ASTM F2901-19

Standard Guide for Selecting Tests to Evaluate Potential Neurotoxicity of Medical Devices

SIGNIFICANCE AND USE
4.1 The objective of this guide is to recommend a panel of biological tests that can be used in addition to the testing recommended in Practice F748. This guide is designed to detect neurotoxicity caused by medical devices that contact nervous tissue.  
4.2 The testing recommendations should be considered for new materials, established materials with different manufacturing methods that could affect nervous tissue response, or materials used in new nervous tissue applications.  
4.3 Chemical characterization can be used to evaluate similarity for materials with a history of clinical use in a similar nervous tissue application.
SCOPE
1.1 Medical devices may cause adverse effects on the structure and/or function of the nervous system. In this guide, these adverse effects are defined as neurotoxicity. This guide provides background information and recommendations on methods for neurotoxicity testing. This guide should be used with Practice F748, and may be helpful where neurotoxicity testing is needed to evaluate medical devices that contact central and/or peripheral nervous system tissue or cerebral spinal fluid (CSF).
Note 1: The results of these in vitro and in vivo tests may not correspond to actual human response.  
1.2 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.  
1.3 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.

General Information

• Status: Published
• Publication Date: 28-Feb-2019
• ICS: 11.040.01 - Medical equipment in general
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.16 - Biocompatibility Test Methods

Relations

• Replaces: ASTM F2901-13 - Standard Guide for Selecting Tests to Evaluate Potential Neurotoxicity of Medical Devices
• Effective Date: 01-Mar-2019
• Refers: ASTM F756-17 - Standard Practice for Assessment of Hemolytic Properties of Materials
• Effective Date: 01-Mar-2017
• Refers: ASTM F748-16 - Standard Practice for Selecting Generic Biological Test Methods for Materials and Devices
• Effective Date: 01-Apr-2016
• Refers: ASTM F756-13 - Standard Practice for Assessment of Hemolytic Properties of Materials
• Effective Date: 01-Dec-2013
• Refers: ASTM F748-06(2010) - Standard Practice for Selecting Generic Biological Test Methods for Materials and Devices
• Effective Date: 01-Jun-2010
• Refers: ASTM F756-08 - Standard Practice for Assessment of Hemolytic Properties of Materials
• Effective Date: 01-Dec-2008
• Refers: ASTM F1904-98(2008) - Standard Practice for Testing the Biological Responses to Particles <i>in vivo</i>
• Effective Date: 01-Aug-2008
• Refers: ASTM F748-06 - Standard Practice for Selecting Generic Biological Test Methods for Materials and Devices
• Effective Date: 01-Dec-2006
• Refers: ASTM F748-04 - Standard Practice for Selecting Generic Biological Test Methods for Materials and Devices
• Effective Date: 01-May-2004
• Refers: ASTM F1904-98(2003) - Standard Practice for Testing the Biological Responses to Particles In Vivo
• Effective Date: 01-Nov-2003
• Refers: ASTM F756-00 - Standard Practice for Assessment of Hemolytic Properties of Materials
• Effective Date: 10-Jul-2000
• Refers: ASTM F1904-98e1 - Standard Practice for Testing the Biological Responses to Particles In Vivo
• Effective Date: 14-Jan-2000
• Refers: ASTM F748-98 - Standard Practice for Selecting Generic Biological Test Methods for Materials and Devices
• Effective Date: 10-Aug-1998
• Referred By: ASTM E3219-20 - Standard Guide for Derivation of Health-Based Exposure Limits (HBELs)
• Effective Date: 01-Mar-2019

Overview

ASTM F2901-19: Standard Guide for Selecting Tests to Evaluate Potential Neurotoxicity of Medical Devices provides comprehensive guidance for selecting appropriate biological test methods to assess potential neurotoxic effects resulting from the use of medical devices. Developed by ASTM International, this standard is specifically intended for devices that come into contact with nervous tissue, including the central and peripheral nervous systems or cerebrospinal fluid (CSF).

The standard emphasizes the importance of assessing neurotoxicity risks for new materials, materials with modified manufacturing methods, or established materials intended for new neurological applications. It is designed to complement ASTM Practice F748 and works in conjunction with various referenced ASTM and ISO standards relevant to biological evaluation and risk management.

