Effect of ex vivo culture on proliferation and apoptosis of Fancc^-/- Sca1 ⁺c-kit⁺Lin^- (SCL) cells. (A) Expansion of SCL cells in liquid culture. SCL cells were incubated for 48 or 96 hours and the number of Sca1 ⁺c-kit⁺ cells was determined using fluorescence cytometry. The mean fold increase of Sca1 ⁺c-kit⁺ cells from 5 independent experiments is shown. Error bars represent the standard error of the mean (SEM). ^*P < .01, ^**P < .001 comparing Fancc^-/- with WT. (B) Evaluation of primitive and mature clonogenic myeloid cells following ex vivo culture. SCL (10⁶) cells were maintained in liquid culture for 0 to 4 days and then 2 × 10³ cells were plated in semisolid media in triplicate cultures for growth of high proliferating potential colony-forming cells (HPP-CFCs) and low proliferating potential colony forming cells (LPP-CFCs). The mean cumulative colony numbers of HPP-CFCs and LPP-CFCs per culture from 5 independent experiments are shown. The error bars represent the SEM. ^*P < .05, ^**P < .01, ^***P < .001 comparing Fancc^-/- with WT. (C) Evaluation of apoptotic Sca1 ⁺kit⁺ (SC) cells following ex vivo culture. (Left) A representative experiment demonstrating the gating method used for scoring apoptotic SC cells. SC cells were identified as described in “Purification and culture of SCL cells” and then evaluated for apoptosis by TUNEL. Bars indicate the percentage of apoptotic SC cells. The graph (right) shows the mean percentage of apoptotic SC cells from 4 independent experiments ± SEM. Error bars indicate SEM. ^*P < .01, ^**P < .001 comparing Fancc^-/- with WT.