EX-VIVO EXPANSION OF CD34- CORD-BLOOD CELLS(CD38)

CD34+ cord blood (CB) cells were expanded in stromal cell-free long-te rm culture (LTC), in the presence of various combinations of interleuk in-3 (IL-3), stem cell factor (SCF), IL-6, granulocyte-macrophage colo ny-stimulating factor (GM-CSF), and anti-transforming growth factor-be ta (anti-TGF-beta) antibody. The progenitor cell expansion was evaluat ed by monitoring the increase of CD34+ and CD34+ CD38- cells over a pe riod of 21 days. The expansion of immature (B1-CFC, HPP-CFC) and of mo re committed progenitors (CFU-GM, CFU-GEMM, BFU-E) was also evaluated in specific samples. Our results show that (a) CD34+ cell expansion is highly variable depending on the cord blood samples studied, (b) sign ificant correlations between B1-CFC and CD34+CD38- and between total C FU and CD34+ cell expansion are observed, (c) SCF in combination with IL-3 appears to expand cell subsets that continue to express their CD3 4+CD38- phenotype and that generate both immature and committed progen itors, and (d) the addition of IL-6, GM-CSF, or anti-TGF-beta does not significantly improve these expansions.