| IntroductionA large gap in the continuity of a peripheral nerve is, in clinical practice, repaired by autologous nerve grafting, this however, requires the sacrifice of a healthy nerve,usually the sciatic nerve,with permanent functional impairment. Another problem is the shortage of autogenous nerves obtainable, A variety of strategies has therefore been used in attempt to develop alternative repair methods, there have, therefore, been efforts to find a suitable material to replace these autografts. In the present study, various efforts have been devoted to find substances which might replace autografts. Inclding; non -biological grafts, silicone tubes PLA PGA PPE; biological grafts: biological allografts of different tissues, i. e. , vein and membrane tube muscle basal lamina AECM; autologous nerve grafting: dissociate nervous autograft nervous autograft with blood vessels; tissue engineering: artifical nerve. As a sort of natural materials,acelluar nerve grafts are considered to be the effective scaffold for tissue engineered nerve because of its native structure and its bioactive components such as laminin and fibronectin, which might induce axon regeneration, SCs adherence and SCs crawl. Furthermore, such extracted grafts may be less prone to rejection allowing allo or perhaps even xenografting to be used for nerve repair. Experimental study represents that tissue engineered artificial nerves constructed with AECM and SCs are most promising.ObjectivesThe aim of this study was to develop a procedure by which myeline and Schwann cells could be removed from a peripheral nerve while the basal lamina tube, remined intact, and to test if such preparations could be used as allografts for the repair of a gap in the countinuity of the rat sciatic nerve. To explore the efficiency of bridging the peripheral nerve 15mm and 20mm defect by pre - constructed - lateroterminal neurorrhaphy of the sciatic nerve acellular extracellular matrix and the sciatic nerve acellular extracellular matrix adding Schwann cell. This new paradigm offers a possible solution to the major shortcomings of autolo-gous nerve grafts, i. e. , the requirement to sacrifice a healthy nerve and the shortage of graft material available for repair. It the foundational work for tissue engineered artificial nerve researches.MethodsPartI: Rat sciatic nerves segments were acellularized with chemical method and evaluated via gross observations, HE staining, anti - laminin immunohisto-chemical assessment, SEM and tissue compatibility . pre - constructedlOmm, 15mm,20mm tissue - engineered acellular extracellular matrix 2weeks - with peripheral nerves lateroterminalneurorrhaphy, then we developed a novel tissue -engineer scaffolds by bridging 15mm long gap of sciatic nerve in SD rats, while evaluation and examination by scanningelectronmicroscope ( SEM ) , RT - PCR, Horseradishperoxidase ( HRP ) at 2 weeks, 12 weeks after surgery.PartII:The culture of the Schwann cell in tissue engineering and the study of cellular compatibility by the inverted phase contrast microscope methythia-zolyl tetrazolium bromide( MTT) FLC SEM .RT - PCR analysis.Part III: the SD rats were divided randomly into three groups, 10 in each: AECM + SC end - end sature( groupA) ; AECM + SC lateroterminalneurorrhaphy (group B) , AECM + SC lateroterminalneurorrhaphy pre - contructed and end -end suture (group C). Autogenous nerve grafting was used as control group. The movement of limbs . The electromyographic examination light and electron microscopic ,, image analysis and horseradish peroxidase reversal labeling test were done postoperatively.ResultParti: The cellular elements of tissue-engineered acellualr extracellular matrix were eliminated completely, while the original three-dimensional structure and bio-activitive were preserved. No significant different was observed between the experiment groups and the control groups (P <0. 05) were checked up.Partll: There was no difference between the activity of SC cultured on AECM and those of control cells( P >0.05) ,and the DNA of the former was not danagedPartlll: A number of regenerating axons were crossed into the grafts in group B^C and autograft group. The latency and amplitude of the regenerating nerve in group A were lower than that in group B>,C at postoperative 12 ^ 16 weeks ( P < 0. 05 ) , there was statistical difference, But there was statistical difference between group B^C and autograft group . Horseradish peroxidase reversal labeling test showered more labeled motion neurons at the anterior horn of the lumbosacral enlargement in group B^C and autograft group.DisscusionParti: The present study showed that segments from the sciatic nerves of SD rats can be successfully extracted to become acellular, and that such extracted nerves support nerve regeneration when used as allografts for the repair of the sciatic nerve in Wistar rats. The extraction procedure resulted in Schwann cells leaving seemingly intact basal lamina tubes. Immunohistochemistry revealed the presence of laminin in the tubes .Partll: There was no difference between the activity of SC cultured on AECM and those of control cells ( P >0.05 ) ,and the DNA of the former was notdanaged. AECM was compounded with Schwann cells. It showed good cellular compatibility, no antigenicity or low antigenicity. Schwann cells on AECM showed spiral movement and tangle.PartIII;AECM adding Shwann cells can repair 20mm sciatic nerve defects. This paradigm could become a useful alternative to autologous nerve grafting and perhaps represent a solution to some of the problems associated with autologous grafting. These findings reveal that AECM of nerve is a new idel biological material for repairing the defected peripheral nerve injury.Conclusions1. this new pre - contructed paradigm offers a potential solution to repairing a long gap of peripheral nerve. Distance of bridging the peripheral nerve defect by pre - constructed - lateroterminal neurorrhaphy of the sciatic nerve acellular extracellular matrix attained to 15mm.2. AECM seeds with SC was suitable to construct tissue - engineered bioar-tificial nerve.3. These findings reveal that AECM combined with Schwann cell is a satisfactory alternative to repair of 20 mm sciatic nerve defects . It the foundational work for tissue engineered artificial nerve researches in clinic.
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