Effect of glucocorticoids on expression of bone remodeling related cells-derived exosomal miRNAs

Objective To investigate the changes of miRNAs in exosomes derived from bone remodeling-related cells stimulated by glucocorticoid. Methods Osteoblasts and osteoclasts were cultured in vitro. Exosomes from the supernatant were collected for transmission electron microscopy, particle size analysis and CD9/CD81 surface marker detection. The proliferation of two kinds of cells was observed using CCK-8 assay after stimulating by different concentrations of dexamethasone (1μg/ml, 10μg/ml, 100μg/ml) for 48 hours. Exosomes were extracted to detect the expression of miR-133, miR-214 and miR-4697 and miR-487. Results The proliferation of both cells could be inhibited by different concentrations of dexamethasone, of which 100μg/ml of dexamethasone had the strongest inhibitory effect. When the concentration of dexamethasone was 100μg/ml, the level of miR-133 in osteoblast exosomes reduced to 45% compared with the control group, meanwhile miR-214 and miR-4697 reduced to 12% and 56%, respectively (P< 0.05). Compared with the control group, when the concentration of dexamethasone was 1μg/ml, the expression of both miR-133 and miR-487 increased 12-fold, and the expression of miR-214 increased 1.67-fold and miR-487 increased 2.12-fold. Conclusion With the increase of glucocorticoid concentration, the content of miR-133, miR-214 and miR-4697 decrease gradually in osteoblast exosomes, while the content of miR-487 increase first and then decrease. After stimulating osteoclasts with low dose glucocorticoid, the content of four miRNAs in exosomes increases, while it decreases in high dose glucocorticoids group.