Nerve guides manufactured from photocurable polymers to aid peripheral nerve repair

Abstract

The peripheral nervous system has a limited innate capacity for self-repair following injury, and surgical intervention is often required. For injuries greater than a few millimeters autografting is standard practice although it is associated with donor site morbidity and is limited in its availability. Because of this, nerve guidance conduits (NGCs) can be viewed as an advantageous alternative, but currently have limited efficacy for short and large injury gaps in comparison to autograft. Current commercially available NGC designs rely on existing regulatory approved materials and traditional production methods, limiting improvement of their design. The aim of this study was to establish a novel method for NGC manufacture using a custom built laser-based microstereolithography (μSL) setup that incorporated a 405nm laser source to produce 3D constructs with ~50μm resolution from a photocurable poly(ethylene glycol) resin. These were evaluated by SEM, invitro neuronal, Schwann and dorsal root ganglion culture and invivo using a thy-1-YFP-H mouse common fibular nerve injury model. NGCs with dimensions of 1mm internal diameter×5mm length with a wall thickness of 250μm were fabricated and capable of supporting re-innervation across a 3mm injury gap after 21 days, with results close to that of an autograft control. The study provides a technology platform for the rapid microfabrication of biocompatible materials, a novel method for invivo evaluation, and a benchmark for future development in more advanced NGC designs, biodegradable and larger device sizes, and longer-term implantation studies.