Effect of endoplasmic reticulum stress on chondrocytes in a rat model of knee osteoarthritis / 中国组织工程研究

ABSTRACT

BACKGROUND: Endoplasmic reticulum (ER) stress has been proved to be related to the occurrence of diabetes, dilated cardiomyopathy and neurodegenerative diseases. Indeed, it is closely associated with osteoarthritis. OBJECTIVE: To explore the effect of ER stress on the chondrocyte viability as well as the occurrence and development of osteoarthritis in rats. METHODS: Rat chondrocytes were isolated and cultured, and the ER stress in the rat chondrocytes was by 10 mg/L tunicamycin. The expression levels of ER stress markers C/EBP-homologous protein and 78 kDa glucose-regulated protein were detected by western blot assay, and the proliferation and apoptosis of chondrocytes were detected by cell counting kit-8 assay and AnnexinV-FITC flow cytometry, respectively. In the in vivo experiment, 15 Sprague-Dawley rats were selected and subjected to anterior cruciate ligament transection and medial meniscectomy to establish an animal model of osteoarthritis. Tunicamycin, tauroursodeoxycholic acid and PBS (blank control group) were respectively injected into the articular cavity, and then the progression of osteoarthritis was assessed by hematoxylin-eosin staining at 4 weeks after treatment. RESULTS AND CONCLUSION: After addition of tunicamycin, the expression levels of C/EBP-homologous protein and 78 kDa glucose-regulated protein were significantly upregulated, the viability of chondrocytes was decreased gradually, while the apoptotic rate was increased significantly. Results from gross observation and hematoxylin-eosin staining suggested that tunicamycin promoted the progression of osteoarthritis and tauroursodeoxycholic acid delayed the deterioration of cartilage in the rats. These findings indicate that ER stress results in the decreased chondrocyte viability and increased apoptosis, which may be an important pathogenesis of osteoarthritis. Additionally, tauroursodeoxycholic acid can effectively alleviate osteoarthritis induced by ER stress.