Dental Pulp Stem Cell-Derived Intracellular Vesicles Promote Cartilage Regeneration and Alleviate Pain in Temporomandibular Joint Osteoarthritis.

INTRODUCTION AND AIMS: Temporomandibular joint osteoarthritis (TMJ-OA) is characterized by cartilage destruction and pain. Although mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have shown therapeutic efficacy, their clinical translation is hampered by low yield and batch-to-batch variability. Recent studies indicate that intracellular vesicles (IVs) can be harvested at markedly higher quantities than EVs while displaying comparable biological profiles. Therefore, this study directly compared high-yield dental pulp stem cell-derived intracellular vesicles (DPSC-IVs) with conventional dental pulp stem cell-derived extracellular vesicles (DPSC-EVs) in terms of their ability to regenerate cartilage matrix and relieve pain in TMJ-OA. METHODS: Following characterization of DPSC-IVs and DPSC-EVs, we first evaluated their effects on the proliferation and migration of rat mandibular condylar chondrocytes (MCCs) using endocytic tracing, CCK-8 assays, and Transwell migration assays. Subsequently, an in vitro inflammation model was established using IL-1β, and Western blot analysis and RT-qPCR were employed to investigate their regulatory effects on cartilage matrix synthesis and inflammatory pathways. Next, an in vivo TMJ-OA model was constructed using sodium monoiodoacetate (MIA). The therapeutic efficacy of the two vesicles on subchondral bone remodelling and condylar cartilage matrix regeneration was multidimensionally validated through micro-CT, RT-qPCR, Western blotting, immunofluorescence and immunohistochemistry staining. Furthermore, their underlying molecular mechanisms for alleviating joint pain were elucidated. RESULTS: At the same therapeutic concentration, both DPSC-IVs and DPSC-EVs markedly enhanced MCCs proliferation and migration and suppressed IL-1β-induced cartilage matrix breakdown and inflammatory gene expression. In a rat TMJ-OA model, they equivalently repaired MIA-induced subchondral bone and condylar cartilage damage and significantly attenuated pain via inhibition of the ERK-CREB-CGRP pathway. CONCLUSION: DPSC-IVs, with higher yield and simpler extraction, deliver therapeutic efficacy comparable to DPSC-EVs, offering a more clinically feasible strategy for TMJ-OA treatment.