The Anti-Inflammatory Effect of miR-140-3p in BMSCs-Exosomes on Osteoarthritis.

PURPOSE OF THE STUDY Articular cartilage injury is a common disease in daily life, with a high incidence. The aim of this study was to investigate the effect and mechanism of miRNA-140-3p in bone mesenchymal stem cells (BMSCs)-derived exosomes under hypoxia on inflammatory articular chondrocytes. MATERIAL AND METHODS To simulate the pathological status of arthritis, rat chondrocytes were used to establish the osteoarthritis (OA) model by IL-1β (10 μg/ml) as a modulating in vitro, and exosomes were isolated by differential ultra-high speed centrifugation. The cell counting kit-8, wound healing and flow cytometry assays were utilized to assess proliferation, migration and apoptosis of chondrocytes, respectively. Lipogenic and chondrogenic differentiation of chondrocytes were detected by oil red O staining and toluidine blue staining individually. The expressions of miR-140-3p and chondrocyte-specific gene mRNA were investigated using qRT-PCR. Western blot was applied to assess chondrocyte associated proteins and BMSC-Exo surface protein markers, and immunohistochemistry was adopted to detect the staining of collagen I and II. RESULTS Under scanning electronic microscope, the shape of exosomes was almost round. Exosome treatment prominently impaired the inhibition of chondrocytes' proliferative and migrative ability by IL-1β. It was found hypoxia had a more marked impact on proliferation, expression of collagen II and apoptosis in OA chondrocytes than normoxia, as well as a stronger effect on weakening adipose differentiation and enhancing chondrogenic differentiation in inflammatory chondrocytes. Furthermore, incubation with BMSC-Exo overexpressing miR-140-3p can remarkably increase the survival rate and migration in inflammatory chondrocytes. In addition, overexpression of miR-140-3p was found to enhance the chondrogenic differentiation of inflammatory chondrocytes. Furthermore, we found that the healing effect of exosomes on inflammatory chondrocytes under hypoxic conditions was produced by a rise in miR-140-3p expression within them and that hypoxia-mediated upregulation of miR-140-3p expression occurred through HIF-1α. CONCLUSIONS Under hypoxia, BMSC-Exo enhanced the chondrogenic phenotype, increased the viability of inflammatory chondrocytes. The overexpression of miR-140-3p in BMSC-Exo is beneficial to protect joints and delaying the pathogenesis in OA. Key words: HIF-1α, apoptosis, lipogenic differentiation, chondrogenic differentiation.