Key Topics

• Scope of Neurotoxicity Testing

  • Framework for evaluating adverse effects of medical devices on the nervous system
  • Tailored for devices in contact with central or peripheral nervous tissue, or CSF

• Testing Recommendations

  • Guidance for use with new or changed materials and devices used in novel neurological applications
  • Stresses the importance of chemical characterization for materials with prior clinical use

• Types of Evaluations

  • Cytotoxicity: Initial screening to evaluate cell toxicity using relevant assays
  • Genotoxicity: Assesses potential for DNA damage, especially for novel or proliferative-device materials
  • Implantation Studies: Includes histopathological and neurobehavioral assessments using animal models selected based on intended device use
  • Pyrogen and Endotoxin Testing: Minimizes risk of neuroinflammatory responses
  • Hemolysis and Wear Particle Testing: Identifies potential toxicity from blood-contact or device wear
  • Developmental Neurotoxicity: Addresses the specific risks for devices intended for pediatric or prenatal applications
  • Device-Drug/Biologic Compatibility: Evaluates interactions for combination devices to ensure no increase in neurotoxicity risk

• Consideration of Nonclinical and Clinical Data

  • Encourages a holistic approach, integrating material characterization, nonclinical tests, clinical studies, post-market surveillance, and the device's intended use

Applications

ASTM F2901-19 is essential for:

• Medical Device Manufacturers

  • Provides a systematic approach to neurotoxicity assessment in the development and regulatory submission of neuromedical devices

• Regulatory Affairs and Quality Assurance

  • Supports compliance with international safety standards, helping to demonstrate due diligence in risk assessment for products contacting nervous tissue

• Research and Development

  • Aids in material selection, device design, and preclinical evaluation by outlining key biological tests for neurotoxicity

• Clinical and Risk Management Teams

  • Facilitates the identification of potential neurotoxic risks prior to market release, contributing to safer and more effective devices

Diagnostic, therapeutic, and implantable devices that interface directly or indirectly with neural tissues, and devices that deliver drugs to neurological spaces, will benefit significantly from the guidance contained in this standard.

Related Standards

• ASTM F748 - Practice for Selecting Generic Biological Test Methods for Materials and Devices
• ASTM F756 - Assessment of Hemolytic Properties of Materials
• ASTM F1904 - Testing Biological Responses to Particles in vivo
• ISO 10993 Series - Biological Evaluation of Medical Devices:
  • ISO 10993-1: Risk management process
  • ISO 10993-3: Genotoxicity, carcinogenicity, and reproductive toxicity
  • ISO 10993-5: In Vitro Cytotoxicity
  • ISO 10993-6: Local effects after implantation
  • ISO 10993-11: Systemic toxicity
  • ISO 10993-18: Chemical characterization of materials
• ANSI/AAMI ST72 - Bacterial Endotoxins Test Methodologies
• USP <151> & <161> - Pyrogen and endotoxin test methods for medical devices

Keywords: neurotoxicity testing, medical device safety, biocompatibility, nervous tissue, neurodegeneration, chemical characterization, biomedical standards, regulatory compliance

By following ASTM F2901-19, organizations can effectively identify, evaluate, and manage the risks of neurotoxicity in medical devices, ultimately enhancing patient safety and supporting product approval processes.

Standards Content (Sample)

