LOX deletion in MKs leads to changes in bone volume and mechanical strength in male mice. (A) Representative micro–computed tomography (μCT) images from femurs of Pf4Cre+/+/LOXfl/fl mice and matching controls. The upper panel shows a distal femoral metaphysis, and the lower panel shows a femoral middiaphysis. Nine Pf4Cre+/+/LOXfl/fl and 7 Pf4Cre+/+ 17-week-old male mice were analyzed. (B) Three-point bending of the femoral diaphysis from the same femurs used for μCT and histology. This assay determines bone mechanical properties. Work to maximum moment (mJ), apparent bending modulus (GPa), and apparent ultimate stress (MPa) are shown. The rest of the 3-point bending parameters can be found in supplemental Figure 6. Plots are mean ± SD for the above number of mice. ∗P < .05. (C) Quantitative analysis of the ratio osteoid (red)/mineralized bone (green) for trabecular bones. Femurs of Pf4Cre+/+/LOXfl/fl mice and matching controls were stained with picrosirius red, fast green, and alcian blue, providing discrimination between mineralized and unmineralized (osteoid) bone. Osteoid appears red, mineralized bone appears green, and cartilage appears blue. Measurements are presented as mean ± SD. Analysis of the trabecular bone was conducted 50 μm distant from the edge of the growth plate, extending 300 μm. Four Pf4Cre+/+/LOXfl/fl and 4 Pf4Cre+/+ 17-week-old male mice were analyzed. EApp, apparent modulus of elasticity; ns, not significant; Work to Ult moment, work to ultimate momentum.
