Fig. 3: Cell-extrinsic Cxcr4-mediated regulation of the skeletal landscape.

A Schematic diagram for the generation of CD45.2→CD45.1 short (3 wks)- or long (16 wks)-term BM chimeras. Mouse icons were created using the Biorender software (Biorender.com, agreement number: VX255VH9TZ). B Proportions of WT or mutant donor CD45.2⁺ LSK SLAM and leukocytes recovered from the BM and blood of BM chimeras in CD45.1⁺ WT recipients 16 weeks after transplantation. Statistics were calculated with the nonparametric Kruskal–Wallis H test (^###p = 0.0008 for SLAM and <0.0001 for Leukocytes) and the unpaired two-tailed Student’s t test (+/1013 vs WT **p = 0.0036, 1013/1013 vs WT ***p = 0.0004, for SLAM; +/1013 vs WT ***p = 0.0003, 1013/1013 vs WT ***p < 0.0001, for Leukocytes). C Absolute numbers of SSCs and OPCs in bone fractions of BM chimeras in CD45.1⁺ recipients. Statistics were calculated with the nonparametric Kruskal–Wallis H test (^##p = 0.009 for SSC and ^###p = 0.0006) and the unpaired two-tailed Student’s t test (1013/1013 vs WT **p = 0.0012, +/1013 vs 1013/1013 ^§§p = 0.0076, for SSC; ^+/1013 vs WT *p = 0.029, 1013/1013 vs WT ***p < 0.0001, +/1013 vs 1013/1013 ^§p = 0.022, for OPC). Data (means ± SEM) in (B) and (C) are from three independent experiments with n = 14 mice in total for WT, +/1013, and 1013/1013 donor groups, respectively, except for blood chimerism analysis (n = 11, 9, and 8 mice in total for WT, +/1013, and 1013/1013 donor groups, respectively). D Sixteen weeks after transplantation, BM sections from WT CD45.1⁺ recipient mice were immunostained for Opn in association with DAPI (bars: 250 μm). Trabeculae are indicated by white arrows. Images are representative of at least three independent determinations. E Left: Proportions of WT or mutant donor CD45.2⁺ LSK SLAM and leukocytes recovered from the BM and blood of BM chimeras in CD45.1⁺ WT recipients 3 weeks after transplantation. Right: Absolute numbers of SSCs and OPCs. Data (means ± SEM) are from three independent experiments with n = 6 (SLAM) or 7 (SSC and OPC), 10, and 8 mice in total for WT, +/1013, and 1013/1013 donor groups, respectively, except for blood chimerism analysis (n = 6, 5, and 4 mice in total for WT, +/1013, and 1013/1013 donor groups, respectively). Statistics were calculated with the nonparametric Kruskal–Wallis H test (^##p = 0.0083 for leukocytes; ^#p = 0.047 for SSC; ^#p = 0.018 for OPC) and the unpaired two-tailed Student’s t test (+/1013 vs WT *p = 0.021, 1013/1013 vs WT **p = 0.0014, for leukocytes; +/1013 vs WT *p = 0.046, 1013/1013 vs WT *p = 0.029, for SSC; +/1013 vs WT *p = 0.034, 1013/1013 vs WT *p = 0.01, for OPC). F–I 3D representative images of trabecular or cortical composites (F and H) and µCT analyses of trabecular or cortical parameters (G and I) of femurs from WT or mutant BM-chimeric CD45.1⁺ WT recipients 4 months after transplantation. Ct.BV = cortical bone volume; Ct.Th = cortical thickness. Data (means ± SEM) in (G) and (I) are from two independent experiments with n = 5, 5, and 4 mice in total for WT, +/1013, and 1013/1013 donor groups, respectively. Statistics were calculated with the nonparametric Kruskal–Wallis H test (^##p = 0.0085 for BV/TV; ^##p = 0.0069 for Tb.Nb; ^###p = 0.0001 for Tb.Sp; ^#p = 0.033 for Ct.BV) and the unpaired two-tailed Student’s t test (1013/1013 vs WT *p = 0.028, +/1013 vs 1013/1013 ^§p = 0.028 for BV/TV; 1013/1013 vs WT *p = 0.011, +/1013 vs 1013/1013 ^§§p = 0.0088 for Tb.Nb; +/1013 vs WT *p = 0.044, 1013/1013 vs WT ***p < 0.0001, +/1013 vs 1013/1013 ^§§§p = 0.0006 for Tb.Sp; 1013/1013 vs WT *p = 0.014, +/1013 vs 1013/1013 ^§p = 0.016 for Ct.BV). Donor WT and mutant mice and Boy/J (CD45.1) WT recipient mice were females at 8 weeks of age. Source data are provided as a Source data file.