chitosan. It may have use in the regulation of devices containing chitosan by appropriate authorities.  
4.2 The chitosan salts covered by this guide may be gelled, extruded, or otherwise formulated into biomedical devices for use as tissue-engineered medical products or drug delivery devices for implantation as determined to be appropriate, based on supporting biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue-engineered medical product or drug delivery application.  
4.3 To ensure that the material supplied satisfies requirements for use in TEMPs, several general areas of characterization should be considered. These include identity of chitosan, physical and chemical characterization and testing, impurities profile, and performance-related tests.
SCOPE
1.1 This guide covers the evaluation of chitosan salts suitable for use in biomedical or pharmaceutical applications, or both, including, but not limited to, tissue-engineered medical products (TEMPS).  
1.2 This guide addresses key parameters relevant for the functionality, characterization, and purity of chitosan salts.  
1.3 As with any material, some characteristics of chitosan may be altered by processing techniques (such as molding, extrusion, machining, assembly, sterilization, and so forth) required for the production of a specific part or device. Therefore, properties of fabricated forms of this polymer should be evaluated using test methods that are appropriate to ensure safety and efficacy.  
1.4 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website (http://www.epa.gov/mercury/faq.htm) for additional information. Users should be aware that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.  
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
4.1 The degree of deacetylation of chitosan salts is an important characterization parameter since the charge density of the chitosan molecule is responsible for potential biological and functional effects.  
4.2 The degree of deacetylation (% DDA) of water-soluble chitosan salts can be determined by 1H nuclear magnetic resonance spectroscopy (1H NMR). Several workers have reported on the NMR determination of chemical composition and sequential arrangement of monomer units in chitin and chitosan. The test method described is primarily based on the work of Vårum et al. (1991),5 which represents the first publication on routine determination of chemical composition in chitosans by solution state 1H NMR spectroscopy. This test method is applicable for determining the % DDA of chitosan chloride and chitosan glutamate salts. It is a simple, rapid, and suitable method for routine use. Quantitative 1H NMR spectroscopy reports directly on the relative concentration of chemically distinct protons in the sample, consequently, no assumptions, calibration curves or calculations other than determination of relative signal intensity ratios are necessary.  
4.3 In order to obtain well-resolved NMR spectra, depolymerization of chitosans to a number average degree of polymerization (DPn) of ~15 to 30 is required. This reduces the viscosity and increases the mobility of the molecules. Although there are several options for depolymerization of chitosans, the most convenient procedure is that of nitrous acid degradation in deuterated water. The reaction is selective, stoichiometric with respect to GlcN, rapid, and easily controlled (Allan & Peyron, 1995).6 The reaction selectively cleaves after a GlcN-residue, transforming it into 2,5-anhydro-D-mannose (chitose), consequently, depletion of GlcN after depolymerization is expected. On the other hand, the chitose unit displays characteristic 1H NMR signals the intensity of which may be estimated and utilized in the calculation of % DDA,...
SCOPE
1.1 This test method covers the determination of the degree of deacetylation in chitosan and chitosan salts intended for use in biomedical and pharmaceutical applications as well as in Tissue Engineered Medical Products (TEMPs) by high-resolution proton NMR (1H NMR). A guide for the characterization of chitosan salts has been published as Guide F2103.  
1.2 The test method is applicable for determining the degree of deacetylation (% DDA) of chitosan chloride and chitosan glutamate salts and is valid for % DDA values from 50 up to and including 99. It is simple, rapid, and suitable for routine use. Knowledge of the degree of deacetylation is important for an understanding of the functionality of chitosan salts in TEMP formulations and applications. This test method will assist end users in choosing the correct chitosan for their particular application. Chitosan salts may have utility in drug delivery applications, as scaffold or matrix material, and in cell and tissue encapsulation applications.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
4.1 The degree of deacetylation of chitosan, as well at the molar mass and molar mass distribution, determines the functionality of chitosan in an application. For instance, functional and biological effects are highly dependent upon the composition and molar mass of the polymer.  
4.2 This test method describes procedures for measurement of molar mass of chitosan chlorides and glutamates, and chitosan base, although it in principle applies to any chitosan salt. The measured molar mass is that for chitosan acetate, since the mobile phase contains acetate as counter ion. This value can further be converted into the corresponding molar mass for the chitosan as a base, or the parent salt form (chloride or glutamate).  
4.3 Light scattering is one of very few methods available for the determination of absolute molar mass and structure, and it is applicable over the broadest range of molar masses of any method. Combining light scattering detection with size exclusion chromatography (SEC), which sorts molecules according to size, gives the ability to analyze polydisperse samples, as well as obtaining information on branching and molecular conformation. This means that both the number-average and mass-average values for molar mass and size may be obtained for most samples. Furthermore, one has the ability to calculate the distributions of the molar masses and sizes.  
4.4 Multi-angle laser light scattering (MALS) is a technique where measurements of scattered light are made simultaneously over a range of different angles. MALS detection can be used to obtain information on molecular size, since this parameter is determined by the angular variation of the scattered light. Molar mass may in principle be determined by detecting scattered light at a single low angle (LALLS). However, advantages with MALS as compared to LALLS are: (1) less noise at larger angles, (2) precision of measurements is improved by detecting at several angles, and (3) the ability to detect angular v...
SCOPE
1.1 This test method covers the determination of the molar mass of chitosan and chitosan salts intended for use in biomedical and pharmaceutical applications as well as in tissue engineered medical products (TEMPs) by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALS). A guide for the characterization of chitosan salts has been published as Guide F2103.  
1.2 Chitosan and chitosan salts used in TEMPs should be well characterized, including the molar mass and polydispersity (molar mass distribution) in order to ensure uniformity and correct functionality in the final product. This test method will assist end users in choosing the correct chitosan for their particular application. Chitosan may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
4.1 This guide contains a listing of those characterization parameters that are directly related to the functionality of alginate. This guide can be used as an aid in the selection and characterization of the appropriate alginate for a particular application. This guide is intended to give guidance in the methods and types of testing necessary to properly characterize, assess, and ensure consistency in the performance of a particular alginate. It may have use in the regulation of these devices by appropriate authorities.  
4.2 The alginate covered by this guide may be gelled, extruded, or otherwise formulated into biomedical devices for use in tissue-engineered medical products or drug delivery devices for implantation as determined to be appropriate, based on supporting biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application. Further guidance for immobilizing or encapsulating living cells or tissue in alginate gels can be found in Guide F2315.  
4.3 To ensure that the material supplied satisfies requirements for use in TEMPS, several general areas of characterization should be considered. These are: identity of alginate, physical and chemical characterization and testing, impurities profile, and performance-related tests.
SCOPE
1.1 This guide covers the evaluation of alginates suitable for use in biomedical or pharmaceutical applications, or both, including, but not limited to, Tissue Engineered Medical Products (TEMPs).  
1.2 This guide addresses key parameters relevant for the functionality, characterization, and purity of alginates.  
1.3 As with any material, some characteristics of alginates may be altered by processing techniques (such as molding, extrusion, machining, assembly, sterilization, and so forth) required for the production of a specific part or device. Therefore, properties of fabricated forms of this polymer should be evaluated using test methods that are appropriate to ensure safety and efficacy and are not addressed in this guide.  
1.4 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website (http://www.epa.gov/mercury/faq.htm) for additional information. Users should be aware that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
4.1 The European Pharmacopoeia (Ph. Eur.) as well as the United States Pharmacopeia (USP) describe several dissolution and drug release setups for tablets, capsules, transdermal patches and suppositories (USP , USP , Ph. Eur. 2.9.3, Ph. Eur. 2.9.4). However, up to this point no pharmacopoeia standardized in-vitro release test has been established for parenteral dosage forms which provide sustained drug release, for example, implants.  
4.2 An appropriately designed in-vitro release test would be favorable in the early stage of development of biomolecule-releasing scaffolds for TEMPs, as well as in quality control, and may help to reduce the number of animal experiments.  
4.3 Appendix X1 provides a tabulated overview of published in-vitro release studies performed with biomaterial scaffolds loaded with biomolecules.  
4.4 One goal of in-vitro release studies is to simulate the in-vivo conditions as closely as possible, but with sufficiently simplifying abstraction. The simplification comprises two general aspects: the amount of fluid or release medium in contact with the implant to simulate the physiological environment, and the composition of that release medium.
SCOPE
1.1 To describe general principles of developing and/or using an in vitro assay to evaluate biomolecule release from biomaterials scaffolds for TEMPs, with examples from the literature  
1.2 The guide will address scaffolds that do not contain seeded cells; general principles may still apply but may need to be modified if cells are part of the TEMPs.  
