Regulatory Considerations for Human 
Cells, Tissues, and Cellular and 
Tissue-Based Products:  Minimal 
Manipulation and Homologous Use 
 
 
Guidance for Industry and 
Food and Drug Administration Staff 
 
 
 
 
 
 
 
 
 
 
 
 
 
For questions on the content of this guidance, contact Center for Biologics Evaluation and 
Research (CBER), Office of Communication, Outreach, and Development (OCOD) at 240-402-
8010 or 800-835-4709.  For questions about this document concerning products regulated by 
Center for Devices and Radiological Health (CDRH), contact the CDRH product jurisdiction 
officer at CDRHProductJurisdiction@fda.hhs.gov.  If you need additional assistance with 
regulation of combination products, contact the Office of Combination Products (OCP) at 301-
796-8930. 
 
 
 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Biologics Evaluation and Research 
Center for Devices and Radiological Health 
Office of Combination Products 
July 2020 
  Contains Nonbinding Recommendations 
Regulatory Considerations for Human 
Cells, Tissues, and Cellular and Tissue-
Based Products:  Minimal Manipulation 
and Homologous Use  
 
 
Guidance for Industry and 
Food and Drug Administration Staff 
 
Additional copies are available from: 
Office of Communication, Outreach and Development 
Center for Biologics Evaluation and Research 
Food and Drug Administration 
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Silver Spring, MD 20993 
Phone:  800-835-4709 or 240-402-8010 
ocod@fda.hhs.gov  
https://www.fda.gov/vaccines-blood-biologics/guidance-compliance-regulatory-information-
biologics/biologics-guidances 
or 
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Guidance and Policy Development 
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or 
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combination@fda.gov 
https://www.fda.gov/CombinationProducts/default.htm  
  Contains Nonbinding Recommendations 
Table of Contents 
 
 
I.  INTRODUCTION............................................................................................................. 1 
II.  BACKGROUND ............................................................................................................... 2 
III.  QUESTIONS AND ANSWERS REGARDING MINIMAL MANIPULATION ....... 7 
A.  General Concepts .................................................................................................. 7 
B.  Structural Tissue ................................................................................................... 8 
C.  Cells or Nonstructural Tissues ........................................................................... 14 
IV.  QUESTIONS AND ANSWERS REGARDING HOMOLOGOUS USE ................... 16 
V.  REGULATORY SCOPE AND COMPLIANCE POLICY ........................................ 22 
A.  Scope of FDAs Regulation of HCT/Ps ............................................................. 22 
B.  Compliance and Enforcement Policy Regarding Certain Regulatory 
Requirements....................................................................................................... 22 
VI.  ADDITIONAL INFORMATION .................................................................................. 23 
i  Contains Nonbinding Recommendations 
Regulatory Considerations for Human Cells, Tissues, and Cellular 
and Tissue-Based Products:  Minimal Manipulation and 
Homologous Use  
 
 
Guidance for Industry and  
Food and Drug Administration Staff 
 
 
This guidance represents the current thinking of the Food and Drug Administration (FDA or 
Agency) on this topic.  It does not establish any rights for any person and is not binding on FDA 
or the public.  You can use an alternative approach if it satisfies the requirements of the 
applicable statutes and regulations.  To discuss an alternative approach, contact the FDA staff 
responsible for this guidance as listed on the title page. 
 
 
I.  INTRODUCTION 
 
We, FDA, are providing you, human cells, tissues, and cellular and tissue-based product 
(HCT/P) manufacturers, healthcare providers, and FDA staff, with our current thinking on the 
criteria under Title 21 of the Code of Federal Regulations (CFR) Part 1271, specifically the  
21 CFR 1271.10(a)(1) criterion of minimal manipulation and the 21 CFR 1271.10(a)(2) criterion 
of homologous use.   
 
This guidance supersedes the guidance of the same title dated November 2017 and corrected 
December 2017.1  This guidance revises section V. to extend the period of enforcement 
discretion through May 31, 2021.  
 
The interpretation of the minimal manipulation and homologous use criteria and definitions of 
related key terms have been of considerable interest to industry stakeholders since the criteria 
and definitions were first proposed.2  This guidance is intended to improve stakeholders 
understanding of the definitions of minimal manipulation in 21 CFR 1271.3(f) and homologous 
use in 21 CFR 1271.3(c).  It will also facilitate stakeholders understanding of how the 
regulatory criteria in 21 CFR 1271.10(a)(1) and (2) apply to their HCT/Ps.3  In addition, the 
November 2017 version of the guidance informed manufacturers, healthcare providers, and other 
interested persons that over the next 36 months (through November 2020), we intended to 
                                                 
1 This document was updated December 2017 to correct language to remove references to autologous and non-
autologous (allogeneic) products in section V.B. (Compliance and Enforcement Policy Regarding Certain 
Regulatory Requirements). 
 
2 Establishment Registration and Listing for Manufacturers of Human Cellular and Tissue-Based Products 63 FR 
26744 at 26748-26749 (May 14, 1998).  (Tissue Registration and Listing; Proposed Rule) 
3 This guidance does not address the classification and/or assignment of HCT/Ps that do not meet the criteria for 
regulation solely under section 361 of the Public Health Service (PHS) Act and 21 CFR Part 1271. 
1  Contains Nonbinding Recommendations 
exercise enforcement discretion under limited conditions with respect to the investigational new 
drug (IND) application and premarket approval (biologics license application (BLA)) 
requirements, for certain HCT/Ps.  The current version of this guidance explains that FDA intends 
to exercise such enforcement discretion for a longer period of time:  through May 2021.  
 
The November 2017 version of the guidance finalized the document entitled Minimal 
Manipulation of Human Cells, Tissues, and Cellular and Tissue-Based Products (HCT/Ps); Draft 
Guidance for Industry and Food Administration Staff dated December 2014, and Homologous 
Use of Human Cells, Tissues, and Cellular and Tissue-Based Products (HCT/Ps); Draft Guidance 
for Industry and FDA Staff dated October 2015.  It also finalized certain material related to 
adipose tissue that was included in draft guidance entitled Human Cells, Tissues, and Cellular 
and Tissue-Based Products (HCT/Ps) from Adipose Tissue:  Regulatory Considerations; Draft 
Guidance for Industry dated December 2014 (Adipose Draft Guidance).  This material, together 
with the material related to adipose tissue included in the final guidance entitled Same Surgical 
Procedure Exception under 21 CFR 1271.15(b); Questions and Answers Regarding the Scope of 
the Exception dated November 2017, superseded the Adipose Draft Guidance.  Accordingly, we 
did finalize the Adipose Draft Guidance, and that draft guidance was withdrawn in November 
2017.  Finally, the November 2017 version of the guidance superseded the document entitled 
Minimal Manipulation of Structural Tissue (Jurisdictional Update); Guidance for Industry and 
FDA Staff dated September 2006 (2006 Guidance).  
 
In general, FDAs guidance documents,including this guidance, do not establish legally 
enforceable responsibilities.  Instead, guidances describe FDAs current thinking on a topic and 
should be viewed only as recommendations, unless specific regulatory or statutory requirements 
are cited.  The use of the word should in FDAs guidances means that something is suggested or 
recommended, but not required.   
 
