Changes Of Microstructure And ERK1/2 Signal Protein In Cartilage And Subchondral Bone Of Patients With Knee OA

Objectives To investigate the changes of cartilage and subchondral bone microstructure and ERK1/2 pathway in tibial plateau nonsclerotic and sclerotic zones of patients with knee osteoarthritis(OA),and to explore the pathogenesis of OA and to further study the pathogenesis of hemophilic arthropathy pathogenesis laid the foundation.Methods Collected abandoned tibial plateau tissue from which patients with osteoarthritis after total knee replacement surgery from January 2016 to April 2016 in Tongji University,Yangpu Hospital(n=22).After gross observation,the cartilage and subchondral bone were divided into nonsclerotic and sclerotic zones,and bone cartilage tissue was drawn in the corresponding area,then which were divided into two groups.One group was stained with toluidine blue to observe the pathological changes,observating tissue and cell microstructure characteristics through scanning and transmission electron microscopy,evaluating the microstructure of subchondral bone by Micro-CT scanning system,and evaluateing its bone tissue metrological changes(n sclerotic zones =22,n nonsclerotic zones =18).Another group separated cartilage from the subchondral bone,was detected the expression of ERK1/2 total protein and phosphorylated protein by Western blot(n sclerotic zones=22,n nonsclerotic zones =18).Results 1 Compared with nonscleroic zones of the cartilage and subchondral bone in the articular tibial plateau of the knee,the hard tissue toluidine blue staining showed that the cartilage morphology of the scleroic zone was chaotic,the cartilage layer became thinner,fibrosis,local may have broken,and even formating micro-cracks of subchondral bone,chondrocytes are reduced and the level of unclear arrangement is poor,subchondral bone trabecular dense,number and thickness are increased.Compared with the nonscleroic zone,scanning electron microscopy showed that the cartilage morphology of the scleroic zone was chaotic,thinner,surface collagen fibers were arranged disorder,exposed and locally broken,and the cracks in the subchondral bone were observed.Cartilage surface collagen coated cells of the ball atrophy was abnormal.The subchondral bone plate with microfractures was thickened,trabecular bone was thicked,narrowing gap,wovening.Bone lacunae become less,uneven distribution,collagen fiber surface roughness,was wheat bran-like,arranged in disorder,the surface of osteoblasts become more narrow.Compared with the nonscleroic zone,the transmission electron microscopy showed that the nucleus of the chondrocytes in the scleroic zone was irregular,and the rough endoplasmic reticulum was dilated,the Golgi apparatus was underdeveloped,mitochondrial edema,decreased lipid,reduced glycogen,and cartilage edema,bone matrix collagen fibers sparse,poor arrangement;bone cell nuclear condensation,nuclear membrane is unclear,inclusions shrinkage,no slender processes,organelles rare,bone matrix collagen fibers sparse arrangement is poor;osteoclasts mitochondria irregular and edema,secondary lysosomes more,bright microfilament reduction,bone matrix collagen fibers sparse,poor arrangement;osteoblast shrinkage,the surface has a small protrusion,and adjacent osteoblasts to form a gap junction,rough endoplasmic reticulum rich,contains many matrix vesicles,golgi developed,bone matrix collagen fibers evenly distributed;visible multiple microvascular formation.Compared with the nonscleroic zones,Micro-CT showed that 2D and 3D reconstruction images showed that the subchondral bone plate thickened and the density increased in the scleroic zones,the trabecular bone structure was more thicker which showed plate-like structure,the trabecular thickness was increased and the trabeculae gap become smaller;compared with the nonscleroic zones,statistical analysis of bone histomorphometric parameters in scleroic zone showed that the mineral density of subchondral bone(t = 7.931,P <0.001),bone volume fraction(t = 11.959,P <0.001),the number of trabecular bone(t = 6.212,P <0.001),bone trabecular thickness(t = 8.070,P <0.001)increased,trabecular space(t = 8.566,P <0.001)and structural model index(t = 10.803,P <0.001)decreased,the difference was statistically significant.2 There was no significant difference in ERK1/2 total protein expression between cartilage and subchondral bone in the sclerotic and nonsclerotic znoes of OA tibial plateau(t =1.926,P =0.062;t =1.753,P =0.088).However the phosphorylation of ERK1/ 2 in the sclerotic zone was significantly higher than that in the nonsclerotic zone(t =15.038,P<0.001;t =20.368,P <0.001),the difference was statistically significant.Conclusions The cartilage and subchondral bone microstructure and ERK1/2 signal protein in OA sclerosis zones are different from nonsclerosis zones.The changes of cartilage and subchondral bone microstructure and ERK1/2 signal protein in sclerosis zones are one of the important characteristics of OA patients.