1.3 In vitro release assessment of biomolecules from matrices is a valuable tool for screening biomolecule-scaffold interactions, as well as characterization, and/or quality control.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

ABSTRACT
This guide addresses material characteristics of raw or virgin materials in a nonfabricated form that will ultimately undergo additional processing into growth, support, or delivery vehicles for cells or biomolecules. The substrate material shall have specifications for an extensive set of chemical and physical properties prescribed. Test methods shall be performed in order to determine the chemical and physical properties of the material.
SIGNIFICANCE AND USE
4.1 The physico-chemical characteristics of the raw or starting material used in regenerative medicine scaffolds carries significant potential to affect product performance by influencing cell behavior and/or the release of bioactive molecules or drugs. This guide describes recommended specifications or characterizations of raw or starting materials to ensure reproducibility prior to their fabrication into implantable tissue-engineering scaffolds and/or controlled release matrices.
SCOPE
1.1 This document provides guidance on writing a materials specification for raw or starting materials intended for use in tissue engineering scaffolds for growth, support, or delivery of cells and/or biomolecules. This guide does not apply to materials that are already in a scaffold form or are finished tissue-engineered medical products.  
1.2 The purpose of this guide is to provide a compendium of relevant existing standards and test methods for materials already commonly used within medical products and to provide characterization guidance for interim use of raw materials for which a standard does not exist.  
1.3 This guide covers specifications and characterizations of all the major classes of materials including polymers, ceramics, metals, composites, and natural tissues of human, animal, or plant origin. This guide does not apply to pharmaceuticals.  
1.4 This guide is focused on specification of chemical, physical, and mechanical properties of the raw or starting material. It does not include safety and biocompatibility requirements since safety and biocompatibility testing is typically done on materials fabricated into a final form to include all possible effects of fabrication and sterilization techniques.  
1.5 Compliance with materials specifications developed in accordance with this standard may not necessarily result in a material suitable for its intended purpose. Additional testing specific to the intended use may be required.

SIGNIFICANCE AND USE
4.1 The composition and sequential structure of alginate, as well as the molar mass and molar mass distribution, determines the functionality of alginate in an application. For instance, the gelling properties of an alginate are highly dependent upon the composition and molar mass of the polymer.  
4.2 Light scattering is one of very few methods available for the determination of absolute molar mass and structure, and it is applicable over the broadest range of molar masses of any method. Combining light scattering detection with size exclusion chromatography (SEC), which sorts molecules according to size, gives the ability to analyze polydisperse samples, as well as to obtain information on branching and molecular conformation. This means that both the number-average and mass-average values for molar mass and size may be obtained for most samples. Furthermore, one has the ability to calculate the distributions of the molar masses and sizes.  
4.3 Multi-angle laser light scattering (MALS) is a technique where measurements are made simultaneously over a range of different angles and used to determine the scattering at 0°, which directly relates to molecular weight. MALS detection can be used to obtain information on molecular size, since this parameter is determined by the angular variation of the scattered light. This can be related to branching, aggregation, and molecular conformation. Molar mass can also be determined by detecting scattered light at a single low angle (LALS) and assuming that this is not significantly different from the scattering at 0°.  
4.4 Size exclusion chromatography uses columns, which are typically packed with polymer particles containing a network of uniform pores into which solute and solvent molecules can diffuse. While in the pores, molecules are effectively trapped and removed from the flow of the mobile phase. The average residence time in the pores depends upon the size of the solute molecules. Molecules that are larger than the ...
SCOPE
1.1 This test method covers the determination of the molar mass (typically expressed as grams/mole) of sodium alginate intended for use in biomedical and pharmaceutical applications as well as in tissue-engineered medical products (TEMPs) by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALS). A guide for the characterization of alginate has been published as Guide F2064.  
1.2 Alginate used in TEMPs should be well characterized, including the molar mass and polydispersity (molar mass distribution) in order to ensure uniformity and correct functionality in the final product. This test method will assist end users in choosing the correct alginate for their particular application. Alginate may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
4.1 This guide contains a listing of those characterization parameters that are directly related to the functionality of hyaluronan. This guide can be used as an aid in the selection and characterization of the appropriate hyaluronan for a particular application. This guide is intended to give guidance in the methods and types of testing necessary to properly characterize, assess, and ensure consistency in the performance of a particular hyaluronan. It may have use in the regulation of these devices by appropriate authorities.  
4.2 The hyaluronan covered by this guide may be gelled, cross-linked, extruded, or otherwise formulated into biomedical devices for use in tissue engineered medical products or drug delivery devices for implantation as determined to be appropriate, based on supporting biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application.  
4.3 To ensure that the material supplied satisfies requirements for use in TEMPs, several general areas of characterization should be considered. These are: identity of hyaluronan, physical and chemical characterization and testing, impurities profile, and performance-related tests.
SCOPE
1.1 This guide covers the evaluation of hyaluronan suitable for use in biomedical or pharmaceutical applications, or both, including, but not limited to, Tissue Engineered Medical Products (TEMPs).  
1.2 This guide addresses key parameters relevant to the characterization and purity of hyaluronan.  
1.3 As with any material, some characteristics of hyaluronan may be altered by processing techniques, such as cross-linking and sterilization, required for the production of a specific formulation or device. Therefore, properties of fabricated forms of this polymer should be evaluated using test methods that are appropriate to ensure safety and efficacy and are not addressed in this guide.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.

SIGNIFICANCE AND USE
4.1 The objective of this guide is to provide guidance in the characterization of Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs). This guide contains a listing of physical and chemical parameters that are directly related to the function of collagen. This guide can be used as an aid in the selection and characterization of the appropriate collagen starting material for the specific use. Not all tests or parameters are applicable to all uses of collagen.  
4.2 The collagen covered by this guide may be used in a broad range of applications, forms, or medical products, for example (but not limited to) medical devices, tissue engineered medical products (TEMPs) or cell, drug, or DNA delivery devices for implantation. The use of collagen in a practical application should be based, among other factors, on biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application.  
4.3 The following general areas should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs. These are source of collagen, chemical and physical characterization and testing, and impurities profile.  
4.4 The following documents or other appropriate guidances from appropriate regulatory bodies relating to the production, regulation, and regulatory approval of TEMPs products should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs:    
FDA CFR:  
21 CFR 3: Product Jurisdiction:  
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=3    
21 CFR 58: Good Laboratory Practice for Nonclinical Laboratory Studies:  
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=58    
FDA/CDRH CFR and Guidances:  
21 CFR Part 803: Medical Device ...
SCOPE
1.1 This guide for characterizing collagen-containing biomaterials is intended to provide characteristics, properties, and test methods for use by producers, manufacturers, and researchers to more clearly identify the specific collagen materials used. With greater than 20 types of collagen and the different properties of each, a single document would be cumbersome. This guide will focus on the characterization of Type I collagen, which is the most abundant collagen in mammals, especially in skin and bone. Collagen isolated from these sources may contain other types of collagen, for example, Type III and Type V. This guide does not provide specific parameters for any collagen product or mix of products or the acceptability of those products for the intended use. The collagen may be from any source including, but not limited to, animal or cadaveric sources, human cell culture, or recombinant sources. The biological, immunological, or toxicological properties of the collagen may vary, depending on the source material. The properties of the collagen prepared from each of the above sources must be thoroughly investigated, as the changes in the collagen properties as a function of source materials is not thoroughly understood. This guide is intended to focus on purified Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs); some methods may not be applicable for gelatin or tissue implants. This guide may serve as a template for characterization of other types of collagen.  
1.2 The biological response to collagen in soft tissue has been well documented by a history of clinical use (1, 2)2 and laboratory studies (3, 4, 5, 6). Biocompatibility and appropriateness of use for a specific application(s) is the responsibility of the product manufacturer.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included ...

SIGNIFICANCE AND USE
4.1 The term “surface texture” is used to describe the local deviations of a surface from an ideal shape. Surface texture usually consists of long wavelength repetitive features that occur as results of chatter, vibration, or heat treatments during the manufacture of implants. Short wavelength features superimposed on the long wavelength features of the surface, which arise from polishing or etching of the implant, are referred to as roughness.  
4.2 This guide provides an overview of techniques that are available for measuring the surface in terms of Cartesian coordinates and the parameters used to describe surface texture. It is important to appreciate that it is not possible to measure surface texture per se, but to derive values for parameters that can be used to describe it.
SCOPE
1.1 This guide describes some of the more common methods that are available for measuring the topographical features of a surface and provides an overview of the parameters that are used to quantify them. Being able to reliably derive a set of parameters that describe the texture of biomaterial surfaces is a key aspect in the manufacture of safe and effective implantable medical devices that have the potential to trigger an adverse biological reaction in situ.  
1.2 This guide is not intended to apply to porous structures with average pore dimensions in excess of approximately 50 nm (0.05 μm).  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
4.1 This guide contains a listing of those characterization parameters that are directly related to the functionality of alginate. This guide can be used as an aid in the selection and characterization of the appropriate alginate for a particular application. This guide is intended to give guidance in the methods and types of testing necessary to properly characterize, assess, and ensure consistency in the performance of a particular alginate. It may have use in the regulation of these devices by appropriate authorities.  
