miR‐329‐3p in Bone Marrow Mesenchymal Stem Cells‐Derived Exosomes Promotes Bone Regeneration in Diabetic Fractures by Alleviating the SIRT3‐Mediated Oxidative Stress via Inhibiting LSD1

Purpose: Influence of bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (Exo) on fracture healing in diabetes mellitus (DM) was investigated. Methods: Serum LSD1, SIRT3, superoxide dismutase (SOD), and malondialdehyde (MDA) were detected in patients with diabetic fractures. Under high-glucose (HG) conditions, influences of LSD1, SIRT3, BMSCs-derived Exo, and BMSCs-derived Exo harboring miR-329-3p on osteogenic differentiation and oxidative stress of MC3T3-E1 cells were assayed via ALP staining, western blotting, dichlorofluorescin diacetate (DCFH-DA) staining, and enzyme-linked immunosorbent assay (ELISA). Mice with diabetic fractures were treated by BMSCs, BMSCs-derived Exo, or a combination of BMSCs and GW4869. Western blotting and immunohistochemistry examined protein expression in fracture tissues. Results: DM patients with nonunion showed higher serum LSD1 and MDA and lower serum SIRT3 and SOD than those with normal fracture healing. In HG-induced MC3T3-E1 cells, LSD1 silencing upregulated SIRT3, RUNX2, OPG, and SOD, increased mature osteoblasts, and reduced reactive oxygen species (ROS) and MDA; SIRT3 silencing revered these results. LSD1 downregulated SIRT3, RUNX2, OPG, and SOD, reduced mature osteoblasts, and enhanced ROS and MDA in HG-induced MC3T3-E1 cells; BMSCs-derived Exo abrogated these influences. BMSCs-derived Exo harboring miR-329-3p suppressed LSD1 and ROS, upregulated SIRT3, RUNX2, and OPG, and increased mature osteoblasts in HG-induced MC3T3-E1 cells. BMSCs transplantation in diabetic fracture mice elevated SIRT3, ALP, RUNX2, OPG, and miR-329-3p and reduced LSD1 in fracture tissues; miR-329-3p silencing in BMSCs or GW4869 treatment of mice counteracted these effects. Conclusion: BMSCs-derived Exo harboring miR-329-3p induces bone regeneration in diabetic fractures by relieving the SIRT3-mediated oxidative stress via inhibiting LSD1. It has potential in treating diabetic fractures.