FDA Regulation of Exosome and Extracellular Vesicle Therapeutic Products

FDA regulation of exosome and extracellular vesicle therapeutic products

Exosome and extracellular vesicle (EV) products intended to treat human disease are regulated by FDA's Center for Biologics Evaluation and Research (CBER) as drugs and biological products. That means they need an investigational new drug application (IND) for clinical study and a biologics license application (BLA) before marketing. FDA has stated this position in warning letters since 2019. It has also issued a public safety notification after serious adverse events in patients treated with unapproved products marketed as containing exosomes. This article covers the legal classification, what an IND for an EV product must show on manufacturing and characterization, and the enforcement record against unapproved exosome products.

Classification: why exosomes are biologics, not "361 HCT/Ps"

The HCT/P definition and its exclusions

Much of the confusion in the exosome market comes from treating exosomes as human cells, tissues, and cellular and tissue-based products (HCT/Ps), which can avoid premarket review if they meet the 21 CFR 1271.10(a) criteria. Under 21 CFR 1271.3(d), HCT/Ps are "articles containing or consisting of human cells or tissues that are intended for implantation, transplantation, infusion, or transfer into a human recipient" ²⁰. The definition expressly excludes "secreted or extracted human products, such as milk, collagen, and cell factors," with semen as the only exception ²¹.

FDA's guidance Regulatory Considerations for Human Cells, Tissues, and Cellular and Tissue-Based Products: Minimal Manipulation and Homologous Use repeats this point. Secreted or extracted human products are not HCT/Ps. Secreted body fluids such as amniotic fluid generally are not HCT/Ps, although cells obtained from those fluids generally are ³⁶³⁷. The guidance says the regulatory status of products that are not HCT/Ps is beyond its scope ³⁸. FDA's earlier Proposed Approach to Regulation of Cellular and Tissue-Based Products also excluded products secreted by or extracted from cells or tissues and said other rules generally cover them ³⁹.

The practical result is that an acellular vesicle preparation does not fit the 361 HCT/P pathway in the first place. In its warning letters, FDA usually does not run the four-part 1271.10(a) analysis on exosome products. It classifies them directly as drugs and biologics (see the enforcement section below).

The 361 versus 351 framework, for context

For products that are HCT/Ps, regulation solely under section 361 of the PHS Act requires that the product meet all four criteria in 21 CFR 1271.10(a) ²⁴:

1. Minimally manipulated.
2. Intended for homologous use only, as shown by labeling, advertising, or other indications of the manufacturer's objective intent ²⁵.
3. Not combined with another article, except water, crystalloids, or a sterilizing, preserving, or storage agent, provided the addition raises no new clinical safety concerns ²⁶.
4. Either no systemic effect and no dependence on the metabolic activity of living cells for its primary function, or, if either applies, autologous use, allogeneic use in a first- or second-degree blood relative, or reproductive use ²⁷.

Under 21 CFR 1271.20, an HCT/P that fails these criteria and does not qualify for a 1271.15 exception "will be regulated as a drug, device, and/or biological product under the act and/or section 351 of the PHS Act" ³⁹². FDA's guidance describes the same tiered analysis. It assesses the same-surgical-procedure exception first, and if any criterion is unmet, premarket review generally applies ¹⁶⁶¹⁶⁷.

This matters for exosomes when a product marketed as an "exosome" product actually contains cellular or tissue material. In the August 14, 2026 letter to R3 Medical Companies, FDA said the manufacturing process for ReBellaXO and ReBellaXOL "does not appear to isolate exosomes" ²⁰⁴²⁰⁵. FDA then analyzed those umbilical cord-derived products as HCT/Ps. It found that no 1271.15 exception applied and that they failed the homologous-use criterion, so they were not regulated solely under section 361 ²¹¹²¹². Either way the product ends up under section 351. The label alone does not set the analysis.

Statutory basis in enforcement correspondence

FDA's warning letters cite two statutes. The first is the drug definition in FD&C Act section 201(g)(1). The second is the biological product definition in PHS Act section 351(i) ¹⁸⁹¹⁷². At the regulatory level, 21 CFR 600.3 defines "biological product" to include a "protein, or analogous product... applicable to the prevention, treatment, or cure of a disease or condition of human beings" ³⁰⁹. FDA's standard formulation, repeated across letters, is that exosome products intended to treat human diseases or conditions are regulated as drugs and biological products subject to premarket review and approval ^298183171. More recent letters extend this to exosomes intended to "affect the body's structure or function" ³⁰¹³²².