4.2 The alginate covered by this guide may be gelled, extruded, or otherwise formulated into biomedical devices for use in tissue-engineered medical products or drug delivery devices for implantation as determined to be appropriate, based on supporting biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application. Further guidance for immobilizing or encapsulating living cells or tissue in alginate gels can be found in Guide F2315.  
4.3 To ensure that the material supplied satisfies requirements for use in TEMPS, several general areas of characterization should be considered. These are: identity of alginate, physical and chemical characterization and testing, impurities profile, and performance-related tests.
SCOPE
1.1 This guide covers the evaluation of alginates suitable for use in biomedical or pharmaceutical applications, or both, including, but not limited to, Tissue Engineered Medical Products (TEMPs).  
1.2 This guide addresses key parameters relevant for the functionality, characterization, and purity of alginates.  
1.3 As with any material, some characteristics of alginates may be altered by processing techniques (such as molding, extrusion, machining, assembly, sterilization, and so forth) required for the production of a specific part or device. Therefore, properties of fabricated forms of this polymer should be evaluated using test methods that are appropriate to ensure safety and efficacy and are not addressed in this guide.  
1.4 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website (http://www.epa.gov/mercury/faq.htm) for additional information. Users should be aware that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
4.1 The term “surface texture” is used to describe the local deviations of a surface from an ideal shape. Surface texture usually consists of long wavelength repetitive features that occur as results of chatter, vibration, or heat treatments during the manufacture of implants. Short wavelength features superimposed on the long wavelength features of the surface, which arise from polishing or etching of the implant, are referred to as roughness.  
4.2 This guide provides an overview of techniques that are available for measuring the surface in terms of Cartesian coordinates and the parameters used to describe surface texture. It is important to appreciate that it is not possible to measure surface texture per se, but to derive values for parameters that can be used to describe it.
SCOPE
1.1 This guide describes some of the more common methods that are available for measuring the topographical features of a surface and provides an overview of the parameters that are used to quantify them. Being able to reliably derive a set of parameters that describe the texture of biomaterial surfaces is a key aspect in the manufacture of safe and effective implantable medical devices that have the potential to trigger an adverse biological reaction in situ.  
1.2 This guide is not intended to apply to porous structures with average pore dimensions in excess of approximately 50 nm (0.05 μm).  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
4.1 The objective of this document is to provide guidance in the production, characterization, testing, and standardization of: (a) collagen polymers as a starting material for surgical implants, substrates for tissue-engineered medical products (TEMPs), vehicles for therapeutic cells and molecules, and 3D in-vitro tissue systems for basic research, drug development, and toxicity testing; and (b) self-assembled collagen-based materials produced with collagen polymer formulations. This guide can be used as an aid in the selection, characterization, and standardization of the appropriate collagen polymer starting material as well as associated self-assembled collagen-based products for a specific use. Not all tests or parameters are applicable to all uses of collagen.  
4.2 The collagen covered by this guide may be used in a broad range of applications, forms, or medical products, for example (but not limited to) wound and hemostatic dressings, surgical implants or injectables, hybrid medical devices, tissue-engineered medical products (TEMPs), injectable or implantable delivery vehicles for therapeutic cells, molecules, and drugs, and 3D in-vitro tissue systems or models for basic research, drug development, and toxicity testing. The practical application of the collagen polymers and associated self-assembled collagen-based materials should be based, among other factors, on biocompatibility, application-specific performance measures, as well as chemical, physical, and biological test data. Recommendations in this guide should not be interpreted as a guarantee of success for any research or medical application.  
4.3 The following general areas should be considered when determining if the collagen supplied satisfies requirements for use in the above mentioned medical and research applications: source of collagen polymer, impurities profile, and comprehensive chemical, physical, and biological characterization and testing.  
4.4 The following documents or other rele...
SCOPE
1.1 This guide for characterizing polymerizable collagens is intended to provide characteristics, properties, test methods, and standardization approaches for use by producers, manufacturers, and researchers to identify specific collagen polymer formulations and associated self-assembled collagen-based products produced with these formulations. This guide will focus on the characterization of polymer forms of Type I collagen, which is the most abundant collagen in mammalian connective tissues and organs, including skin, bone, tendon, and blood vessels. Type I collagen may be derived from a variety of sources including, but not limited to, animal or cadaveric tissues, cell culture, recombinant, and chemical synthesis. This guide is intended to focus on purified Type I collagen polymers as a starting material for wound and hemostatic dressings, surgical implants, substrates for tissue-engineered medical products (TEMPs), delivery vehicles for therapeutic cells or molecules, and 3D in-vitro tissue systems for basic research, drug development, and toxicity testing. Polymerizable or self-assembly implies that the collagen composition exhibits spontaneous macromolecular assembly from its components in the absence of the addition of exogenous factors including cross-linking agents. Self-assembling collagen polymers may include, but are not limited to: (1) tissue-derived atelocollagens, monomers, and oligomers; (2) collagen proteins and peptides produced using recombinant technology; and (3) chemically synthesized collagen mimetic peptides. It should be noted that the format of associated self-assembled collagen-based products also will vary and may include injectable solutions that polymerize in situ as well as preformed sheets, particles, spheres, fibers, sponges, matrices/gels, coatings, films, and other forms. This guide may serve as a template for characterization and standardization of other fibrillar collagen types that d...

SIGNIFICANCE AND USE
4.1 This document describes the basic principles that need to be followed to obtain a mean value of the Darcy permeability coefficient for structures that consist of a series of interconnected voids or pores. The coefficient is a measure of the permeability of the structure to fluid flowing through it that is driven by a pressure gradient created across it.  
4.2 The technique is not sensitive to the presence of closed or blind-end pores (Fig. 1).  
4.3 Values of the permeability coefficient can be used to compare the consistency of manufactured samples or to determine what the effect of changing one or more manufacturing settings has on permeability. They can also be used to assess the homogeneity and anisotropy of tissue scaffolds. Variability in the permeability coefficient can be also be indicative of:  
4.3.1 Internal damage within the sample e.g., cracking or permanent deformation.  
4.3.2 The presence of large voids, including trapped air bubbles, within the structure.  
4.3.3 Surface effects such as a skin formed during manufacture.  
4.3.4 Variable sample geometry.  
4.4 This test method is based on the assumption that the flow rate through a given sample subjected to an applied pressure gradient is constant with time.Note 1—If a steady state flow condition isn’t reached, then this could be due to structural damage (i.e., crack formation or the porous structure deformed as a result of the force being placed upon it by the fluid flowing through it). Sample deformation in the form of stretching (bowing) can also occur for less resilient structures as a result of high fluid flow rates. This topic is discussed in more detail in Section 7.  
4.5 Care should be taken to ensure that hydrophobic materials are fully wetted out when using water or other aqueous-based liquids as permeants.  
4.6 Conventionally, the pressure differential created across a sample is measured as a function of both increasing and decreasing flow rates. An alternative approach, whi...
SCOPE
1.1 This guide describes test methods suitable for determining the mean Darcy permeability coefficient for a porous tissue scaffold, which is a measure of the rate at which a fluid, typically air or water, flows through it in response to an applied pressure gradient. This information can be used to optimize the structure of tissue scaffolds, to develop a consistent manufacturing process, and for quality assurance purposes.  
1.2 The method is generally non-destructive and non-contaminating.  
1.3 The method is not suitable for structures that are easily deformed or damaged. Some experimentation is usually required to assess the suitability of permeability testing for a particular material/structure and to optimize the experimental conditions.  
1.4 Measures of permeability should not be considered as definitive metrics of the structure of porous tissue scaffolds and should complement measures obtained by other investigative techniques e.g., scanning electron microscopy, gas flow porometry and micro-computer x-ray tomography (ASTM F2450).  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
5.1 Scaffolds potentially may be metallic, ceramic, polymeric, natural, or composite materials. Scaffolds are usually porous to some degree, but may be solid. Scaffolds can range from mechanically rigid to gelatinous and can be either absorbable/degradable or nonresorbable/nondegradable. The scaffold may or may not have a surface treatment. Because of this large breadth of possible starting materials and scaffold constructions, this guide cannot be considered as exhaustive in its listing of potentially applicable tests. A voluntary guidance for the development of tissue-engineered products can be found in Omstead, et al (1).13 Guide F2027 contains a listing of potentially applicable test methods specific to various starting materials. Guidance regarding the evaluation of absorbable polymeric materials and constructs can be found in Guide F2902. Guidance regarding the evaluation of collagen-based materials can be found in Guide F2212. Guidance regarding the evaluation of scaffolds composed of ceramic or mineral based material is available in Guide F2883. Similarly, guidance for the assessment of unique aspects of scaffolds based on hydrogels (for example, gel kinetics, mechanical stability, and mass transport properties) may be found in Guide F2900.  
