Functional recurrent laryngeal nerve regeneration using a silicon tube containing a collagen gel in a rat model

• Published in: PloS one 2020-08, Vol.15 (8), p.e0237231-e0237231
• Main Authors: Asai, Ryohei, Ishii, Sohei, Mikoshiba, Ikuo, Kazama, Tomohiko, Matsuzaki, Hiroumi, Oshima, Takeshi, Matsumoto, Taro
• Format: Article
• Language: English
• Subjects: Atrophy; Biology and Life Sciences; Collagen; Collagen (type I); Computer simulation; Electromyography; Experiments; General anesthesia; Health aspects; Laboratory animals; Medical instruments; Medical research; Medical silicones; Medicine; Medicine and Health Sciences; Morphology; Muscles; Nerve regeneration; Nerves; Nervous system; Neurological disorders; Otolaryngology; Recurrent laryngeal nerve; Regeneration; Research and Analysis Methods; Restoration; Rodents; Silicon; Supervision; Surgery; Sutures; Tubes; Vocal organs
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0237231

In this study, we examined the effect of differing gap lengths on regeneration of transected recurrent laryngeal nerves using silicon tubes containing type I collagen gel and the ability of this regeneration to result in restoration of vocal fold movements in rats. We simulated nerve gaps in Sprague-Dawley rats by transecting the left recurrent laryngeal nerves and bridged the nerve stumps using silicon tubes containing type 1 collagen gel. Three experimental groups, in which the gap lengths between the stumps were 1, 3, or 5 mm, were compared with a control group in which the nerve was transected but was not bridged. After surgery, we observed vocal fold movements over time with a laryngoscope. At week 15, we assessed the extent of nerve regeneration in the tube, histologically and electrophysiologically. We also assessed the degree of atrophy of the thyroarytenoid muscle (T/U ratio). Restoration of vocal fold movements was observed in 9 rats in the 1-mm group, in 6 rats in the 3-mm group, and in 3 rats in the 5-mm group. However, in most rats, restoration was temporary, with only one rat demonstrating continued vocal fold movements at week 15. In electromyograph, evoked potentials were observed in rats in the 1-mm and 3-mm groups. Regenerated tissue in the tube was thickest in the 1-mm group, followed by the 3-mm and 5-mm groups. The regenerated tissue showed the presence of myelinated and unmyelinated nerve fibers. In assessment of thyroarytenoid muscle atrophy, the T/U ratio was highest in the 1-mm group, followed by the 3-mm and 5-mm groups. We successfully regenerated the nerves and produced a rat model of recurrent laryngeal nerve regeneration that demonstrated temporary recovery of vocal fold movements. This rat model could be useful for assessing novel treatments developing in the future.