Cord blood banking for clinical transplantation.

Cord blood (CB) stem and progenitor cells from related donors have been transplanted for past 20 years and from unrelated donors issued by public CB banks for 16 years. This brief look at public CB banking highlights aspects of its current status to suggest that accomplishing the currently required tasks, though no small undertaking, is not enough: much remains to be contributed. CB banking started in the 1930s, collecting blood for transfusion and showed that CB could be effectively collected, stored and administered intravenously without negative consequences. The realization that it contains hematopoietic 'stem' cells (actually, colony-forming units) followed discoveries elsewhere in hematopoiesis research, while HLA and unrelated BMT were being investigated. Progress in the exploration of ethnically stratified HLA allele frequencies, together with plausible neonatal (partial) immunological tolerance, seemed to predict initially frequent, unavoidable, but sufficiently tolerable HLA mismatching with CB grafts. Gluckman et al. and Boyse et al. proved that HLA-identical sibling CB grafts led to definitive engraftment. Technical developments in processing and freezing enabled public banks to accumulate large inventories and to supply grafts that could succeed despite major HLA incompatibility and low cell doses and provide hope for universal access to unrelated-donor transplantation. Public CB banking has thrived worldwide. Regulation and accreditation defined Good Tissue Practice in the CB banking environment and provided accepted do's, don't's and how to's. Startling advances continue to be made, not only technical, but including the description of molecular regulation in the function of natural killer and other cells involved in allogeneic recognition that will have dramatic effects and will permit further improvement in CB selection and use.