Printed Nerve Guides Aid Peripheral Nerve Repair

Researchers at the University of Sheffield (United Kingdom) developed a new method for fabricating three dimensional (3D) printed NGCs using customizable computer aided design (CAD) design and photocurable poly(ethylene glycol) resin as the substrate material. A custom built, laser direct writing microstereolithography (μSL) system that incorporated a 405 nm laser source was used to produce the 3D NGC constructs, with ∼50 μm resolution.

The researchers used the μSL system to fabricate 5-mm long NGCs with an internal diameter of 1 mm, and a wall thickness of 250 μm. They then evaluated the NGCs in an vitro mouse model, microscopically examining neuronal, Schwann, and dorsal root ganglion cultures. An in vivo fibular nerve injury model was also implemented to study repair. The researchers found that the NGC guides enabled nerve repair across an injury gap of 3 mm over 21 days. The study was published online on February 14, 2015, in Biomaterials.

“The advantages of these 3D printed NGCs over previous conventional guidance channels are that 3D printing enables adaptation on a case-by-case basis and regeneration is comparable to that seen with grafts,” concluded lead author graduate student Christopher Pateman, MSc, and colleagues. The team is also testing the ability of the NGCs to restore nerve function over larger gaps, as well as the use of biodegradable raw materials.

NGCs are designed not only to act as a guide for the regenerating nerve end, but also to modulate the internal environment and to promote host regeneration. While commercially available devices show similar efficacy to autograft surgery for short injury gap repair, their efficacy for gaps beyond 20 mm is limited, since they are fabricated as a simple tube. Using μSL—an additive technique—offers the ability to produce scaffolds and devices containing intricate microstructures using resin pre-polymers under CAD control.

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