 
II.  BACKGROUND 
 
HCT/Ps are defined in 21 CFR 1271.3(d) as articles containing or consisting of human cells or 
tissues that are intended for implantation, transplantation, infusion, or transfer into a human 
recipient.4  Because of the unique nature of HCT/Ps, FDA proposed and in 2005 implemented a 
tiered, risk-based approach to the regulation of HCT/Ps.  Although FDA is authorized to apply 
                                                 
4 Examples of HCT/Ps include, but are not limited to, bone, ligament, skin, dura mater, heart valve, cornea, 
hematopoietic stem/progenitor cells derived from peripheral and cord blood, manipulated autologous chondrocytes, 
epithelial cells on a synthetic matrix, and semen or other reproductive tissue.  The following articles are not 
considered HCT/Ps:  (1) Vascularized human organs for transplantation; (2) Whole Blood or blood components or 
blood derivative products subject to listing under 21 CFR Parts 607 and 207, respectively; (3) Secreted or extracted 
human products, such as milk, collagen, and cell factors, except that semen is considered an HCT/P; (4) Minimally 
manipulated bone marrow for homologous use and not combined with another article (except for water, crystalloids, 
or a sterilizing, preserving, or storage agent, if the addition of the agent does not raise new clinical safety concerns 
with respect to the bone marrow); (5) Ancillary products used in the manufacture of HCT/P; (6) Cells, tissues, and 
organs derived from animals other than humans; (7) In vitro diagnostic products as defined in 21 CFR 809.3(a); and 
(8) Blood vessels recovered with an organ, as defined in 42 CFR 121.2 that are intended for use in organ 
transplantation and labeled For use in organ transplantation only (21 CFR 1271.3(d)). 
 
Please note, the regulatory status of products identified as not being HCT/Ps is beyond the scope of this guidance. 
2  Contains Nonbinding Recommendations 
the requirements in the Federal Food, Drug, and Cosmetic Act (FD&C Act) and the Public 
Health Service Act (PHS Act) to those products that meet the definition of drug, biologic, or 
device, under this tiered, risk-based approach, those HCT/Ps that meet specific criteria or fall 
within detailed exceptions do not require premarket review and approval.  In developing the 
tiered, risk-based approach the agency focused on public health and regulatory concerns, 
including how transmission of communicable disease can be prevented; what processing controls 
are necessary to prevent contamination that could result in an unsafe or ineffective product, and 
to preserve integrity and function so that the products will work as they are intended; and how 
clinical safety and effectiveness can be assured.  The tiered, risk-based approach is contained in a 
set of regulations commonly referred to as the tissue rules, issued by FDA through notice and 
comment rulemaking, under the communicable disease authority of section 361 of the PHS Act 
(42 U.S.C. 264).  These regulations explain the types of HCT/Ps that do not require premarket 
approval; and the registration, manufacturing, and reporting steps that must be taken to prevent 
the introduction, transmission, and spread of communicable disease by these HCT/Ps.  These 
regulations can be found in 21 CFR Part 12715. 
 
In 21 CFR 1271.10, the regulations identify the criteria for regulation solely under section 361 of 
the PHS Act and 21 CFR Part 1271.  An HCT/P is regulated solely under section 361 of the PHS 
Act and 21 CFR Part 1271 if it meets all of the following criteria (21 CFR 1271.10(a)): 
 
1)  The HCT/P is minimally manipulated; 
2)  The HCT/P is intended for homologous use only, as reflected by the labeling, advertising, 
or other indications of the manufacturers objective intent; 
3)  The manufacture of the HCT/P does not involve the combination of the cells or tissues 
with another article, except for water, crystalloids, or a sterilizing, preserving, or storage 
agent, provided that the addition of water, crystalloids, or the sterilizing, preserving, or 
storage agent does not raise new clinical safety concerns with respect to the HCT/P; and 
4)  Either: 
i)  The HCT/P does not have a systemic effect and is not dependent upon the metabolic 
activity of living cells for its primary function; or 
ii)  The HCT/P has a systemic effect or is dependent upon the metabolic activity of living 
cells for its primary function, and: 
a)  Is for autologous use; 
b)  Is for allogeneic use in a first-degree or second-degree blood relative; or 
c)  Is for reproductive use. 
 
If an HCT/P does not meet the criteria set out in 21 CFR1271.10(a), and the establishment that 
manufactures the HCT/P does not qualify for any of the exceptions in 21 CFR 1271.156, the 
                                                 
5 See Human Cells, Tissues, and Cellular and Tissue-Based Products; Establishment Registration and Listing; 
Final Rule, 66 FR 5447 (January 19, 2001); Eligibility Determination for Donors of Human Cells, Tissues, and 
Cellular and Tissue-Based Products; Final Rule, 69 FR 29786 (May 25, 2004); Current Good Tissue Practice for 
Human Cell, Tissue, and Cellular and Tissue-Based Product Establishments; Inspection and Enforcement; Final 
Rule, 69 FR 68612 (November 24, 2004). 
6 See the Same Surgical Procedure Exception under 21 CFR 1271.15(b):  Questions and Answers Regarding the 
Scope of the Exception; Guidance for Industry dated November 2017 available at:  
https://www.fda.gov/media/89920/download.  
3  Contains Nonbinding Recommendations 
HCT/P will be regulated as a drug, device, and/or biological product under the FD&C Act, 
and/or section 351 of the PHS Act (42 U.S.C. 262), and applicable regulations, including  
21 CFR Part 1271, and premarket review will be required. 
 
Minimal Manipulation 
 
Section 1271.10(a)(1) (21 CFR 1271.10(a)(1)) provides that one of the criteria for an HCT/P to 
be regulated solely under section 361 of the PHS Act and the regulations in Part 1271 is that the 
HCT/P is minimally manipulated.  As defined in 21 CFR 1271.3(f), minimal manipulation 
means: 
 
1)  For structural tissue, processing that does not alter the original relevant characteristics of 
the tissue relating to the tissues utility for reconstruction, repair, or replacement; 
2)  For cells or nonstructural tissues, processing that does not alter the relevant biological 
characteristics of cells or tissues.  
 
FDA discussed these terms in the preamble to the HCT/P Establishment Registration and Listing 
final rule7 and the 2006 Guidance.  However, we have received requests from stakeholders to 
provide additional guidance that explains our current thinking related to meeting the criterion in 
21 CFR 1271.10(a)(1).  This guidance supersedes the 2006 Guidance. 
 
Please note that if information does not exist to show that the processing meets the definition of 
minimal manipulation, FDA considers the processing of an HCT/P to be more than minimal 
manipulation that cannot qualify for regulation solely under section 361 of the PHS Act and  
21 CFR Part 12718. 
 
Homologous Use 
 
Section 1271.10(a)(2) (21 CFR 1271.10(a)(2)) provides that one of the criteria for an HCT/P to 
be regulated solely under section 361 of the PHS Act and the regulations in Part 1271 is that the 
HCT/P is intended for homologous use only, as reflected by the labeling, advertising, or other 
indications of the manufacturers objective intent.  As defined in 21 CFR 1271.3(c), 
homologous use means the repair, reconstruction, replacement, or supplementation of a 
recipients cells or tissues with an HCT/P that performs the same basic function or functions in 
the recipient as in the donor.  This criterion reflects the Agencys conclusion that there would be 
increased safety and effectiveness concerns for HCT/Ps that are intended for a non-homologous 
use, because there is less basis on which to predict the products behavior, whereas HCT/Ps for 
homologous use can reasonably be expected to function appropriately (assuming all of the other 
criteria are also met)9. 
 
                                                 
7 Human Cells, Tissues, and Cellular and Tissue-Based Products; Establishment Registration and Listing 66 FR 
5447 at 5457 (January 19, 2001).  (Tissue Registration and Listing; Final Rule). 
8 See the proposed rule, Establishment Registration and Listing for Manufacturers of Human Cellular and Tissue-
Based Products 63 FR 26744 at 26748-26749 (May 14, 1998).  (Tissue Registration and Listing; Proposed Rule) 
9 Proposed Approach to Regulation of Cellular and Tissue-Based Products, dated February 28, 1997 62 FR 9721 
(March 4, 1997) page 19. (1997 Proposed Approach).  
4  Contains Nonbinding Recommendations 
In applying the homologous use criterion, FDA will determine what the intended use of the 
HCT/P is, as reflected by the labeling, advertising, and other indications of a manufacturers 
objective intent, and will then apply the homologous use definition. 
 