5.2 Each TEMP scaffold product is unique and may require testing not within the scope of this guide or other guidance documents. Users of this guide are encouraged to examine the references listed herein and pertinent FDA or other regulatory guidelines or practices, and conduct a literature search to identify other procedures particularly pertinent for evaluation of their specific scaffold material (2,3,4). It is the ultimate responsibility of the TEMP scaffold designer to determine the appropriate testing, whether or not it is described in this guide.  
5.3 A listing of potentially applicable tests for characterizing and analyzing the materials utilized to fabricate the scaffold may be found in Guide F2027. However, ...
SCOPE
1.1 This guide is a resource of currently available test methods for the characterization of the compositional and structural aspects of biomaterial scaffolds used to develop and manufacture tissue-engineered medical products (TEMPs).  
1.2 The test methods contained herein guide characterization of the bulk physical, chemical, mechanical, and surface properties of a scaffold construct. Such properties may be important for the success of a TEMP, especially if they affect cell retention, activity and organization, the delivery of bioactive agents, or the biocompatibility and bioactivity within the final product.  
1.3 This guide may be used in the selection of appropriate test methods for the generation of an original equipment manufacture (OEM) specification. This guide also may be used to characterize the scaffold component of a finished medical product.  
1.4 This guide is intended to be utilized in conjunction with appropriate characterization(s) and evaluation(s) of any raw or starting material(s) utilized in the fabrication of the scaffold, such as described in Guide F2027.  
1.5 This guide addresses natural, synthetic, or combination scaffold materials with or without bioactive agents or biological activity. This guide does not address the characterization or release profiles of any biomolecules, cells, drugs, or bioactive agents that are used in combination with the scaffold. A determination of the suitability of a particular starting material and/or finished scaffold structure to a specific cell type and/or tissue engineering application is essential, but will require additional  in vitro and/or in vivo evaluations considered to be outside the scope of this guide.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability ...

SIGNIFICANCE AND USE
4.1 The degree of deacetylation of chitosan, as well at the molar mass and molar mass distribution, determines the functionality of chitosan in an application. For instance, functional and biological effects are highly dependent upon the composition and molar mass of the polymer.  
4.2 This test method describes procedures for measurement of molar mass of chitosan chlorides and glutamates, and chitosan base, although it in principle applies to any chitosan salt. The measured molar mass is that for chitosan acetate, since the mobile phase contains acetate as counter ion. This value can further be converted into the corresponding molar mass for the chitosan as a base, or the parent salt form (chloride or glutamate).  
4.3 Light scattering is one of very few methods available for the determination of absolute molar mass and structure, and it is applicable over the broadest range of molar masses of any method. Combining light scattering detection with size exclusion chromatography (SEC), which sorts molecules according to size, gives the ability to analyze polydisperse samples, as well as obtaining information on branching and molecular conformation. This means that both the number-average and mass-average values for molar mass and size may be obtained for most samples. Furthermore, one has the ability to calculate the distributions of the molar masses and sizes.  
4.4 Multi-angle laser light scattering (MALS) is a technique where measurements of scattered light are made simultaneously over a range of different angles. MALS detection can be used to obtain information on molecular size, since this parameter is determined by the angular variation of the scattered light. Molar mass may in principle be determined by detecting scattered light at a single low angle (LALLS). However, advantages with MALS as compared to LALLS are: (1) less noise at larger angles, (2) the precision of measurements are greatly improved by detecting at several angles, and (3) the ability to det...
SCOPE
1.1 This test method covers the determination of the molar mass of chitosan and chitosan salts intended for use in biomedical and pharmaceutical applications as well as in tissue engineered medical products (TEMPs) by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALS). A guide for the characterization of chitosan salts has been published as Guide F2103.  
1.2 Chitosan and chitosan salts used in TEMPs should be well characterized, including the molar mass and polydispersity (molar mass distribution) in order to ensure uniformity and correct functionality in the final product. This test method will assist end users in choosing the correct chitosan for their particular application. Chitosan may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
4.1 Although the test method can be used for assessment of the bioactivity of crude preparations of rhBMP-2, it has only been validated for use with highly pure (>98 % by weight protein purity) preparations of rhBMP-2.
SCOPE
1.1 This test method describes the method used and the calculation of results for the determination of the  in-vitro biological activity of rhBMP-2 using the mouse stromal cell line W-20 clone 17 (W-20-17). This clone was derived from bone marrow stromal cells of the W++ mouse strain.2  
1.2 This test method (assay) has been qualified and validated based upon the International Committee on Harmonization assay validation guidelines3 (with the exception of interlaboratory precision) for the assessment of the biological activity of rhBMP-2. The relevance of this in vitro test method to in vivo bone formation has also been studied. The measured response in the W-20 bioassay, alkaline phosphatase induction, has been correlated with the ectopic bone-forming capacity of rhBMP-2 in the in vivo  Use Test (UT). rhBMP-2 that was partially or fully inactivated by targeted peracetic acid oxidation of the two methionines was used as a tool to compare the activities. Oxidation of rhBMP-2 with peracetic acid was shown to be specifically targeted to the methionines by peptide mapping and mass spectrometry. These methionines reside in a hydrophobic receptor binding pocket on rhBMP-2. Oxidized samples were compared alongside an incubation control and a native control. The 62, 87, 98, and 100 % oxidized samples had W-20 activity levels of 62, 20, 7, and 5 %, respectively. The incubation and native control samples maintained 100 % activity. Samples were evaluated in the UT and showed a similar effect of inactivation on bone-forming activity. The samples with 62 % and 20 % activity in the W-20 assay demonstrated reduced levels of bone formation, similar in level with the reduction in W-20 specific activity, relative to the incubation control. Little or no ectopic bone was formed in the 7 and 5 % active rhBMP-2 implants.  
1.3 Thus, modifications to the rhBMP-2 molecule in the receptor binding site decrease the activity in both the W-20 and UT assays. These data suggest that a single receptor binding domain on rhBMP-2 is responsible for both in-vitro and in-vivo activity and that the W-20 bioassay is a relevant predictor of the bone-forming activity of rhBMP-2.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
4.1 This document provides guidance for users who wish to obtain quantifiable data from images of tissue scaffolds manufactured from polymers that include both high water content gels and woven textiles.  
4.2 Information derived from tissue scaffold images can be used to optimize the structural characteristics of the matrix for a particular application, to develop better manufacturing procedures or to provide a measure of quality assurance and product traceability. Fig. 1 provides a summary of the key stages of image capture and analysis.
FIG. 1 Key Stages in Image Capture, Storage, and Analysis  
4.3 There is a synergy between the analysis of pores in tissue scaffolds and that of particles that is reflected in standards cited and in the analysis described in Section 9. Guide E1919 provides a compendium of standards for particle analysis that includes measurement techniques, data analytical and sampling methodologies.
SCOPE
1.1 This guide covers the factors that need to be considered in obtaining and interpreting images of tissue scaffolds including technique selection, instrument resolution and image quality, quantification and sample preparation.  
1.2 The information in this guide is intended to be applicable to porous polymer-based tissue scaffolds, including naturally derived materials such as collagen. However, some materials (both synthetic and natural) may require unique or varied sample preparation methods that are not specifically covered in this guide.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
4.1 The degree of deacetylation of chitosan salts is an important characterization parameter since the charge density of the chitosan molecule is responsible for potential biological and functional effects.  
4.2 The degree of deacetylation (% DA) of water-soluble chitosan salts can be determined by  1H nuclear magnetic resonance spectroscopy (1H NMR). Several workers have reported on the NMR determination of chemical composition and sequential arrangement of monomer units in chitin and chitosan. The test method described is primarily based on the work of Vårum et al. (1991),5 which represents the first publication on routine determination of chemical composition in chitosans by solution state  1H NMR spectroscopy. This test method is applicable for determining the % DA of chitosan chloride and chitosan glutamate salts. It is a simple, rapid, and suitable method for routine use. Quantitative  1H NMR spectroscopy reports directly on the relative concentration of chemically distinct protons in the sample, consequently, no assumptions, calibration curves or calculations other than determination of relative signal intensity ratios are necessary.  
4.3 In order to obtain well-resolved NMR spectra, depolymerization of chitosans to a number average degree of polymerization (DPn) of ~15 to 30 is required. This reduces the viscosity and increases the mobility of the molecules. Although there are several options for depolymerization of chitosans, the most convenient procedure is that of nitrous acid degradation in deuterated water. The reaction is selective, stoichiometric with respect to GlcN, rapid, and easily controlled (Allan & Peyron, 1995).6 The reaction selectively cleaves after a GlcN-residue, transforming it into 2,5-anhydro-D-mannose (chitose), consequently, depletion of GlcN after depolymerization is expected. On the other hand, the chitose unit displays characteristic  1H NMR signals the intensity of which may be estimated and utilized in the calculation of % DA...
