In Situ Repair Of Nerve Defects By Tissue Engineered Nerve Grafts Constructed From Traumatic Neuroma

ObjectiveTissue engineered nerve grafts are widely used as a method for replacement of autologous nerve grafts for the repair of peripheral nerve defects.The core factors of tissue engineered nerve scaffolds usually include ideal seed cells,physical scaffold materials,neurotrophic factors,and extracellular matrix.In this study,based on traumatic neuroma tissue,it was composited with chitosan cannula to construct a novel tissue engineered nerve graft for the in situ repair of residual nerve defects(10 mm)caused by the removal of neuroma,and the repair effects were evaluated.Methods(1)A traumatic neuroma model of SD rat was established by simple transection of the sciatic nerve and ligation of the proximal septal end.The validity of the model was verified by ultrasound elastography and immunohistochemical staining,and the components of neuroma tissue were identified.(2)In vitro,the neuroma tissues were co cultured with Schwann cells(SCs)and dorsal root ganglia(DRG),respectively.Immunofluorescence staining,ELISA and CCK8 were used to evaluate the secretion and proliferation of Schwann cells,and axonal growth of dorsal root ganglion.(3)Through animal experiments,tissue engineered nerve grafts were constructed by combining neuroma tissue microparticles and chitosan cannula to repair nerve defects caused by neuroma resection in situ(10mm).The experimental animals were randomly divided into three groups:Neuroma(chitosan cannula filled with neuroma tissue microparticles,n=10),Hollow(hollow chitosan cannula,n=10),Sham(sham operation group,n=10).The repair effects of the sciatic nerve defect in rats were evaluated by histological,morphological,electrophysiological and other methods.Results(1)3 weeks after the construction of traumatic neuroma model,ultrasonic detection and postoperative gross observation showed that the nerve proximal stump formed typical bulbous structure;histological staining revealed that the structure of the normal nerve fibers in the structure was damaged obviously,arranged in a chaotic way,and it contained lots of Schwann cells,laminin(laminin)and fibronectin(fibronectin),suggesting that the model was successfully constructed.(2)The results of co-culture in vitro showed that the neuroma tissue could significantly(p<0.05)accelerate the growth of DRG axons and promote the proliferation and secretion of Schwann cells.(3)In vivo,2 weeks after surgery,the longitudinal histological staining of the nerve grafts showed that the nerve fiber regeneration speed in Neuroma group was higher than that of Hollow group;12 weeks after surgery,the electrophysiological and histological evaluation of nerve regeneration and target organ recovery results in Neuroma group were all better than Hollow group(p<0.05).Conclusion(1)Through the method of sciatic nerve transection and ligation of the proximal stump,neuroma model was successfully constructed;(2)The neuroma contains a large number of Schwann cells,neural tissue derived extracellular matrix components and neurotrophic factors;(3)Tissue engineered nerve graft constructed by neuroma tissue microparticlescan be used for in situ repair of nerve defect left by resection of neuroma.