Phenotypic maintenance of chondrocytes in vitro under tensile stress enhanced by the extract of clematis chinensis / 中国组织工程研究

ABSTRACT

BACKGROUND: Mechanical load is crucial for the degeneration of chondrocytes and the development of osteoarthritis. Clematis chinensis can improve the inflammatory microenvironment of osteoarthritis, but its effect on mechanical load-induced degeneration of chondrocytes has not been elucidated. OBJECTIVE: To study the effect and mechanism of the extracts of Clematis chinensis on the degenerative changes of chondrocytes induced by intermittent cyclic mechanical tension (ICMT) in vitro. METHODS: Chondrocytes of the rabbit knee joint were isolated by type II collagenase digestion method and identified by Alcian blue staining. There were five groups in the experiment Blank group, ICMT group, high-, medium- and low-dose Clematis chinensis groups. There was no intervention in the blank group, and the other groups were subjected to ICMT (10% tensile strength, 0.5 Hz, 8 hours per day, for a total of 2 days) for inducing chondrocyte degeneration. Three Clematis chinensis groups were concurrently given 0.5, 1, 2 g/L extracts of Clematis chinensis, respectively. The intervention time was 48 hours. Cell counting kit-8 assay was used for detection of chondrocyte proliferation. FITC-phalloidin staining was used for observation of cytoskeleton morphology. Real-time quantitative PCR and western blot assay were used for determination of collagen type II, matrix metalloproteinase 13, and transforming growth factor β at protein and gene levels, respectively. RESULTS AND CONCLUSION: (1) Compared with the blank group, the cytoskeleton of chondrocytes stimulated by ICMT was long- stretched, the proliferation activity of chondrocytes decreased, and the expressions of collagen type II and transforming growth factor β were down-regulated, while the expression of matrix metalloproteinase 13 was up-regulated. (2) Compared with the ICMT group, the extract of Clematis chinensis could promote the proliferation of chondrocytes, up-regulate the expressions of transforming growth factor β and collagen II, and down-regulate the expression of matrix metalloproteinase 13 in a concentration-dependent manner. To conclude, the extract of Clematis chinensis can inhibit the catabolism of chondrocyte induced by ICMT through regulating the expression of transforming growth factor β, promote the synthesis of extracellular matrix of chondrocytes, and maintain the phenotypic stability of chondrocytes.