Clinical Data

The promising results of UCB as an alternative source of HSCs in pediatric related- and unrelated-donor transplantation generated worldwide interest. In 1992, in an attempt to more quickly learn the true risks and benefits of UCBT, the International Cord Blood Transplant Registry (ICBTR), now a part of the International Bone Marrow Transplant Registry (IBMTR), was established as a repository of clinical data on the outcomes of patients who received UCB. EuroCord, a registry and forum for the development of cooperative studies within the European community, was formed in 1995. Success in the pediatric population eventually led to UCBT for adult diseases. Analyses of UCBT clinical data have shown that the most important factor in predicting the rate and likelihood of engraftment is the number of nucleated cells infused (cell dose = TNC/kg). On the basis of the increased body mass of adults, the reduced cell dose limits the utility of UCB in this population. GVHD appears to occur less frequently following UCBT as compared to transplantation from BM and PB sources. This is thought to be a consequence of the immature immune characteristics of UCB. As a result of the reduced rates of GVHD, a greater degree of HLA disparity is allowed, further enlarging the potential-donor pool. Given the immature immune function of UCB grafts, a diminished graft-versus-leukemia (GVL) effect has been postulated but not observed. GVL effect following UCBT is believed to be the result of early CD3CD16/56+ NK-cell recovery eventually followed by T-cell reconstitution. Transplant-related mortality (TRM) following UCBT remains a significant limitation, particularly in the adult population, and is most often a result of the conditioning regimen, failed or delayed engraftment (infection and/or hemorrhage), or GVHD.

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