Basic Research on Recurrent Laryngeal Nerve Regeneration for Recovery of the Laryngeal Function

Problems associated with recurrent laryngeal nerve injury include (1) the loss of motoneurons in the nucleus ambiguous, (2) degeneration and poor regeneration of neural fibers, (3) degeneration of the motor neural endplate and atrophy of the laryngeal muscle, and (4) misdirected reinnervation. For (1)-(3), the value of novel therapies, including gene therapies, has been reported. However, even if morphological regeneration is achieved, recovery of the laryngeal motor function is difficult because of (4) misdirected reinnervation. We investigated the value of a neural regeneration tube (a polyglycolic acid [PGA] tube filled with collagen fibers: PGA-C tube) as a scaffold and a novel inhibition therapy for misdirection by inhibiting sensory and autonomic nerve fiber regeneration. We confirmed that the PGA-C tube can be used not only as a scaffold but also as a drug delivery system for nerve regeneration. We also confirmed the effect of TrkA inhibitors, which block the NGF-TrkA pathway and affect the regeneration of sensory/automatic nerves, thus preventing misdirected regeneration of motor and sensory nerves and promoting the regeneration of motor neurons to achieve functional recovery.