Peripheral nerve injuries are common in clinical practice due to trauma or deliberate surgical resection. The typical treatment to an extended nerve gap, nerve autografting, is limited by many drawbacks. We found that chitosan and polyglycolic acid (PGA) are both polymers biocompatible to nerve tissue. Based on this, we developed an artificial nerve graft composed of a chitosan conduit inserted with longitudinal PGA filaments, and the graft was utilized to bridge dog sciatic nerve across a 30-mm long defect. After 6 months, we observed that the defected sciatic nerve trunk had been reconstructed with restoration of nerve continuity, with functional recovery for conducting electrical impulses and axonal transport, and with target skeletal muscles re-innervated, thereby improving the locomotion activities of the operated limb. To meet clinical trial, under the approval of the ethics committee and the informed consent of the patients, we performed 8 clinical cases to examine the feasibility of the chitosan/PGA artificial nerve graft for repairing median or ulnar nerves across 25-mm to 35-mm long defects in human patient. During the 3-year follow-up period, functional recovery of the injured nerves was assessed by pinch gauge test, hydraulic hand dynamometry, static two point discrimination and touch test with monofilaments, in couple with electrophysiological examinations. The motor and sensory function of the median and ulnar nerves demonstrated an ongoing recovery post implantation, reaching M4 and S3+ levels during the follow-up period. The results indicate that the chitosan/PGA artificial nerve graft could be used for surgical repair of extended defects in major peripheral nerves in the human.
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