Fig. 5
Phenotype of mice in which vRANK is forcibly expressed in monocyte/ macrophage-lineage cells using the LysM-Cre system. In LysM-Cre/vRANK mice, no macroscopic changes were observed in external appearance or internal organs. However, as shown by µCT (A), an increase in bone volume was observed. The BV/TV analysis (A, right) demonstrated a significant increase compared to control WT mice (*, P < 0.05). On the other hand, in control WT mice, thicker trabeculae were predominantly found in the metaphysis, gradually narrowing toward the diaphysis. In contrast, LysM-Cre/vRANK mice exhibited an irregular distribution of thick and thin trabeculae, suggesting a potential abnormality in bone remodeling. (B) Macrophages were cultured ex vivo from the spleens of control WT and LysM-Cre/vRANK mice, and osteoclast differentiation was induced by treatment with sRANKL. The upper panels show circular coverslips inserted into culture plates stained with TRAcP, and the lower panels present magnified views of these coverslips, where cultured multinucleated osteoclast-like cells are visible as red-stained cells. TRAcP-positive multinucleated cell formation was reduced in LysM-Cre/vRANK mice compared to WT. Quantification of TRAcP-positive multinucleated cells per unit area (B, right graph) revealed a significant decrease in osteoclast formation in LysM-Cre/vRANK mice (**, P < 0.02) (n = 5, all male, 8 weeks old).
