Low miR‐182‐5p Expressing Extracellular Vesicles Derived From Human Bone Marrow Stromal Cells of Subjects With Steroid‐Induced Osteonecrosis of the Femoral Head Aggravate Disease Progression

ABSTRACT Steroid‐induced osteonecrosis of the femoral head (SONFH) is a refractory, progressive disease. However, the underlying mechanisms that aggravate femoral head necrosis remain unclear. Extracellular vesicles (EVs) act as molecular carriers in intercellular communication. We hypothesize that EVs derived from human (h) bone marrow stromal cells (BMSC) resident in SONFH lesion areas promote the pathogenesis of SONFH. In the present study, we determined the modulatory effects of SONFH‐hBMSCs‐derived EVs on the pathogenesis of SONFH in vitro and in vivo. We found that the expression of hsa‐miR‐182‐5p was downregulated in SONFH‐hBMSCs and EVs isolated from those hBMSCs. After tail vein injection, EVs isolated from hBMSCs transfected with hsa‐miR‐182‐5p inhibitor aggravated femoral head necrosis in the SONFH mouse model. We conclude that miR‐182‐5p regulates bone turnover in the SONFH mouse model via targeting MYD88 and subsequent upregulation of RUNX2 expression. We further assume that EVs derived from hBMSCs resident in SONFH lesion areas aggravate femoral head necrosis by downregulating miR‐182‐5p secreted from hBMSC located outside these lesions. We suggest that miR‐182‐5p could provide a novel target for future therapeutic approaches to treat or prevent SONFH. © 2023 American Society for Bone and Mineral Research (ASBMR). Schematic summary and conclusion of the present study. EVs derived from BMSCLesion regulate osteogenic differentiation, MAPK, and NF‐κB signaling pathways by inhibiting expression of miR‐182‐5p, which targets MYD88 3′ UTR, resulting in inhibition of MYD88 gene expression.