Repair of intra-thoracic autonomic nerves using chitosan tubes.

We investigated the safety and usefulness of chitosan nano/microfiber mesh tubes (C-tubes) in regenerating damaged thoracic autonomic nerves. Animal experiments were performed in six dogs. The right thoracic sympathetic nerve (Experiment 1, n=3) and phrenic nerve (Experiment 2, n=3) were resected and sutured with C-tubes. After surgery, in Experiment 1, Horner's syndrome was observed. In Experiment 2, mobility of diaphragm was assessed by chest X-ray imaging. Nerve regeneration was assessed pathologically in both experiments. All six dogs survived without complication throughout the observational period. In Experiment 1, sympathetic nerve began to regenerate inside the C-tube at three months. At 7 and 12 months after surgery, the sympathetic nerves were connected. Though all three dogs had right Horner's syndrome after surgery, it improved at 12 months. In Experiment 2, at 12 months, the phrenic nerves were connected in two of the three dogs. In X-ray imaging, though all three dogs had eventration of the diaphragm, the right diaphragm moved in response to breathing in the dogs in which phrenic nerve regenerated. C-tubes can be safely used to facilitate the regeneration of damaged sympathetic and phrenic nerves and the restoration of their lost functions.