Umbilical cord blood transplantation.

Interest in umbilical cord blood as an alternative source of hematopoietic stem cells is growing rapidly. Umbilical cord blood offers the clinician a source of hematopoietic stem cells that are readily available and rarely contaminated by latent viruses. Moreover, the collection of umbilical cord blood poses no risk to the donor; there is no need for general anesthesia or blood replacement, and the procedure causes no discomfort. Whether cord blood lymphocytes are as likely to cause GVHD as lymphocytes from older individuals is unknown. Current clinical experience would suggest that the incidence may be low. Few of the patients who have thus far received umbilical cord blood, including recipients of HLA-disparate grafts, have developed clinically significant GVHD. These results and associated laboratory findings pose intriguing possibilities for the future of umbilical cord blood stem cells in the setting of unrelated-donor transplantation. With the marked incidence of Grade 2 to 4 acute GVHD that is currently observed after unrelated-donor bone marrow transplantation, a reduction in incidence or severity would be a major advance in this field. In the setting of autologous marrow transplantation, there are other intriguing possibilities; for example, cord blood may be an optimal source of pluripotential stem cells for use in gene therapy. As detailed in Broxmeyer's review, the large-scale collection and storage of cord blood stem cells is no longer just a concept; it has become a reality. Pilot programs for the banking of unrelated-donor umbilical cord blood have already begun in the United States and Europe.(ABSTRACT TRUNCATED AT 250 WORDS)