FDA has received many inquiries from manufacturers about whether their HCT/Ps meet the 
minimal manipulation and/or homologous use criteria.  Additionally, transplant and healthcare 
providers often need to know this information about the HCT/Ps that they are considering for use 
in their patients.  This guidance provides examples of different types of HCT/Ps and how the 
regulations in 21 CFR 1271.10(a)(1) and (2) apply to them, and provides general principles that 
can be applied to HCT/Ps that may be developed in the future.  In some of the examples, the 
HCT/Ps may fail to meet more than one of the four criteria in 21 CFR 1271.10(a).  The following 
flowchart illustrates how manufacturers and healthcare providers should apply the criteria 
outlined in 21 CFR 1271.15(b)10 and 1271.10(a) for HCT/Ps: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                                 
10 For additional information about applying the exception in 21 CFR 1271.15(b), see the Same Surgical Procedure 
Exception under 21 CFR 1271.15(b):  Questions and Answers Regarding the Scope of the Exception; Guidance for 
Industry dated November 2017. 
5  Contains Nonbinding Recommendations 
 
 
 
Flowchart to illustrate how to apply the criteria in 21 CFR 1271.15(b) and 1271.10(a) 
 
 
Does your product meet the 
definition of an HCT/P in  
21 CFR 1271.3(d)? 
 
No  Yes 
The regulations in   Does the same surgical 
21 CFR Part 1271 do not  procedure exception in  
apply  21 CFR 1271.15(b) apply?  
No  Yes 
Does your HCT/P meet all four of the following criteria in  
You are not required to 
21 CFR 1271.10(a): 
  The HCT/P is minimally manipulated;  comply with the 
  The HCT/P is intended for homologous use only;  requirements in  
  The HCT/P is not combined with another article (with some  21 CFR Part 1271 
limited exceptions); and 
  The HCT/P does not have a systemic effect and is not 
dependent upon the metabolic activity of living cells for its 
primary function;  
or,  
The HCT/P has a systemic effect or is dependent upon the 
metabolic activity of living cells for its primary function, and is 
for autologous use; for allogeneic use in a first or second 
degree blood relative; or for reproductive use. 
No  Yes 
Your HCT/P is regulated as a drug, device, 
Your HCT/P is regulated solely under 
and/or biological product under the FD&C 
section 361 of the PHS Act, and 
Act and/or section 351 of the PHS Act, 
regulations in 21 CFR Part 1271 
and applicable regulations   
6  Contains Nonbinding Recommendations 
III.  QUESTIONS AND ANSWERS REGARDING MINIMAL MANIPULATION 
 
A.  General Concepts 
 
1.  How do the regulations define minimal manipulation?  
 
Section 1271.3(f) provides two definitions of minimal manipulation, one that 
applies to structural tissue and one that applies to cells or nonstructural tissues.  
For structural tissue, minimal manipulation means that the processing of the 
HCT/P does not alter the original relevant characteristics of the tissue relating to 
the tissues utility for reconstruction, repair, or replacement (21 CFR 
1271.3(f)(1)).  For cells or nonstructural tissues, minimal manipulation means that 
the processing of the HCT/P does not alter the relevant biological characteristics 
of cells or tissues (21 CFR 1271.3(f)(2)). 
 
Original relevant characteristics of structural tissues generally include the 
properties of that tissue in the donor that contribute to the tissues function or 
functions.  Similarly, relevant biological characteristics of cells or nonstructural 
tissues generally include the properties of the cells or nonstructural tissues in the 
donor that contribute to the cells or tissues function(s).  Processing that alters the 
original characteristics of the HCT/P, raises increased safety and effectiveness 
concerns for the HCT/P because there would be less basis on which to predict the 
products function after transplantation.11  Thus, the determination of whether an 
HCT/P is minimally manipulated is based on the effect of manufacturing on the 
original relevant characteristics of the HCT/P as the HCT/P exists in the donor, 
and not based on the intended use of the HCT/P in the recipient.  
 
2.  Why is there a different definition of minimal manipulation for 
structural tissue and for cells or nonstructural tissue? 
 
Under the regulations, HCT/Ps are considered either structural tissues or 
cells/nonstructural tissue, based on the characteristics of the tissue in the donor.  
This distinction, which was first described in the 1997 Proposed Approach for the 
regulation of cell and tissue-based products, is reflected in the definitions of 
minimal manipulation for structural tissue and cells/nonstructural tissue.  
Structural HCT/Ps generally raise different safety and efficacy concerns than do 
cells or nonstructural tissues.12 
   
                                                 
11 See the Proposed Approach to Regulation of Cell and Tissue-Based Products page 19. (1997 Proposed 
Approach) 
12 See the Proposed Approach to Regulation of Cell and Tissue-Based Products page 20 (many structural HCT/Ps 
are conventional tissues with a long established history of safe use).  (1997 Proposed Approach) 
7  Contains Nonbinding Recommendations 
 
3.  How do I determine whether an HCT/P is structural tissue or 
cellular/nonstructural tissue for purposes of applying the minimal 
manipulation criterion? 
 
To apply the minimal manipulation criterion, you first determine whether the 
HCT/P is structural or cellular/nonstructural.  This determination is made based 
on the characteristics of the HCT/P in the donor, before recovery and before any 
processing that takes place.  Then, you apply the appropriate definition to 
determine whether the HCT/P has been minimally manipulated. 
 
HCT/Ps may perform multiple functions and FDA acknowledges that structural 
tissues contain cells.  FDA also acknowledges that some manufacturers assert that 
an HCT/P has both a structural and cellular/nonstructural function.  However, 
under the regulations, HCT/Ps are considered either structural tissues or 
cells/nonstructural tissues.  HCT/Ps that physically support or serve as a barrier or 
conduit, or connect, cover, or cushion are generally considered structural tissues 
for the purpose of applying the HCT/P regulatory framework.  Examples of 
structural tissue are provided in question 6 (see section III.B. of this guidance).  
HCT/Ps that serve metabolic or other biochemical roles in the body such as 
hematopoietic, immune, and endocrine functions, are generally considered 
cells/nonstructural tissues for the purpose of applying the HCT/P regulatory 
framework.  Examples of cells or nonstructural tissues are provided in question 15 
(see section III.C. of this guidance). 
 
4.  What is processing of an HCT/P? 
 
Processing is defined as any activity performed on an HCT/P, other than recovery, 
donor screening, donor testing, storage, labeling, packaging, or distribution, such 
as testing for microorganisms, preparation, sterilization, steps to inactivate or 
remove adventitious agents, preservation for storage, and removal from storage  
(21 CFR 1271.3(ff)).  Processing also includes cutting, grinding, shaping, 
culturing, enzymatic digestion, and decellularization. 
 
5.  Which processing steps should be considered in determining whether 
an HCT/P is minimally manipulated? 
 
You should consider all of the processing steps. 
 
B.  Structural Tissue 
 
1.  What types of tissues are considered structural tissues? 
 
Tissues that physically support or serve as a barrier or conduit, or connect, cover, 
or cushion in the donor are generally considered structural tissues for the purposes 
of determining the applicable regulatory definition. 
8  Contains Nonbinding Recommendations 
 
Examples of structural tissues include: 
 
  Bone; 
  Skin; 
  Amniotic membrane and umbilical cord; 
  Blood vessel; 
  Adipose tissue; 
  Articular cartilage; 
  Non-articular cartilage; and 
  Tendon or ligament 
 
2.  Why is adipose tissue considered a structural tissue for the purpose of 
applying the HCT/P regulatory framework? 
 
Adipose tissue is typically defined as a connective tissue composed of clusters of 
cells (adipocytes) surrounded by a reticular fiber network and interspersed small 
blood vessels, divided into lobes and lobules by connective tissue septa.13  
Additionally, adipose tissue contains other cells, including preadipocytes, 
fibroblasts, vascular endothelial cells, and macrophages.14  Adipose tissue 
provides cushioning and support for other tissues, including the skin and internal 
organs, stores energy in the form of lipids, and insulates the body, among other 
functions.  While adipose tissue has multiple functions, because it is 
predominantly composed of adipocytes and surrounding connective tissues that 
provide cushioning and support to the body, FDA considers adipose tissue to be a 
structural tissue for the purpose of applying the HCT/P regulatory framework. 
 
