QiangGuYin-containing serum improves osteogenic differentiation via regulating osteoclast-derived exosomal miR-27b-3p.

Osteoclast-derived exosomes play a critical role in suppressing osteogenic differentiation, contributing to postmenopausal osteoporosis (PMOP). QiangGuYin (QGY), a traditional Chinese herbal formula, has demonstrated efficacy in alleviating PMOP progression. This study aimed to elucidate the mechanism by which QGY modulates osteoclast-derived exosome-mediated inhibition of osteogenesis. Exosomes were isolated from osteoclasts treated with QGY-containing serum or control serum. Bone marrow mesenchymal stem cells (BMMSCs) were used to evaluate osteogenic differentiation by Western blotting, alkaline phosphatase (ALP) activity assay, and Alizarin Red S staining. And qRT-PCR, Western blotting, immunofluorescence and immunohistochemistry were conducted to detect the expression of miR-27b-3p, DKK2 and the activation level of β-catenin pathway. Spearman's correlation analysis was used to evaluate relationships among exosomal miR-27b-3p, DKK2, β-catenin, and bone microarchitecture parameters. Osteoclast-derived exosomes significantly inhibited osteogenic differentiation, an effect reversed by QGY-containing serum. QGY-containing serum increased the abundance of miR-27b-3p in osteoclast-derived exosomes. MiR-27b-3p inhibitor abolished the protective effects of QGY. DKK2 was identified as a direct target of miR-27b-3p and was upregulated by osteoclast-derived exosomes but suppressed by QGY-containing serum. DKK2 overexpression blocked QGY-containing serum-mediated rescue of osteogenic differentiation and β-catenin pathway. In PMOP rats, QGY increased serum exosomal miR-27b-3p levels, suppressed DKK2 expression and enhanced β-catenin level in femoral tissues. Significant correlations were observed among exosomal miR-27b-3p, DKK2, β-catenin and bone quality indices. QGY-containing serum alleviates osteoclast-derived exosome-induced osteogenic differentiation inhibition via the miR-27b-3p/DKK2/β-catenin signaling, providing a mechanistic basis for the clinical application of QGY in PMOP treatment.