Constructing conductive conduit with conductive fibrous infilling for peripheral nerve regeneration

Abstract

Nerve conduits are essential for guiding the regeneration of injured peripheral nerves, and empty conduits usually cannot perform satisfactorily due to problems with cell migration and nutrient transportation. Taking the electrophysiological features of nervous tissues into consideration, in this study, a conductive conduit filled with parallel-aligned conductive fibers was constructed, and its potential for enhancing peripheral nerve regeneration was evaluated in vivo. The conductive fibers were prepared via depositing a polypyrrole (PPY) shell onto electrospun parallel-aligned poly(lactide-co-glycolide) (PLGA) fibers. The conductive conduit was prepared from PLGA/PPY emulsion via dip-coating on a mandrel. Both materials were non-cytotoxic to PC12 cells and were able to promote cell proliferation and differentiation. Moreover, the aligned fibers provided strong orientation guidance for nerve fibers. Sciatic nerve defects were created in Sprague-Dawley rats, and empty or fiber-filled conduits were sutured into the defects. Meanwhile, the control groups received PLGA conduits or autografts. Twelve weeks post-operation, the fiber-filled conductive conduit showed much better nerve regeneration outcomes than both the PLGA conduit and the empty conductive conduit and showed comparable results to the autograft in terms of electrophysiological properties, sciatic function indices, and regenerated myelinated nerve fibers as well as axon diameter and myelin thickness. It is possible that the oriented conductive fibers in the conductive conduit provide a favorable micro-environment for nerve growth due to their capacity to transmit self-originated electrical stimulation between cells. The results of animal testing confirmed the feasibility of using combined conductive conduits for guiding nerve regeneration.