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.