Figure 5. The engraftment defect of HSCs in S/G₂/M is corrected by treatment of the host, but not the cells, with SDF-1G2.

(A) Effect of injecting prospective recipients 2 hours after irradiation and 2 hours prior to transplant with 10 ng/ml SDF-1G2 (+) or PBS (–). Starting equivalents of 4,000 G₁ cells per recipient mouse or 12,000 S/G₂/M cells per recipient mouse were similarly tested. Both 14.5-dpc FL and 3-wk BM HSCs in S/G₂/M engrafted only when transplanted into SDF-1G2–treated recipients, whereas treated recipients were no more likely to be engrafted long-term by HSCs in G₁ than were untreated recipients. Results are combined from 3 independent experiments. (B) Effect of in vitro treatment of sorted Ter119^– FL cells in G₁ or S/G₂/M for 30 minutes at 37°C in serum-free medium plus the indicated additives on CRU detection. In vitro treatment had no significant effect on the number of mice that subsequently showed multilineage repopulation from starting cells in either G₁ or S/G₂/M. Results are combined from 3 independent experiments.