SCOPE
1.1 This test method covers the determination of the degree of deacetylation in chitosan and chitosan salts intended for use in biomedical and pharmaceutical applications as well as in Tissue Engineered Medical Products (TEMPs) by high-resolution proton NMR (1H NMR). A guide for the characterization of chitosan salts has been published as Guide F2103.  
1.2 The test method is applicable for determining the degree of deacetylation (% DA) of chitosan chloride and chitosan glutamate salts and is valid for % DA values from 50 up to and including 99. It is simple, rapid, and suitable for routine use. Knowledge of the degree of deacetylation is important for an understanding of the functionality of chitosan salts in TEMP formulations and applications. This test method will assist end users in choosing the correct chitosan for their particular application. Chitosan salts may have utility in drug delivery applications, as a scaffold or matrix material, and in cell and tissue encapsulation applications.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The objective of this guide is to provide guidance in the characterization of Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs). This guide contains a listing of physical and chemical parameters that are directly related to the function of collagen. This guide can be used as an aid in the selection and characterization of the appropriate collagen starting material for the specific use. Not all tests or parameters are applicable to all uses of collagen.
The collagen covered by this guide may be used in a broad range of applications, forms, or medical products, for example (but not limited to) medical devices, tissue engineered medical products (TEMPs) or cell, drug, or DNA delivery devices for implantation. The use of collagen in a practical application should be based, among other factors, on biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application.
The following general areas should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs. These are source of collagen, chemical and physical characterization and testing, and impurities profile.
The following documents or other appropriate guidances from appropriate regulatory bodies relating to the production, regulation and regulatory approval of TEMPs products should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs:
SCOPE
1.1 This guide for characterizing collagen-containing biomaterials is intended to provide characteristics, properties, and test methods for use by producers, manufacturers, and researchers to more clearly identify the specific collagen materials used. With greater than 20 types of collagen and the different properties of each, a single document would be cumbersome. This guide will focus on the characterization of Type I collagen, which is the most abundant collagen in mammals, especially in skin and bone. Collagen isolated from these sources may contain other types of collagen, for example, Type III and Type V. This guide does not provide specific parameters for any collagen product or mix of products or the acceptability of those products for the intended use. The collagen may be from any source, including, but not limited to, animal or cadaveric sources, human cell culture, or recombinant sources. The biological, immunological, or toxicological properties of the collagen may vary, depending on the source material. The properties of the collagen prepared from each of the above sources must be thoroughly investigated, as the changes in the collagen properties as a function of source materials is not thoroughly understood. This guide is intended to focus on purified Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs); some methods may not be applicable for gelatin or tissue implants. This guide may serve as a template for characterization of other types of collagen.
1.2 The biological response to collagen in soft tissue has been well documented by a history of clinical use (1, 2) and laboratory studies (3, 4, 5, 6). Biocompatibility and appropriateness of use for a specific application(s) is the responsibility of the product manufacturer.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 WarningMercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for detail...

SIGNIFICANCE AND USE
This guide contains a listing of those characterization parameters that are directly related to the functionality of chitosan. This guide can be used as an aid in the selection and characterization of the appropriate chitosan or chitosan salt for a particular application. This standard is intended to give guidance in the methods and types of testing necessary to properly characterize, assess, and ensure consistency in the performance of a particular chitosan. It may have use in the regulation of devices containing chitosan by appropriate authorities.
The chitosan salts covered by this guide may be gelled, extruded, or otherwise formulated into biomedical devices for use as tissue-engineered medical products or drug delivery devices for implantation as determined to be appropriate, based on supporting biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue-engineered medical product or drug delivery application.
To ensure that the material supplied satisfies requirements for use in TEMPs, several general areas of characterization should be considered. These include identity of chitosan, physical and chemical characterization and testing, impurities profile, and performance-related tests.
SCOPE
1.1 This guide covers the evaluation of chitosan salts suitable for use in biomedical or pharmaceutical applications, or both, including, but not limited to, tissue-engineered medical products (TEMPS).
1.2 This guide addresses key parameters relevant for the functionality, characterization, and purity of chitosan salts.
1.3 As with any material, some characteristics of chitosan may be altered by processing techniques (such as molding, extrusion, machining, assembly, sterilization, and so forth) required for the production of a specific part or device. Therefore, properties of fabricated forms of this polymer should be evaluated using test methods that are appropriate to ensure safety and efficacy.
1.4 WarningMercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website (http://www.epa.gov/mercury/faq.htm) for additional information. Users should be aware that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
This guide contains a listing of those characterization parameters that are directly related to the functionality of hyaluronan. This guide can be used as an aid in the selection and characterization of the appropriate hyaluronan for a particular application. This guide is intended to give guidance in the methods and types of testing necessary to properly characterize, assess, and ensure consistency in the performance of a particular hyaluronan. It may have use in the regulation of these devices by appropriate authorities.
The hyaluronan covered by this guide may be gelled, cross-linked, extruded, or otherwise formulated into biomedical devices for use in tissue engineered medical products or drug delivery devices for implantation as determined to be appropriate, based on supporting biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application.
To ensure that the material supplied satisfies requirements for use in TEMPs, several general areas of characterization should be considered. These are: identity of hyaluronan, physical and chemical characterization and testing, impurities profile, and performance-related tests.
SCOPE
1.1 This guide covers the evaluation of hyaluronan suitable for use in biomedical or pharmaceutical applications, or both, including, but not limited to, Tissue Engineered Medical Products (TEMPs).
1.2 This guide addresses key parameters relevant to the characterization and purity of hyaluronan.
1.3 As with any material, some characteristics of hyaluronan may be altered by processing techniques, such as cross-linking and sterilization, required for the production of a specific formulation or device. Therefore, properties of fabricated forms of this polymer should be evaluated using test methods that are appropriate to ensure safety and efficacy and are not addressed in this guide.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.

SIGNIFICANCE AND USE
The composition and sequential structure of alginate determines the functionality of alginate in an application. For instance, the gelling properties of an alginate are highly dependent upon the monomer composition and sequential structure of the polymer. Gel strength will depend upon the guluronic acid content (FG) and also the average number of consecutive guluronate moieties in G-block structures (NG>1).
Chemical composition and sequential structure of alginate can be determined by 1H- and 13C-nuclear magnetic resonance spectroscopy (NMR). A general description of NMR can be found in 761> of the USP24-NF19. The NMR methodology and assignments are based on data published by Grasdalen et al. (1979, 1981, 1983). , , The NMR technique has made it possible to determine the monad frequencies FM (fraction of mannuronate units) and FG (fraction of guluronate units), the four nearest neighboring (diad) frequencies FGG, FMG, FGM, FMM, and the eight next nearest neighboring (triad) frequencies FGGG, FGGM, FMGG, FMGM, FMMM, FMMG, FGMM, FGMG. Knowledge of these frequencies enables number averages of block lengths to be calculated. NG is the number average length of G-blocks, and NG>1 is the number average length of G-blocks from which singlets (-MGM-) have been excluded. Similarly, NM is the number average length of M-blocks, and NM>1 is the number average length of M-blocks from which singlets (-GMG-) have been excluded.  13C NMR must be used to determine the M-centered triads and NM>1. This test method describes only the 1H NMR analysis of alginate. Alginate can be well characterized by determining FG and NG>1.
In order to obtain well-resolved NMR spectra, it is necessary to reduce the viscosity and increase the mobility of the molecules by depolymerization of alginate to a degree of polymerization of about 20 to 50. Acid hydrolysis is used to depolymerize the alginate samples. Freeze-drying, followed by dissolution in 99 % D2O, and another freeze-drying before dissolut...
SCOPE
1.1 This test method covers the determination of the composition and monomer sequence of alginate intended for use in biomedical and pharmaceutical applications as well as in Tissue Engineered Medical Products (TEMPs) by high-resolution proton NMR (1H NMR). A guide for the characterization of alginate has been published as Guide F2064.
1.2 Alginate, a linear polymer composed of β-D-mannuronate (M) and its C-5 epimer α-L-guluronate (G) linked by β-(1>4) glycosidic bonds, is characterized by calculating parameters such as mannuronate/guluronate (M/G) ratio, guluronic acid content (G-content), and average length of blocks of consecutive G monomers (that is, NG>1). Knowledge of these parameters is important for an understanding of the functionality of alginate in TEMP formulations and applications. This test method will assist end users in choosing the correct alginate for their particular application. Alginate may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The ability to culture functional tissue to repair damaged or diseased tissues within the body offers a viable alternative to xenografts or heterografts. Using the patient’s own cells to produce the new tissue offers significant benefits by limiting rejection by the immune system. Typically, cells harvested from the intended recipient are cultured in vitro using a temporary housing or scaffold. The microstructure of the scaffold, that is, its porosity, the mean size, and size distribution of pores and their interconnectivity is critical for cell migration, growth and proliferation (Appendix X1). Optimizing the design of tissue scaffolds is a complex task, given the range of available materials, different manufacturing routes, and processing conditions. All of these factors can, and will, affect the surface texture, surface chemistry, and microstructure of the resultant scaffolds. Factors that may or may not be significant variables depend on the characteristics of a given cell type at any given time (that is, changes in cell behavior due to the number of passages, mechanical stimulation, and culture conditions).  
