A regenerative electrode scaffold for peripheral nerve interfacing

Novel approaches to peripheral nerve interfacing are required to establish the stable, high-resolution connections demanded by the emerging generation of advanced neuroprosthetic devices. Here we propose a nanofiber scaffold-based design for a regenerative electrode capable of establishing significant numbers of stable and selective electrical connections with subsets of peripheral nerve. The design features one or more polyimide thin-film electrode arrays integrated within a layered nanofiber scaffold such that regenerating axons from a transected nerve are directed across the embedded electrodes. In-vitro and in-vivo experiments with a rat peripheral nerve model were performed to validate and optimize the ability of our regenerative electrode scaffold (RES) to direct axonal regeneration across an implanted electrode array. Immunostaining of cultured dorsal root ganglia revealed that migrating Schwann cells and extending neurites can be directed along oriented nanofibers and across an overlaid polyimide electrode in-vitro. RES´s were then fabricated and implanted between the stumps of transected rat tibial nerves (n=10). After 3-6 weeks the scaffolds were explanted and stained to characterize regeneration through the RES´s. Staining revealed robust axonal regeneration through the scaffolds. This regeneration was directed as close as several microns to the surfaces of the integrated electrode arrays. Staining also revealed minimal inflammatory response at the electrode array site. Additionally, the same results were obtained in the absence of an intact distal stump. In conclusion, our results suggest the feasibility of this design for use in interfacing an amputated nerve stump. Electrophysiological capabilities of the interface and facilitation of long term trophic support for the nerve will be examined in future experiments.