Umbilical cord blood banking for unrelated transplantation: Evaluation of cell separation and storage methods

Cost-efficient umbilical cord blood (UCB) banking requires well-standardize d methods of volume reduction and storage. To compare UCB fractionation usi ng a technique of hydroxyethyl starch (HES) sedimentation with the Ficoll ( double) and Percoll methods, 50 whole units was allocated randomly to each procedure. HES resulted in a significantly better recovery of mononuclear c ells (57.5%), granulocyte/macrophage colony-forming units (CFU-GM) (88.4%), and CD34(+) cells (87.4%) and lesser volume reduction (85.5%). HES was the least laborious, time consuming, and expensive of the three procedures, co sting 3.4- and 4.4-fold less than the Ficoll and Percoll methods, respectiv ely. Five units processed by each method was frozen in 4.5-mL cryotubes und er optimal conditions. After thawing, the greatest degree of recovery of vi able nucleated cells and number of CFU-GM per unit were obtained using the HES procedure. Using 4.5-mL cryotubes, the calculated number of units that could be stored in 600-L containers was 3.8- and 2.2-fold higher for Ficoll - and Percoll-separated than for HES-separated units, respectively. Neverth eless, the higher direct costs of the density gradient separation procedure s outweighed their lower storage cost. For long-term cryopreservation, we a ssessed the freezing of HES-processed units in 50-mL cryobags and their spe cifically designed canisters, We found cell recoveries similar to those obt ained with cryotubes, but storage capacity was decreased. Special racks des igned for these canisters resulted in a 5-fold increase over the number of units stored in standard cryobags, This system also is feasible for Percoll - and Ficoll-separated units, resulting in comparable storage costs for the three separation methods, We conclude that this HES procedure and the 50-m L cryobags constitute a cost-efficient system for large-scale UCB banking. (C) 1999 International Society for Experimental Hematology, Published by El sevier Science Inc.