Emodin Enhances Chondrogenic Differentiation Potential in Fibrocartilage Stem Cells for Temporomandibular Joint Cartilage Regeneration

INTRODUCTION: Temporomandibular Joint Osteoarthritis (TMJOA) is a degenerative disease mainly characterized by cartilage degeneration. Regeneration of condylar cartilage plays a crucial role in enhancing joint function and mitigating the advancement of TMJOA. Emodin has shown efficacy in promoting osteogenesis and inhibiting extracellular matrix degradation, suggesting its potential as a novel therapeutic approach for promoting condylar cartilage regeneration. METHODS: In this study, we isolated and characterized distinct Fibrocartilage Stem Cells (FCSCs) from the condyles of Sprague Dawley rats. Proliferation and differentiation of FCSCs were assessed using the Cell Counting Kit-8 (CCK-8) assay and two-dimensional (2D) monolayer cultures. Western blot and Quantitative Real-Time PCR (qRT-PCR) analyses were conducted to evaluate the expression levels of bone and cartilage anabolic metabolism markers. RESULTS: The CCK-8 assay demonstrated a dose-dependent increase in cell proliferation, and the peak cell viability was observed at approximately 20 μM (P < 0.01). Analysis using qRT-PCR revealed significant upregulation of the fibrocartilage-specific marker, specifically Col I (P < 0.0001), alongside the concurrent downregulation of adipogenic markers Ppar-γ and LPL (P < 0.05), as well as osteogenic markers ACAN and ALP. Western blot analysis further confirmed elevated levels of Col I and reduced levels of ACAN and ALP following treatment with 20 μM. DISCUSSION: Our findings demonstrated that emodin selectively promoted the differentiation of FCSCs towards chondrogenic lineages within a specific concentration range in vitro. CONCLUSION: In conclusion, emodin enhanced the fibrocartilage-specific differentiation of FCSCs, indicating the potential therapeutic application of emodin in regenerating cartilage in the Temporomandibular Joint (TMJ).