Novel flexible nerve conduits made of water-based biodegradable polyurethane for peripheral nerve regeneration

Peripheral nerve conduits were fabricated from bio-degradable polyurethane (PU) which was synthesized by a waterborne process. The biodegradable PU was based on poly(epsilon-caprolactone) diol and polyethylene butylene adipate diol (2:3 molar ratio) as the soft segment. Conduits formed by the freeze-drying process had asymmetric microporous structure. The PU nerve conduits were used to bridge a 10-mm gap in rat sciatic nerve. Nerve regeneration was evaluated by walking track analysis, magnetic resonance imaging (MRI), electrophysiological, and histological analyses. Results demonstrated that after 6 weeks, walking function was recovered by 40%. MR images showed that the transected nerve was reconnected after 3 weeks and the diameter of the regenerated nerve increased from 3 to 6 weeks. The nerve conduction velocity of the regenerated nerve reached 50% of the normal value after 6 weeks. Histological examination revealed that the cross-sectional area of the regenerated nerve at the midconduit was 0.24 mm(2) after 6 weeks. The efficacy of PU nerve conduits based on functional recovery and histology was superior to that of commercial conduits (Neurotube). The PU nerve conduit developed in this study may be a potential candidate for clinical peripheral nerve tissue engineering. (C) 2017 Wiley Periodicals, Inc.