To evaluate whether processing of adipose tissue would meet the regulatory 
definition of minimal manipulation, you should consider whether the processing 
alters the original relevant characteristics of the adipose tissue relating to its utility 
to provide cushioning and support.   
 
3.  If my HCT/P is a structural tissue, how do I determine whether it is 
minimally manipulated? 
 
To evaluate whether processing of a structural tissue would meet the regulatory 
definition of minimal manipulation, you should consider whether the processing 
alters an original relevant characteristic of the tissue, relating to the tissues utility 
for reconstruction, repair, or replacement as structural tissue.   
 
   
                                                 
13 Chapter 6. Adipose Tissue. In: Mescher AL. eds. Junqueira's Basic Histology: Text & Atlas, 13e. New York: 
McGraw-Hill; 2013. http://accessmedicine.mhmedical.com/content.aspx?bookid=574&Sectionid=42524592. 
14 Brown SA, Levi, B, Lequeux, C, et al. Basic Science Review on Adipose Tissue for Clinicians. Plast. Reconstr. 
Surg. 126:1936, 2010. 
9  Contains Nonbinding Recommendations 
4.  What are original relevant characteristics of structural tissues? 
 
Original relevant characteristics of structural tissues generally include the 
properties of that tissue in the donor that contribute to the tissues function or 
functions.  For purposes of determining whether a structural HCT/P is minimally 
manipulated, a tissue characteristic is original if it is present in the tissue in the 
donor.  A structural tissue characteristic is relevant if it could have a meaningful 
bearing on the tissues utility for reconstruction, repair, or replacement.  The 
structural tissues utility for reconstruction, repair, or replacement relates to how 
that tissue functions in the donor.  Examples of relevant characteristics of 
structural tissues include strength, flexibility, cushioning, covering, 
compressibility, and response to friction and shear. 
 
5.  How does changing the size or shape of the structural tissue affect 
whether an HCT/P is minimally manipulated? 
 
Structural tissues may be processed by various machining and other mechanical 
methods to change the size or shape of the HCT/P.  Such processing can be either 
minimal manipulation or more than minimal manipulation depending on whether 
the processing alters the original relevant characteristics of the structural tissue 
relating to its utility for reconstruction, repair, or replacement. 
 
Example 10-1:  Original relevant characteristics of bone relating to its utility to 
support the body and protect internal structures include strength, and resistance to 
compression.  Milling, grinding, and other methods for shaping and sizing bone 
may generally be considered minimal manipulation when they do not alter bones 
original relevant characteristics relating to its utility to support the body and 
protect internal structures. 
 
a.  A manufacturer performs threading and other mechanical machining 
procedures to shape bone into dowels, screws, and pins.  The HCT/Ps 
are generally considered minimally manipulated because the 
processing does not alter the bones original relevant characteristics 
relating to its utility to support the body and protect internal structures. 
 
b.  A manufacturer grinds bone to form bone chips and particles.  The 
HCT/Ps would generally be considered minimally manipulated 
because the processing does not alter the bones original relevant 
characteristics relating to its utility to support bodily structures.15 
 
                                                 
15 Refer to the Jurisdictional Update:  Human Demineralized Bone Matrix dated January 19, 2001 (DBM 
Guidance) https://www.fda.gov/combination-products/jurisdictional-updates/jurisdictional-update-human-
demineralized-bone-matrix  for information relating to the regulatory classification of demineralized bone matrix 
(DBM).  The guidance remains applicable to HCT/Ps that are DBM products.  However, the DBM Guidance is 
based on factors that are specific to DBM products.  The DBM Guidance document does not inform analyses to 
determine whether HCT/Ps other than DBM have been minimally manipulated and we do not consider it to be 
applicable to HCT/Ps other than DBM. 
10  Contains Nonbinding Recommendations 
c.  A manufacturer exposes bone to acid at elevated temperature to 
demineralize bone and dissolve collagen in order to form a gel.  
The HCT/P is generally considered more than minimally 
manipulated because the processing alters the bones original 
relevant characteristics relating to its utility to support the body 
and protect internal structures. 
 
Example 10-2:  Original relevant characteristics of amniotic membrane relating to 
its utility to serve as a barrier generally include the tissues physical integrity, 
tensile strength, and elasticity. 
 
a.  A manufacturer processes amniotic membrane to preserve it and 
package it in sheets.  The HCT/P generally is considered minimally 
manipulated because the processing does not alter the original relevant 
characteristics of the HCT/P relating to its utility to serve as a barrier. 
 
b.  A manufacturer grinds and lyophilizes amniotic membrane and 
packages it as particles.  The HCT/P generally is considered more than 
minimally manipulated because the processing alters the original 
relevant characteristics of the HCT/P relating to its utility to serve as a 
barrier. 
 
Example 10-3:  Original relevant characteristics of fascia lata, relating to its utility 
to cover muscle and aid in movement, generally include its strength, flexibility, 
and its fibrous, sheet-like configuration.  A manufacturer grinds sheets of fascia 
lata into particles.  The HCT/P generally is considered more than minimally 
manipulated because the processing alters the original relevant characteristics of 
the HCT/P relating to its utility to cover muscle and aid in movement. 
 
Example 10-4:  The original relevant characteristics of skin relating to its utility to 
serve as a protective covering generally include its large surface area, keratinized, 
water-resistant epithelial layer (epidermis), and dense, strong, and flexible 
connective tissue layer (dermis). 
 
a.  A manufacturer processes skin by mechanical meshing and 
cryopreservation and packages it in sheets as meshed skin.  The 
HCT/P generally is considered minimally manipulated because the 
processing does not alter the original relevant characteristics of the 
skin relating to its utility as a protective covering. 
 
b.  A manufacturer processes skin by removing the epidermis and then 
grinding the dermis into particles.  The HCT/P generally is considered 
more than minimally manipulated because the processing alters the 
original relevant characteristics of skin related to its utility as a 
protective covering. 
 
11  Contains Nonbinding Recommendations 
6.  How does removal of cells from structural tissue affect whether an 
HCT/P is minimally manipulated? 
 
Structural tissues may contain both extracellular matrix and cellular components, 
and any alteration of these components that relates to the structural tissues utility 
for reconstruction, repair, or replacement generally would be considered more 
than minimal manipulation.  However, separation of structural tissue into 
components in which the original relevant characteristics relating to the tissues 
utility for reconstruction, repair, or replacement are not altered generally would be 
considered minimal manipulation.  For example, extraction or separation of cells 
from structural tissue in which the remaining structural tissues original relevant 
characteristics relating to its utility for reconstruction, repair, or replacement 
remain unchanged generally would be considered minimal manipulation.16 
 
While some structural tissues may undergo processing that alters the cellular or 
extracellular matrix components without altering the original relevant 
characteristics of the tissue, the same processing may alter the original relevant 
characteristics of a different structural tissue.  Therefore, to assess whether a 
processing step alters the original relevant characteristics of a structural tissue 
relating to its utility for reconstruction, repair, or replacement, you should 
consider the effects of the processing on the properties that contribute to the 
specific tissues function in the donor, for each type of tissue you manufacture. 
 
Example 11-1:  Original relevant characteristics of adipose tissue relating to its 
utility to provide cushioning and support generally include its bulk and lipid 
storage capacity.  A manufacturer processes adipose tissue by removing the cells, 
which leaves the decellularized extracellular matrix portion of the HCT/P.  The 
HCT/P generally is considered more than minimally manipulated because the 
processing alters the original relevant characteristics of the HCT/P relating to its 
utility to provide cushioning and support.   
 
Example 11-2:  Original relevant characteristics of the amniotic membrane related 
to its utility to serve as a barrier generally include its physical integrity, tensile 
strength, and elasticity.  A manufacturer processes amniotic tissue to remove the 
chorion and other cells.  The HCT/P generally is considered minimally 
manipulated because the processing does not alter the original relevant 
characteristics of the HCT/P relating to its utility to serve as a barrier. 
 
