Expansion of CD34+ cells from human umbilical cord blood by FL and/or TPO gene transfected human marrow stromal cell lines

To elucidate the effect of gene transfected marrow stromal cell on expansion of human cord blood CD34+ cells, a culture system was established in which FL and TPO genes were transfected into human stromal cell line HFCL. To establish gene transfected stromal cells co-culture system, cord blood CD34+ cells were purified by using a magnetic beads sorting system. The number of all cells and the number of CD34+ cells and CFC (CFU-GM and BFU-E) were counted in different culture systems. The results showed that in all 8 culture systems, SCF+IL-3+HFT manifested the most potent combination, with the number of total nucleated cells increasing by (893.3±52.1)-fold, total progenitor cells (CFC) by (74.5±5.2)-fold and CD34+ cells by 15.7-fold. Maximal expansions of CFC and CD34+ cells were observed at the end of the second week of culture. Within 14 days of culture, (78.1±5.5)-fold and (57.0±19.7)-fold increases in CFU-GM and BFU-E were obtained. Moreover, generation of LTC-IC from amplified CD34+ cells within 2