Rapid isolation and serum-free expansion of human CD34+ cells

Human CD34+ cells were isolated from bone marrow from normal volunteers and expanded under serum-free culture conditions. CD34+ cells were cultured with interleukin-3 (IL-3), IL-1, and stem cell factor and expanded in granulocyte-macrophage colony-forming units, erythroid blast-forming units, and CD34+ cell number during the first 7-14 days of incubation. By contrast, cultures maintained in fetal calf serum under identical conditions showed much reduced expansion, as measured by all of the above parameters. The level of expansion of the CD34+ cells was dependent on the combination of growth factors used during culture. The data establish the feasibility of serum-free expansion of progenitors and suggest the clinical use of this procedure for the generation of expanded progenitor cell products for transfusion after chemotherapy to minimize treatment-related cytopenias.