SCF/TPO surface-engineered LVs selectively promote gene transfer in CB CD34⁺ LTC-IC–derived colonies. CD34⁺ CB cells were incubated with TPO-displaying (G/TPOHA), SCF-displaying (G/SCFSUx), or codisplaying (G/TPOHA/SCFSUx) HIV-derived vectors for 72 hours. The gene transfer efficiency in the CD34⁺ LTC-IC–derived colonies (% GFP⁺ colonies) are shown. Data are shown as means ± SD, n = 3.