Stereolithography of PEG Hydrogel Multi-Lumen Nerve Regeneration Conduits

Abstract

Peripheral nerve regeneration conduits available today are single lumen conduits. Multi-lumen conduits offer advantages over currently available conduits in that multiple lumen better mimic the natural structure of the nerve, provide a greater surface area for neurite extension, and allow for more precisely located growth factors or support cells within the scaffold. This work describes and demonstrates the use of the stereolithography (SL) rapid prototyping technique for fabricating multi-lumen nerve guidance conduits (NGCs) out of photopolymerizable poly(ethylene glycol) (PEG). NGCs were fabricated from PEG-dimethacrylate (PEG-dma) molecular weight 1000 with 30% (w/v) aqueous solution and 0.5% (w/v) of the photoinitiator Irgacure 2959. The selection of the PEG-dma and photoinitiator concentration was based on previous work [13]. A 3D Systems 250/50 SL machine with a 250 μm laser beam diameter was used for the experiments in a slightly modified process where the NGCs were fabricated on a glass slide within a small flat-bottom cylindrical container placed on top of the SL machine’s original build platform. SL successfully manufactured three-dimensional, multi-layered and multi-material NGCs with varying overall NGC lengths and lumen sizes. Minimum lumen size, spacing, and geometric accuracy were constrained by the laser beam diameter and path, curing characteristics of the polymer solution, and UV transmission properties of the polymer solution and cured PEG-dma. Overall lengths of the NGCs were constrained by the ability of the conduit to self-support its own construction. Multiple material conduits were demonstrated by varying the build solution during the layering process. In summary, SL shows promise for fabrication of bioactive NGCs using PEG hydrogels, and the use of SL in this application offers the additional advantage of easily scaling up for mass production.