Experimental Study On Cryopreservation Of Tendon Allografts By Vitrfication

Objective To evaluate the feasibility of preservation by vitrification and the effectiveness of vitrified tendon as allografts.Methods 108 tendons were harvested from 18rabbits as the transplanted materials,and 54 tendons were preserved by vitrification,54 by slow-freezing for 14 days,respectively.The 27 rabbits were used as the transplanted subjects,and were divided into three groups,Group A(fresh tendonial autografts),Group B(vitrified tendonial allograft )Group C (frozen tendonial allograft).The morphologic changes,mechanical capability of tendon grafts were observed or detected,which in order to comprehend what happened after cryopreservition.By means of comparing with fresh tendons and frozen tendons in vitro,thus we could know the benefit and shortcoming of vitrification method.The tendons were allotransplanted. After operation,the rabit were sacrificed in 3,8,12 weeks,and grafts were harvested to observe the morphological changes,immunologic rejection and biomechanical changes.By means of comparing with fresh flexor tendon autografts and frozen flexor tendon allografts,to evaluate the feasibility of vitrified tendons being used as allografts.Results Before transplantation,the integrated rate of Group B was 92.4%,which was significantly better than that of Group C(54.2%,P＜0.01).After transplantation,Group C was more heavy adhesion around tendon than that of Group A,B.In Group A,B,new collagen fibers and significantly increased and reconstructed than that of Group C.The tendon extracellular matrix could be preserved perfectly by vitrification, and which was better than freezing method.And creep and stress relaxation phenomenon could be found among the three kind of tendon.And biomechanical capability among the fresh,vitrified and frozen tendons was no significantly different.The fresh,vitrified and frozen tendons were transplanted by autografts and allografts,and wound got good healing,but there was middling level or even more heavy adhesion around tendon.Tendon cells in the vitrified tendon decreased significantly at 3 weeks after transplantion,and in the part of connection there were a great quantity small collagen fibers and fibroblast to fill in.Quantity of cells in the vitrified tendon had already approach to the normal at 8 weeks.And in the part of tendon connection, quantity of tendon cells significantly increased and small and thick collagen fibers arranged at interval at 12 weeks.Three kind of tendons still belong to viscoelastic body,and creep and stress relaxation phenomenon were similar. we found the area of cross section in the part of tendon connection gradually decreased following with time.The biomechanical capability of vitrified tendons was better than the frozen,but which was inferior to the fresh.The vitrified and frozen tendon grafts were found light immunologic rejection after implantation.Conclusions The tendon extracellular matrix could be preserved perfectly by vitrification.There were no obviously difference between the vitrificed and fresh tendon.The fresh,vitrified and frozen tendons were transplanted by autografts and allografts,the vitrified and frozen tendon grafts were found light immunologic rejection after implantation,but which didn't affect tendon healing and reconstruction.In short,the results of vitrification are superior to freezing method.lt may be valuable for tendon allografts in clinical application and building tenson bank.