LONG-TERM GENERATION OF COLONY-FORMING CELLS (CFC) FROM CD34-CORD BLOOD-CELLS( HUMAN UMBILICAL)

Human umbilical cord blood cells represent a potential alternative to bone marrow as a source of stem and progenitor cells for allogeneic tr ansplantation. Therefore, many studies are underway to evaluate the nu mber of cord blood stem cells and their amplification potential. We an alyze here the amplification potential of CD34+ cord blood cells in li quid cultures stimulated with stem cell factor (SCF) in combination wi th interleukin-3 (IL-3), erythropoietin (Epo) or granulocyte colony-st imulating factor (G-CSF) under serum-deprived conditions. We report th at under certain circumstances (stimulation with SCF and IL-3, replaci ng of the medium and growth factors every 3-4 days, no change of the i nitial culture flask, 37-degrees-C as incubation temperature), CD34+ c ells give rise to differentiated cells and progenitor cells for more t han two months. During this period, more than 10(10) differentiated ce lls and 10(6) progenitor cells are generated from 0.25 - 1 x 10(4) CD3 4+ cells in the absence of a stromal layer. These data highlight the h igh proliferative and differentiative potential of cord blood stem cel ls and, because the culture procedures are relatively simple and do no t require a stromal layer, open the way to the clinical use of ex vivo stem cell expansion.