Viability testing methods vary by supplier and lot. Ask what method was used and what sample was tested before treating a reported percentage as comparable across products.
Viability can change between tissue recovery and final testing; freezing, thawing and storage conditions can all reduce the proportion of live cells. If viability data is provided, confirm it was measured on the specific lot or a matched sample, not assumed from the source tissue alone.
A 2026 analysis of six commercial WJ products found low cell viability with only rare viable MSCs. Viability data, when available, is one of the more direct ways to evaluate a cell-related claim on a tissue product; ask whether it was measured on the actual lot shipped rather than on a different reference sample.
Viability data, when available, is a more concrete basis for evaluating a cell-related claim than marketing language alone.