Exosomes-derived miR-125-5p from cartilage endplate stem cells regulates autophagy and ECM metabolism in nucleus pulposus by targeting SUV38H1

The study aimed to explore the effects of normal CESC-derived exosomes (N-CESC-exo) on autophagy, apoptosis and extracellular matrix (ECM) metabolism of nucleus pulposus cells (NPCs) and their underlying molecular mechanisms in vivo and in vitro. Tert-buty l hydroperoxide (TBHP) was used to induce CESCs and NPCs degeneration models in vitro. Flow cytometry and TUNEL staining were used to assess apoptosis. Proteins expression were detected by Western blotting. qRT-PCR was applied to detect miR-125-5p and SUV39H1 expression. The miRNA differences were analyzed by bioinformatics. Dual-luciferase reporter assay was applied to detect the target relationship. The degeneration of intervertebral disc tissue was observed by hematoxylin-eosin (H&E) staining. The disc damage was assessed with Safranin-O and Fast Green staining. LC3B expression was detected by immunofluorescence. We observed that NPCs could ingest N-CESC-exo. N-CESC-exo reduced degenerated nucleus pulposus cells (TBHP-NPC) apoptosis, bax, MMP13, and p62 expression, while increased bcl2, ACAN, LC3-II/I expression, and the fluorescence intensity of GFP-LC3. Bioinformatics analysis confirmed that miR-125-5p was low expression, while SUV39H1 was overexpressed in IDD. Further, the dual-luciferase reporter assays confirmed the targeting relationship between miR-125-5p and SUV39H1. CESC-exomiR-125-5p inhibited TBHP-NPCs apoptosis by inhibiting SUV39H1, bax, MMP13, and p62 expression, while increased bcl2, ACAN, LC3-II/I expression, and the fluorescence intensity of GFP-LC3, thereby alleviating rat IDD.