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: F2901 − 19
Standard Guide for
Selecting Tests to Evaluate Potential Neurotoxicity of
Medical Devices
This standard is issued under the fixed designation F2901; 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 2.2 Other Referenced Documents:
ISO 10993-1 Biological Evaluation of Medical Devices—
1.1 Medical devices may cause adverse effects on the
Part 1: Evaluation andTestingWithin a Risk Management
structure and/or function of the nervous system. In this guide,
Process
these adverse effects are defined as neurotoxicity. This guide
ISO 10993-3 Biological Evaluation of Medical Devices—
provides background information and recommendations on
Part 3: Tests for Genotoxicity, Carcinogenicity, and Re-
methods for neurotoxicity testing. This guide should be used
productive Toxicity
with Practice F748, and may be helpful where neurotoxicity
ISO 10993-5 Biological Evaluation of Medical Devices—
testing is needed to evaluate medical devices that contact
Part 5: Tests for In Vitro Cytotoxicity
central and/or peripheral nervous system tissue or cerebral
ISO 10993-6 Biological Evaluation of Medical Devices—
spinal fluid (CSF).
Part 6: Tests for Local Effects After Implantation
NOTE 1—The results of these in vitro and in vivo tests may not
correspond to actual human response.
ISO 10993–11 Biological Evaluation of Medical Devices—
Part 11: Tests for Systemic Toxicity
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the ISO 10993-18 Biological Evaluation of Medical Devices—
responsibility of the user of this standard to establish appro- Part 18: Chemical Characterization of Materials
priate safety, health, and environmental practices and deter- ANSI/AAMI ST72 Bacterial Endotoxins—Test
mine the applicability of regulatory limitations prior to use. Methodologies, Routine Monitoring, and Alternatives to
1.3 This international standard was developed in accor-
Batch Testing
dance with internationally recognized principles on standard- USP <151> Rabbit Pyrogen Test
ization established in the Decision on Principles for the
USP <161> Transfusion and Infusion Assemblies and Simi-
Development of International Standards, Guides and Recom-
lar Medical Devices
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
3. Summary of Guide
3.1 This is an informative guide and should be used with
2. Referenced Documents
Practice F748.
2.1 ASTM Standards:
3.2 The duration of contact between the tissue and medical
F748 PracticeforSelectingGenericBiologicalTestMethods
device should be considered when determining the appropriate
for Materials and Devices
F756 Practice for Assessment of Hemolytic Properties of panel of testing. This guide may not address neurosurgical
instruments or medical devices that have transient incidental
Materials
F1904 Practice for Testing the Biological Responses to contact with the nervous system due to the limited tissue
Particles in vivo contact duration.
3.3 The evaluation of neurotoxicity should be considered in
conjunction with material characterization and other informa-
This guide is under the jurisdiction of ASTM Committee F04 on Medical and
tion such as non-clinical tests, clinical studies, post-market
Surgical Materials and Devices and is the direct responsibility of Subcommittee
experience, and intended use.
F04.16 on Biocompatibility Test Methods.
Current edition approved March 1, 2019. Published March 2019. Originally
approved in 2012. Last previous edition approved in 2013 as F2901 – 13. DOI:
10.1520/F2901–19.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM 4th Floor, New York, NY 10036, http://www.ansi.org.
Standards volume information, refer to the standard’s Document Summary page on Available from U.S. Pharmacopeia (USP), 12601Twinbrook Pkwy., Rockville,
the ASTM website. MD 20852-1790, http://www.usp.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2901 − 19
4. Significance and Use in-vitro test with cytogenetic evaluation of chromosomal
damage with mammalian cells or an in-vitro mouse lymphoma
4.1 The objective of this guide is to recommend a panel of
tk assay. Additionally, for devices containing novel materials
biological tests that can be used in addition to the testing
an in-vivo test for chromosomal damage using rodent he-
recommended in Practice F748. This guide is designed to
matopoietic cells should be considered if the quantities of
detect neurotoxicity caused by medical devices that contact
materials in the test extract following exhaustive extraction of
nervous tissue.
the devices are above the threshold of detection of the in vivo
4.2 The testing recommendations should be considered for
assay. See ISO 10993-3 and the 2016 CDRH Biocompatibility
new materials, established materials with different manufactur-
Guidance(seeX1.5)foradditionalinformationongenotoxicity
ing methods that could affect nervous tissue response, or
testing.
materials used in new nervous tissue applications.
6.2.3 Implantation—The use of a clinically relevant implan-
4.3 Chemical characterization can be used to evaluate simi-
tation study is recommended.The implantation site and animal
larity for materials with a history of clinical use in a similar
model should be selected and justified according to the
nervous tissue application.
