Figure 5. OPN promotes the formation of h-type vessels in subchondral bone of OA. (A) HUVECs were treated with rmOPN (100 ng/mL) and neutralizing antibody (1.0 μg/mL) for 24 h, and tubes were measured using a tube formation assay; scale bars = 100 μm, n = 6. (B) Representative images and quantitative analysis of Brdu (green) immunofluorescence in HUVECs treated with rmOPN (100 ng/mL) and neutralizing antibody (1.0 μg/mL) for 24 h; scale bars = 25 μm, n = 6. (C, D) Representative images and quantitative analysis of CD31 and Endomucin (EMCN) co-immunostaining in tibial subchondral bone of an OA mouse model treated with vehicle, rmOPN or neutralizing antibody, and sham group. Positive cells were indicated with arrows. Boxed area is magnified in the corner. Scale bars = 50 μm. Data are shown as mean ± s. d. and were analyzed by one-way ANOVA, n = 6, *P < 0.05, **P < 0.01.