ASTM F2450-18
(Guide)Standard Guide for Assessing Microstructure of Polymeric Scaffolds for Use in Tissue-Engineered Medical Products
Standard Guide for Assessing Microstructure of Polymeric Scaffolds for Use in Tissue-Engineered Medical Products
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.
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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.
Designation: F2450 − 18
Standard Guide for
Assessing Microstructure of Polymeric Scaffolds for Use in
1
Tissue-Engineered Medical Products
This standard is issued under the fixed designation F2450; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D4404 Test Method for Determination of Pore Volume and
Pore Volume Distribution of Soil and Rock by Mercury
1.1 This guide covers an overview of test methods that may
Intrusion Porosimetry
be used to obtain information relating to the dimensions of
E128 Test Method for Maximum Pore Diameter and Perme-
pores, the pore size distribution, the degree of porosity,
ability of Rigid Porous Filters for Laboratory Use
interconnectivity, and measures of permeability for porous
E1294 Test Method for Pore Size Characteristics of Mem-
materials used as polymeric scaffolds in the development and
brane Filters UsingAutomated Liquid Porosimeter (With-
manufacture of tissue-engineered medical products (TEMPs).
3
drawn 2008)
This information is key to optimizing the structure for a
E1441 Guide for Computed Tomography (CT) Imaging
particularapplication,developingrobustmanufacturingroutes,
F316 Test Methods for Pore Size Characteristics of Mem-
and providing reliable quality control data.
brane Filters by Bubble Point and Mean Flow Pore Test
1.2 The values stated in SI units are to be regarded as
F2150 Guide for Characterization and Testing of Biomate-
standard. No other units of measurement are included in this
rial Scaffolds Used in Tissue-Engineered Medical Prod-
standard.
ucts
1.3 This standard does not purport to address all of the
F2603 Guide for Interpreting Images of Polymeric Tissue
safety concerns, if any, associated with its use. It is the
Scaffolds
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to use.
3.1 Definitions:
1.4 This international standard was developed in accor-
3.1.1 bioactive agent, n—any molecular component in, on,
dance with internationally recognized principles on standard-
or within the interstices of a device that is intended to elicit a
ization established in the Decision on Principles for the
desired tissue or cell response.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
3.1.1.1 Discussion—Growth factors and antibiotics are typi-
Barriers to Trade (TBT) Committee.
cal examples of bioactive agents. Device structural compo-
nents or degradation byproducts that evoke limited localized
2. Referenced Documents
bioactivity are not bioactive agents.
2
2.1 ASTM Standards:
3.1.2 blind (end)-pore, n—a pore that is in contact with an
D2873 Test Method for Interior Porosity of Poly(Vinyl
exposed internal or external surface through a single orifice
Chloride) (PVC) Resins by Mercury Intrusion Porosim-
smaller than the pore’s depth.
3
etry (Withdrawn 2003)
3.1.3 closed cell, n—a void isolated within a solid, lacking
any connectivity with an external surface. Synonym: closed
pore
1
This guide is under the jurisdiction of ASTM Committee F04 on Medical and
Surgical Materials and Devices and is the direct responsibility of Subcommittee
3.1.4 hydrogel, n—a water-based open network of polymer
F04.42 on Biomaterials and Biomolecules for TEMPs.
chains that are cross-linked either chemically or through
Current edition approved Nov. 15, 2018. Published December 2018. Originally
approved in 2004. Last previous edition approved in 2010 as F2450 – 10. DOI: crystalline junctions or by specific ionic interactions.
10.1520/F2450-18.
2
3.1.5 macropore/macroporosity (life sciences),n—a struc-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ture (including void spaces) sized to allow substantially unre-
Standards volume information, refer to the standard’s Document Summary page on
stricted passage of chemicals, biomolecules, viruses, bacteria,
the ASTM website.
3
and mammalian cells. In implants with interconnecting pores,
The last approved version of this historical standard is referenced on
www.astm.org. macroporosity provides dimensions that allow for ready tissue
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F2450 − 10 F2450 − 18
Standard Guide for
Assessing Microstructure of Polymeric Scaffolds for Use in
1
Tissue-Engineered Medical Products
This standard is issued under the fixed designation F2450; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. 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 guidestandard 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 safety, health, and healthenvironmental practices and to
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.
2. Referenced Documents
2
2.1 ASTM Standards:
D2873 Test Method for Interior Porosity of Poly(Vinyl Chloride) (PVC) Resins by Mercury Intrusion Porosimetry (Withdrawn
3
2003)
D4404 Test Method for Determination of Pore Volume and Pore Volume Distribution of Soil and Rock by Mercury Intrusion
Porosimetry
E128 Test Method for Maximum Pore Diameter and Permeability of Rigid Porous Filters for Laboratory Use
3
E1294 Test Method for Pore Size Characteristics of Membrane Filters Using Automated Liquid Porosimeter (Withdrawn 2008)
E1441 Guide for Computed Tomography (CT) Imaging
F316 Test Methods for Pore Size Characteristics of Membrane Filters by Bubble Point and Mean Flow Pore Test
F2150 Guide for Characterization and Testing of Biomaterial Scaffolds Used in Tissue-Engineered Medical Products
F2603 Guide for Interpreting Images of Polymeric Tissue Scaffolds
3. Terminology
3.1 Definitions:
3.1.1 bioactive agent, n—any molecular component in, on, or within the interstices of a device that is intended to elicit a desired
tissue or cell response.
3.1.1.1 Discussion—
1
This guide is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee F04.42
on Biomaterials and Biomolecules for TEMPs.
Current edition approved March 1, 2010Nov. 15, 2018. Published April 2010December 2018. Originally approved in 2004. Last previous edition approved in 20092010
as F2450 – 09.F2450 – 10. DOI: 10.1520/F2450-10.10.1520/F2450-18.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
F2450 − 18
Growth factors and antibiotics are typical examples of bioactive agents. Device structural components or degradation byproducts
that evoke limited localized bioactivity are not bioactive agents.
3.1.2 blind (end)-pore, n—a pore that is in contact with an exposed internal or external surface through a single orifice smaller
than the pore’s depth.
3.1.3 closed cell, n—a void isolated within a solid, lacking any connectivity with an external surface. Synonym: closed pore
3.1.4 hydrogel, n—a water-based open network of polymer chains that are cross-linked either chemically or through crystalline
junctions or by specific ionic interactions.
3.1.5 macropore/macroporosity (life sciences) , n—a structure (including
...
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