Enhanced axonal regeneration and functional recovery of the injured sciatic nerve in a rat model by lithium-loaded electrospun nanofibrous scaffolds

Increasing evidence indicates that engineered nerve grafts have great potential for the regeneration of peripheral nerve injuries(PNIs).While most studies have focused only on the topographical features of the grafts,we have considered both the biophysical and biochemical manipulations in our applied nanoscaffold.To achieve this,we fabricated an electrospun nanofibrous scaffold(ENS)containing polylactide nanofibers loaded with lithium(Li)ions,a Wnt/β-catenin signaling activator.In addition,we seeded human adipose-derived mesenchymal stem cells(hADMSCs)onto this engineered scaffold to examine if their differentiation toward Schwann-like cells was induced.We further examined the efficacy of the scaffolds for nerve regeneration in vivo via grafting in a PNI rat model.Our results showed that Li-loaded ENSs gradually released Li within 11 d,at concentrations ranging from 0.02 to(3.64±0.10)mmol/L,and upregulated the expression of Wnt/β-catenin target genes(cyclinD1 and c-Myc)as well as those of Schwann cell markers(growth-associated protein 43(GAP43),S100 calcium binding protein B(S100B),glial fibrillary acidic protein(GFAP),and SRY-box transcription factor 10(SOX10))in differentiated hADMSCs.In the PNI rat model,implantation of Li-loaded ENSs with/without cells improved behavioral features such as sensory and motor functions as well as the electrophysiological characteristics of the injured nerve.This improved function was further validated by histological analysis of sciatic nerves grafted with Li-loaded ENSs,which showed no fibrous connective tissue but enhanced organized myelinated axons.The potential of Li-loaded ENSs in promoting Schwann cell differentiation of hADMSCs and axonal regeneration of injured sciatic nerves suggests their potential for application in peripheral nerve tissue engineering.