Analysis of hematopoietic stem cells and progenitor cells in human umbilical cord blood.

Human umbilical cord blood (HUC) has been considered as a possible source of hematopoietic stem and progenitor cells for transplantation. In this study, we characterized mononuclear cells and hematopoietic stem/progenitor cells in cord blood and compared them to those in human peripheral blood (HPB). The concentration of mononuclear cells in HUC was twice as high as that in HPB. The percentage of CD34-positive cells in HUC was 4.0 times that in HPB and the result of subset analysis suggested that HUC involves many immature cells. The plating efficiency of colony forming unit in mononuclear cells in HUC was 0.446±0.295%, 14.4 times higher than in HPB. Thus, HUC contains a large number of hematopoietic stem cells. In addition the rate of CFU-GM and CFU-mix in HUC was more than in HPB. It is suggested that HUC is better source of stem/progenitor cells. The limitation of HUC as a potential source of transplantable hematopoietic stem cells is its small quantity. It is necessary to develop a method to expand the number of hematopoietic stem/progenitor cells in HUC to obtain enough cells for allogeneic transplantation in adults.