HSCs lacking hypoxia-induced Vegfa expression have impaired competitive reconstitution potential. Test cells (2 × 105; CD45.2) and competitor cells (2 × 105; CD45.1) were transplanted to lethally irradiated recipients. Results are shown from 1 representative experiment of 2 performed where 3 different donors per genotype were injected into 4-5 recipients each. Test cell contribution to PB at (A) 4 weeks, *P = .0107, t test, (B) 8 weeks, **P = .0014, t test, and (C) 15 weeks after transplantation, ***P < .0001, t test. (D) Lineage distribution of engrafted cells in PB at 15 weeks after transplantation. Bars represent mean ± SD. (E) Test cell contribution to the BM LSK compartment at 15 weeks after transplantation. **P = .0023, Mann-Whitney test. (F) CRU frequency was determined by limiting-dilution transplantations. Percentages of recipients with negative engraftment of test cells are plotted against the cell dose given. n = 5 recipient mice per cell dose and n = 3 donors per genotype. Poisson distribution gives that 1 CRU is present at the derived cell dose where the frequency of negatively engrafted recipients is 37%.
