Comparison of BM transduction efficiencies and donor cell engraftment in hemophilia A mice following reduced-intensity TBI or nonmyeloablative BU-ATS conditioning regimens. (A) Flow cytometric histogram of GFP fluorescence 1 week after the third transduction with the MSGV-sfVIIIΔB vector at an MOI of 5 (sfVIIIΔB). The percentage of GFP⁺ transduced BM cells is indicated. (B) Southern blot analyses of ApaI/BstBI-digested genomic DNAs hybridized with a fVIII probe (top panel) and a Gapdh probe (bottom panel) showing the relative vector copy number per cell for the transduced BM cell populations that were transplanted into 550 cGy TBI– or BU-ATS–conditioned BAL-fVIIIKO mice. The results presented are representative of 2 independent experiments. (C) The percentage of GFP⁺ PB cells in 550 cGy TBI– or BU-ATS–conditioned hemophilia A mice that received MSGV-sfVIIIΔB–transduced BM cells as determined by quantitative flow cytometric analysis at various time points after transplantation. Error bars represent the SEM.