Expansion of NOD/SCID repopulating cells by shSTK38. (A) Transduced CD34⁺ cells were transplanted into NOD/SCID mice, either 1 day after transduction or after 11 and 26 days of ex vivo culture. The transplanted cell doses were expansion equivalents of the indicated numbers of input day 0 CD34⁺ cells before transduction. The level of human engraftment in bone marrow 7 weeks after transplantation is shown. (B) Day 26 shSTK38 expanded cells show lymphoid and myeloid engraftment in NOD/SCID mice. FACS plots from a representative mouse. (C) Day 26 shSTK38 expanded cells engraft in secondary recipient NOD/SCID mice. Half a femur equivalent of bone marrow from primary recipient mice was transplanted to a total of 10 secondary recipients. Engraftment levels were analyzed in bone marrow after 7 weeks. FACS plots showing engrafted human cells in 1 of 2 recipients with a clear contribution of human cells.