Chitosan-based nerve guidance conduits functionalized with fibroblast-derived extracellular vesicles promote peripheral nerve regeneration via miR-143-3p delivery.

Fibroblasts, one of the core cellular components of peripheral nerves, play a pivotal role during peripheral nerve regeneration; however, whether extracellular vesicles (EVs) derived from peripheral nerve fibroblasts promote nerve regeneration remains unclear. In this study, we first demonstrated that EVs derived from peripheral nerve fibroblasts (fibroblasts-EVs) significantly promoted the growth and regeneration of motor and sensory neurons in vitro. In order to assess the application of fibroblasts-EVs in nerve grafting, we constructed a chitosan-based, fibroblast-EV-loaded nerve guidance conduit (NGC) and utilized it to bridge a 12-mm long sciatic nerve defect in rats. A series of functional and morphological assessments showed that EV-loaded NGCs significantly accelerated the recovery of sensory, motor, and electrophysiological functions, stimulated the growth and remyelination of regenerated axons, and alleviated denervation-induced atrophy of target muscles. To elucidate the underlying molecular mechanisms, we screened miRNAs enriched in fibroblast-EVs through miRNA sequencing. Among these miRNAs, miR-143-3p with the highest abundance was identified as a potential regulator of axon regeneration. Further investigations revealed that miR-143-3p promoted nerve regeneration by targeting Limk1, a negative regulator of axonal growth. This study expands our understanding of the role of fibroblasts in peripheral nerve regeneration and suggests that our developed bioactive material-based NGCs may present a promising design of tissue-engineered nerve grafts for peripheral nerve repair.