Investigate the Regulatory Role of Parathyroid Hormone on Condylar Fibrocartilage Homeostasis

ABSTRACT Introduction Condylar fibrocartilage regeneration after injury has been hindered by its poor self‐repair capacity. Injection of parathyroid hormone (PTH) has been proven to effectively delay cartilage damage in osteoarthritis. In this study, we investigated the regulatory effect of PTH on the homeostasis of condylar fibrocartilage. Methods FCSCs were extracted and exposed to a high PTH environment from rats to analyze the transcriptional changes. The condyles of mice were cultured ex vivo and exposed to high PTH to observe changes in cartilage. Parathyroidectomy induced PTH‐deficient rats were locally injected with PTH to observe its effects on cartilage homeostasis. Results High PTH environment could promote chondrogenic differentiation of FCSCs early, while weakening at late phase. The ex vivo culture of mouse condyle under PTH stimulation enhanced the proliferation of chondrocytes early, which were replaced by hypertrophic chondrocytes. The degradation of cartilage matrix also grew distinct under high PTH. PTH deficiency induced osteoarthritis‐like changes in rats, characterized by cartilage layers disorder, chondrocyte reduction, and matrix degradation. Exogenous PTH could reverse fibrocartilage degeneration. Conclusion The maintenance of PTH homeostasis is crucial for maintaining the function of temporomandibular condylar FCSCs. Exogenous PTH can ameliorate the characteristics associated with rat temporomandibular joint osteoarthritis.