The total nucleated cell count (TNC) is a major factor in the acceptance or rejection of an umbilical cord blood (UCB) unit. Yet it is stem cell potency that will decide whether a UCB unit has the capability to engraft and repopulate the patient after transplantation. The colony-forming cell (CFC) assay has been employed in a retrospective manner in order to document the possibility of growth potential of stem cell products destined for transplantation. Although some centers count and differentiate colonies, many use the assay to document either growth or no-growth because the results are difficult to interpret and provide little predictive value. Subjectivity and lack of an external standard to which the assay can be calibrated and validated means that the CFC assay can neither be employed as a reliable and reproducible stem cell potency assay, nor can it be used to define release criteria of UCB products for transplantation. A cell potency and release assay is required by standards and regulatory organizations. Viability and CD34 may be important for engraftment, but cannot measure stem cell potency. In a recent article in
Disclosures: Rich:HemoGenix, Inc: Equity Ownership, Owner and CEO of Company, Patents & Royalties.