Flt3 Ligand prolongs survival of CD34 (+++) human umbilical cord blood myeloid progenitors in serum-depleted culture medium

Flt3 Ligand (L), a newly identified stimulating/co-stimulating cytokine for hematopoietic stem and progenitor cells, was assessed for its capacity, in comparison to that of steel factor, to prolong the survival in culture of hematopoietic stem and progenitor cells from CD34(+++) human cord blood. The addition of Flt3-L to serum-depleted cultures significantly prolonged the survival of high-proliferative-potential colony-forming cells (HPP-CFC) as well as that of multipotential (CFU-GEMM) and granulocyte-macrophage (CFU-GM) progenitor cells. The concentrations of Flt3-L necessary for these effects were similar to those of SLF, and low concentrations of Flt3-L and SLF which were inactive when used alone were active in these effects when used together. These results may be of practical value for short-term storage, treatment and/or transport of purified populations of cord blood stem and progenitor cells.