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Regulatory reference
361 HCT/P vs 351 Biologic: Where Exosomes Sit
Reviewed by ExaVeyra Sciences editorial team · Updated 9 August 2026
An exosome product does not qualify as a 361 HCT/P. The four criteria in 21 CFR 1271.10 are cumulative, and an isolated vesicle preparation fails at least two of them before the analysis reaches the harder questions. That places exosomes under section 351 of the Public Health Service Act, which means premarket review. This page sets out the four criteria in full, so the reasoning can be checked rather than taken on trust.
The distinction matters commercially because the two pathways are not two grades of the same thing. A 361 HCT/P reaches the clinic through registration and listing. A 351 biologic reaches the clinic through an approved biologics license application, or through an investigational new drug application in a trial. There is no third route, and no amount of documentation converts one into the other.
The four criteria, verbatim
Section 1271.10 asks whether an HCT/P is regulated solely under section 361 of the PHS Act. It answers that it is, if it meets all of the following criteria:
- The HCT/P is minimally manipulated;
- The HCT/P is intended for homologous use only, as reflected by the labeling, advertising, or other indications of the manufacturer’s objective intent;
- 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
- The HCT/P does not have a systemic effect and is not dependent upon the metabolic activity of living cells for its primary function.
Why an exosome preparation falls outside it
Start with minimal manipulation. For cells or nonstructural tissues, minimal manipulation means processing that does not alter the relevant biological characteristics of the cells or tissues. Isolating vesicles from conditioned medium is not that. Culture, separation, and concentration are the entire point of the process, and the resulting article is not the starting tissue in a preserved state. It is a fraction of what the cells secreted.
Then consider what an exosome preparation is. The first criterion presupposes an HCT/P, defined as an article containing or consisting of human cells or tissues intended for implantation, transplantation, infusion, or transfer into a human recipient. An isolated vesicle preparation contains neither cells nor tissue. It is acellular. That is the same reasoning several states use, and it is why a stem cell statute written around cells and tissues does not reach exosomes either.
Homologous use compounds the problem rather than solving it. Homologous use means the product performs the same basic function in the recipient as in the donor. Because the criteria are cumulative, this question is only reached if the earlier ones are satisfied, which for an isolated vesicle preparation they are not.
| Criterion | Typical exosome preparation | Result |
|---|---|---|
| Minimally manipulated | Culture, isolation, and concentration alter the relevant biological characteristics | Not met |
| Homologous use only | Not reached; the analysis fails earlier | Not reached |
| No combination with another article | Formulation buffers may qualify, but this does not rescue the others | Not decisive |
| No systemic effect, not dependent on living cells | Arguable, and immaterial once the first criterion fails | Not decisive |
What the FDA has actually said
The agency addressed exosomes directly in its Public Safety Notification on Exosome Products, issued after reports of serious adverse events in Nebraska involving unapproved products marketed as containing exosomes. Two statements from that notification carry the regulatory weight.
Read the second statement carefully, because most summaries drop its qualifier. It is scoped to exosomes used to treat diseases and conditions in humans. That scope is what separates a therapeutic claim from research use and from topical aesthetic supply. It is not a loophole and it does not make an unapproved product approved. It does mean that the regulatory trigger in FDA’s own framing is the intended use, and intended use is established by labeling, advertising, and the manufacturer’s objective intent, exactly as the second 1271.10 criterion says.
The notification is equally direct about the argument that exosome products sit outside the drug and biologic rules altogether. FDA describes clinics claiming that these products do not fall under the regulatory provisions for drugs and biological products, and answers that the claim is simply untrue.
What this means for a practice sourcing material
The practical consequence is narrower than it first appears. The 361 versus 351 question governs how a product may be marketed and what claims may attach to it. It is not a question a purchasing practice resolves through paperwork, and no certificate of analysis, however complete, moves a product from one pathway to the other.
What documentation does establish is provenance and quality: what the material is, which lot it came from, what testing it passed, and under what conditions it was manufactured and stored. Those are the questions a supplier can answer, and they are the questions a practice should be asking. They are also, notably, the questions Tennessee wrote into statute when it became the first state to reference exosome-based regenerative products by name.
- Intended use is set by labeling, advertising, and objective intent, not by internal understanding.
- A 361 determination is not available for an isolated vesicle preparation, so nothing turns on arguing it.
- Premarket review under section 351 means an approved BLA, or an IND for investigational use in a trial.
- Documentation answers provenance and quality questions, which are real and answerable, rather than pathway questions, which are not.
This article summarizes publicly available federal regulation for licensed practitioner education. It is not legal advice, medical advice, or regulatory guidance, and it does not establish that any particular product or practice is compliant. Confirm current federal and state obligations with qualified counsel.
Sources
- 21 CFR 1271.10, criteria for regulation solely under section 361 (accessed 9 August 2026)
- 21 CFR Part 1271, Human Cells, Tissues, and Cellular and Tissue-Based Products (accessed 9 August 2026)
- FDA, Public Safety Notification on Exosome Products (accessed 9 August 2026)
- FDA guidance, Regulatory Considerations for HCT/Ps: Minimal Manipulation and Homologous Use (accessed 9 August 2026)
- FDA guidance, Same Surgical Procedure Exception under 21 CFR 1271.15(b) (accessed 9 August 2026)