ABSTRACT
BACKGROUND: Preliminary studies have shown that numerous antioxidants exhibit antiarthritic effects due to their inhibition on inflammatory factors. With the antioxidant and anti-inflammatory abilities whether protocatechuic acid is effective in the treatment of osteoarthritis has never been reported. OBJECTIVE: To investigate the biological effect of protocatechuic acid on interleukin-1β induced chondrocyte including phenotype and cellular metabolism in vitro, thereby providing a potential agent in osteoarthritis treatment, METHODS: The chondrocytes of neonatal rat femur were collected, intervened by 10 mg/L interleukin-1β to establish the degenerative model, and treated by 10, 30 and 50 mg/L protocatechuic acid. The study was approved by the Laboratory Animal Ethical Committee of Guangxi Medical University in October 2017, with the approval No. 201710008. RESULTS AND CONCLUSION: Protocatechuic acid effectively promoted chondrocyte growth in the range of 10-50 mg/L, while the dose of 30 mg/L was the strongest. Protocatechuic acid also enhanced the synthesis of the extracellular matrix and the mRNA expression of aggrecan, collagen II and Sox9, and downregulating the expression of the matrix metalloproteinase 13 (a marker of inflammatory factor). To conclude, protocatechuic acid exerts a positive effect on the proliferation and phenotypic maintenance of articular chondrocytes, providing reference for its use in the treatment of osteoarthritis and repair of degenerative articular cartilage in vivo.
ABSTRACT
Due to the poor repair ability of cartilage tissue, regenerative medicine still faces great challenges in the repair of large articular cartilage defects. Quercetin is widely applied as a traditional Chinese medicine in tissue regeneration including liver, bone and skin tissues. However, the evidence for its effects and internal mechanisms for cartilage regeneration are limited. In the present study, the effects of quercetin on chondrocyte function were systematically evaluated by CCK8 assay, PCR assay, cartilaginous matrix staining assays, immunofluorescence assay, and western blotting. The results showed that quercetin significantly up-regulated the expression of chondrogenesis genes and stimulated the secretion of GAG (glycosaminoglycan) through activating the ERK, P38 and AKT signalling pathways in a dose-dependent manner. Furthermore, in vivo experiments revealed that quercetin-loaded silk protein scaffolds dramatically stimulated the formation of new cartilage-like tissue with higher histological scores in rat femoral cartilage defects. These data suggest that quercetin can effectively stimulate chondrogenesis in vitro and in vivo, demonstrating the potential application of quercetin in the regeneration of cartilage defects.