Expansion of multipotent stromal and OBCs in NHD13 mice that are nonfunctional. (A) Flow cytometry gating strategy used to identify BM Lin⁻/CD45⁻ nonhematopoietic cells, Lin⁻/CD45⁻/CD31⁻/CD51⁺/Sca1⁻ OBCs, and Lin⁻/CD45⁻/CD31⁻/CD51⁺/Sca1⁺ MSCs. The first 3 plots represent WT mice, and the last 2 plots show overlay of populations from concatenated NHD13 (red) and WT mice (black) data. (B-C) Frequency of MSCs within total BM pool (B) and Lin⁻/CD45⁻ nonhematopoietic pool (C) of NHD13 and WT mice. (D-E) Number of total CFU fibroblasts (identified by staining with crystal violet) (D) and alkaline phosphatase–positive CFU fibroblasts (E) from 1 × 10⁶ BM cells after 10 to 14 days in culture. Data from 2 separate experiments and NHD13 data points represent mean of triplicate cultures normalized to mean of WT group. (F-G) Frequency of OBCs within total BM pool (F) and Lin⁻/CD45⁻ nonhematopoietic pool (G) of NHD13 and WT mice. (H) Peripheral blood serum osteocalcin levels measured by enzyme-linked immunosorbent assay. (I-J) Femoral trabecular number (I) and thickness (J) as measured by micro–computed tomography. (K-L) Number of alkaline phosphatase–positive CFU-OBs (K) and Von Kossa–positive bone nodules (L) formed by 4 × 10⁶ BM cells after 17 days of culture in mineralization media. Each data point represents mean number of CFU-OBs from triplicate cultures. (M) Peripheral blood serum CCL3 levels measured by Luminex xMAP assay. (N) Number of histologically identified osteoclasts as TRAP⁺ endosteal-associated cells. (O) Peripheral blood serum C-telopeptides (CTX) levels measured by enzyme-linked immunosorbent assay. All mice used in analyses are 20 ± 3 weeks of age. For all graphs, *P < .05; **P < .01; mean and standard error of the mean are shown.