Recurrent laryngeal nerve regeneration using a self-assembling peptide hydrogel

Objectives/Hypothesis To regenerate defected recurrent laryngeal nerves (RLNs), various methods have been developed. However, no consistently effective treatments are currently available because of their insufficient functional recovery. RADA16-I, a self-assembling peptide used clinically as a hemostat, reportedly supports neurite outgrowth and functional synapse formation in vitro. The purpose of this study was to investigate the effect of RADA16-I hydrogels on transected RLNs in rats. Study Design Animal experiments with controls. Methods Fifteen adult rats were divided into the following three groups: RADA16-I (+), RADA16-I (-), and neurectomy. A 6-mm gap of the left RLN was bridged using an 8-mm silicone tube in the RADA16-I (-) and RADA16-I (+) groups. Subsequently, RADA16-I hydrogel was injected into the tube in the RADA16-I (+) group. The surgical incisions were closed without any further treatment in the neurectomy group. After 8 weeks, laryngoscopy and electrophysiological and histological examinations were performed to evaluate the effect of RADA16-I on nerve regeneration and thyroarytenoid muscle atrophy. Results Although most rats in the three groups exhibited no improvements of their vocal fold movement, partial recovery was observed in one rat in the RADA16-I (+) group. The neurofilament-positive areas and the number of myelinated nerves in the RADA16-I (+) group were significantly higher than in the RADA16-I (-) group. The area of the left thyroarytenoid muscle in the RADA16-I (+) group was significantly larger than that of the neurectomy group. Conclusions Our results suggested that RADA16-I hydrogel was effective for RLN regeneration. Level of Evidence NA Laryngoscope, 2019