intended clinical use of the medical device. The test period
should include an acute implantation period as well as other
5. Terminology
appropriate time intervals determined by the clinical exposure
5.1 Definitions:
time, or go beyond the point where a tissue response steady
5.1.1 device-drug/biologic compatibility—data demonstrat-
state has been reached. The time course of the study should
ing that drug, biologic and/or excipient and device materials
adequately characterize the response to implantation (e.g.,
arecompatibleifaspecificdrugorbiologicisreferencedinthe
absorbable dural substitute devices) and should be designed
device labeling.
and justified based on the intended clinical use. The study
should include both histopathology and neurobehavioral as-
5.1.2 fluid path—where fluids contact the channels in the
device or component, and then the fluid enters the body. sessments. In addition to the use of hematoxylin and eosin
(H&E) which is a general morphological stain, more sensitive
6. Tests for Neurotoxicity
and specific histopathological assessments should be
considered, including methods that are capable of enhancing
6.1 Testing should be performed on the final sterilized
and quantification of neurodegeneration, astrogliosis, micro-
device, representative samples from the final sterilized device,
glia activation, and myelinopathy. See Polikov et al. (1) ,
ormaterialsprocessedinthesamemannerasthefinalsterilized
Schmued et al. (2), and O’Callaghan et al. (3) and Bolon et al.
device. Representative samples should take into consideration
(4) for examples of detection methods using Fluor-Jade for
all component materials that have direct or indirect tissue
contact in appropriate ratios undergoing all the same detection of neurodegeneration, glial fibrillary acidic protein
(GFAP) for detection of astrogliosis, and Macrophage-1 anti-
manufacturing,cleaning,andsterilizationprocessesasthefinal
sterilized device. Testing of individual materials may be useful gen (MAC-1), Isolectin IB4, or ionized calcium binding
adaptor molecule 1 (IBA-1) for detection of microglia activa-
for research and development, but the definitive neurotoxicity
evaluation should include all materials in the final version of tion and luxol fast blue for myelin degeneration. Tissue
sectioning should include the implant-tissue interface and
the device. The test article should be exposed to all phases of
manufacturing including processing, cleaning, sterilization, include sectioning of sufficient area around the implant to
and packaging. ensure that the potential effects of diffusion of degradable
6.1.1 A complete description of all device materials and and/or leachable materials are captured in the histological
reagents used during manufacturing and processing should be analysis. Consideration should be given to whether cross or
provided with information on the source, purity, and toxicity transverse sectioning best captures the area of interest depend-
profile. Chemical characterization studies can provide addi-
ing on the anatomical region. A functional observation battery
tional information on the device safety profile. See ISO (5) designed to detect signs of neurobehavioral dysfunction is
10993-18 for information on chemical characterization of
recommended to complement the histopathological assess-
materials. ments. See ISO 10993-6 Annex D for additional information
on implantation in brain tissue including functional
6.2 The following tests should be considered to assess
assessments, and stains for histopathological evaluation.
neurotoxicityofmedicaldeviceswithinthescopeofthisguide.
6.2.4 Pyrogen Testing—Pyrogen testing on the final steril-
6.2.1 Cytotoxicity—Cytotoxicity assays are sensitive
ized medical device is recommended to reduce the likelihood
screening tools that generally serve as a starting point for
of a neuroinflammatory response to the device. Material-
evaluating medical device biocompatibility. See X1.4 for
mediated pyrogen testing should be conducted using the rabbit
information on neuro-cytotoxicity testing.
pyrogen test (see USP <151> and ISO 10993–11, Annex F).
6.2.2 Genotoxicity—Nervous tissue contains proliferating
Endotoxin testing with an assay such as the Limulus Amebo-
cell populations, and can respond to device implantation with
cyte Lysate (LAL) assay should be conducted in compliance
a proliferative response. Nervous tissue is also known to give
rise to various tumor types. To ensure that medical devices do
not include genotoxic chemicals, the use of a panel of
genotoxicity tests is recommended. The panel of genotoxicity
The boldface numbers in parentheses refer to the list of references at the end of
tests should include a test for gene mutation in bacteria and an this standard.
F2901 − 19
with ANSI/AAMI ST72 and USP <161>. The endotoxin limit used as a component of delivery systems) may warrant the
for a medical device is dependent on the intended use and type evaluation of the compatibility between the device and the
of patient contact. drug. This includes both the effect of the device on the drug
6.2.5 Indirect Hemolysis—Indirect (extract) hemolysis test- (drugpotency,composition,pHlevel,etc.)andtheeffectofthe
ing on the final sterilized medical device is recommended for drug on the device (e.g., extractables/leachables profil
...

