The Research Of The Influence On The Biochemical Environment Of The Chondrocyte Stressed By The Long-Time Non-Axial Cyclic Tensile Loading

ObjectsBeing short of nutrition of the blood and the low generation ability of extracellular matrix, the impact of reparation of injured cartilage is the major reason of the severe types of arthritis. In the research of different models, it is hard to compare the result of which, is to get the intensity, frequency and manner in different. It is proven that the 20%tensile magnitude of dynamic stress is effected on the mono-cell can reduce the component of the cartilage, and up-regulate the expression of MMP1,3,9. Persistent tensile stress make the matrix of cartilage into regeneration and alteration of the component of extracellular matrix. And the cyclic tensile stress would be the antagonism of the cytokine of inflammation (e.g. IL-1βand TNF-α) which is exist around the chondrocyte,The objects of our research is the alteration of gene expression of the enzymes about the catabolism and anabolism of chondrocyte (MMP3, MMP13, ADAMTS-5, TGF-β1) which cultivated on the cell monolayer and is effected by cyclic tensile stress for a longer time, and the difference biochemical environment of chondrocyte which is effected by different magnitude of tensile stress.Materials and methodsThe cartilage were isolated from the hip and knee of new Zealand rabbits, and is digested into mono-cell. And the cells was seeded in the concentration of 5*106/pore in the Flexercell type 1 plate. Until the cells grow on the condition of deuto-fusion, we do not effect the tensile stress to the chondrocyte, then we set the plate on the FLEXERCELL-5000T tension system. Our research adapt the design of two factor ANOVA, with grouping into low magnitude, high magnitude and control. The timing group divide into the 3rd day and 5th day, with effecting tensile stress for 8 hours one day. At each timing plot,the chondrocyte is tested by Toluidine blue dyeing with observation by microscope,and qRT-PCR for research the gene expression of MKP3,MMP13,ADAMTS-5,TGF-β1.ResultsThe gene expression of MMP3 and ADAMTS-5 of each effected group is up-regulated in the 3rd day, and get lower in the 5th day than the 3rd day. The expression of MMP13 of each effecting groups get higher than the control group, and the expression of high magnitude group continue to be higher in the 5th day than the 3rd day, but the low magnitude group get no alteration. In the grouping comparison, the expression of MMP-13 of high magnitude group is always higher than the low magnitude group. The expression of TGF-β1 of effecting group is always higher than the control one, and the expression of low magnitude group is both higher than the high group. ConclusionThe low magnitude tension(5%) can enhance the metabolism of chondrocyte, includes the anabolism and catabolism, and make protect action on the chondrocyte. The high magnitude tension stress would urge extracellular matrix to resolve, and the severe kinds of enzymes of catabolism created by chondrocyte up-regulated in different timing. Specially, the MMP-13 play an important role in the catabolism of cartilage. The TGF-β1 may take a crucial role in the pathological repair of injured cartilage.