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

CD34⁺ cells were isolated from fresh MPB and BM and cultured in vitro as described in “Materials and methods.” On day 5, cells were harvested, washed, stained with Hst, and sorted to obtain cells in G₀/G₁ and S/G₂+M. These fractions were stained with CFSE and transplanted into conditioned NOD/SCID mice. A sample was retained to confirm, with PI staining, the cell cycle status of sorted G₀/G₁ (light bars) and S/G₂+M (dark bars) cells prior to transplantation (d 5 sorted G₀/G₁ & S/G₂+M), while another was maintained in culture for an additional 40 hours (d 5 cult + 40h). 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 3 to 7 G₀/G₁ and 3 to 6 S/G₂+M measurements from MPB and BM samples from 6 independent experiments.