Example 11-3:  The original relevant characteristics of skin relating to its utility to 
serve as a protective covering generally include its large surface area, keratinized, 
water-resistant epithelial layer (epidermis), and dense, strong, and flexible 
connective tissue layer (dermis).  A manufacturer processes skin to remove 
epidermis and freeze-dries and packages the remaining connective tissue, as  
   
                                                 
16 See the Proposed Rule Establishment Registration and Listing for Manufacturers of Human Cellular and Tissue-
Based Products 63 FR 26744 at 26748.  (May 14, 1998).  (Tissue Registration and Listing; Proposed Rule) 
12  Contains Nonbinding Recommendations 
decellularized dermis.  The HCT/P generally is considered minimally manipulated 
because the processing does not alter the original relevant characteristics of the 
HCT/P relating to its utility to serve as a protective covering. 
 
7.  How does changing the physical state of the structural HCT/P affect 
whether it is minimally manipulated? 
 
In addition to mechanical methods, there are other types of processing that may 
alter the physical state of a structural tissue, such as chemical modification.  If the 
mechanical, chemical, or other method of modification alters the HCT/Ps 
physical state relating to its utility for reconstruction, repair, or replacement, then 
the HCT/P is generally considered more than minimally manipulated. 
 
Example 12-1:  The original relevant characteristics of cartilage relating to its 
utility to perform its load-bearing and other physical functions generally include 
firmness, smoothness, flexibility, and resistance to deformation.  A manufacturer 
processes cartilage allograft by homogenizing it into a slurry.  The HCT/P 
generally is considered more than minimally manipulated because the processing 
alters the original relevant characteristics of the HCT/P relating to its utility to 
absorb shock and reduce friction between joints. 
 
Example 12-2:  The original relevant characteristics of ligament relating to its 
utility to attach bone to bone and aid in movement and stability generally include 
its tensile strength which is imparted by the bundled fibrous collagen.  A 
manufacturer processes ligament to disaggregate the collagen fibers.  The HCT/P 
generally is considered more than minimally manipulated because the processing 
alters the original relevant characteristics of the HCT/P relating to its utility to aid 
in movement and stability. 
 
8.  How does storage affect whether a structural tissue is minimally 
manipulated? 
 
Storage that does not alter the original relevant characteristics of a structural 
tissue relating to its utility for reconstruction, repair, or replacement would 
generally be considered minimal manipulation.  For example, an HCT/P that is 
placed in a tissue medium and refrigerated, such as stored in a buffer solution; or 
an HCT/P that is cryopreserved and stored in liquid nitrogen vapor, would 
generally meet the minimal manipulation criterion.17 
   
                                                 
17 According to 21 CFR 1271.10(a)(3), to meet the criteria for regulation solely under section 361 of the PHS Act 
and 21 CFR Part 1271, the manufacture of the HCT/P does not involve the combination of the cells or tissues with 
another article, except for water, crystalloids, or a sterilizing, preserving, or storage agent, provided that the addition 
of water, crystalloids, or the sterilizing, preserving, or storage agent does not raise new clinical safety concerns with 
respect to the HCT/P. 
13  Contains Nonbinding Recommendations 
9.  I isolate cells from structural tissue to produce a cellular therapy 
product.  What definition of minimal manipulation would apply? 
 
If you isolate cells from structural tissue, the definition of minimal manipulation 
for structural tissue applies, regardless of the method used to isolate the cells.  
This is because the assessment of whether the HCT/P is a structural tissue or 
cellular/nonstructural tissue is based on the characteristics of the HCT/P as it 
exists in the donor, prior to recovery and any processing that takes place. 
 
Example 14-1:  Original relevant characteristics of adipose tissue relating to its 
utility to provide cushioning and support generally include its bulk and lipid 
storage capacity.  A manufacturer recovers adipose tissue by tumescent 
liposuction and processes (e.g., enzymatically digests, mechanically disrupts, etc.) 
the adipose tissue to isolate cellular components (with or without subsequent cell 
culture or expansion), commonly referred to as stromal vascular fraction, which is 
considered a potential source of adipose-derived stromal/stem cells.  The 
definition of minimal manipulation for structural tissue applies. 
 
In this example, the HCT/P generally is considered more than minimally 
manipulated because the processing breaks down and eliminates the adipocytes 
and the surrounding structural components that provide cushioning and support, 
thereby altering the original relevant characteristics of the HCT/P relating to its 
utility for reconstruction, repair, or replacement. 
 
C.  Cells or Nonstructural Tissues 
 
Under the regulatory framework for HCT/Ps, minimal manipulation of cells or 
nonstructural tissues is defined as processing that does not alter the relevant biological 
characteristics of cells or tissues (21 CFR 1271.3(f)(2)). 
 
1.  What types of tissue are considered cells or nonstructural tissues? 
 
Cells or nonstructural tissues are generally those that serve predominantly 
metabolic or other biochemical roles in the body such as hematopoietic, immune, 
and endocrine functions. 
 
Examples of cells or nonstructural tissues include: 
 
  Reproductive cells or tissues (e.g., oocytes); 
  Hematopoietic stem/progenitor cells (e.g., cord blood)18; 
  Lymph nodes and thymus; 
                                                 
18 Bone marrow is a source of hematopoietic stem/progenitor cells.  Minimally manipulated bone marrow for 
homologous use and not combined with another article (with certain exceptions), is not considered an HCT/P (21 
CFR 1271.3(d)(4)).  However, bone marrow that is more than minimally manipulated, intended by the manufacturer 
for a non-homologous use, or combined with another article with limited exceptions, meets the definition of an 
HCT/P and is subject to the regulations in 21 CFR Part 1271. 
14  Contains Nonbinding Recommendations 
  Parathyroid glands; 
  Peripheral nerve; and 
  Pancreatic tissue. 
 
Secreted body fluids (e.g., amniotic fluid) are generally not considered HCT/Ps.19  
Cells from secreted body fluids are generally considered HCT/Ps, and the 
definition of minimal manipulation for cells or nonstructural tissues would apply.  
 
2.  What are relevant biological characteristics of cells or nonstructural 
tissues? 
 
Relevant biological characteristics of cells or nonstructural tissues generally 
include the properties of the cells or nonstructural tissues in the donor that 
contribute to the cells or tissues function or functions. 
 
Examples of relevant biological characteristics of cells or nonstructural tissues 
include differentiation and activation state, proliferation potential, and metabolic 
activity.  Processing that alters any relevant biological characteristics of cells or 
nonstructural tissues generally would be considered more than minimal 
manipulation. 
 
Example 16-1:  Relevant biological characteristics of hematopoietic 
stem/progenitor cells generally include the ability to repopulate the bone marrow 
by self-renewal and by differentiating along myeloid and lymphoid cell lines. 
 
a.  Hematopoietic stem/progenitor cells are circulating in increased 
numbers in the peripheral blood of a donor after administration of 
mobilizing agent.  A manufacturer performs cell selection on the 
mobilized peripheral blood apheresis product to obtain a higher 
concentration of hematopoietic stem/progenitor cells for 
transplantation.  The HCT/P would generally be considered minimally 
manipulated because the concentrated peripheral blood 
stem/progenitor cells are not altered with regard to their relevant 
biological characteristics to repopulate the bone marrow. 
 
b.  A manufacturer uses hematopoietic stem/progenitor cells to produce 
terminally differentiated cells by culturing the cells under specific 
conditions.  This HCT/P derived from hematopoietic stem/progenitor 
cells would generally be considered more than minimally manipulated 
because the processing alters the cells relevant biological 
characteristics of multipotency and capacity for self-renewal. 
 
   
                                                 
19 21 CFR 1271.3(d) states, ...The following articles are not considered HCT/Ps:...(3) secreted or extracted human 
products such as milk, collagen, and cell factors, except that semen is considered an HCT/P. 
15  Contains Nonbinding Recommendations 
c.  A manufacturer of a placental/umbilical cord blood product performs 
cell selection and incubates the selected cells in a laboratory vessel 
containing culture media and growth factors to achieve large numbers 
of cells capable of long-term repopulation of the bone marrow.  This 
HCT/P derived from cord blood would generally be considered more 
than minimally manipulated because the processing affects the 
production of intracellular or cell-surface proteins and other markers 
of cell lineage, activation state, and proliferation, thereby altering the 
cells relevant biological characteristics of multipotency and capacity 
for self-renewal. 
 