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: F2901 − 13 F2901 − 19
Standard Guide for
Selecting Tests to Evaluate Potential Neurotoxicity of
Medical Devices
This standard is issued under the fixed designation F2901; 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 Medical devices may cause adverse effects on the structure and/or function of the nervous system. In this guide, these
adverse effects are defined as neurotoxicity. This guide provides background information and recommendations on methods for
neurotoxicity testing. This guide should be used with Practice F748, and may be helpful where neurotoxicity testing is needed to
evaluate medical devices that contact central and/or peripheral nervous system tissue or cerebral spinal fluid (CSF).
NOTE 1—The results of these in vitro and in vivo tests may not correspond to actual human response.
1.2 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.3 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
2.1 ASTM Standards:
F748 Practice for Selecting Generic Biological Test Methods for Materials and Devices
F756 Practice for Assessment of Hemolytic Properties of Materials
F1904 Practice for Testing the Biological Responses to Particles in vivo
2.2 Other Referenced Documents:
ISO 10993-1 Biological Evaluation of Medical Devices—Part 1: Evaluation and Testing Within a Risk Management Process
ISO/AAMI/ANSIISO 10993-3 :2003 Biological Evaluation of Medical Devices—Part 3: Tests for Genotoxicity,
Carcinogenicity, and Reproductive Toxicity
ISO/AAMI/ANSIISO 10993-5 :2009 Biological Evaluation of Medical Devices—Part 5: Tests for In Vitro Cytotoxicity
ISO 10993-6 Biological Evaluation of Medical Devices—Part 6: Tests for Local Effects After Implantation
ISO 10993–11 : 2006 Biological Evaluation of Medical Devices—Part 11: Tests for Systemic Toxicity
ISO/AAMI/ANSIISO 10993-18 Biological Evaluation of Medical Devices—Part 18: Chemical Characterization of Materials
ANSI/AAMI ST72ANSI/AAMI ST72 :2010 Bacterial Endotoxins—Test Bacterial Endotoxins—Test Methodologies, Routine
Monitoring, and Alternatives to Batch Testing
USP <151> Rabbit Pyrogen Test
USP <161> Transfusion and Infusion Assemblies and Similar Medical Devices
3. Summary of Guide
3.1 This is an informative guide and should be used with Practice F748.
This guide is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee F04.16
on Biocompatibility Test Methods.
Current edition approved Feb. 1, 2013March 1, 2019. Published February 2013March 2019. Originally approved in 2012. Last previous edition approved in 20122013
as F2901 – 12.F2901 – 13. DOI: 10.1520/F2901–13. 10.1520/F2901–19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from U.S. Pharmacopeia (USP), 12601 Twinbrook Pkwy., Rockville, MD 20852-1790, http://www.usp.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2901 − 19
3.2 The duration of contact between the tissue and medical device should be considered when determining the appropriate panel
of testing. This guide may not address neurosurgical instruments or medical devices that have transient incidental contact with the
nervous system due to the limited tissue contact duration.
3.3 The evaluation of neurotoxicity should be considered in conjunction with material characterization and other information
such as non-clinical tests, clinical studies, post-market experience, and intended use.
4. Significance and Use
4.1 The objective of this guide is to recommend a panel of biological tests that can be used in addition to the testing
recommended in Practice F748. This guide is designed to detect neurotoxicity caused by medical devices that contact nervous
tissue.
4.2 The testing recommendations should be considered for new materials, established materials with different manufacturing
methods that could affect nervous tissue response, or materials used in new nervous tissue applications.
4.3 Chemical characterization can be used to evaluate similarity for materials with a history of clinical use in a similar nervous
tissue application.
5. Terminology
5.1 Definitions:
5.1.1 device-drug/biologic compatibility—data demonstrating that drug, biologic and/or excipient and device materials are
compatible if a specific drug or biologic is referenced in the device labeling.
5.1.2 fluid path—where fluids contact the channels in the device or component, and then the fluid enters the body.
6. Tests for Neurotoxicity
6.1 Testing should be performed on the final sterilized device, representative samples from the final sterilized device, or
materials processed in the same manner as the final sterilized device. Representative samples should take into consideration all
component materials that have direct or indirect tissue contact in appropriate ratios undergoing all the same manufacturing,
cleaning, and sterilization processes as the final sterilized device. Testing of individual materials may be useful for research and
development, but the definitive neurotoxicity evaluation should include all materials in the final version of the device. The test
article should be exposed to all phases of manufacturing including processing, cleaning, sterilization, and packaging.
6.1.1 A complete description of all device materials and reagents used during manufacturing and processing should be provided
