Optimization of cryopreservation condition for hematopoietic stem cells from umbilical cord blood

The conditions for cryopreservation of CD34(+) hematopoietic stem cells (HSC) from umbilical cord blood (UCB) were optimized with a new cryo-medium containing 10% ethylene glycol (EG) and 2% dimethyl sulfoxide (Me(2)SO) using a controlled-rate freezing (CRF) method. After the cryopreservation of mononuclear cells (MNC) from UCB, recoveries of MNC, CD34(+) cells, and total colony-forming units (CFU) were significantly improved compared to those in the control cryo-medium containing 10% Me(2)SO and 2% Dextran-40 (P<0.05). This study shows that the new cryo-medium and CRF method provide better recoveries of MNC, HSC and total CFU than the control cryo-medium and isopropylalcohol freezing (IPA) method. Therefore, this cryo-medium, combined with the CRF method, is valuable for optimizing cryopreservation conditions for HSC from UCB to obtain satisfactory HSC recovery.