Colony-forming potential in cord allografts: a 2021 study explained

What colony-forming potential actually measures

A colony-forming unit assay, often shortened to CFU-f, is a laboratory method used to test whether a cell population contains cells capable of adhering to a plastic culture surface and multiplying into a visible colony. The ISCT minimal criteria are plastic adherence, CD73/CD90/CD105 expression and tri-lineage differentiation. The 2021 study separately assessed colony-forming potential.

The assay matters for cord tissue allografts because marketing language in this category sometimes implies a product contains living, functional stem cells without stating what evidence supports that claim. A colony-forming assay is one objective way to test whether a sample actually contains cells that behave the way a stem cell is defined to behave, rather than relying on a description of the tissue source alone.

The 2021 evaluation of commercial cord allograft products

A 2021 study published in the American Journal of Sports Medicine evaluated commercial umbilical cord allograft products for colony-forming potential and protein composition. Across the five products tested, the researchers did not find colony-forming mesenchymal stromal cells in any of them.

These were processed, off-the-shelf allografts in the same general category as current cord tissue allografts, not experimental or unprocessed tissue. The absence of a colony-forming signal does not mean the tissue is free of all cellular material; it means the specific functional test commonly used to demonstrate stem cell content did not show a positive result in that sample set.

How this lines up with later analyses of Wharton's jelly products

A more recent critical evaluation of Wharton's jelly-derived biologics examined six commercial products and reported low total cell counts and low viability, with only rare viable mesenchymal stromal cells identified. The direction of that finding is consistent with the 2021 result rather than contradicting it.

Taken together, these are two independent evaluations, using different product sets and somewhat different methods, that reported consistent directional findings: low or absent colony-forming and viable mesenchymal stromal cell content in the specific products each study tested. These findings should not be extended to other products, lots, or suppliers that were not part of either evaluation.

Why 'stem cell' is not accurate labeling for the products these studies tested

The products examined in these two evaluations were not documented to meet the combined ISCT bar described above. Evaluations like these support describing the specific tested products as perinatal tissue allografts or Wharton's jelly matrix products rather than stem cell products; broader claims about products that were not tested should not be inferred from this evidence.

FDA has also flagged the use of 'stem cell' language in connection with regenerative medicine products as something that creates confusion for both buyers and patients when the underlying documentation does not support it. How a specific product or claim should be labeled is a determination for the distributor's and clinic's own regulatory counsel, not something this article can resolve generally.

What this means for how distributors and clinics describe these products

A practical way to apply this evidence is to describe products factually, by tissue source and processing method, rather than by an unverified cellular claim. Terms like 'perinatal tissue allograft' or 'Wharton's jelly matrix product' describe what is known without implying a functional stem cell content that hasn't been demonstrated for the lot in question.

Clinics evaluating a supplier's marketing language should ask what specific testing, if any, stands behind a cellular claim, and whether that testing was performed on the lot being purchased or is a general statement about the product category.

Questions to ask before accepting a colony-forming or viability claim

If a supplier's materials reference cell content, viability, or colony formation, it is reasonable to ask for the specifics behind the statement before relying on it.

These products are not FDA approved or licensed for any disease or condition. Information is for licensed healthcare professionals and is not medical or legal advice.

• Ask which specific lots or batches were tested for colony-forming potential, not just the product category in general.
• Ask whether the cited data is proprietary and unpublished or appears in a peer-reviewed source that can be read directly.
• Ask whether any claim about living cells distinguishes between total cell count and functionally viable, colony-forming cells.
• Request the underlying ISCT minimal-criteria data, including surface markers and differentiation testing, if a stem cell claim is being made.