BRCA2 from LepR⁺ stromal cells is required for the maintenance of HSCs in the BM. (A) Schematic presentation of experimental design. (B) BM cellularity in 2 tibias and 2 femurs from mice of the indicated genotypes. Quantification of absolute BM cell numbers normalized to mouse body size are shown; control (Ctr): Brca2^fl/fl mice (n = 6-8). (C) Increased HSC frequency in LepR-Cre;Brca2^fl/fl mice. Representative flow plots (left) and quantification (right) of LSK (top) or SLAM (signaling lymphocyte activation molecule: LSKCD48^–CD150⁺) (bottom) cells are shown (n = 6-8). (D) Frequencies of hematopoietic progenitor populations in the BM. Representative flow cytometry plots (left) of common lymphoid progenitors, common myeloid progenitors, megakaryocyte/erythroid progenitor (MEPs), and granulocyte/monocyte progenitor (GMPs) in the BM of LepR-Cre;Brca2^+/+ and LepR-Cre;Brca2^fl/fl mice, along with the frequency (right) of each population (n = 6-8). (E) Increased myeloid colonies generated by WBMCs from LepR-Cre;Brca2^fl/fl. Approximately 1000 cells from the indicated mice were plated in a cytokine-supplemented methylcellulose medium. Colonies were enumerated on day 7 (n = 6-8). (F) Increased frequency of mbHSCs in LepR-Cre;Brca2^fl/fl mice. Representative flow plots of mbHSCs (LSKCD150⁺CD48^–CD61⁺) (left); and quantification (right) in the BM of LepR-Cre;Brca2^fl/fl and LepR-Cre;Brca2^fl/fl mice are shown (n = 6-8). The number of mice analyzed per genotype is shown for each bar in each panel. The results are presented as mean ± standard deviation of 3 independent experiments. One-way analysis of variance (ANOVA) was performed to compare groups (Ctr, LepR-Cre, Osx1-Cre, and VE-Cre). Normality of the data was examined using the Shapiro-Wilk test. If the data were normally distributed, ANOVA was used, followed by t tests. Otherwise, the Kruskal-Wallis test was used, followed by Wilcoxon rank sum tests. ∗P < .05; ∗∗P < .01.