Biomimetically Assembled Conductive Nerve Conduit For Peripheral Nerve Repair

Peripheral nerve injury(PNI)is the loss of peripheral nerve structure and/or function caused by traffic accidents,construction accidents,tissue resection and other injuries.The length of peripheral nerve injury is relatively short(<5mm),and can selfregenerate after suturing,but the long-distance nerve defect incapable of healing needs nerve manipulation and bridging such as self-lifting nerve transplantation.With the development of new biomaterials,nerve conduits have become a hot research field for repairing peripheral nerve injury.At present,most of the nerve conduits are simple hollow cylindrical tubular structures,but this simple structure is not tissue-inductive for cell adhesion and proliferation,and is easy to collapse without internal support.In addition,the nerve conduit lacks conductivity,which is not conducive to nerve conduction and electrical stimulation of lower limb muscles.In this study,hollow conductive nerve conduits were prepared by wet-spinning method,and injectable hydrogel microspheres were designed as the inner fillers of the conduits.In situ,threedimensional nerve scaffolds self-assembled inside the nerve conduits.The results show that:1.The wet-spinning method can rapidly prepare hollow tubes with controlled size and morphology,and adjustable mechanical properties;After being modified by polydopamine and polypyrrole,the conduit has high biocompatibility and good conductivity.PC 12 cells can grow on the inner surface of the catheter,and its conductivity can promote nerve electrical conduction in the defect model,leading to lower limb muscle contraction.2.After the 100-400 μm hydrogel microspheres prepared by the emulsion crosslinking method were respectively modified with orthogonal reaction groups,they could be crosslinked in situ after mixing and injecting to form porous scaffold,which had high stability under physiological conditions,and could be used as three-dimensional scaffold materials to promote the three-dimensional culture of cells.In addition,axonal elongation was observed in SD suckling rat dorsal root ganglion cultured inside the scaffold in vitro,After 10 days culture of the dorsal root ganglion in the scaffold,the axons could be observed to extend outward along the internal gap of the scaffold.3.In the rat sciatic nerve defect model,the bionic composite conduit has the ability to promote the recovery of nerve function in rats.The recovery of various nerve function indicators at 16 weeks after operation indicated that it can promote the recovery of motor function of rats,alleviate the muscle atrophy of lower limbs,and promote the recovery of nerve electrophysiological function.The constructed biomimetic composite nerve scaffold in this project can adjust the size and mechanical properties.The internal scaffold can be injected and can be used for three-dimensional growth of cells,and has the potential to load drugs,growth factors and even cells.It provides a potential strategy for the development of multifunctional nerve scaffolds.