Isolation, characterization and ex vivo expansion of CD34+ cells from umbilical cord blood

Problem. Umbilical cord blood (UCB) represents an alternative to bone marrow or peripheral blood as a source of hemopoietic progenitors that can be transplanted in an autologous or allogeneic setting, particularly in children. Methods. UCB CD34⁺ cells were purified by magnetic cell sorting, analyzed by flow cytometry, tested for proliferative response and clonogenic capability in the presence of SCF+IL-6 (CSF2) or SCF+IL-6 + IL-3 + GM-CSF + G-CSF + EPO (CSF6). Results. Median CD34⁺ yield was 84.5%, median CD34⁺ population purity was 96%. The starting CD34⁺ population, that was predominantly CD38⁺, HLA-DR⁺ and CD33⁺, expanded 11-15 fold by CSF2 and 35-67 fold by CSF6 stimulation. The CD34⁺CD33⁺ and CD34^-CD33⁺ subsets expanded more in the presence of the CSF2 than of the CSF6 combination. CSF6 was more efficient than CSF2 in increasing CFU-GM, CFU-E and/or BFU-E. Conclusions. These data suggest that a selective amplification of different types of hemopoietic progenitors may be obtained by varying cytokine combinations.