Peripheral nerve regeneration is a complicated and long-term medical challenge that requires suitable guides for bridging nerve injury gaps and restoring nerve functions. Many natural and synthetic polymers have been used to fabricate nerve conduits as well as luminal fillers for achieving desired nerve regenerative functions. It is important to understand the intrinsic properties of these polymers and techniques that have been used for fabricating nerve conduits. Previously extensive reviews have been focused on the biological functions and in vivo performance of polymeric nerve conduits. In this paper, we emphasize on the structures, thermal and mechanical properties of these naturally derived synthetic polymers, and their fabrication methods. These aspects are critical for the performance of fabricated nerve conduits. By learning from the existing candidates, we can advance the strategies for designing novel polymeric systems with better properties for nerve regeneration. 1. Introduction Peripheral nerve injury is a serious health problem that affects 2.8% of trauma patients annually [1]. There are around 360,000 cases of upper extremity paralytic syndromes in the United States and more than 300,000 peripheral nerve injuries in Europe on an annual basis [2]. These cases can potentially lead to lifelong disabilities although peripheral nerves exhibit the capacity of self-regeneration for less severe injury. Researchers have developed various strategies for better recovery of nerve functions. End-to-end suturing is one effective method for short nerve gaps whereas tubular structures are necessary for bridging longer gaps [3]. Autologous nerve grafts are considered as “gold standard” for bridging long gaps, but they suffer from limited tissue availability, donor site morbidity, and potential mismatch of tissue structure and size [1–3]. Therefore, various bioengineered nerve grafts have been developed from polymeric materials that have well-tailored properties and dimensions to meet the requirements for peripheral nerve regeneration. These materials range from naturally derived polymers to conventional nondegradable and biodegradable synthetic polymers. Generally, an ideal nerve guide should be non-cytotoxic, highly permeable, and sufficiently flexible with suitable degradation rate and products to provide guidance for regenerative axons and to minimize swelling and inflammatory responses [4]. Inner luminal fillers, offering larger surface area and platform for incorporating bioactive substances, are often used to improve the performance of nerve
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