Calling a product "cosmetic" or "for research use" does not change this. In the Kimera Labs letter, FDA found that XoGlo and XoGlo Pro were marketed to treat diseases or conditions despite the firm's statement that they were for cosmetic use. XoGlo labeling referred to treating skin damage after facial injury ²⁴²²⁴³. In the Supreme Rejuvenation letter, FDA classified the products as unlicensed biologics "notwithstanding" research-use language on the website ¹⁸⁹¹⁷².

The end of enforcement discretion

FDA's November 2017 regenerative medicine policy gave time-limited enforcement discretion on IND and BLA requirements for certain HCT/Ps. The July 2020 update of the minimal manipulation guidance extended that discretion through May 31, 2021 ⁴⁰¹⁶⁸. When announcing the extension, FDA said the policy did not cover products with reported or potentially significant safety concerns, and it told patients to confirm that a product was FDA-approved or under study in an IND ^119138139. Even during the discretion period, FDA said it would prioritize higher-risk routes for enforcement: intravenous injection or infusion, aerosol inhalation, intraocular injection, and injection or infusion into the central nervous system ¹⁶⁹. Exosome products were never a clean fit for a policy written for HCT/Ps, and FDA warned exosome sellers during that window (Stemell 2019, Invitrx and EUCYT 2020, Create Wellness 2020) ^181183182298.

IND expectations: manufacturing and characterization

FDA has not issued an exosome-specific CMC guidance. Sponsors of EV therapeutics therefore work from the general IND regulations, the cell and gene therapy CMC guidances, and the inspectional observations in exosome warning letters, which show where FDA sees deficiencies.

Regulatory baseline: 21 CFR 312.23(a)(7)

The IND's CMC section must describe the composition, manufacture, and control of the drug substance and drug product. In every phase it must provide "sufficient information ... to assure the proper identification, quality, purity, and strength of the investigational drug" ³⁸⁹. In a Phase 1 submission, emphasis "should generally be placed on the identification and control of the raw materials and the new drug substance," and final specifications "are not expected until the end of the investigational process" ³⁸⁹. Stability data are required in all phases for the planned duration of the investigation, and the sponsor should submit information amendments as development and scale expand ³⁹⁰.

Source material and donor eligibility

EV products are made from human cell sources such as mesenchymal stromal cells, Wharton's jelly, and umbilical cord. That makes source control and donor eligibility central. CBER's somatic cell therapy CMC guidance (Content and Review of CMC Information for Human Somatic Cell Therapy INDs) asks for:

• A detailed account of the cells, cell banks, reagents, and excipients.
• Tissue recovery and processing steps, purification, donor screening and testing, and final formulation.
• The source and testing of all materials, including the tissue and cell type used ⁹⁷⁹⁸.

The April 2024 draft guidance Considerations for the Use of Human- and Animal-Derived Materials in the Manufacture of Cell and Gene Therapy and Tissue-Engineered Medical Products names extracellular vesicles and exosomes as "cell-derived particles" ³⁴⁰³⁴¹. It addresses them as manufacturing materials and potential impurities rather than as stand-alone therapeutics ²⁸. Its recommendations still apply directly to EV producer-cell systems:

• Donor eligibility under 21 CFR Part 1271, subpart C, for human-derived cells and cell particles ³⁴².
• Testing of cell banks for sterility, mycoplasma, and relevant human adventitious agents. Listed methods include in vitro and in vivo assays, transmission electron microscopy, PCR for human pathogens, and retrovirus testing where cells contact non-human materials ³⁴³³⁴⁴.
• Where bank testing is limited, a showing that the drug substance or product is free of adventitious agents ³⁴⁵.

The guidance also notes that establishing complete absence of residual cells is technically challenging ³⁴⁶. For an EV product, this bears on whether the product is truly acellular.

Characterization, identity, purity, and safety testing

The somatic cell therapy CMC guidance recommends testing cell banks, in-process materials, and final product for identity, purity (including endotoxin), and potency. It also recommends microbiological safety testing for sterility, mycoplasma, and adventitious viral agents, with acceptance criteria and release specifications appropriate to the stage of development ⁹⁹¹⁰⁰. For EVs, identity and purity testing must confirm that the product contains what it claims. The R3 Medical letter shows the risk. FDA questioned whether "exosome" products were exosome isolates at all ²⁰⁴²⁰⁵, and that finding moved the case into an HCT/P analysis.

