Nerve guide conduits for peripheral nerve injury repair: A review on design, materials and fabrication methods

Peripheral nerves can sustain injuries due to loss of structure and/or function of peripheral nerves because of accident, trauma and other causes, which leads to partial or complete loss of sensory, motor, and autonomic functions and neuropathic pain. Even with the extensive knowledge on the pathophysiology and regeneration mechanisms of peripheral nerve injuries (PNI), reliable treatment methods that ensure full functional recovery are scant. Nerve autografting is the current gold standard for treatment of PNI. Given the limitations of autografts including donor site morbidity and limited supply, alternate treatment methods are being pursued by the researchers. Neural guide conduits (NGCs) are increasingly being considered as a potential alternative to nerve autografts. The anatomy of peripheral nerves, classification of PNI, and current treatment methods are briefly yet succinctly reviewed. A detailed review on the various designs of NGCs, the different materials used for making the NGCs, and the fabrication methods adopted is presented in this work. Much progress had been made in all the aspects of making an NGC, including the design, materials and fabrication techniques. The advent of advanced technologies such as additive manufacturing and 3D bioprinting could be beneficial in easing the production of patient-specific NGCs. NGCs with supporting cells or stem cells, NGCs loaded with neurotropic factors and drugs, and 4D printed NGCs are some of the futuristic areas of interest. STATEMENT OF SIGNIFICANCE: Neural guide conduits (NGCs) are increasingly being considered as a potential alternative to nerve autografts in the treatment of peripheral nerve injuries. A detailed review on the various designs of NGCs, the different materials used for making the NGCs, and the fabrication methods (including Additive Manufacturing) adopted is presented in this work.