Abstract 20 A Rapid and Sensitive IL-3-Based Assay Reveals How Various Pre-Processing Conditions Affect the Potency of Hematopoietic Stem Cells in Fresh Cord Blood Units

Abstract

IntroductionOptimized procedures to collect, process, and store cord blood (CB) units are crucial to ensure stem cell product quality; however, current methods to assess hematopoietic stem cell (HSC) potency are time-consuming or lack sensitivity. Therefore, developing methods that rapidly and accurately portray HSC potency in fresh blood is important to help optimize clinical outcomes.ObjectiveWe sought to adapt to fresh CB a potency assay previously developed for HSCs contained in cryopreserved CB [Simard et al. Transfusion. 2019;59(6):2074-2083.]. We next used the assay to evaluate the impact of various CB processing conditions on HSC potency.MethodsFresh CB units were exposed to various pre-processing storage conditions (ie, temperature changes and various anticoagulants). Units were then analyzed at various time points up to 96 hours using traditional iShage and colony-forming assays, in parallel with the IL-3-based potency assay.ResultsFor CB units maintained at room temperature (RT), the potency measured with the IL-3-based assay (ie, the proportion of IL-3-responsive CD34+ cells as measured by pStat5 activation) linearly decreased over time. A potency of 69% was observed when tested within 0-24 hours, compared with 56% and 40% in the 24-48–hour and the 48-72–hour groups, respectively. In addition, the IL-3-based assay showed that pre-processing storage at 4°C prevented this loss of HSC potency. By contrast, the HSC count by iShage and the CFU numbers remained unchanged with time or temperature variations.DiscussionThe newly developed IL3-based assay appears reliable and sensitive to characterize the potency of CD34+ cells in fresh CB. In addition, this assay indicated that HSC potency linearly decreased with time when CB units were maintained at RT but remained stable when units were stored at 4°C pre-processing. This temperature-related difference was not observed with traditional assays, indicating that the test could be a complementary tool to characterize CB units in research and operational settings.