Tissue scaffolds are typically assessed using an overall value for scaffold porosity and a range of pore sizes, though the distribution of sizes is rarely quantified. Published mean pore sizes and distributions are usually obtained from electron microscopy images and quoted in the micrometer range. Tissue scaffolds are generally complex structures that are not easily interpreted in terms of pore shape and size, especially in three dimensions. Therefore, it is difficult to quantifiably assess the batch-to-batch variance in microstructure or to make a systematic investigation of the role that the mean pore size and pore size distribution has on influencing cell behavior based solely on electron micrographs (Tomlins et al, (1)).  
Fig. 1 gives an indication of potential techniques that can be used to characterize the structure of porous tissue scaffolds and...
SCOPE
1.1 This guide covers an overview of test methods that may be used to obtain information relating to the dimensions of pores, the pore size distribution, the degree of porosity, interconnectivity, and measures of permeability for porous materials used as polymeric scaffolds in the development and manufacture of tissue-engineered medical products (TEMPs). This information is key to optimizing the structure for a particular application, developing robust manufacturing routes, and providing reliable quality control data.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This guide does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The term “surface texture” is used to describe the local deviations of a surface from an ideal shape. Surface texture usually consists of long wavelength repetitive features that occur as results of chatter, vibration, or heat treatments during the manufacture of implants. Short wavelength features superimposed on the long wavelength features of the surface, which arise from polishing or etching of the implant, are referred to as roughness.  
This guide provides an overview of techniques that are available for measuring the surface in terms of Cartesian coordinates and the parameters used to describe surface texture. It is important to appreciate that it is not possible to measure surface texture per se, but to derive values for parameters that can be used to describe it.
SCOPE
1.1 This guide describes some of the more common methods that are available for measuring the topographical features of a surface and provides an overview of the parameters that are used to quantify them. Being able to reliably derive a set of parameters that describe the texture of biomaterial surfaces is a key aspect in the manufacture of safe and effective implantable medical devices that have the potential to trigger an adverse biological reaction in situ.
1.2 This guide is not intended to apply to porous structures with average pore dimensions in excess of approximately 50 nm (0.05 μm).
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The objective of this guide is to provide guidance in the characterization of Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs). This guide contains a listing of physical and chemical parameters that are directly related to the function of collagen. This guide can be used as an aid in the selection and characterization of the appropriate collagen starting material for the specific use. Not all tests or parameters are applicable to all uses of collagen.
The collagen covered by this guide may be used in a broad range of applications, forms, or medical products, for example (but not limited to) medical devices, tissue engineered medical products (TEMPs) or cell, drug, or DNA delivery devices for implantation. The use of collagen in a practical application should be based, among other factors, on biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application.
The following general areas should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs. These are source of collagen, chemical and physical characterization and testing, and impurities profile.
The following documents or other appropriate guidances from appropriate regulatory bodies relating to the production, regulation and regulatory approval of TEMPs products should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs: FDA CFR: 21 CFR 3: Product Jurisdiction:  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=3 21 CFR 58: Good Laboratory Practice for Nonclinical Laboratory Studies:  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=58  FDA/CDRH CFR and Guidances: 21 CFR Part 803: Medical Device Reporting:  http://www.accessdata.fda.gov/scripts/cdrh/cfd...
SCOPE
1.1 This guide for characterizing collagen-containing biomaterials is intended to provide characteristics, properties, and test methods for use by producers, manufacturers, and researchers to more clearly identify the specific collagen materials used. With greater than 20 types of collagen and the different properties of each, a single document would be cumbersome. This guide will focus on the characterization of Type I collagen, which is the most abundant collagen in mammals, especially in skin and bone. Collagen isolated from these sources may contain other types of collagen, for example, Type III and Type V. This guide does not provide specific parameters for any collagen product or mix of products or the acceptability of those products for the intended use. The collagen may be from any source, including, but not limited to, animal or cadaveric sources, human cell culture, or recombinant sources. The biological, immunological, or toxicological properties of the collagen may vary, depending on the source material. The properties of the collagen prepared from each of the above sources must be thoroughly investigated, as the changes in the collagen properties as a function of source materials is not thoroughly understood. This guide is intended to focus on purified Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs); some methods may not be applicable for gelatin or tissue implants. This guide may serve as a template for characterization of other types of collagen.
1.2 The biological response to collagen in soft tissue has been well documented by a history of clinical use (1, 2) and laboratory studies (3, 4, 5, 6). Biocompatibility and appropriateness of use for a specific application(s) is the responsibility of the product manufacturer.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in...

SIGNIFICANCE AND USE
The ability to culture functional tissue to repair damaged or diseased tissues within the body offers a viable alternative to xenografts or heterografts. Using the patient’s own cells to produce the new tissue offers significant benefits by limiting rejection by the immune system. Typically, cells harvested from the intended recipient are cultured in vitro using a temporary housing or scaffold. The microstructure of the scaffold, that is, its porosity, the mean size, and size distribution of pores and their interconnectivity is critical for cell migration, growth and proliferation (Appendix X1). Optimizing the design of tissue scaffolds is a complex task, given the range of available materials, different manufacturing routes, and processing conditions. All of these factors can, and will, affect the surface roughness, surface chemistry, and microstructure of the resultant scaffolds. Factors that may or may not be significant variables depend on the characteristics of a given cell type at any given time (that is, changes in cell behavior due to the number of passages, mechanical stimulation, and culture conditions).  
Tissue scaffolds are typically assessed using an overall value for scaffold porosity and a range of pore sizes, though the distribution of sizes is rarely quantified. Published mean pore sizes and distributions are usually obtained from electron microscopy images and quoted in the micrometer range. Tissue scaffolds are generally complex structures that are not easily interpreted in terms of pore shape and size, especially in three-dimensions. Therefore, it is difficult to quantifiably assess the batch-to-batch variance in microstructure or to enable a systematic investigation to be made of the role that the mean pore size and pore size distribution has on influencing cell behavior based solely on electron micrographs (Tomlins et al, (1)).  
Fig. 1 gives an indication of potential techniques that can be used to characterize the structure of porous tissu...
SCOPE
1.1 This guide covers an overview of test methods that may be used to obtain information relating to the dimensions of pores, the pore size distribution, the degree of porosity, interconnectivity, and measures of permeability for porous materials used as polymeric scaffolds in the development and manufacture of tissue engineered medical products (TEMPs). This information is key to optimizing the structure for a particular application, developing robust manufacturing routes, and for providing reliable quality control data.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This guide does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.

ABSTRACT
This guide addresses material characteristics of raw or virgin materials in a nonfabricated form that will ultimately undergo additional processing into growth, support, or delivery vehicles for cells or biomolecules. The substrate material shall have specifications for an extensive set of chemical and physical properties prescribed. Test methods shall be performed in order to determine the chemical and physical properties of the material.
SIGNIFICANCE AND USE
The physico-chemical characteristics of the raw or starting biomaterial used in regenerative medicine scaffolds carries significant potential to affect product performance by influencing cell behavior and/or the release of bioactive molecules or drugs. This guide describes recommended specifications or characterizations of raw or starting biomaterials to ensure reproducibility prior to their fabrication into implantable tissue engineering scaffolds and/or controlled release matrices.
SCOPE
1.1 This document provides guidance on writing a materials specification for raw or starting biomaterials intended for use in tissue engineering scaffolds for growth, support, or delivery of cells and/or biomolecules. This guide does not apply to biomaterials that are already in a scaffold form or are finished tissue-engineered medical products.  
1.2 The purpose of this guide is to provide a compendium of relevant existing standards and test methods for biomaterials already commonly used within medical products and to provide characterization guidance for interim use of raw biomaterials for which a standard does not exist.  
1.3 This guide covers specifications and characterizations of all the major classes of materials including polymers, ceramics, metals, composites, and natural tissues of human, animal, or plant origin. This guide does not apply to pharmaceuticals.
1.4 This guide is focused on specification of chemical, physical, and mechanical properties of the raw or starting material. It does not include safety and biocompatibility requirements since safety and biocompatibility testing is typically done on materials fabricated into a final form to include all possible effects of fabrication and sterilization techniques.  
1.5 Compliance with materials specifications developed in accordance with this standard may not necessarily result in a material suitable for its intended purpose. Additional testing specific to the intend use may be required.

SIGNIFICANCE AND USE
The composition and sequential structure of alginate determines the functionality of alginate in an application. For instance, the gelling properties of an alginate are highly dependent upon the monomer composition and sequential structure of the polymer. Gel strength will depend upon the guluronic acid content (FG) and also the average number of consecutive guluronate moieties in G-block structures (NG>1).
