A Rapid and Accurate Method for the Stem Cell Viability Evaluation: The Case of the Thawed Umbilical Cord Blood

The umbilical cord blood (UCB) is a major source of hematopoietic progenitor cells. These cells can be cryopreserved for possible future use. In order to evaluate the viability of cryopreserved progenitor cells, a small amount of cells is thawed and subjected to the trypan blue exclusion test in order to count the dead (blue) cells and the live (white) cells. We used the Promega Glo-Max luminometer along with the CytoTox-Glo Cytotoxicity kit and the manufacturer's protocol as an alternative and rapid assay compared to the traditional trypan blue exclusion test. The calculated viability percentages were similar between the 2 assays, but the counting time for a whole 96-well plate is only 30 min. The CytoTox-Glo kit is a time-saving assay for the accurate evaluation of progenitor cell viability following cryopreservation and thawing.