Fabricating Nerve Conduits with Proper Candidate Materials Can Increase Chance of Peripheral Nerve Regeneration

Fabricating Nerve Conduits with Proper Candidate Materials Can Increase Chance of Peripheral Nerve Regeneration
Maliheh Jahromi Dastjerdi,^1,* Shahnaz Razavi ,²
1. Department of Anatomical Sciences, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
2. Department of Anatomical Sciences, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Introduction: Introduction Peripheral nerve damage is a common clinical complication of traumatic injury occurring after accident, tumorous outgrowth, or surgical side effects. Although the new methods and biomaterials have been improved recently, regeneration of peripheral nerve gaps is still a challenge. In a small nerve injury with gap less than 1cm, regeneration is possible when two nerve stumps can be brought together (i.e. end-to-end suturing) without tension. In the larger peripheral nerve gaps, it is possible to regenerate PNS injury by applying the procedure of rejoining of nerve segments including implantation of autografts, the gold standard method, andinsertion of artificial nerve guidance conduits (NGCs) between nerve stumps. However, autologous nerve graft approaches are limited by donor site morbidity, increased surgical complications, diameter mismatch between the recipient nerve and the graft. In this situation, the application of biodegradable nerve conduits made by tissue engineering would involve protecting the nerve from interference the surrounding tissue, directing the regenerating axons from the proximal stump into the distal nerve stump and playing a more significant clinical role to regenerate the nerve better. The conduit is tubular structure designed to bridge nerve injury sites; it acts as a guide for the regenerating nerve stumps. To facilitate neural regeneration, an ideal nerve guidance conduit (NGC) should possess particular properties including biodegradability, biocompatibility, permeability, flexibility, low-toxicity, having anti-microbial activity, well-aligned orientation, proper porosity and minimal swelling, being conductive, nutrient diffusible and controlled release of drugs and neurotrophic factors capability. Different biomaterials used for fabricating nerve guidance conduits are classified into natural and artificial materials. Due to their ability to mimic the extracellular matrix (ECM), some natural biomaterials such as laminin, collagen, elastin, hyaluronic acid and fibrinogen have been of great interest to investigators, particularly in the field of nerve tissue engineering. Chitosan, alginate and silk fibroin (SF), are also three natural polymers widely used in tissue engineering. One of the major challenges in using natural polymers in tissue engineering is their poor mechanical properties. Synthetic polymers are another type of materials that have been frequently used for the fabrication of nerve conduit. Compared with their natural counterparts, synthetic polymers have advantages such as tunable mechanical properties and tailorable properties via modulating their chemical properties. However, they have shown some limitations in terms of transplant rejection. Some of synthetic polymers include poly (L-lactic acid) (PLLA), poly (ε-caprolactone) (PCL), Poly (lactic-co-glycolic) acid (PLGA) Silicone polymer and Poly (dimethylsiloxane) (PDMS). However, much research is currently underway to develop artificial nerve conduits which may serve as guiding channels for regenerating axons thus reducing the need for donor tissue. In this Review presents different types of artificial nerve grafts used to repair peripheral nerve injuries. These include synthetic and natural polymers. Also, the effect of their repair on peripheral nerve damage in recent research has been investigated.
Methods: Different biomaterials used for fabricating nerve guidance conduits are classified into natural and artificial materials. Due to their ability to mimic the extracellular matrix (ECM), some natural biomaterials such as laminin, collagen, elastin, hyaluronic acid and fibrinogen have been of great interest to investigators, particularly in the field of nerve tissue engineering. Chitosan, alginate and silk fibroin (SF), are also three natural polymers widely used in tissue engineering. One of the major challenges in using natural polymers in tissue engineering is their poor mechanical properties. Synthetic polymers are another type of materials that have been frequently used for the fabrication of nerve conduit. Compared with their natural counterparts, synthetic polymers have advantages such as tunable mechanical properties and tailorable properties via modulating their chemical properties. However, they have shown some limitations in terms of transplant rejection. Some of synthetic polymers include poly (L-lactic acid) (PLLA), poly (ε-caprolactone) (PCL), Poly (lactic-co-glycolic) acid (PLGA) Silicone polymer and Poly (dimethylsiloxane) (PDMS).
Results: However, much research is currently underway to develop artificial nerve conduits which may serve as guiding channels for regenerating axons thus reducing the need for donor tissue.
Conclusion: In this Review presents different types of artificial nerve grafts used to repair peripheral nerve injuries. These include synthetic and natural polymers. Also, the effect of their repair on peripheral nerve damage in recent research has been investigated.
Keywords: Biomaterial, Nerve conduits, Peripheral nerve, Regeneration, Implantation