MOTS-c-modified functional self-assembly peptide hydrogels enhance the activity of nucleus pulposus-derived mesenchymal stem cells of intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) is characterized by oxidative-stress driven progressive apoptosis and senescence of nucleus pulposus mesenchymal stem cells (NP-MSCs). MOTS-c, a 16-amino acid peptide encoded by the mitochondrial 12S rRNA open reading frame, has emerged as a key regulator of cellular metabolism, oxidative stress, and senescence. This study investigated the therapeutic potential of MOTS-c in countering tert-butyl hydroperoxide (TBHP)-induced oxidative damage in NP-MSCs, and we developed a novel biomaterial strategy for IDD treatment.Key findings include. MECHANISTIC PROTECTION: MOTS-c significantly attenuated TBHP-induced NP-MSC apoptosis (Annexin V+/PI + cells reduced by 48 %, p < 0.001), senescence (SA-β-gal + cells decreased by 52 %, p < 0.005), and ROS overproduction (35 % reduction, p < 0.0001) via activation of the AMPK/SIRT1 pathway. Pharmacological inhibition of SIRT1 abolished these protective effects, confirming pathway specificity. FUNCTIONAL HYDROGEL DESIGN: A sustained-release MOTS-c delivery system (RAD/RMOTS-c) was engineered by conjugating MOTS-c to the self-assembling RADA16-I peptide. The hydrogel exhibited a β-sheet-rich nanofibrous structure (fiber diameter: 362.6 nm), shear-thinning rheology (viscosity: 131-217 Pa s), and sustained peptide release over 7 days. IN VITRO EFFICACY: RAD/RMOTS-c enhanced NP-MSC viability (1.8-fold vs. control, p < 0.005) and extracellular matrix (ECM) synthesis, elevating collagen II/aggrecan expression (2.3-fold, p < 0.05) while suppressing collagen I (63 % reduction, p < 0.001).In Vivo Therapeutic Validation: In a rat IDD model, RAD/RMOTS-c injection preserved disc height (DHI%: 82.4 vs. 58.7 in IDD group, p < 0.001), restored T2-weighted MRI signals (1.5-fold increase, p < 0.001), and reduced histological degeneration scores by 44 % compared to untreated controls (p < 0.001). INNOVATION AND IMPACT: This work (1) demonstrates the association between MOTS-c's anti-degenerative effects and AMPK/SIRT1 signaling in NP-MSCs and (2) pioneers a peptide-hydrogel hybrid system that synergistically combines mitochondrial protection with structural support for disc regeneration. The findings can advance IDD therapy toward biology-driven, minimally invasive solutions, aligning with the paradigm of functional biomaterials for degenerative diseases.