RDTR/SCFHA-LVs target gene transfer to hCD34⁺ cells in the total CB MC population. MCs were isolated from fresh CB using a Ficoll gradient and cultured in the absence of RetroNectin. MCs were incubated with LVs pseudotyped with RDTR or VSV-G in the presence of human rSCF (50 ng/mL) or with vectors co-displaying RDTR or VSV-G with the SCFHA glycoprotein without addition of cytokines at MOI = 10 (A,C) and/or MOI = 1 (A-B). (A) At day 3 after transduction, cells were evaluated for CD34⁺ surface marker and GFP expression by FACS (means ± SD, n = 4). (B) The percentage of GFP⁺ cells in early progenitors (CD34⁺ cells), T cells (CD3⁺ cells), B cells (CD19⁺ cells), and natural killer cells (CD56⁺ cells) in the transduced MC population is indicated. MOI = 1 was used and the mean fluorescence intensities (MFIs) are indicated. The data are representative of 3 experiments. (C) Comparison of the transduction efficiencies between the different lineages in the CB MC population transduced by RD/SCFHA LVs or VSV-G LVs. After 48 hours of transduction, early progenitor cells (CD34⁺ cells), T cells (CD3⁺ cells), B cells (CD19⁺ cells), and monocytes (CD14⁺ cells) were isolated from the MC fraction, each cell lineage was continued in culture for 6 days as indicated, and transduction was analyzed by FACS (means ± SD, n = 3).