Cell cycle analysis of ex vivo–expanded MPB and BM CD34⁺ cells recovered from the BM and spleen of NOD/SCID transplantation recipients 40 hours AT.

CD34⁺ cells were isolated from fresh MPB (light bars) and BM (dark bars) and cultured in vitro as described in “Materials and methods” and in the legend of Figure 2. On day 5, cells were harvested, washed, stained with CFSE, and transplanted into conditioned NOD/SCID mice. A sample was retained for cell cycle analysis of day 5 cells (d 5 ex vivo cult), while another was maintained in culture for an additional 40 hours (d 5 cult + 40 h). Human CFSE⁺cells were isolated by flow cytometric cell sorting 40 hours AT from BM (AT/BM) and spleen (AT/Spl) cells. Cell cycle status of all groups of cells was determined by PI staining. Each bar represents the mean ± SD of 2 measurements for MPB and 3 to 4 measurements for BM samples from 4 independent experiments.