Regulatory reference
CMC Requirements for Exosome Products
Reviewed by ExaVeyra Sciences editorial team · Updated 9 August 2026
Chemistry, manufacturing and controls is the part of a submission that answers a single question: can you make this product the same way twice, and prove it. For an extracellular vesicle product the answer runs through identity, purity, potency, sterility, endotoxin, and adventitious agents. This page sets out what each of those means in practice, which assays actually satisfy them, and what changed in 2026.
The four lot release attributes
The general biological products standards at 21 CFR part 610 set the frame. A manufacturer completes conformity testing on each lot before release, and the attributes are identity, purity, potency, and sterility. Each has a specific regulatory meaning that is narrower than its ordinary English sense.
| Attribute | What the regulation means by it | Typical EV assay |
|---|---|---|
| Identity | Specific enough to identify the product as the one on the label and distinguish it from anything else processed in the same laboratory | Tetraspanin marker panel (CD9, CD63, CD81) by western blot or flow cytometry |
| Purity | Relative freedom from extraneous matter, including residual moisture, other volatiles, and pyrogenic substances | Particle-to-protein ratio, residual host cell protein, residual DNA |
| Potency | In vitro or in vivo tests specifically designed for the product so as to indicate its potency | A functional assay tied to mechanism, not a particle count |
| Sterility | Testing of each lot of final container material, per 21 CFR 610.12 | USP <71> sterility, or a validated rapid method |
Characterisation: counting and sizing
Particle concentration and size distribution are the baseline characterisation for any vesicle preparation, and the method matters because the numbers are not interchangeable between platforms.
- Nanoparticle tracking analysis tracks Brownian motion to derive a size distribution and concentration. Widely used, sensitive to dilution and camera settings, and it does not distinguish vesicles from similarly sized non-vesicular particles.
- Microfluidic resistive pulse sensing measures particles individually as they pass through a pore, giving a count that is less operator-dependent but requires an appropriate cartridge size range.
- Tunable resistive pulse sensing works on a similar principle with an adjustable pore.
- Electron microscopy confirms morphology but is not quantitative on its own.
Because platforms disagree, a particle count is only meaningful alongside the method that produced it. A certificate of analysis reporting a concentration without naming the instrument and method is not telling you enough to compare it against anything.
Safety testing
Three tests carry most of the safety weight, and one of them is routinely cited from a rule that no longer exists.
| Test | Reference | Note |
|---|---|---|
| Sterility | 21 CFR 610.12; USP <71> | Lot-specific. The 2011 amendments moved away from prescribed methods toward validated ones suitable for the product |
| Bacterial endotoxin | USP <85> | Gel-clot, kinetic turbidimetric, or chromogenic LAL methods |
| Mycoplasma | USP <63> | 21 CFR 610.30 was REVOKED effective 2020. Material citing it as a current requirement is out of date |
What FDA changed in 2026
In January 2026 FDA published its flexible approach to CMC requirements for cell and gene therapy products. The practical effect is that early-phase expectations are lighter than a great deal of older commentary suggests.
- Before an investigational product is manufactured for phase 2 or 3 trials, the manufacturer is not expected to comply with 21 CFR part 211. See 21 CFR 210.2(c).
- Final specifications for drug substance and drug product are not expected until the end of the investigational process, so INDs may provide permissive product quality release acceptance criteria during investigational studies.
- Process and method validation is reviewed on a lifecycle basis, on the understanding that approaches are refined over time.
- Moving from phase 1 into efficacy studies, CBER will allow minor manufacturing changes supported by comparability data without expecting overly stringent comparability packages.
- CBER will consider flexibility in establishing release specifications at BLA review, recognising that small patient populations do not always allow many lots to support specifications.
None of this lowers the bar for the finished product. It changes when the bar applies, which for a sponsor planning an investigational programme is the more useful thing to know.
Why this matters to a practice that is not a sponsor
Most practices reading this will never file an IND. The reason the CMC vocabulary is worth having anyway is that it is the vocabulary a certificate of analysis is written in, and it is increasingly the vocabulary state law is written in.
Tennessee Public Chapter 1016, effective 1 July 2026, defines regenerative medicine therapy partly by what a manufacturer documents, and it asks specifically for particle counts for exosome-based regenerative products, a viscosity report for Wharton’s jelly, a lot-specific sterility report, and a certificate of analysis for each product before use on a patient. Those are CMC concepts, lifted into a state statute. A practice that understands what each one is for can tell a complete supplier document from a decorative one.
- Ask which method produced a particle count, not just the number.
- Check that sterility and endotoxin results are lot-specific rather than a type certificate.
- Treat a potency claim that rests on particle count alone as unsupported.
- Note the date on the document, and whether its regulatory citations are current.
This article summarizes publicly available federal regulation and FDA guidance 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. Guidance documents represent FDA’s current thinking and are not binding. Confirm current obligations with qualified counsel.
Sources
- 21 CFR Part 610, General Biological Products Standards (accessed 9 August 2026)
- 21 CFR 610.12, Sterility (accessed 9 August 2026)
- Federal Register, Revocation of the Test for Mycoplasma (21 CFR 610.30) (accessed 9 August 2026)
- FDA, Flexible Requirements for Cell and Gene Therapies to Advance Innovation (accessed 9 August 2026)
- FDA draft guidance, Potency Assurance for Cellular and Gene Therapy Products (accessed 9 August 2026)
- Tennessee Public Chapter 1016 (2026), enacted text (accessed 9 August 2026)