The Effect Of Mechanical Condition On The Human Osteochondral Allograft In Storage Media

Objective Osteochondral allograft is well accepted to treat cartilage defect.A prolong storage method is required for the establishment of the tissue bank of osteochondral allograft,and providing tissue resource to clinic for repairing cartilage defect. In this study, mechanical environment was supposed to benefit the storage of cartilage in vitro,so a mechanical environment was loaded on traditional tissue culture media,then chondrocytes function and ultrastructure of ECM was observed to identify the effect of mechanical environment on osteochondral allograft in tissue culture media, and further to enhance the performance of catilage storaged in commonly used tissue cultrure media.Materials and methods Condyles of femur from 6 donators aged from 20 to 40 were ramomly divided into 3 groups including: 1,Control group, fresh osteochondral samples were detected in 24 hours without storage.2, Common tissue cultrure media group(common group),fresh osteochondral samples were storaged in DMEM medias within 20%FBS, medias were storaged in incubator with 37℃,5%CO2 and saturated humidity for 2 weeks.[1]3,Mechanical loading tissue cultrure group(mechanical group),fresh osteochondral samples were storaged in DMEM medias within 20%FBS, medias were put in a shaking table and storaged in a incubator with 37℃,5%CO2 and saturated humidity for 2 weeks. The shaking table was used as a dynamic loading device for osteochondral allograft in storage media to simulate the mechanical environment of normal articular cartilage in vivo. The device worked at the frequency of 1Hz. Western bloting was used to analyse the change ofβ-actin protein expression at articular cartilage in each group to investigating the effects of loading condition on the chondrocytes function.Transmission electron microscopy was used for observing the collagen ultrastructure at articular cartilage in each group.Results Compared with the control group,β-actin in articular cartilage in both loading group and common group decreased at 2 weeks after storage(P<0.05,P<0.01);The mechanical group kept the expression ofβ-actin in articular cartilage significantly better than that in common group in static condition,especially in deep zone(P<0.05,P<0.01).Electron microscopy showed that in mechanical group,collagen net-work was still existed,but fibra density and fascl fiber was decreased,collagen fiber was diffusely dissolved and destroied, average diameter of collagen fiber decresed to 74.6±25.6nm,compared with the control group(P<0.05);in common group , collagen was destroied significantly, fibra density and fascl fiber was decreased significantly, arrangement was disorder, average diameter of collagen fiber decresed to 51.2±11.5nm ,compared with the control group and loading group(P<0.01).Conclusion Mechanical condition benefit preserving chondrocytes function and collagen ultrastructure at articular cartilage in human osteochondral allograft in storage media. The dynamic uncontact-loading may provide a better method in banking human osteochondral allograft,and a better tissue resource for treating cartilage defect.