Fig. 1.
Effect of GPR55 ligands on human and mouse osteoclast formation. (A) Human monocytes were cultured in the presence of 1 nM to 1 μM CBD for 7 days and then were fixed and stained for αvβ3 (vitronectin receptor, VNR) to quantify osteoclast number. Immunofluorescence intensity was measured and expressed relative to control cultures. Data are mean ± SEM; n = 6 or 7 independent experiments, with 5 replicates for each. ANOVA with Dunnett's post-test; **, P < 0.01; ***, P < 0.001 compared with control. (B and C) BMMs from wild-type mice (black bar) and GPR55−/− mice (white bar) were cultured in the presence of 5 nM to 1 μM O-1602 (B) or 1 nM to 1 μM LPI (C) for 5 days and then were fixed and stained for TRAP. The number of TRAP-positive multinucleated cells (MNCs) was counted and expressed as a percentage of control. Data are mean ± SEM; n = 4 or 5 experiments, 5 replicates for each. ANOVA with Bonferroni post-test; *, P < 0.05; ***, P < 0.001 compared with control; #, P < 0.05; ##, P < 0.01; ###, P < 0.001 compared with wild type. (D) Representative images of TRAP-positive MNCs (arrowheads) generated from wild-type and GPR55−/− macrophages after treatment with vehicle (control) or 100 nM O-1602. (Scale bar: 50 μm.)