Figure 6. Transduction with UMG-LV6 carrying the MLL-AF9 fusion oncogene enhances the growth and clonogenicity of human CD34⁺ cells.

CD34⁺ cells purified from cord blood were transduced with void UMG-LV6 vector or UMG-LV6 carrying the MLL-AF9 cDNA (UMG-LV6-MA). (A) FACS analysis of CD34⁺ cells 5 days after transduction. The percentages of EGFP positive cells are indicated. (B) Q-RT-PCR analysis of the expression of MLL-AF9 in CD34⁺ cells transduced with UMG-LV6-MA. The expression level was compared to that of the MLL-AF9-positive THP-1 cells, assumed as 1. (C) 1×10⁴ CD34⁺ cells transduced with void UMG-LV6 vector or with UMG-LV6-MA/well were plated in triplicate in 6-well plates in cytokine-driven cultures in the presence of 100 ng/ml of stem cell factor, FLT3 ligand and thrombopoietin. The culture medium was refreshed weekly, and the cell numbers were determined two weeks after plating. (D) The number of clonogenic progenitors in CD34⁺ cells transduced with void UMG-LV6 vector or with UMG-LV6-MA after two weeks of cytokine-driven culture was determined by clonogenic assays in methylcellulose as described in Matherials and Methods.