 
IV.  QUESTIONS AND ANSWERS REGARDING HOMOLOGOUS USE 
 
1.  What is the definition of homologous use? 
 
Homologous use means the repair, reconstruction, replacement, or supplementation of a 
recipients cells or tissues with an HCT/P that performs the same basic function or 
functions in the recipient as in the donor (21 CFR 1271.3(c)), including when such cells 
or tissues are for autologous use.  We generally consider an HCT/P to be for homologous 
use when it is used to repair, reconstruct, replace, or supplement: 
 
  Recipient cells or tissues that are identical (e.g., skin for skin) to the donor 
cells or tissues, and perform one or more of the same basic functions in the 
recipient as the cells or tissues performed in the donor; or, 
 
  Recipient cells or tissues that may not be identical to the donors cells or tissues, 
but that perform one or more of the same basic functions in the recipient as the 
cells or tissues performed in the donor.20 
 
Example 17-1:  A heart valve is transplanted to replace a dysfunctional heart valve.  This 
is homologous use because the donor heart valve performs the same basic function in the 
donor as in the recipient of ensuring unidirectional blood flow within the heart. 
 
Example 17-2:  Pericardium is intended to be used as a wound covering for dura mater 
defects.  This is homologous use because the pericardium is intended to serve as a 
covering in the recipient, which is one of the basic functions it performs in the donor. 
 
If an HCT/P is intended for use as an unproven treatment for a myriad of diseases or 
conditions, the HCT/P is likely not intended for homologous use only.21 
 
   
                                                 
20 Establishment Registration and Listing for Manufacturers of Human Cellular and Tissue-Based Products 63 FR 
26744 at 26748-26749 (May 14, 1998).  (Tissue Registration and Listing; Proposed Rule) 
21 Human Cells, Tissues, and Cellular and Tissue-Based Products; Establishment Registration and Listing 66 FR 
5447 at 5457 (January 19, 2001).  (Tissue Registration and Listing; Final Rule) 
16  Contains Nonbinding Recommendations 
2.  What does FDA mean by repair, reconstruction, replacement, or 
supplementation of a recipients cells or tissues? 
 
Repair generally means the physical or mechanical restoration of tissues, including by 
covering or protecting.  For example, FDA generally would consider skin removed from 
a donor and then transplanted to a recipient in order to cover a burn wound to be a 
homologous use.  Reconstruction generally means surgical reassembling or re-forming. 
For example, reconstruction generally would include the reestablishment of the physical 
integrity of a damaged aorta.22  Replacement generally means substitution of a missing 
tissue or cell, for example, the replacement of a damaged or diseased cornea with a 
healthy cornea or the replacement of donor hematopoietic stem/progenitor cells in a 
recipient with a disorder affecting the hematopoietic system that is inherited, acquired, or 
the result of myeloablative treatment.  Supplementation generally means to add to, or 
complete.  For example, FDA generally would consider the implantation of dermal matrix 
into the facial wrinkles to supplement a recipients tissues and the use of bone chips to 
supplement bony defects to be homologous uses.  Repair, reconstruction, replacement, 
and supplementation are not mutually exclusive functions and an HCT/P could perform 
more than one of these functions for a given intended use. 
 
3.  What does FDA mean by the same basic function or functions in the 
definition of homologous use? 
 
For the purpose of applying the HCT/P regulatory framework, the same basic function or 
functions of HCT/Ps are considered to be those basic functions the HCT/P performs in 
the body of the donor, which, when transplanted, implanted, infused, or transferred, the 
HCT/P would be expected to perform in the recipient.  It is not necessary for the HCT/P 
in the recipient to perform all of the basic functions it performed in the donor in order to 
meet the definition of homologous use.  However, to meet the definition of homologous 
use, any of the basic functions that the HCT/P is expected to perform in the recipient 
must be a basic function that the HCT/P performed in the donor. 
 
The basic function of an HCT/P is what it does from a biological/physiological point of 
view, or is capable of doing when in its native state.23  By basic we mean the function 
or functions that are commonly attributed to the HCT/P as it exists in the donor.  Basic 
functions are well understood; it should not be necessary to perform laboratory, pre-
clinical, or clinical studies to demonstrate a basic function or functions for the purpose of 
applying the HCT/P regulatory framework.  Also, clinical effects of the HCT/P in the  
   
                                                 
22 Current Good Tissue Practice for Human Cell, Tissue, and Cellular and Tissue-Based Product Establishments; 
Inspection and Enforcement 69 FR 68612 at 68643 (November 24, 2004) states, HCT/Ps with claims for 
reconstruction or repair can be appropriately regulated solely under section 361 of the PHS Act, if such HCT/P 
meets all the criteria in  1271.10, including minimal manipulation and homologous use. 
23 Establishment Registration and Listing for Manufacturers of Human Cellular and Tissue-Based Products, 63 FR 
26744 at 26749 (May 14, 1998).  (Tissue Registration and Listing; Proposed Rule) 
17  Contains Nonbinding Recommendations 
recipient that are not basic function or functions of the HCT/P in the donor would 
generally not be considered basic function or functions of the HCT/P for the purpose of 
applying the definition of homologous use. 
 
Basic functions of a structural tissue would generally be to perform a structural function 
for example, to physically support or serve as a barrier or conduit, or connect, cover, or 
cushion. 
 
Basic functions of a cellular or nonstructural tissue would generally be a metabolic or 
biochemical function, such as, hematopoietic, immune, and endocrine functions. 
 
Example 19-1:  Sources of hematopoietic stem/progenitor cells (HPCs) include cord 
blood, peripheral blood, and bone marrow.24  The basic functions of HPCs include 
forming and replenishing the lymphohematopoietic system. 
 
a.  HPCs from mobilized peripheral blood are intended for transplantation into an 
individual with a disorder affecting the hematopoietic system that is inherited, 
acquired, or the result of myeloablative treatment.  This is homologous use 
because the peripheral blood product performs the same basic function of 
reconstituting the hematopoietic system in the recipient. 
 
b.  HPCs from bone marrow are intended for infusion into an artery with a 
balloon catheter for the purpose of limiting ventricular remodeling following 
acute myocardial infarction.  This is not homologous use because limiting 
ventricular remodeling is not a basic function of bone marrow. 
 
c.  HPCs from cord blood are intended for intravenous infusion to treat cerebral 
palsy purportedly through the repair of damaged tissue in the brain through 
paracrine signaling or differentiation into neuronal cells.  This is not homologous 
use because there is insufficient evidence to support that repair of neurologic 
tissue through paracrine signaling or differentiation into neuronal cells is a basic 
function of these cells in the donor. 
 
Example 19-2:  The basic functions of the cornea include protecting the eye and serving 
as its outermost lens.  A corneal graft is transplanted to a patient with corneal blindness.  
This is homologous use because a corneal graft performs the same basic functions in the 
donor as in the recipient. 
 
Example 19-3:  The basic functions of a vein or artery include serving as a conduit for 
blood flow throughout the body.  A cryopreserved vein or artery is used for arteriovenous 
access during hemodialysis.  This is homologous use because the vein or artery is 
supplementing the vessel as a conduit for blood flow. 
 
