Characterization of cord blood stem/progenitor cells (high proliferative potential colony-forming cells).

A population of very primitive cells has been purified from umbilical-cord blood. These primitive cells appear to be the equivalent of murine, high-proliferative potential, colony-forming cells (HPP-CFC). This analogy is based on the size of the colonies (1 to > 2.5 mm in diameter) and the replating potential of up to the fifth generation of individual colonies. At a single-cell level and in the presence of serum, increasing numbers of cytokines resulted in increasing numbers of HPP-CFC colonies. No HPP-CFC colonies were detected in the absence of serum, suggesting that additional cytokines are required for formation of these high-proliferative potential colonies.