Early apoptosis in CD34+ cells as a potential heterogeneity in quality of cryopreserved umbilical cord blood


Il-Hoan Oh, MD, PhD, Catholic Cell Therapy Centre, The Catholic University of Korea, 505, Banpo-Dong, Seocho-Ku, Seoul 137-701, Korea.
E-mail: iho@catholic.ac.kr


The increased use of umbilical cord blood (UCB) raises issues regarding the quality of cryopreserved UCB. This study investigated whether early apoptosis of CD34+ cells is part of the functional heterogeneity of cryopreserved UCB. Annexin V binding of CD34+PI(−) cells showed wide variations in both fresh and cryopreserved UCBs, with greater variation among units frozen for >5 years. Xenotransplantation of sorted cells into non-obese diabetic severe combined immunodeficient mice demonstrated that the Annexin V assay identified most repopulating activities in UCB units. Thus, early apoptosis of CD34+ cells could influence the outcome of transplantation using cryopreserved UCB.