Effect of Mpl ligand on survival of hematopoietic progenitor cells from marrow of myelosuppressed p53

^−/− mice compared with carrier-treated p53^−/− mice. Mice were given 80 mg/kg carboplatin intravenously, and 7.5 Gy Cs-137 TBI, then either PEG-rmMGDF or carrier (1-2 mice per group). Bone marrow cells were collected 2 days later and plated in methylcellulose-containing medium with IL-3 (2 dishes per bone marrow sample). Colonies were scored on day 13, and colony sizes were classified as large (> 500 cells/colony), medium (200-400 cells/colony), or small (15-150 cells/colony). Untreated (top panel) colonies formed from bone marrow collected from mice that received no carboplatin/TBI. Bars represent mean ± SEM. The trend was reproducible in a repeat experiment.