Effect And Mechanism Of Salidroside On Chondrocyte Transplantation In The Treatment Of Articular Cartilage Defect

Objective: Cartilage is an important issue of the body.The hyaline articular cartilage,which is attached to the surface of the knee,has the important functions of lubrication and dispersing pressure during daily activities.People may appear improper exercise,obesity,aging and other problems maybe lead to cartilage defects in daily life.The lack of blood vessels and nerves around the chondrocytes limits the ability of self-repair.If not treated in time,it can develop into arthritis and affect the patient’s daily life.Autologous chondrocyte implantation is commonly used for the treatment of cartilage defects.The operation begins with the extraction of autologous chondrocytes from the patient.In order to get enough chondrocytes,it is necessary to expand them in vitro and transplant them back to the defect site.However,the chondrocytes in vitro may change the cartilage phenotype and form fibrocartilage,which will affect the repair effect.The addition of Transforming growth factor beta 1 in clinic can promote the proliferation of chondrocytes and maintain their phenotype.The high cost and functional heterogeneity of Transforming growth factor beta 1limit its clinical application,so it is necessary to look for economic and safe alternatives.The aim of this The addition of Transforming growth factor beta 1in clinic can promote the proliferation of chondrocytes and maintain their phenotype.The high cost and functional heterogeneity of Transforming growth factor beta 1 limit its clinical application,so it is necessary to look for economic and safe alternatives.The aim of this study is to develop new drugs that can promote the proliferation of chondrocytes and avoid their dedifferentiation.study is to develop new drugs that can promote the proliferation of chondrocytes and avoid their dedifferentiation.Methods:(1)The ability of interaction between salidroside and chondrocyte-specific protein was studied by molecular docking technique firstly.(2)At the cellular level,our study observed the toxic effect of salidroside on chondrocytes through MTT experiment.The effect of salidroside on chondrocyte viability was analyzed by the live/ dead cell staining and the content of DNA.The effect of salidroside on the secretion of extracellular matrix in chondrocytes was analyzed by Safranin o staining and glycosaminoglycan content determination.The effects of salidroside on cell morphology were observed by HE staining and phalloidin staining.The expression of phenotype-related genes in chondrocytes was analyzed by q RT-PCR,and the expression level of type I collagen and type II collagen were observed by immunofluorescence.(3)In vivo experiment,SD rats were used to establish the cartilage defect model,and the control group was set up,the cartilage cells treated with salidroside and the untreated ones were implanted into the defect site respectively.After 4 weeks of repair,the joints were sampled for general observation,histological staining and the content of type II collagen was observed by immunohistochemical staining,to judge the effect of the repair.(4)The possible signal pathways involved in the regulation of salidroside on chondrocytes were detected by ELISA and q RT-PCR.Results:(1)Molecular docking showed that salidroside could bind to glycosaminoglycans and type II collagen in extracellular matrix.(2)Cell experiment.The number of salidroside cells in the concentration of0.33-10.66 μm was more than that in the control group,and the number of salidroside cells in the concentration of 1.33 μm was the most.The number of living cells in the salidroside group was more than that in the control group.Safranin-O staining showed more positive staining in the salidroside group.The content of glycosaminoglycan in salidroside was higher than that in control group(p < 0.05).HE staining and phalloidin staining showed that salidroside had no effect on the morphology of chondrocytes.q RT-PCR results showed that salidroside could significantly up-regulate the expression of phenotype-related genes in chondrocytes and down-regulate the expression of type I collagen,the difference was statistically significant when compared with the control group(p< 0.05).The expression of type II collagen was more and type I collagen was less in the control group than in the control group in the Immunofluorescence staining.(3)In vivo experiments.After 4 weeks of operation,the macroscopic score was significantly higher in the implantation of chondrocytes treated with salidroside than in the implantation of untreated cells.The results of histological staining showed that the repair of hyaline cartilage was promoted by the chondrocytes used for autologous chondrocyte transplantation in the treatment of salidroside.Without salidroside,the repaired cartilage was mainly fibrocartilage Immunohistochemical staining showed that the content of type II collagen in cartilage was higher when the cells treated with salidroside were repaired.(4)Mechanism Studies.Elisa and q RT-PCR showed that the expression of tgf-β and Smad3 gene was higher significance than control group,but had no effect on BMP2/smad1 signal.Conclusion:(1)Salidroside can effectively maintain the phenotype of chondrocytes and inhibit their dedifferentiation when cultured in vitro.(2)In the model of cartilage defect,salidroside can obviously repair the cartilage defect of rats.(3)salidroside promotes chondrocyte proliferation and maintains its phenotype by activating tgf-β/SMAD3 signal.Therefore,salidroside may be a potential drug for chondrocyte autotransplantation to promote chondrocyte proliferation and maintain its phenotype in vitro.