Administration of mircoRNA-135b-reinforced exosomes derived from MSCs ameliorates glucocorticoid-induced osteonecrosis of femoral head (ONFH) in rats.

Exosomes were found to exert a therapeutic effect in the treatment of osteonecrosis of the femoral head (ONFH), while miR-135b was shown to play an important role in the development of ONFH. In this study, we investigated the effects of concomitant administration of exosomes and miR-135b on the treatment of ONFH. A rat mode of ONFH was established. TEM, Western blotting and nanoparticle analysis were used to characterize the exosomes collected from human-induced pluripotent stem cell-derived mesenchymal stem cells (hiPS-MSC-Exos). Micro-CT was used to observe the trabecular bone structure of the femoral head. Real-time PCR, Western blot analysis, IHC assay, TUNEL assay, MTT assay and flow cytometry were performed to detect the effect of hiPS-MSC-Exos and miR-135b on cell apoptosis and the expression of PDCD4/caspase-3/OCN. Moreover, computational analysis and luciferase assay were conducted to identify the regulatory relationship between PDCD4 mRNA and miR-135b. The hiPS-MSC-Exos collected in this study displayed a spheroidal morphology with sizes ranging from 20 to 100 nm and a mean concentration of 1 × 1012 particles/mL. During the treatment of ONFH, the administration of hiPS-MSC-Exos and miR-135b alleviated the magnitude of bone loss. Furthermore, the treatment of MG-63 and U-2 cells with hiPS-MSC-Exos and miR-135b could promote cell proliferation and inhibit cell apoptosis. Moreover, PDCD4 mRNA was identified as a virtual target gene of miR-135b. HiPS-MSC-Exos exerted positive effects during the treatment of ONFH, and the administration of miR-135b could reinforce the effect of hiPS-MSC-Exos by inhibiting the expression of PDCD4.