                                                 
24 See Establishment Registration and Listing for Manufacturers of Human Cellular and Tissue Based Products, 
63 FR 26744 at 26749 (May 14, 1998).  (Tissue Registration and Listing; Proposed Rule) 
18  Contains Nonbinding Recommendations 
Example 19-4:  The basic functions of amniotic membrane include serving as a selective 
barrier for the movement of nutrients between the external and in utero environment, 
protecting the fetus from the surrounding maternal environment, and serving as a 
covering to enclose the fetus and retain fluid in utero. 
 
a.  Amniotic membrane is used for bone tissue replacement to support bone 
regeneration following surgery to repair or replace bone defects.  This is not a 
homologous use because bone regeneration is not a basic function of amniotic 
membrane. 
 
b.  An amniotic membrane product is used for wound healing and/or to reduce 
scarring and inflammation.  This is not homologous use because wound 
healing and reduction of scarring and inflammation25 are not basic functions 
of amniotic membrane. 
 
c.  An amniotic membrane product is applied to the surface of the eye to cover or 
offer protection from the surrounding environment in ocular repair and 
reconstruction procedures.  This is homologous use because serving as a 
covering and offering protection from the surrounding environment are basic 
functions of amniotic membrane.26 
 
Example 19-5:  The basic functions of pericardium include covering, protecting against 
infection, fixing the heart to the mediastinum, and providing lubrication to allow normal 
heart movement within chest.  Autologous pericardium is used to replace a dysfunctional 
heart valve in the same patient.  This is not homologous use because facilitating 
unidirectional blood flow is not a basic function of pericardium. 
 
The use of an HCT/P from adipose tissue for the repair, reconstruction, replacement, or 
supplementation of adipose tissue would be considered a homologous use.  In these situations, 
FDA would consider the HCT/P from adipose tissue to be performing the same basic function in 
the recipient as in the donor.  In contrast, the use of an HCT/P from adipose tissue for the 
treatment of a degenerative, inflammatory, or demyelinating disorder would generally be 
considered a non-homologous use. 
 
Example 19-6:  The basic functions of adipose tissue include providing cushioning and 
support for other tissues, including the skin and internal organs, storing energy in the 
form of lipids, and insulating the body. 
 
                                                 
25 Reducing scarring, angiogenesis, and inflammation are potential clinical effects in the recipient but are not basic 
functions of amniotic membrane in the donor; therefore, they are not considered homologous uses of amniotic 
membrane. 
26 Bio-Tissue 2001 RFD available at:  https://www.fda.gov/media/74873/download . 
 
19  Contains Nonbinding Recommendations 
a.  Adipose tissue is used to fill voids in the face or hands (e.g., for cosmetic 
reasons).  This is homologous use because providing cushioning and support, 
is a basic function of adipose tissue.27  
 
b.  An HCT/P from adipose tissue is used to treat musculoskeletal conditions 
such as arthritis or tendonitis by regenerating or promoting the regeneration of 
articular cartilage or tendon.  This is generally not considered a homologous 
use because regenerating or promoting the regeneration of cartilage or tendon 
is not a basic function of adipose tissue. 
 
c.  An HCT/P from adipose tissue is used to treat neurological disorders such as 
multiple sclerosis by limiting the autoimmune reaction and promoting 
remyelinization.  This is generally not considered a homologous use because 
limiting the autoimmune reaction and promoting remyelinization are not basic 
functions of adipose tissue. 
 
d.  Adipose tissue is used for transplantation into the subcutaneous areas of breast 
for reconstruction or augmentation procedures.  This is homologous use 
because providing cushioning and support is a basic function of adipose 
tissue.28 
 
20.  Does my HCT/P have to be used in the same anatomic location to perform 
the same basic function or functions? 
 
An HCT/P may perform the same basic function or functions even when it is not used in 
the same anatomic location where it existed in the donor.29  A transplanted HCT/P could 
 
replace missing tissue, or repair, reconstruct, or supplement tissue that is missing or 
damaged, either when placed in the same or different anatomic location, as long as it 
performs the same basic function(s) in the recipient as in the donor. 
 
Example 20-1:  The basic functions of skin include covering, protecting the body from 
external force, and serving as a water-resistant barrier to pathogens or other damaging 
agents in the external environment.  The dermis is the elastic connective tissue layer of 
the skin that covers, provides support and protects the body from mechanical stress. 
 
                                                 
27 Some cosmetic procedures involving reimplantation of autologous adipose tissue that is only rinsed or cleansed 
may meet the exception in 21 CFR 1271.15(b).  For additional information about applying the exception in 21 CFR 
1271.15(b), see the Same Surgical Procedure Exception under 21 CFR 1271.15(b):  Questions and Answers 
Regarding the Scope of the Exception; Guidance for Industry dated November 2017. 
28 Some breast reconstruction or augmentation procedures involving re-implantation of autologous adipose tissue 
that is only rinsed or cleansed may meet the exception in 21 CFR 1271.15(b).  For additional information about 
applying the exception in 21 CFR 1271.15(b), see the Same Surgical Procedure Exception under 21 CFR 
1271.15(b):  Questions and Answers Regarding the Scope of the Exception; Guidance for Industry dated November 
2017. 
29 Human Cells, Tissues, and Cellular and Tissue-Based Products; Establishment Registration and Listing 66 FR 
5447 at 5457 (January 19, 2001).  (Tissue Registration and Listing; Final Rule) 
20  Contains Nonbinding Recommendations 
a.  An acellular dermal product is used for supplemental support, protection, 
reinforcement, or covering for a tendon.  This is homologous use because in 
both anatomic locations, the dermis provides support and protects the soft 
tissue structure from mechanical stress. 
 
b.  An acellular dermal product is used for tendon replacement or repair.  This is 
not homologous use because serving as a connection between muscle and 
bone is not a basic function of dermis. 
 
Example 20-2:  The basic functions of bone are supporting the body and protecting 
internal structures such as the brain.  Allogeneic mineralized or demineralized cortical 
human bone is used to supplement the recipients bone for repair, replacement, and 
reconstruction of bony voids or gaps involving the extremities, cranium, and spinal 
column; or for augmentation for posterior lateral fusions in the spinal column.  These are 
homologous uses because in all locations, the HCT/P is supplementing the recipients 
bone, for the purpose of supporting the body or protecting internal structures. 
 
Example 20-3:  The basic functions of pancreatic islets include regulating glucose 
homeostasis within the body.  Pancreatic islets are transplanted into the liver through the 
portal vein for preservation of endocrine function after pancreatectomy.  This is 
homologous use because the regulation of glucose homeostasis is a basic function of 
pancreatic islets. 
 
21.  What does FDA mean by intended for homologous use in 21 CFR 
1271.10(a)(2)? 
 
The regulatory criterion in 21 CFR 1271.10(a)(2) states that the HCT/P is intended for 
homologous use only, as reflected by the labeling, advertising, or other indications of the 
manufacturers objective intent. 
 
Labeling includes the HCT/P label and any written, printed, or graphic materials that 
supplement, explain, or are textually related to the product, and which are disseminated 
by or on behalf of its manufacturer.30  Advertising includes information, other than 
labeling, that originates from the same source as the product and that is intended to 
supplement, explain, or be textually related to the product (e.g., print advertising, 
broadcast advertising, electronic advertising (including the Internet), statements of 
company representatives).31 
 
An HCT/P is intended for homologous use when its labeling, advertising, or other 
indications of the manufacturers objective intent refer to only homologous uses for the 
HCT/P.  When an HCT/Ps labeling, advertising, or other indications of the 
                                                 
30 Human Cells, Tissues, and Cellular and Tissue-Based Products; Establishment Registration and Listing 66 FR 
5447 at 5457 (January 19, 2001).  (Tissue Registration and Listing; Final Rule) 
31 Id. 
21  Contains Nonbinding Recommendations 
manufacturers objective intent refer to non-homologous uses, the HCT/P would not meet 
the homologous use criterion in 21 CFR 1271.10(a)(2). 
 
22.  What does FDA mean by manufacturers objective intent in 21 CFR 
1271.10(a)(2)? 
 
A manufacturers objective intent is determined by the expressions of the manufacturer or 
its representatives, or may be shown by the circumstances surrounding the distribution of 
the article.  A manufacturers objective intent may, for example, be shown by labeling 
claims, advertising matter, or oral or written statements by the manufacturer or its 
representatives.  It may be shown by surrounding circumstances under which a HCT/P is 
offered for a purpose for which it is neither labeled nor advertised. 
 
