and Blood Institute. The analysis confirmed the hypothesis transplants matched with the recipient for four of six human leukocyte antigens (HLAs) is not as effective those matched at six of six antigens. The study also demonstrated that, with increased cell dose, a five of six match has survival rates almost identical to that of a six of six match.

The committee proposes the creation of a National Cord Blood Stem Cell Bank Program. The committee makes specific recommendations for the organization and administration, data management, and quality control in the national program that would best serve the needs of both the donors and the patients requiring stem cell transplants.

Stem cells, a primitive type of cell found in all animals, are capable of both self-renewal and differentiation into more specialized cells. These capacities offer great potential for regenerative medicine. This report recommends the development of an integrated system for the therapeutic use of one specific type of stem cell found in humans, the hematopoietic progenitor cell (HPC), which is a multipotent stem cell responsible for the continual production of the diverse array of normal blood cells. Because of the potential of HPCs to reconstitute bone marrow and peripheral blood, they have been used for the treatment of patients with bone marrow damage from either chemotherapy or underlying hematological failure for several decades.

HPCs can be obtained from a variety of sources including bone marrow, mobilized peripheral blood, and umbilical cord blood collected from the placentas of recently delivered infants. HPCs obtained from cord blood appear to have some advantages over HPCs obtained from bone marrow or peripheral blood. Among them, immune cells from umbilical cord blood are less mature1 than those from other sources, so their transplantation results in a lower risk of graft-versus-host disease, a common immune response to transplantation that can be fatal. In addition, cord blood is readily available, carries a low potential for infectious disease transmission, and involves minimal risk to the mother or the infant at the time of collection.

Because of these advantages over bone marrow, cord blood has the potential to be an excellent resource, opening up the possibility of transplantation to patients who either can not find a human leukocyte antigen (HLA) match within the bone marrow donor pool, or who are too ill to be able to wait for the sometimes lengthy process of searching and then har-

1  

Due to differences in T cells and other differentiated cells of the immune system.



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