Potential use of hematopoietic stem cells after radiation injury.

Bone marrow transplantation has been used for several years in the treatment of hematopoietic system malfunction. However, this particular therapy option has had minimal benefit when the hematopoietic system failure results from radiation exposure, such as that after the Chernobyl accident. In the last ten years, there has been considerable progress in the development of methods to encourage stem cell repopulation with the application of hematopoietic growth factors, and to reconstitute the hematopoietic system with stem cells extracted from the peripheral blood. Problems with allogeneic bone marrow or peripheral blood stem cell transplantation as a therapy option include graft-versus-host disease and a shortage of human leukocyte antigen (HLA)-matched donors. These problems can be overcome if an autologous bone marrow or peripheral blood transplant is performed, but this is not always practical. Another approach to combat these difficulties is the use of umbilical cord blood as a source of donor cells, since placental blood is rich in stem cells and less prone to lead to graft-versus-host disease than mature blood.