Umbilical cord blood transplantation and cord blood banking

Bone marrow transplantation is currently an important treatment modality for leukemias, aplastic anemia, hereditary immunodeficiency and some metabolic diseases. However, bone marrow transplantation has two major limiting factors: First, it is not easy to find an Human Lymphocyte Antigen (HLA) matched donor in a timely manner. Second, there is the problem of graft-versus host disease (GVHD). Recently, hematopoietic progenitor cells were found in umbilical cord blood. Thus, placental blood, previously considered a waste product, now constitutes an alternative source of hematopoietic stem cells for bone marrow reconstitution. Since 1989, umbilical cord blood transplantation has been tried in place of traditional bone marrow transplantation for bone marrow reconstitution. Recent clinical experience has been encouraging and cord blood transplantation is tending to become an established treatment modality. The use of placental/cord blood, in some respects, offers advantages over bone marrow transplantation, so that more and more it has been used in lieu of traditional bone marrow transplantation. Cord blood is readily available, contains a higher concentration of hematopoietic progenitor cells, carries no risk for donors, has very low risk of transmitting infectious diseases (especially cytomegalovirus), is generally less expensive, is associated with a lower incidence of GVHD and offers the opportunity to target ethnic and racial minority groups. However, cord blood transplantation is limited by the small amount of cord blood available (not sufficient for adult patients), its short clinical experience, the long term results not yet being available, the absence of data regarding the effect of long term storage, the lack of an uniform storage protocol and standardized quality control procedures, and unresolved legal and ethical issues. In addition to cord blood transplantation, the culture and ex-vivo expansion of stem cells from cord blood provide great opportunities for research in the areas of immunology and gene therapy. All these factors have promoted the establishment of cord blood banks around the world. Approximately 15,000 cord blood units are currently stored and available for transplant. It is anticipated that, in the next 5 years, a total of 50,000 units will be reached. This number may be sufficient to provide for the majority of cord blood transplantation procedures. Cord blood transplantation and the establishment of cord blood banks around the world will obviously have a deep impact upon related medical and life sciences.