Clinical use of umbilical cord blood hematopoietic stem cells

Umbilical cord blood hematopoietic stem cells coming from related or unrelated donors are an alternative source of hematopoietic stem cells for patients undergoing transplantation for a wide variety of diseases. In the unrelated donor transplant setting, shorter time to transplant, which is particularly relevant to patients requiring urgent transplantation, and tolerance of 1-2 human leukocyte antigen mismatch, which increases the chance of finding a suitable donor, are evident advantages over bone marrow transplantation. The speed of engraftment is slower after cord blood transplantation but it is counterbalanced by a lower incidence of severe graft-versus-host disease. Cell dose and human leukocyte antigen are major factors influencing outcome after umbilical cord blood transplantation. Retrospective comparisons of clinical outcomes between unrelated cord blood and unrelated bone transplantation in children and adults have shown similar results, showing the value of this source of hematopoietic stem cell for transplantation. This review describes the recent clinical results and discusses developing research strategies aimed at optimizing the results of cord blood transplantation. (C) 2006 American Society for Blood and Marrow Transplantation.