Mesenchymal Stem Cell-Derived Exosomes miR-143-3p Attenuates Diabetic Kidney Disease by Enhancing Podocyte Autophagy via Bcl-2/Beclin1 Pathway

<b>Objective</b>: Diabetic kidney disease (DKD) is characterized by podocyte injury and impaired autophagy. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) exhibit therapeutic potential for DKD, yet their mechanisms remain unclear. This study investigated whether BMSC-Exos restore podocyte autophagy via the miR-143-3p/Bcl-2/Beclin1 axis to delay DKD progression. <b>Methods</b>: A high-glucose (HG)-induced podocyte injury model was established using mouse podocytes (MPC5). Autophagy-related proteins (Beclin1, Bcl-2, LC3) and the injury marker desmin were analyzed by Western blot and immunofluorescence (IF). High-throughput sequencing identified BMSC-Exos-enriched miRNAs, with the miR-143-3p/Bcl-2 targeting relationship validated by dual-luciferase reporter assays. BMSCs transfected with miR-143-3p mimic or inhibitor were used to assess exosomes effects on autophagy and podocin expression. In vivo, DKD mice received tail vein injections of modified BMSC-Exos, followed by evaluation of physiological parameters, biochemical indices, and renal histopathology. <b>Results</b>: BMSC-Exos were successfully isolated and characterized. Fluorescence microscopy confirmed exosomes internalization by HG-treated MPC5 cells. BMSC-Exos upregulated Beclin1 and LC3-II while downregulating Bcl-2 and desmin, indicating enhanced autophagy. High-throughput sequencing revealed miR-143-3p enrichment in BMSC-Exos, and Bcl-2 was confirmed as a direct target of miR-143-3p. Exosomes from miR-143-3p mimic-transfected BMSCs further promoted autophagy and podocin expression. In DKD mice, BMSC-Exos reduced blood glucose, urinary albumin-to-creatinine ratio (UACR), and ameliorated renal damage, whereas miR-143-3p inhibition attenuated these effects. <b>Conclusions</b>: BMSC-Exos deliver miR-143-3p to target Bcl-2, thereby activating Beclin1-mediated autophagy and ameliorating DKD. This study elucidates a novel autophagy regulatory mechanism supporting BMSC-Exos as a cell-free therapy for DKD.