Chemical composition and sequential structure of alginate can be determined by 1H- and 13C-nuclear magnetic resonance spectroscopy (NMR). A general description of NMR can be found in 761> of the USP24-NF19. The NMR methodology and assignments are based on data published by Grasdalen et al. (1979, 1981, 1983). , , The NMR technique has made it possible to determine the monad frequencies FM (fraction of mannuronate units) and FG (fraction of guluronate units), the four nearest neighboring (diad) frequencies FGG, FMG, FGM, FMM, and the eight next nearest neighboring (triad) frequencies FGGG, FGGM, FMGG, FMGM, FMMM, FMMG, FGMM, FGMG. Knowledge of these frequencies enables number averages of block lengths to be calculated. NG is the number average length of G-blocks, and NG>1 is the number average length of G-blocks from which singlets (-MGM-) have been excluded. Similarly, NM is the number average length of M-blocks, and NM>1 is the number average length of M-blocks from which singlets (-GMG-) have been excluded.  13C NMR must be used to determine the M-centered triads and NM>1. This test method describes only the 1H NMR analysis of alginate. Alginate can be well characterized by determining FG and NG>1.
In order to obtain well-resolved NMR spectra, it is necessary to reduce the viscosity and increase the mobility of the molecules by depolymerization of alginate to a degree of polymerization of about 20 to 50. Acid hydrolysis is used to depolymerize the alginate samples. Freeze-drying, followed by dissolution in 99 % D2O, and another freeze-drying before dissolut...
SCOPE
1.1 This test method covers the determination of the composition and monomer sequence of alginate intended for use in biomedical and pharmaceutical applications as well as in Tissue Engineered Medical Products (TEMPs) by high-resolution proton NMR (1H NMR). A guide for the characterization of alginate has been published as Guide F 2064.
1.2 Alginate, a linear polymer composed of β-D-mannuronate (M) and its C-5 epimer α-L-guluronate (G) linked by β-(1—>4) glycosidic bonds, is characterized by calculating parameters such as mannuronate/guluronate (M/G) ratio, guluronic acid content (G-content), and average length of blocks of consecutive G monomers (that is, NG>1). Knowledge of these parameters is important for an understanding of the functionality of alginate in TEMP formulations and applications. This test method will assist end users in choosing the correct alginate for their particular application. Alginate may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The degree of deacetylation of chitosan salts is an important characterization parameter since the charge density of the chitosan molecule is responsible for potential biological and functional effects.
The degree of deacetylation (% DA) of water-soluble chitosan salts can be determined by  1H nuclear magnetic resonance spectroscopy (1H NMR). Several workers have reported on the NMR determination of chemical composition and sequential arrangement of monomer units in chitin and chitosan. The test method described is primarily based on the work of Vårum et al. (1991), which represents the first publication on routine determination of chemical composition in chitosans by solution state  1H NMR spectroscopy. This test method is applicable for determining the % DA of chitosan chloride and chitosan glutamate salts. It is a simple, rapid, and suitable method for routine use. Quantitative  1H NMR spectroscopy reports directly on the relative concentration of chemically distinct protons in the sample, consequently, no assumptions, calibration curves or calculations other than determination of relative signal intensity ratios are necessary.
In order to obtain well-resolved NMR spectra, depolymerization of chitosans to a number average degree of polymerization (DPn) of ~15 to 30 is required. This reduces the viscosity and increases the mobility of the molecules. Although there are several options for depolymerization of chitosans, the most convenient procedure is that of nitrous acid degradation in deuterated water. The reaction is selective, stoichiometric with respect to GlcN, rapid, and easily controlled (Allan & Peyron, 1995). The reaction selectively cleaves after a GlcN-residue, transforming it into 2,5-anhydro-D-mannose (chitose), consequently, depletion of GlcN after depolymerization is expected. On the other hand, the chitose unit displays characteristic  1H NMR signals the intensity of which may be estimated and utilized in the calculation of % DA, eliminating th...
SCOPE
1.1 This test method covers the determination of the degree of deacetylation in chitosan and chitosan salts intended for use in biomedical and pharmaceutical applications as well as in Tissue Engineered Medical Products (TEMPs) by high-resolution proton NMR (1H NMR). A guide for the characterization of chitosan salts has been published as Guide F 2103.
1.2 The test method is applicable for determining the degree of deacetylation (% DA) of chitosan chloride and chitosan glutamate salts and is valid for % DA values from 50 up to and including 99. It is simple, rapid, and suitable for routine use. Knowledge of the degree of deacetylation is important for an understanding of the functionality of chitosan salts in TEMP formulations and applications. This test method will assist end users in choosing the correct chitosan for their particular application. Chitosan salts may have utility in drug delivery applications, as a scaffold or matrix material, and in cell and tissue encapsulation applications.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The composition and sequential structure of alginate, as well as the molar mass and molar mass distribution, determines the functionality of alginate in an application. For instance, the gelling properties of an alginate are highly dependent upon the composition and molar mass of the polymer.
Light scattering is one of very few methods available for the determination of absolute molar mass and structure, and it is applicable over the broadest range of molar masses of any method. Combining light scattering detection with size exclusion chromatography (SEC), which sorts molecules according to size, gives the ability to analyze polydisperse samples, as well as obtaining information on branching and molecular conformation. This means that both the number-average and mass-average values for molar mass and size may be obtained for most samples. Furthermore, one has the ability to calculate the distributions of the molar masses and sizes.
Multi-angle laser light scattering (MALS) is a technique where measurements are made simultaneously over a range of different angles. MALS detection can be used to obtain information on molecular size, since this parameter is determined by the angular variation of the scattered light. Molar mass may in principle be determined by detecting scattered light at a single low angle (LALLS). However, advantages with MALS as compared to LALLS are: (1) less noise at larger angles, (2) the precision of measurements are greatly improved by detecting at several angles, and (3) the ability to detect angular variation allows determination of size, branching, aggregation, and molecular conformation.
Size exclusion chromatography uses columns, which are typically packed with polymer particles containing a network of uniform pores into which solute and solvent molecules can diffuse. While in the pores, molecules are effectively trapped and removed from the flow of the mobile phase. The average residence time in the pores depends upon the size of the...
SCOPE
1.1 This test method covers the determination of the molar mass of sodium alginate intended for use in biomedical and pharmaceutical applications as well as in tissue engineered medical products (TEMPs) by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALS). A guide for the characterization of alginate has been published as Guide F 2064.
1.2 Alginate used in TEMPs should be well characterized, including the molar mass and polydispersity (molar mass distribution) in order to ensure uniformity and correct functionality in the final product. This test method will assist end users in choosing the correct alginate for their particular application. Alginate may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The composition and sequential structure of alginate, as well as the molar mass and molar mass distribution, determines the functionality of alginate in an application. For instance, the gelling properties of an alginate are highly dependent upon the composition and molar mass of the polymer.
Light scattering is one of very few methods available for the determination of absolute molar mass and structure, and it is applicable over the broadest range of molar masses of any method. Combining light scattering detection with size exclusion chromatography (SEC), which sorts molecules according to size, gives the ability to analyze polydisperse samples, as well as obtaining information on branching and molecular conformation. This means that both the number-average and mass-average values for molar mass and size may be obtained for most samples. Furthermore, one has the ability to calculate the distributions of the molar masses and sizes.
Multi-angle laser light scattering (MALS) is a technique where measurements are made simultaneously over a range of different angles. MALS detection can be used to obtain information on molecular size, since this parameter is determined by the angular variation of the scattered light. Molar mass may in principle be determined by detecting scattered light at a single low angle (LALLS). However, advantages with MALS as compared to LALLS are: (1) less noise at larger angles, (2) the precision of measurements are greatly improved by detecting at several angles, and (3) the ability to detect angular variation allows determination of size, branching, aggregation, and molecular conformation.
Size exclusion chromatography uses columns, which are typically packed with polymer particles containing a network of uniform pores into which solute and solvent molecules can diffuse. While in the pores, molecules are effectively trapped and removed from the flow of the mobile phase. The average residence time in the pores depends upon the size of the...
SCOPE
1.1 This test method covers the determination of the molar mass of sodium alginate intended for use in biomedical and pharmaceutical applications as well as in tissue engineered medical products (TEMPs) by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALS). A guide for the characterization of alginate has been published as Guide F 2064.
1.2 Alginate used in TEMPs should be well characterized, including the molar mass and polydispersity (molar mass distribution) in order to ensure uniformity and correct functionality in the final product. This test method will assist end users in choosing the correct alginate for their particular application. Alginate may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The objective of this guide is to provide guidance in the characterization of Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs). This guide contains a listing of physical and chemical parameters that are directly related to the function of collagen. This guide can be used as an aid in the selection and characterization of the appropriate collagen starting material for the specific use. Not all tests or parameters are applicable to all uses of collagen.