 
V.  REGULATORY SCOPE AND COMPLIANCE POLICY  
 
A.  Scope of FDAs Regulation of HCT/Ps 
 
As noted in the Background section of this guidance, this guidance only applies to 
products and establishments that are subject to FDAs regulations in 21 CFR Part 1271.  
Establishments that meet the same surgical procedure exception in 21 CFR 1271.15(b) 
are not subject to FDAs regulations in 21 CFR Part 1271.  This guidance also does not 
apply to products that fall outside the definition of HCT/P in 21 CFR 1271.3(d).  For 
example, platelet rich plasma (PRP, blood taken from an individual and given back to the 
same individual as platelet rich plasma) is not an HCT/P under 21 CFR Part 1271 
because it is a blood product.  Accordingly, FDA does not apply the criteria in 21 CFR 
1271.10(a) to PRP, and PRP is outside the scope of this guidance. 
 
B.  Compliance and Enforcement Policy Regarding Certain Regulatory 
Requirements 
 
To give manufacturers time to determine if they need to submit an IND or marketing 
application in light of this guidance and, if such an application is needed, to prepare the 
IND or marketing application, FDA generally intends to exercise enforcement discretion 
through May 31, 2021,32 with respect to the IND and the premarket approval 
requirements for HCT/Ps that do not meet one or more of the 21 CFR 1271.10(a) criteria, 
provided that use of the HCT/P does not raise reported safety concerns or potential 
significant safety concerns. 
 
FDA intends to focus enforcement actions on products with higher risk, including based 
on the route and site of administration.  For example, actions related to products with 
routes of administration associated with a higher risk (e.g., those administered by 
                                                 
32 The November 2017 guidance, corrected in December 2017 provided a period of 36 months, through November 
2020, in which FDA intended to exercise enforcement discretion.  This enforcement discretion period now extends 
through May 2021. 
 
22  Contains Nonbinding Recommendations 
intravenous injection or infusion, aerosol inhalation, intraocular injection, or injection or 
infusion into the central nervous system) will be prioritized over those associated with a 
lower risk (e.g., those administered by intradermal, subcutaneous, or intra-articular 
injection).  HCT/Ps that are intended for non-homologous use, particularly those intended 
to be used for the prevention or treatment of serious and/or life-threatening diseases and 
conditions, are also more likely to raise significant safety concerns than HCT/Ps intended 
for homologous use because there is less basis on which to predict the products behavior 
in the recipient, and use of these unapproved products may cause users to delay or 
discontinue medical treatments that have been found safe and effective through the New 
Drug Application or BLA approval processes. 
 
Regenerative medicine is a complex and rapidly evolving field.  Accordingly, FDA will 
continue to reassess its application of the HCT/P regulatory framework, including the 
minimal manipulation and homologous use criteria in 21 CFR 1271.10(a), as additional 
scientific evidence emerges in this field.  
 
 
VI.  ADDITIONAL INFORMATION 
 
23.  What regulations apply if my HCT/P is regulated as a biological product?33 
 
HCT/Ps that are regulated as biological products are subject to section 351 of the PHS 
Act and the FD&C Act and require premarket approval.  Such HCT/Ps are subject to the 
applicable drug regulations, including the requirements in 21 CFR Parts 210 and 211, and 
the applicable requirements in 21 CFR Parts 600 through 680.  Such products are also 
regulated under section 361 of the PHS Act and are subject to requirements in 21 CFR 
Part 1271 designed to prevent the introduction, transmission, and spread of 
communicable diseases.  Pursuant to these regulations, you are required to register as an 
establishment, and list your HCT/Ps (21 CFR 1271.1(b)(2)) (see section VI. question 25 
of this document). 
 
In order to lawfully market a biological product, a biologics license must be in effect  
(PHS Act 42 U.S.C. 262(a)).  Such licenses are issued only after a determination by FDA 
that the establishment(s) and the biological products meet the applicable requirements to 
ensure the continued safety, purity, and potency of such products (21 CFR 601.2(d)).  For 
clinical studies of investigational drug products, the sponsor must have an IND 
application in effect in accordance with the FD&C Act (21 U.S.C. 355(i)) and FDA 
regulations (21 CFR Part 312 and 21 CFR 601.21).  See section VI. question 27 of this 
document about obtaining more information regarding the IND process. 
 
   
                                                 
33 Some HCT/Ps may be regulated as devices.  For more information about device regulation, see CDRHs webpage 
Device Advice  Overview of Medical Device Regulation at 
https://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/Overview/default.htm. 
23  Contains Nonbinding Recommendations 
24.  What must I do if my HCT/P meets the criteria for regulation solely under 
section 361 of the PHS Act and 21 CFR Part 1271? 
 
If you are a domestic or foreign establishment that manufactures an HCT/P that is 
regulated solely under section 361 of the PHS Act and 21 CFR Part 1271, you must, in 
accordance with 21 CFR 1271.1(b)(1): 
 
1) Register with FDA (see section VI. question 25 of this guidance); 
2) Submit to FDA a list of each HCT/P manufactured; and 
3) Comply with all applicable requirements contained in 21 CFR Part 1271. 
 
Establishment means a place of business under one management, at one general physical 
location that engages in the manufacture of HCT/Ps, including: 
 
1) Any individual, partnership, corporation, association, or other legal entity 
engaged in the manufacture of HCT/Ps; and 
2) Facilities that engage in contract manufacturing services for a manufacturer of 
HCT/Ps (21 CFR 1271.3(b)). 
 
Manufacture means, but is not limited to, any or all steps in the recovery, processing, 
storage, labeling, packaging, or distribution of any human cell or tissue, and the screening 
and testing of the cell or tissue donor (21 CFR 1271.3(e)). 
 
25.  Must I register as an HCT/P manufacturer? 
 
FDA regulations require establishments that perform one or more steps in the 
manufacture of HCT/Ps to register and submit a list of products with the Agency.  If you 
are a manufacturer that is required to register, you must do so within five days after 
beginning operations (21 CFR 1271.21(a)).  Registrations must be updated annually in 
December (21 CFR 1271.21(b)), except if the ownership or location of the establishment 
changes, or if there is a change in the United States agent's name, address, telephone 
number, or email address, in which case, you must submit an amendment to the 
registration within 30 calendar days of the change (21 CFR 1271.26). 
 
26.  How can I get more information about the appropriate regulatory 
considerations for my HCT/P? 
 
The Agency provides two mechanisms through which a manufacturer may obtain a 
recommendation or decision regarding the classification of an HCT/P: 
 
1) The Tissue Reference Group (TRG), a group that includes representatives from 
CBER and CDRH, provides product sponsors with an informal process through 
which they may obtain an Agency recommendation regarding the application of 
the criteria in 21 CFR 1271.10(a) to their HCT/Ps for a given indication. 
Information about this process as well as what you may want to include to 
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facilitate review of your request can be found at:  https://www.fda.gov/vaccines-
blood-biologics/tissue-tissue-products/tissue-reference-group . 
 
2) A Request for Designation (RFD) may be submitted to the Office of 
Combination Products (OCP) to obtain a formal Agency decision regarding the 
regulatory identity or classification of an HCT/P (21 CFR Part 3).  A description 
of that process and information on how to submit an RFD can be found at: 
https://www.fda.gov/combination-products/rfd-process.  Additional information 
may be found at https://www.fda.gov/regulatory-information/search-fda-
guidance-documents/how-write-request-designation-rfd.  You may also submit a 
Pre-RFD to OCP to obtain preliminary feedback on the classification for your 
HCT/P as well as assistance on how to prepare an RFD.  Additional information 
may be found at https://www.fda.gov/regulatory-information/search-fda-
guidance-documents/how-write-request-designation-rfd. 
 
27.  How can I obtain more information about the IND process for my HCT/P 
that requires premarket approval? 
 
Further information about IND requirements for biological products may be obtained 
through the Division of Regulatory Project Management, Office of Tissues and Advanced 
Therapies, at 240-402-8190 or mail to:OTATRPMS@fda.hhs.gov. 
 
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