Electrical gastrodin-polyurethane spiral conduits with micro/nano-structure for accelerating peripheral nerve regeneration

Peripheral nerve injuries tend to cause the proximal nerve unable to contact the corresponding target organ, resulting in sensory and motor dysfunction. The simple filling materials within nerve conduits are often inadequate for axonal ingrowth and directional regeneration. In this study, to enhance the guidance effect and achieve physiologically adaptive function, a 3D nanofibrous polyurethane (PU) scaffold with oriented microchannels was engineered using electrospinning and manual curling techniques. The electrospun fibrous membranes can be manually curled up into tubular structures with spiral and longitudinal multi-channels. The immunoregulatory and conductive properties were developed by being grafted gastrodin and aniline trimer (AT, 2.6 % and 5 %). Gastrodin stimulated proliferation of neural cells and expression of neuroblast-related genes. Electroactive AT produced an electrical signal in combination with electrical stimulation (ES) to accelerate the elongation and growth of Schwann cells (SCs) and neurite outgrowth of PC12 cells. The in vivo experiments revealed that the releasing gastrodin and electrical signals created prohealing microenvironment for alleviating inflammation and promoting vascularization. Of note, the topological structure provided well-organized internal support for the cells to spread, as well as the migration of SCs and the directional elongation of regenerating axons. The adaptive electroactivity of gastrodin-PU-AT5 % further ensured nerve signal transmission, ultimately promoted remyelination through upregulation of Rap1 and mTOR signaling pathways; thereby enhancing functional and structural regeneration. This scaffold design strategy will push forward the application of nerve conduits in long-distance peripheral nerve injury.