Potency

FDA's final guidance Potency Tests for Cellular and Gene Therapy Products (January 2011) supports building potency measurement in stages during development. Where one assay is insufficient, it allows a complementary assay matrix. For licensure, it expects a validated assay or matrix with defined acceptance criteria ^72737475.

The December 2023 draft guidance Potency Assurance for Cellular and Gene Therapy Products would supersede the 2011 guidance when finalized ⁴⁵⁶⁶⁶⁷. It takes a risk-based approach that combines process design, material control, in-process testing, and lot-release potency assays, and it states that release testing alone cannot adequately assure potency ⁶⁸⁶⁹. Sponsors should:

• Identify potency-related critical quality attributes (CQAs) and select assays guided by an understanding of the mechanism of action ⁴⁹⁴¹.
• Describe the potency assurance strategy in the IND.
• In the initial IND, either set out lot-release assays and acceptance criteria or explain how other controls give adequate early-phase assurance ⁶⁰⁶³.

This is a major hurdle for EV products, where the active moiety (protein, RNA cargo, or membrane-associated factors) and the mechanism are often poorly defined.

Phase-appropriate CGMP

Under Current Good Manufacturing Practice for Phase 1 Investigational Drugs (July 2008), most Phase 1 biological drugs are exempt from 21 CFR Part 211 under 21 CFR 210.2(c). They remain subject to statutory CGMP ²⁸⁹. FDA expects:

• Written procedures, controlled equipment and environments, and accurate records ²⁹¹²⁹².
• A written QC plan ²⁹³.
• For aseptically processed products, ISO 5 aseptic manipulation and media process simulation ²⁹⁴.

Commercial distribution falls under full CGMP. The Kimera and Invitrx letters below show the deficiencies FDA cites most often for EV manufacturers.

FDA enforcement precedents involving unapproved exosome products

The public safety notification

In a December 6, 2019 announcement, FDA said it had issued a safety alert on exosome products. The alert followed multiple reports of serious adverse events in Nebraska patients treated with unapproved products marketed as containing exosomes ¹¹⁰¹³⁷. Later warning letters routinely cite this Public Safety Notification on Exosome Products, while noting that the adverse events were not attributed to the recipient's own products ^326227254263.

Warning letters naming exosome products

Patterns across the enforcement record

• Claims drive classification. In every letter, FDA's jurisdictional hook is the intended use shown by websites, social media, and videos. The claims range from COVID-19 and dementia to hair restoration and skin rejuvenation ^255258351298.
• Exosomes are usually classified without a 361 analysis. Many letters run the 1271.10(a) analysis only on co-marketed cellular products (cord blood, Wharton's jelly, UC-MSC) and classify the exosome products directly as 351 biologics ^184187191228. The exception is a product whose composition suggests it is not really an exosome isolate (R3 Medical) ²⁰⁴²¹¹.
• An IND does not permit commercialization. The Kimera letter makes clear that an IND in effect for one product does not authorize commercial distribution or test marketing, or distribution outside the IND ²⁴⁵¹⁸⁶.
• Recurring CGMP themes. Inspected EV manufacturers were cited for unvalidated aseptic processing, inadequate environmental monitoring, failure to investigate sterility failures, inadequate raw material testing, unvalidated identity, strength, quality, and purity tests, and expiry dating without stability data ^{246247248249250251208216328329330}.
• Recent letters cluster in 2025–2026. Of the fifteen letters above, eight were issued between May 2025 and October 2026, all from CBER. Four of them carry the subject "Unapproved New Drugs/Unlicensed Biological Product Violations" ¹⁴⁵⁸³. The recipients include clinics and an IV hydration business as well as manufacturers ¹²¹⁴³.

Practical takeaways for sponsors

• Treat any EV, exosome, or secretome product intended for a therapeutic, structure/function, or disease claim as a 351 biologic that needs an IND before clinical use and a BLA before marketing ²⁹⁸³⁰¹.
• Build the CMC package around 21 CFR 312.23(a)(7) ³⁸⁹. Key elements are donor eligibility and characterization of the producer-cell bank under Part 1271 subpart C ³⁴², identity and purity testing that confirms an acellular vesicle product ²⁰⁴³⁴⁶, and a potency strategy tied to a hypothesized mechanism of action ⁴⁹⁶³.
• Expect CGMP scrutiny of aseptic processing, sterility testing, and stability-based expiry. These are the deficiencies cited most consistently in exosome warning letters ^246249251216.