AN 8-FOLD EX-VIVO EXPANSION OF LONG-TERM CULTURE-INITIATING CELLS FROM UMBILICAL-CORD BLOOD IN STIRRED SUSPENSION-CULTURES

Simultaneous ex vivo expansion of different progenitor cell types may be beneficial for cord blood (CB) transplantation, to overcome a poten tial limitation due to restricted cell numbers. Therefore, 1.5 x 10(6) CD34(+) cells isolated from fresh or thawed CB samples were inoculate d in a large-scale stirred suspension bioreactor and cultured in the p resence of Flt3-L, SCF and IL-3, At days 0, 7, 10, 14, 21 and 28, the spinner cultures were analyzed for viable cells, colony-forming cells (CFC), including erythroid burst-forming unit (BFU-E), granulocyte-mac rophage colony-forming unit (CFU-GM) and granulocyte-erythrocyte-megak aryocyte-monocyte colony-forming unit (CFU-GEMM) as well as long-term culture-initiating cells (LTC-IC), Expansion of thawed CD34(+) cells r esulted in a substantial amplification of total cells (maximal at day 28: 154 +/- 132-fold), CFC (maximal at day 14: 45 +/- 36-fold), CFU-GM (maximal at day 14: 88 +/- 85-fold), CFU-GEMM (maximal at day 7: 4 +/ - 2-fold) and of LTC-IC (maximal at day 10: 8 +/- 3-fold). There was n o significant difference between fresh and thawed CD34(+) cells, These results demonstrate that simultaneously committed progenitors as well as the more immature CFU-GEMM and LTC-IC can be substantially amplifi ed from CD34(+)-enriched CB samples in large-scale stirred suspension cultures within 7-14 days without exhausting the proliferative potenti al and, thus, it may be possible to improve CB transplantation by ex v ivo generated cells.