Cord Blood Stem Cell Transplantation: Banking and Clinical Results

Abstract

Since the demonstration that the number of hematopoietic stem cells contained in one cord blood was sufficient for engrafting children and adults, cord blood banking has developed worldwide. Cord blood banking for allogeneic unrelated and related transplants has several advantages including availability of this source of stem cells, low viral infection rate at birth, speed of search, and the possibility to collect cord blood in ethnic groups underrepresented in bone marrow donors registries. Another possible advantage includes the low risk of acute graft-versus-host disease (GVHD), even with some degree of HLA mismatch. Currently, more than 25 000 units are available for transplantation. To develop and evaluate cord blood transplant (CBT) results, the European Blood and Marrow Transplantation group (EBMT) has organized a concerted action, the Eurocord group. The objectives of Eurocord are to study the properties of hematopoietic progenitors and gene transfer in cord blood; to study the immune function of cord blood lymphocytes; to coordinate and facilitate the exchange of sera and cells from donor and recipients of cord blood transplants; to establish a European registry of patients treated by cord blood transplants; and to design protocols comparing, cord blood transplants with alternative conventional blood and bone marrow hematopoietic stem cell transplants. Recently, Netcord, a nonprofit organization, was created for establishing criteria of qualification and accreditation of cord blood banks, and a network was set up between cord blood banks for facilitating: donor search. The purpose is to ensure the quality of the cord blood units obtained for transplantation and to aid transplant centers in finding suitable units to increase the number of cord blood transplants (CBT) throughout the world. Briefly, recent analysis of the clinical results in 255 CBTs performed in 90 countries has shown that factors associated with better survival in related and unrelated transplants were younger age, diagnosis with better results in children with inborn errors, and acute leukemia in first and second remission. High numbers of nucleated cells in the transplant and recipient-negative CMV serology were also favorable risk factors for survival. The most important factor influencing engraftment was the number of cells infused.