with information on the source, purity, and toxicity profile. Chemical characterization studies can provide additional information
on the device safety profile. See ISO/AAMI/ANSIISO 10993-18 for information on chemical characterization of materials.
6.2 The following tests should be considered to assess neurotoxicity of medical devices within the scope of this guide.
6.2.1 Cytotoxicity—Cytotoxicity assays are sensitive screening tools that generally serve as a starting point for evaluating
medical device biocompatibility. See X1.4 for information on neuro-cytotoxicity testing.
6.2.2 Genotoxicity—Nervous tissue contains proliferating cell populations, and can respond to device implantation with a
proliferative response. Nervous tissue is also known to give rise to various tumor types. To ensure that medical devices do not
include genotoxic chemicals, the use of a panel of genotoxicity tests is recommended. The panel of genotoxicity tests should
include a test for gene mutation in bacteria, bacteria and an in-vitro test with cytogenetic evaluation of chromosomal damage with
mammalian cells or an in-vitro mouse lymphoma tk assay, and assay. Additionally, for devices containing novel materials an
in-vivo test for chromosomal damage using rodent hematopoietic cells. See ISO/AAMI/ANSI 10993-3 cells should be considered
if the quantities of materials in the test extract following exhaustive extraction of the devices are above the threshold of detection
of the in vivo assay. See ISO 10993-3 and the 2016 CDRH Biocompatibility Guidance (see X1.5) for additional information on
genotoxicity testing.
6.2.3 Implantation—The use of a clinically relevant implantation study is recommended. The implantation site and animal
model should be selected and justified according to the intended clinical use of the medical device. The study should test period
should include an acute implantation period as well as other appropriate time intervals determined by the clinical exposure time,
or go beyond the point where a tissue response steady state has been reached. The time course of the study should adequately
characterize the response to implantation (e.g., absorbable dural substitute devices) and should be designed and justified based on
the intended clinical use. The study should include both histopathology and neurobehavioral assessments. In addition to the use
of hematoxylin and eosin (H&E), (H&E) which is a general morphological stain, more sensitive and specific histopathological
assessments should be considered, including methods that are capable of enhancing and quantification of neurodegeneration,
astrogliosis, microglia activation, and myelinopathy. See Polikov et al. (1) , Schmued et al. (2), and O’Callaghan et al. (3) and
Bolon et al. (4) for examples of detection methods using Fluor-Jade for detection of neurodegeneration, glial fibrillary acidic
protein (GFAP) for detection of astrogliosis, and Macrophage-1 antigen (MAC-1), Isolectin IB4, or ionized calcium binding
The boldface numbers in parentheses refer to the list of references at the end of this standard.
F2901 − 19
adaptor molecule 1 (IBA-1) for detection of microglia activation. activation and luxol fast blue for myelin degeneration. Tissue
sectioning should include the implant-tissue interface and include sectioning of sufficient area around the implant to ensure that
the potential effects of diffusion of degradable and/or leachable materials are captured in the histological analysis. Consideration
should be given to whether cross or transverse sectioning best captures the area of interest depending on the anatomical region.
The test period shouldA functional observation battery be(5) determined by the clinical exposure time, or go beyond the point
where a tissue response steady state has been reached. The time course of the study should be designed and justified based on the
intended clinical use. Finally, a functional observation battery designed to detect signs of neurobehavioral dysfunction is
recommended to compliment the histopathological assessments.designed to detect signs of neurobehavioral dysfunction is
recommended to complement the histopathological assessments. See ISO 10993-6 Annex D for additional information on
implantation in brain tissue including functional assessments, and stains for histopathological evaluation.
6.2.4 Pyrogen Testing—Pyrogen testing on the final sterilized medical device is recommended to reduce the likelihood of a
neuroinflammatory response to the device. Material-mediated pyrogen testing should be conducted using the rabbit pyrogen test
(see USP <151> and ISO 10993–11, Annex F). Endotoxin testing with an assay such as the Limulus Amebocyte Lysate (LAL)
assay should be conducted in compliance with ANSI/AAMI ST72 and USP <161>. The endotoxin limit for a medical device is
dependent on the intended use and type of patient contact.
6.2.5 Indirect Hemolysis—Indirect (extract) hemolysis testing on the final sterilized medical device is recommended for devices
that either directly or indirectly contact cerebrospinal fluid. Indirect hemolysis testing will assess the risk of hemolysis caused by
any residuals/leachables from the device that have the potential to indirectly cont
...