The characteristics of umbilical cord blood (UCB) and UCB transplantation.

Umbilical cord blood (UCB) was disclosed to possess the proliferative capacity containing hematopoietic progenitors and has recently been applied for allogeneic transplantation as an attractive alternative to bone marrow or peripheral blood stem cells. UCB contains similar and higher proportions of immature hematopoietic progenitors, compared to bone marrow stem cells, although the number of collectable cells is limited. The yield of collectable UCB volume ranges from 70 to 150 ml. The colony formation of CFU-Mix of UCB was higher, but that of CFU-GM and CFU-E was lower, compared to those of bone marrow. The analyses of expression of differentiation antigens and adhesion molecules on CD34+ cells of UCB by flow cytometer, revealed that the coexpression rates of CD38 and CD44 on CD34+ cells were almost the same, but the mean fluorescence intensity of those was low compared to adult bone marrow. These results indicate that UCB contains more primitive hematopoietic progenitors. UCB transplantation has greater advantages of lower incidences of graft versus host disease, and unlimited number of donors compared with other allogeneic transplantation would widen the indication of transplantation by technical and methodological development.