Engraftment of WT and Tet2^−/− cells collected and processed in 3% O₂ vs ambient air (∼21% O₂), assessed by competitive BM transplantation and limiting-dilution analysis. Five recipient mice per group are shown. Donor (CD45.2⁺) cells were injected intravenously at doses of 12 500, 25 000, and 50 000 cells into lethally irradiated F1 host mice (CD45.1⁺CD45.2⁺) in air or physioxia. Competitor Boy/J BM cells (CD45.1⁺) were injected intravenously at 100 000 cells in air. The percentage of donor-derived cells in the PB was assessed by flow cytometry at months (M) 1, 2, and 4 (A). The percentage of donor-derived cells in the BM was assessed at month 4 (B). Poisson statistical analysis from the limiting-dilution transplantation PB data (C) and BM (E) are shown. Solid line indicates best-fit linear model. Dotted lines represent 95% confidence intervals. Squares represent the percentage of negative mice for each dose. Triangles indicate that all tested mice were positive in this group. Numbers of CRUs in 10⁶ cells in PB (D) and BM (F) are shown. (G) The myeloid (CD11b⁺ and GR1⁺)/lymphoid (CD3⁺ and B220⁺) ratio in the PB at month 4 was assessed by flow cytometry. Engraftment in secondary recipients at month 4 (H) is shown. Data are presented as mean ± standard error of the mean. *P < .05; ****P < .0001 when analyzed by 2-way analysis of variance with a post hoc Tukey’s multiple comparison test and Poisson statistical analysis. CRUs, competitive repopulating units; ns, not significant.