HSCs from LepR-Cre;Brca2^fl/fl mice show compromised repopulation, increased expansion of donor-derived myeloid-biased HSCs, and myeloid output. (A) Schematic presentation of experimental design. (B) Donor (CD45.2⁺) cell engraftment over time in CD45.1⁺ mice that received transplantation with 100 BM SLAM cells from LepR-Cre;Brca2^+/+ or LepR-Cre;Brca2^fl/fl mice and 2 × 10⁵ competing CD45.1⁺ BM cells (n = 6-8). (C) Increased expansion of the donor-derived mbHSCs. These mbHSCs from mice that received transplantation were harvested 4 months after BMT for flow cytometry analysis. Shown are the BM frequencies of LSKs (left), total HSCs (LSKCD150⁺CD48^–) (middle), and mbHSCs (LSKCD150⁺CD48^–CD61⁺) (right) in CD45.2⁺ cell compartment (n = 6-8). (D) Increased myeloid output in mice (CD45.1⁺) that received primary transplantation with SLAM cells from LepR-Cre;Brca2^fl/fl mice (CD45.2⁺). Myeloid (Mac1/Gr1), B-cell (B220), and T-cell (CD3ε) engraftment levels at 4 months are shown (n = 6-8). (E-F) Mean levels of donor CD45.2⁺ cell (E) at 4, 8, 12, and 16 weeks after BMT and lineage engraftment (F) in secondary recipient CD45.1⁺ mice 16 weeks after transplantation with 3 million WBMCs from the primary mice in panel B (n = 6-8). Results are presented as mean ± standard deviation of 3 independent experiments. Two-tailed unpaired t test or Wilcoxon rank sum test was performed to compare LepRCre;Brca2^+/+ vs LepRCre;Brca2^fl/fl in panel C; LepR-Cre;Brca2^+/+ vs LepR-Cre;Brca2^fl/fl at time points 4, 8, 12, or 16 weeks after BMT in panels B and E; LepR-Cre;Brca2^+/+ vs LepR-Cre;Brca2^fl/fl for Mac1⁺Gr1⁺, CD3ε⁺, or B220⁺ cells in panels D and F. ∗P < .05; ∗∗P < .01.