Rolling-sliding Mechanical Compression Slows Down The Decreasing Of Chondrocyte Viability And Mechanical Properties In Osteochondral Allograft Preserved In Culture Medium

The purposeMechanical stimulation of articular cartilage explants will lead to variety of changes.Most previous studies have focused on cyclic mechanical stimulation of chondrocyte or axial compression of cartilage explants.Little information concerning mechanical compression simulate the condition of the human body has been obtained.We have therefore conducted studies where rolling-sliding mechanical compression are applied in vitro to full thickness cartilage explants,in order to investigate bionic stimulation induced variation for cell survival and apoptosis rate and consequent turnover,in addition to type ? collagen/aggrecan/mRNA/expression of related protein changes and mechanical property alterations.MethodsFull thickness 8 mm diameter cartilage disks retaining a thin layer of underlying bone were isolated from the knee joints of 1-2year old mature pig 3-6 h post-mortem,using a specialized apparatus osteochondral harvester.The thickness of these disks was uniform at 10 mm,with about 2 mm representing cartilage,the remainder being subchondral bone.According to previous experimental results,we used a rolling-sliding mechanical compression device for the mechanical loading experiment.Respectively,when save 1day,7 days,14 days for cartilage discs EB / FDA with fluorescence staining to detect cell survival rate,mRNA content,related proteins content and take a picture of the best groups.According to the SPSS 19.0 DATA Analysis,used (?)±S to show all of the digital.Save between each group and different points in each group Safranin O staining IOD value and viability using analysis of variance for repeated measures data.P<0.05 shows this data has Statistical significance.ResultStatic preservation group and the experimental group cell viability after loading saved three days,the experimental group cell survival rate higher than the static group;after loading stored for seven days,and no significant difference in the survival rate of the cells in the experimental group and a static group.Static preservation group compared with the number of apoptotic cells in the experimental group,after loading saved three days,less than the number of apoptotic cells in the experimental group a static group;seven days after loading saved number of apoptotic cells in the experimental group and a static group difference.Cell viability after the results of continuous culture of mechanical stimulation: 3 day loading group was higher than the control group after;The mechanical stimulation during the culturing of cell viability results: 3 day loading group and control group had no significant difference after consistently lower than the control group.In the static preserveation group and the experimental group,the content of proteoglycan and type ? collagen: the experimental group and 7 days a static preservation group showed no significant differences between the proteoglycan,14 days in the experimental group was significantly higher than the static proteoglycan preservation group;save 7 day,type ? collagen content of the experimental group were higher than the static group;save 14 days,type ? collagen content of the experimental group were higher than the static group;load of 2.0,the type ? collagen content decreases.Moisture test: the moisture content of a static group and tsmcmgroup were higher than the fresh group,static group compared with no difference of tsmc group,2.0Mpa abnormal increase in the moisture content of the group.After three days in stimulating cartilage mechanical properties test result:Young's modulus in the fresh group and loading group was significantly higher than the static preservation group;the amount of relaxation in the fresh group and loading group was significantly less than save the group;the amount of creeption in the fresh group and loading group was significantly less than save the group.In the fresh group and a static group,the amount of type ? collagen mRNA did not change in the load group mRNA content increased;static Save Group proteoglycan mRNA content is low compared with the fresh group,the loading group has the highest concentrations of proteoglycan mRNAProtein expression showed that mechanical stimulation can significantly alter the amount caspase3 and bcl-2 and bax mRNA.Bcl-2 mRNA was significantly higher in the static preservation process,the content was significantly higher in the experimental group;Bax mRNA showed no significant change in the static preservation process,the content was significantly lower in the experimental group;Caspase-3mRNA static content decreased in the preservation process,the content was significantly lower in the experimental group.Cytoskeletal proteins actin and vimentin mRNA showed no significant change in the static preservation process,the content was significantly higher in the experimental group;MMP-13 mRNA was significantly higher in the static preservation process,significantly increased in the experimental group content.ConclusionIn the static mechanical stimulation applied to cartilage graft preservation process,we can improve the survival rate of chondrocytes,inhibit apoptosis and delay cartilage extracellular matrix degradation,thereby delaying the decreasing of the mechanical properties of bone cartilage.Mechanical stimulation may reduce the ratio of bax and bcl-2,thereby inhibiting the mitochondrial pathway of apoptosis.Applying an appropriate mechanical stimulation in cartilage preservation can improve the quality of transplants banking,thereby enhancing the osteochondral allografts success rate.