BACKGROUND: Intervertebral disc degeneration (IVDD) is a major cause of spinal disorders, marked by nucleus pulposus cell (NPC) loss and extracellular matrix (ECM) degradation. Exosomes (EXOs), as nanoscale vesicles rich in bioactive molecules, have shown promise in treating degenerative diseases. Duhuo Jisheng decoction (DHJSD), a classical traditional Chinese herbal prescription, has been reported to alleviate IVDD, yet its underlying mechanisms remain unclear.
PURPOSE: To explore whether DHJSD alleviates IVDD via exosome-mediated delivery of miRNAs and to clarify the associated molecular pathways.
METHODS: Differential miRNA expression in IVDD patient nucleus pulposus tissues was identified by bioinformatics and reverse transcription quantitative polymerase chain reaction (RT-qPCR). Active compounds in DHJSD were identified by high-performance liquid chromatography (HPLC). EXOs were isolated from human bone marrow mesenchymal stem cells (hBMSCs) treated with DHJSD-containing serum (5.4, 10.8, 21.6 g/kg) and characterized by transmission electron microscopy, nanoparticle tracking analysis, and Western blotting(WB). miRNA expression in EXOs was analyzed using RT-qPCR. An in vitro IVDD model was established using interleukin-1β (10 ng/ml)-treated human NPCs. Cell viability, apoptosis, mitochondrial function, ferroptosis, and ECM markers were assessed. The interaction between miR-19b-3p and ACSL4 was confirmed by dual-luciferase assay and gain/loss-of-function experiments. Wnt/β-catenin and Hippo signaling involvement was evaluated via WB, immunofluorescence (IF), and rescue assays. In the rat IVDD model, intradiscal injections of DHJSD-EXOs were administered at weeks 1 and 5, with magnetic resonance imaging and histological assessments conducted at week 9.
RESULTS: miR-19b-3p was downregulated in IVDD tissues. DHJSD promoted the secretion of hBMSC-derived EXO enriched in miR-19b-3p, which enhanced NPC proliferation, suppressed apoptosis, and inhibited ferroptosis by targeting ACSL4 and concurrently modulated Wnt/β-catenin (inhibition) and Hippo (activation) pathways. In vivo, DHJSD-EXOs elevated miR-19b-3p expression, reduced ACSL4 levels, and improved disc structure and degeneration grade.
