Figure 1. X-irradiation results in stable reductions in HSC fitness.

A) BM was isolated from Balb/c mice that had been irradiated 3 months before with 5 Gy (or not as the control), and then mixed with BM from non-irradiated GFP-Tg animals at 9:1 ratios. The mixes (or 100% GFP-Tg BM as the control) were then transplanted into lethally irradiated mice at 10⁷ cells/recipient. At 2 month post-irradiation, peripheral blood was collected, stained with PE-Cy7-anti-GR1 plus PE-anti-B220 antibodies, and analyzed for the percentages of GFP⁺ cells in the indicated blood lineages by flow cytometry. For this and all other figures, each filled circle represents data from an individual mouse. B) BM was harvested from GFP-Tg mice that had either been irradiated 6 weeks before with 5 Gy or left untreated (the “test” cells). The indicated numbers of viable GFP⁺ test cells (eg. 1E4 denotes 1×10⁴) were mixed with 10⁶ viable competitor Balb/c (GFP^neg) BM cells isolated from donors that were irradiated 6 weeks prior with 5 Gy. The mixes were injected into lethally irradiated Balb/c recipients. At 5.5 month post transplant, peripheral blood was stained with PE-Cy7-anti-Mac1 plus PE-anti-B220 antibodies, and the percentages of GFP⁺ cells in the MAC1⁺ and B220⁺ lineages are indicated for the 10 recipients/group.