Characterization of cord blood stem/progenitor cells.

Based on in vitro studies, umbilical-cord blood has been used clinically to engraft the hematopoietic systems of children. To evaluate the capacity of a single collection of cord blood to engraft an adult, it is important to consider not only the number, but also the quality of stem/progenitor cells in cord blood. We demonstrate that cord blood contains multipotential progenitor cells, possibly subsets of stem cells, that have extensive self-renewal capacity, as estimated by their capacity to form numerous secondary colonies of multiple lineages in secondary replates from single multipotential colonies. This replating capacity is enhanced by a factor or factors, perhaps novel, in cord blood plasma.