The Effect And Remodeling Process Of Anterior Cruciate Ligament Reconstruction With Semitendinous Tendon And Its Tissue Engineered Products

BackgroundsNowadays,autologous hamstring tendon–HT(the generic name of semitendinosus tendon--ST and gracilis tendon)graft has become the standard material for anterior cruciate ligament(ACL)reconstruction.However,there still remain lots of unknown histological remodeling processes about it,especially in human being.Meanwhile,considering about the increasing application of the free allogenic tendon graft in daily ACL reconstruction surgery,it has become more and more urgent to make further technical breakthrough to improve allograft’s results in ACL reconstruction,so as to achieve similar good results as autologous tendon graft.So it is meaningful to make further understanding about the autologous tendon graft’s remodeling process and the related mechanisms,which would be more helpful to make further understanding about how to improve allograft’s results.So,on the one hand,we plan to make pH modified decellularized ST graft,and explore the effect of both this single material and the combination of this kind of material with autologous tendon derived stem cells(TDSCs)in ACL reconstruction.On the other hand,we plan to evaluate the histological transformation about the autologous ST after being implanted as ACL substitute in human being.Objectives1.To make pH modified decellularized ST materials and to test its basic properties;2.To investigate the effect of ACL reconstruction with this pH modified decellularized ST graft;3.To investigate the effect of ACL reconstruction with the combination of pH modified decellularized ST and autologous TDSCs;4.To investigate the mid/long term histological remodeling process about the autologous ST graft in human ACL reconstructed cases.Methods1.To make pH modified decellularized ST materials with the main regents of trypsin/Triton X-100/peracetic acid followed with sodium hydrogen carbonate neutralization process,and perform light microscope / electron microscope examination,mechanical testing and biocompatibility analysis;2.To perform ACL reconstruction with this pH modified allogenic decellularized ST materials and common allograft in rabbit,make histology,mechanics and micro-CT analysis.3.To perform ACL reconstruction with the complex of pH modified allogenic decellularized ST/autologous TDSCs and common allograft in rabbit,make histology,mechanics and micro-CT analysis;to perform TDSCs tracing examination via Lv-e GFP transfection technique.4.To perform light microscope / transmission electron microscope examination about the mid/long term-ST reconstructed human ACL graft samples.Results1.The pH modified decellularized ST material had been prepared;it is with enough mechanical strength,excellent biocompatibility,porous structure and about pH 7.2.2.The decellularized ST allograft achieved more excellent results than the common allograft at the following items: cellular and vascular ingrowth at week 2 and 4 postoperatively,collagen matrix remodeling and tendon-bone healing from week 2 to 12;ultimate failure load and stiffness at week 12;bone tunnel bone mineral density(BMD)at week 12;3.The complex of decellularized ST and autologous TDSCs got more excellent results than the common allograft at the following items: cellular and vascular ingrowth at week 2 and 4 postoperatively,collagen matrix remodeling and tendon-bone healing from week 2 to 12;ultimate load and stiffness at week 12;bone tunnel BMD at week 4,8 and 12,and better BV/TV at week 8 and 12;the e GFP positive cells were successfully observed from week 4 to 12 in vivo.4.As regard to the human autologous ST reconstructed ACL graft,there were immature cellularity and vascularity,unhealthy metaplasia state in both mid-term and long-term samples;higher percent bimodal collagen distribution mode and lower percent unimodal collagen distribution mode were observed in both groups.Conclusions1 The pH modified decellularized tendon get more excellent biocompatibility than the common decellularized tendon.2.The pH modified decellularized allogenic tendon get more excellent results than the common allogenic tendon in ACL reconstruction.3.The pH modified decellularized allogenic tendon combined with autologous TDSCs make further improvement than the common allogenic tendon in ACL reconstruction,and the implanted TDSCs could successfully integrate into the implanted ACL graft in vivo.4.There are widely-existed bimodal collagen distribution modes in both human mid-term and long-term ACL grafts reconstructed with ST,which the collagen distribution mode is similar to the normal ACL.