Pure platelet-rich plasma delays intervertebral disc degeneration by activating SIRT1-mediated autophagy in nucleus pulposus cells.

BACKGROUND

Intervertebral disc degeneration (IVDD) is characterized by nucleus pulposus cells (NPCs) apoptosis and extracellular matrix (ECM) degradation. Impaired autophagy and mitochondrial dysfunction further accelerate disc degeneration. Pure platelet-rich plasma (P-PRP), enriched in growth factors and low in pro-inflammatory mediators, has shown regenerative potential. However, its mechanism of action, particularly the role of the autophagy-related SIRT1 pathway and mitochondrial homeostasis, remains unclear.

METHODS

Rabbit-derived P-PRP was prepared and analyzed for cellular content and cytokine profiling. NPCs were treated with whole blood or P-PRP, and assessed for viability (CCK-8) and migration (Transwell). An IL-1β-induced degeneration model was established, and groups were treated with SIRT1 activator (SRT1720), inhibitor (EX527), P-PRP, or P-PRP + EX527. Mitochondrial membrane potential (JC-1 staining), and apoptosis (Annexin V/PI flow cytometry) were also measured. Western blotting, immunofluorescence, qPCR, and ELISA were conducted to measure the expression of SIRT1, autophagy-related proteins, and ECM-related markers.

RESULTS

P-PRP promoted the viability and migration of NPCs, reduced apoptosis, and preserved ECM homeostasis in inflammatory conditions. P-PRP enhanced the expression of SIRT1, improved mitochondrial membrane potential, and reduced apoptosis rates. P-PRP upregulated LC3B-II and Beclin-1 expression, while downregulated p62 expression, indicating autophagy activation. EX-527 abrogated the beneficial effects of P-PRP.

CONCLUSION

P-PRP protected against degenerative NPCs by activating functional autophagic flux and restoring mitochondrial function via the SIRT1 signaling axis. These findings provide novel mechanistic insight into PRP-based therapies and identify SIRT1 as a promising target for the treatment of IVDD.