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StemCell Longevita

Laboratory documents

How to verify a cell viability claim

Viability figures are the most quoted and least qualified number in the industry. A percentage means nothing without the method, the timing and the assay it was measured with.

Medically reviewed by:
Prof. Dr. Erdal Karaöz Team
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The short answer

Always ask three questions about any viability figure: measured by what method, measured at what moment, and measured on which batch. Viability at the end of culture, viability at release and viability at the bedside after transport are different numbers, and the last one is the only one that affects you. Ask for the release figure with its method, and ask what the specification threshold is — a documented 85 per cent against a stated limit is more trustworthy than an unsourced 99 per cent.

How to verify it, step by step

These steps work at any clinic, anywhere. Nothing here depends on choosing us.

  1. Ask which assay was used: trypan blue exclusion, acridine orange/propidium iodide, or flow cytometry with a viability dye. Automated dye-exclusion and flow methods can differ by several percentage points.
  2. Ask at what point the sample was taken: post-harvest, at final formulation, at release, or on arrival at the treatment site.
  3. Ask for the release specification, not just the result. A number with no threshold is marketing.
  4. Ask how the product is transported and how long it sits between release and administration, since viability falls with time and temperature excursions.
  5. Ask whether viability is re-checked at the bedside for products with a long transport leg.
  6. Compare the figure with the CoA for your batch. If the website figure and the batch figure differ, the batch figure is the real one.

What good looks like, and what should worry you

Verification signals for Verify cell viability
What you are checkingAn acceptable answerA red flag
Method statedNamed assay, e.g. flow cytometry with 7-AADA bare percentage with no method
Timing stated'At release' or 'at administration', with a timeNo timepoint given
SpecificationA written minimum the batch is judged againstNo threshold exists
Batch-specificYour batch's number, on your CoAOne marketing figure quoted for every patient
TransportTime and temperature controlled and recordedUnknown transit conditions
PlausibilityA realistic range with batch-to-batch variationIdentical perfect figures for every patient

How we grade claims like these: How we evaluate evidence · Editorial standards · Conflict-of-interest disclosure.

Documents to request in writing

Ask by email so the answer is documented. A clinic that cannot send these before payment is telling you something.

  • The viability result for your batch, with method and timepoint
  • The release specification for viability
  • The transport time and temperature record between release and administration
  • Whether a bedside re-check is performed, and its result if so

Do not write it yourself: copy our ready-made email and WhatsApp request.

Frequently asked questions

Higher is better all else being equal, but a viability figure alone does not establish potency, identity or sterility. A highly viable product of the wrong cell type at the wrong dose is still the wrong product.

Because they measure at different moments with different assays. This is exactly why the method and timepoint matter more than the headline number.

Published cell-therapy release specifications commonly sit in the region of 70 to 90 per cent depending on product and method, with fresh products at the higher end. Treat any claim of near-perfect viability at the bedside, quoted identically for every patient, as a marketing number until a batch document supports it.

Batch-level release data are shared with the patient for their own batch, and aggregate ranges are published in our laboratory transparency report rather than as a single promotional figure.

Sources

  1. Dominici et al. Minimal criteria for defining multipotent mesenchymal stromal cells (ISCT position statement)
  2. cell viability assay comparison trypan blue flow cytometry cell therapy — Method-comparison literature.
  3. European Commission EudraLex Volume 4 — GMP guidelines

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Use this on us too

Send these questions to us exactly as written. We answer them with documents, and if something does not apply to your case we say so.

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