Quality reference

Cold Chain Validation and Storage

Reviewed by ExaVeyra Sciences editorial team · Updated 29 August 2026

A certificate of analysis describes material at the moment it was released. Everything after that is handling, and handling is the one part of the chain where a preparation that left the supplier in specification can quietly stop being in specification before anyone opens it.

This page covers what the storage literature actually establishes, why the excursion policy matters more than the target temperature, and the receiving checks that catch a problem while it is still returnable.

Storage conditions are part of what you are buying

Published work on storing vesicle preparations finds that conditions affect measurable properties of the material rather than simply shortening how long it lasts. Particle counts, size distribution and surface markers can all shift depending on how a preparation was held.

The practical consequence is that a mishandled vial is not a weaker version of the same thing. It may be a differently characterised thing, and the certificate in the file no longer describes it.

Decide the freeze and thaw policy deliberately

Repeated freeze and thaw cycles are among the conditions storage studies identify as affecting vesicle preparations. Each cycle is a handling event, and cycles accumulate across the whole chain rather than resetting at each stop.

A practice that thaws a vial, uses part of it, and refreezes the remainder has made that decision whether or not anyone recorded it. Worth deciding deliberately and writing into the procedure.

The excursion policy is the answer worth having

Every supplier can state a storage temperature. The more useful question is what happens when it is not held: how long an excursion is tolerated, at what temperature, and whether the material is still considered in specification afterwards.

A supplier who has validated their product can answer that. A supplier who has not will offer a target temperature and no tolerance, which leaves the judgement with you at the exact moment you have least information.

Receiving checks that take three minutes

  • The shipment arrived within its stated temperature range, with whatever monitor was agreed still readable.
  • The lot on the container matches the lot on the paperwork. A mismatch is a stop, not a note.
  • Coolant is still in the state it should be in. Fully thawed coolant on a cold-chain shipment is an excursion whether or not a monitor recorded one.
  • The container closure is intact and the label legible, including the lot and the date.
  • Time from delivery to storage is recorded, because a shipment that arrived correctly and then sat on a counter has still had an excursion.

The last one is the one most often missed. The cold chain does not end when the courier hands the box over; it ends when the material reaches its storage location.

Write it down, because a record is what you will need

A habit produces no evidence. A short written procedure produces a record, survives staff turnover, and is what a state board, an auditor or a supplier will ask for when a lot is queried.

It is also what makes a claim actionable. A supplier can investigate an excursion you documented at receipt, and cannot do much with one noticed three weeks later.

How ordering works when the chain is handled for you

A supplier who has validated their product can state the storage condition, the excursion tolerance and the shipping method before you order, which is what lets a practice plan around them rather than discover them.

ExaVeyra ships cold-chain material with the storage condition stated and the handling documented, and releases that documentation to NPI-verified practices alongside pricing and the formulary.

Sources

  1. 21 CFR Part 1271, human cells, tissues, and cellular and tissue-based products (accessed 29 August 2026)

Scientific literature

Each source carries the kind of study it was and, where the study enrolled people, how many. Study design decides what a result can establish, so it is stated rather than left to be inferred. Each line also says what that source is carrying on this page.

  1. Görgens A, Corso G, Hagey DW, et al. Identification of storage conditions stabilizing extracellular vesicles preparations. Journal of Extracellular Vesicles, 2022. doi:10.1002/jev2.12238 PMID:35716060In vitroSource 1 supports: Storage conditions tested systematically against measurable properties of the preparation. Cited for the central point that handling changes what the material is, not only how long it lasts.
  2. Sivanantham A, Jin Y Impact of storage conditions on EV integrity, surface markers and cargos. Life, 2022. doi:10.3390/life12050697 PMID:35629364Narrative reviewSource 2 supports: A review of how storage affects vesicle integrity, surface markers and cargo. Cited for the breadth of properties involved, which is why a mishandled vial is not simply a weaker version of the same material.
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Common questions

What storage temperature should these preparations be held at?
The container label governs, and it is set by the supplier who validated the product. A page like this one has no standing to set a specification, and a number quoted here that differed from the label would be actively unhelpful. Ask the supplier for the validated condition and hold to what is printed on the vial.
A shipment arrived warm but the monitor showed no alarm. What now?
Record what you observed, including the state of the coolant, and raise it with the supplier before use. A monitor reports the conditions it sampled; a fully thawed coolant pack is evidence in its own right. This is the point at which a supplier can still investigate the lot.
Can we refreeze a partially used vial?
That is a supplier and prescriber question rather than a general one, and the answer belongs in your procedure rather than in a habit. Freeze and thaw cycles are among the conditions storage studies identify as affecting these preparations, and cycles accumulate across the whole chain.
Does a certificate of analysis cover the material after shipping?
No. It describes the material at release, on the sample tested. Nothing on it speaks to what happened in transit or in your own storage, which is exactly why the receiving checks and the excursion policy matter.

Related reading

Sterility, endotoxin, and mycoplasma testingQualifying a supplier before the first orderMISEV2023 and supplier documentationEvaluating an exosome supplierHow to evaluate an exosome supplier COA

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease. There are no FDA-approved exosome products. Biomolecular signaling vesicle products distributed by ExaVeyra Sciences are supplied for topical aesthetic treatments in clinics and for medical, molecular biology, and biochemistry research applications, and are not tissue products as defined by FDA guidelines.

This guide summarizes publicly available federal regulation for licensed practitioner education. It is for informational purposes only, it is not legal advice, medical advice, or regulatory guidance, and it does not establish that any particular product or practice is compliant. Regulation changes, and state requirements frequently differ from the federal floor. Consult a healthcare attorney licensed in your jurisdiction and your own state boards before acting on anything here.