Research On Chondrocyte Mechanics In Osteoarthritis

The development of osteoarthritis(OA)is a complex process,and mechanics is a key factor in the pathogenesis of osteoarthritis.Many studies have focused on biochemical factors in osteoarthritis,but less on the mechanical effects on the pathogenesis.This study explores three aspects of the mechanics related to chondrocytes:(1)The mechanics of different morphologies of chondrocytes in osteoarthritis.Chondrocytes are fusiform-shaped and flat-shaped when cultured in vitro.They have not been distinguished by different morphological cells in mechanical measurements.This study measured the mechanical properties of different morphologies of chondrocytes and found the Young’s modulus of fusiform chondrocytes was smaller than that of flat cells.The cell elastic modulus is closely related to the arrangement of the cytoskeleton.The cytoskeleton of the fusiform cell is arranged in a single direction,and the cytoskeleton of the flat cell is arranged in different directions.The different arrangement of the cytoskeleton causes flat cells’ modulus to be higher than fusiform cells.Fusiform cells have a faster migration rate than flat cells.(2)Mechanical properties of chondrocytes at different calcium ion concentrations.Calcium ion concentration in synovial fluid of osteoarthritis increases with the deepening of the disease,and calcium plays an important role in the course of osteoarthritis.This study simulates the calcium concentration in the synovial fluid of patients with different degrees of osteoarthritis.The cells are treated with calcium ions at a concentration of 70ug/mL to 150ug/mL.It was found that the elastic modulus,cell and extracellular matrix forces of chondrocytes increased first and then decreased with the increase of calcium ion concentration.The cytoskeletal density was detected by F-actin fluorescence staining.Expression of myosin,type II collagen,proteoglycan,integrin was detected by real-time PCR.The wound healing assay was used to detect the migration of cells at different calcium ion concentrations,and it was found that the migration ability of chondrocytes increased first and then increased with the concentration of calcium ions.(3)Aging mechanics of chondrocytes in osteoarthritis.In the repair of osteoarthritis,the removal of senescent cells plays an important role in the repair of cartilage.In the pathogenesis of osteoarthritis,the hardness of cartilage gradually increases as the disease progresses.This study investigated the effects of chondrocyte aging on different matrix hardness.After hydrogen peroxide induced premature senescence,it was found that chondrocytes growing on harder substrates were more senescent,and chondrocytes growing on softer substrates were less aging.The inflammation-related factors MMP13,il1β and the aging-related gene CDKN2 also decrease as the hardness of the substrate decreases.To explore the possible intrinsic relationship between the mechanical behavior of chondrocytes and their migration behavior,the role of chondrocyte mechanical behavior in the pathogenesis of OA will be clarified,and our understanding of OA pathology will be deepened,thus promoting the development of relevant OA clinical treatment methods.