The collagen covered by this guide may be used in a broad range of applications, forms, or medical products, for example (but not limited to) medical devices, tissue engineered medical products (TEMPs) or cell, drug, or DNA delivery devices for implantation. The use of collagen in a practical application should be based, among other factors, on biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application.
The following general areas should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs. These are source of collagen, chemical and physical characterization and testing, and impurities profile.
The following documents relating to the production, regulation and regulatory approval of TEMPs products should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs: FDA CFR: 21 CFR 3: Product Jurisdiction:  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=3 21 CFR 58: Good Laboratory Practice for Nonclinical Laboratory Studies:  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=58  FDA/CDRH CFR and Guidances: 21 CFR Part 803: Medical Device Reporting:  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=803 21 CFR 812: Investigational...
SCOPE
1.1 This guide for characterizing collagen-containing biomaterials is intended to provide characteristics, properties, and test methods for use by producers, manufacturers, and researchers to more clearly identify the specific collagen materials used. With greater than 20 types of collagen and the different properties of each, a single document would be cumbersome. This guide will focus on the characterization of Type I collagen, which is the most abundant collagen in mammals, especially in skin and bone. Collagen isolated from these sources may contain other types of collagen, for example, Type III and Type V. This guide does not provide specific parameters for any collagen product or mix of products or the acceptability of those products for the intended use. The collagen may be from any source, including, but not limited to animal or cadaveric sources, human cell culture, or recombinant sources. The biological, immunological, or toxicological properties of the collagen may vary depending on the source material. The properties of the collagen prepared from each of the above sources must be thoroughly investigated, as the changes in the collagen properties as a function of source materials is not thoroughly understood. This guide is intended to focus on purified Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs); some methods may not be applicable for gelatin nor for tissue implants. This guide may serve as a template for characterization of other types of collagen.
1.2 The biological response to collagen in soft tissue has been well documented by a history of clinical use (1, 2) and laboratory studies (3, 4, 5, 6). Biocompatibility and appropriateness of use for a specific application(s) is the responsibility of the product manufacturer.
1.3 The following precautionary caveat pertains only to the test method portion, Section 5, of this guide. T...

SIGNIFICANCE AND USE
The degree of deacetylation of chitosan, as well at the molar mass and molar mass distribution, determines the functionality of chitosan in an application. For instance, functional and biological effects are highly dependent upon the composition and molar mass of the polymer.
This test method describes procedures for measurement of molar mass of chitosan chlorides and glutamates, and chitosan base, although it in principle applies to any chitosan salt. The measured molar mass is that for chitosan acetate, since the mobile phase contains acetate as counter ion. This value can further be converted into the corresponding molar mass for the chitosan as a base, or the parent salt form (chloride or glutamate).
Light scattering is one of very few methods available for the determination of absolute molar mass and structure, and it is applicable over the broadest range of molar masses of any method. Combining light scattering detection with size exclusion chromatography (SEC), which sorts molecules according to size, gives the ability to analyze polydisperse samples, as well as obtaining information on branching and molecular conformation. This means that both the number-average and mass-average values for molar mass and size may be obtained for most samples. Furthermore, one has the ability to calculate the distributions of the molar masses and sizes.
Multi-angle laser light scattering (MALS) is a technique where measurements of scattered light are made simultaneously over a range of different angles. MALS detection can be used to obtain information on molecular size, since this parameter is determined by the angular variation of the scattered light. Molar mass may in principle be determined by detecting scattered light at a single low angle (LALLS). However, advantages with MALS as compared to LALLS are: (1) less noise at larger angles, (2) the precision of measurements are greatly improved by detecting at several angles, and (3) the ability to detect angular variati...
SCOPE
1.1 This test method covers the determination of the molar mass of chitosan and chitosan salts intended for use in biomedical and pharmaceutical applications as well as in tissue engineered medical products (TEMPs) by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALS). A guide for the characterization of chitosan salts has been published as Guide F 2103.
1.2 Chitosan and chitosan salts used in TEMPs should be well characterized, including the molar mass and polydispersity (molar mass distribution) in order to ensure uniformity and correct functionality in the final product. This test method will assist end users in choosing the correct chitosan for their particular application. Chitosan may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The degree of deacetylation of chitosan, as well at the molar mass and molar mass distribution, determines the functionality of chitosan in an application. For instance, functional and biological effects are highly dependent upon the composition and molar mass of the polymer.
This test method describes procedures for measurement of molar mass of chitosan chlorides and glutamates, and chitosan base, although it in principle applies to any chitosan salt. The measured molar mass is that for chitosan acetate, since the mobile phase contains acetate as counter ion. This value can further be converted into the corresponding molar mass for the chitosan as a base, or the parent salt form (chloride or glutamate).
Light scattering is one of very few methods available for the determination of absolute molar mass and structure, and it is applicable over the broadest range of molar masses of any method. Combining light scattering detection with size exclusion chromatography (SEC), which sorts molecules according to size, gives the ability to analyze polydisperse samples, as well as obtaining information on branching and molecular conformation. This means that both the number-average and mass-average values for molar mass and size may be obtained for most samples. Furthermore, one has the ability to calculate the distributions of the molar masses and sizes.
Multi-angle laser light scattering (MALS) is a technique where measurements of scattered light are made simultaneously over a range of different angles. MALS detection can be used to obtain information on molecular size, since this parameter is determined by the angular variation of the scattered light. Molar mass may in principle be determined by detecting scattered light at a single low angle (LALLS). However, advantages with MALS as compared to LALLS are: (1) less noise at larger angles, (2) the precision of measurements are greatly improved by detecting at several angles, and (3) the ability to detect angular variati...
SCOPE
1.1 This test method covers the determination of the molar mass of chitosan and chitosan salts intended for use in biomedical and pharmaceutical applications as well as in tissue engineered medical products (TEMPs) by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALS). A guide for the characterization of chitosan salts has been published as Guide F 2103.
1.2 Chitosan and chitosan salts used in TEMPs should be well characterized, including the molar mass and polydispersity (molar mass distribution) in order to ensure uniformity and correct functionality in the final product. This test method will assist end users in choosing the correct chitosan for their particular application. Chitosan may have utility as a scaffold or matrix material for TEMPs, in cell and tissue encapsulation applications, and in drug delivery formulations.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The objective of this guide is to provide guidance in the characterization of Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs). This guide contains a listing of physical and chemical parameters that are directly related to the function of collagen. This guide can be used as an aid in the selection and characterization of the appropriate collagen starting material for the specific use. Not all tests or parameters are applicable to all uses of collagen.
The collagen covered by this guide may be used in a broad range of applications, forms, or medical products, for example (but not limited to) medical devices, tissue engineered medical products (TEMPs) or cell, drug, or DNA delivery devices for implantation. The use of collagen in a practical application should be based, among other factors, on biocompatibility and physical test data. Recommendations in this guide should not be interpreted as a guarantee of clinical success in any tissue engineered medical product or drug delivery application.
The following general areas should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs. These are source of collagen, chemical and physical characterization and testing, and impurities profile.
The following documents relating to the production, regulation and regulatory approval of TEMPs products should be considered when determining if the collagen supplied satisfies requirements for use in TEMPs: FDA CFR: 21 CFR 3: Product Jurisdiction:  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=3 21 CFR 58: Good Laboratory Practice for Nonclinical Laboratory Studies:  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=58  FDA/CDRH CFR and Guidances: 21 CFR Part 803: Medical Device Reporting:  http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/
CFRSearch.cfm?CFRPart=803 21 CFR 812: Investigational...
SCOPE
1.1 This guide for characterizing collagen-containing biomaterials is intended to provide characteristics, properties, and test methods for use by producers, manufacturers, and researchers to more clearly identify the specific collagen materials used. With greater than 20 types of collagen and the different properties of each, a single document would be cumbersome. This guide will focus on the characterization of Type I collagen, which is the most abundant collagen in mammals, especially in skin and bone. Collagen isolated from these sources may contain other types of collagen, for example, Type III and Type V. This guide does not provide specific parameters for any collagen product or mix of products or the acceptability of those products for the intended use. The collagen may be from any source, including, but not limited to animal or cadaveric sources, human cell culture, or recombinant sources. The biological, immunological, or toxicological properties of the collagen may vary depending on the source material. The properties of the collagen prepared from each of the above sources must be thoroughly investigated, as the changes in the collagen properties as a function of source materials is not thoroughly understood. This guide is intended to focus on purified Type I collagen as a starting material for surgical implants and substrates for tissue engineered medical products (TEMPs); some methods may not be applicable for gelatin nor for tissue implants. This guide may serve as a template for characterization of other types of collagen.
1.2 The biological response to collagen in soft tissue has been well documented by a history of clinical use (1, 2) and laboratory studies (3, 4, 5, 6). Biocompatibility and appropriateness of use for a specific application(s) is the responsibility of the product manufacturer.
1.3 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can caus...