Novel Biomolecule‐Infused Gelatin Injectable for Treatment of Recurrent Laryngeal Nerve Injury

Abstract

Objective: Unilateral vocal fold paralysis (UVFP) due to recurrent laryngeal nerve injury (RLN) is a major cause of voice disorders. We have recently identified three biomolecules (agrin, acetylcholine, and neuregulin) with the potential to promote reinnervation after RLN injury. This study aimed to determine if a gelatin injectable with the reinnervating biomolecules will induce site-specific amplification of neurotrophic factor release and reinnervation after RLN injury in unilateral vocal fold paralysis. Methods: C57BL/6 mice underwent RLN transection with the following treatment allocations: saline control (N = 16), biomolecule cocktail only (N = 16), and biomolecule-infused gelatin (N = 16). All injectables were delivered into the denervated thyroarytenoid muscle. Assessment of glottic function was determined via laryngeal electromyography (L-EMG) and stimulated video laryngoscopy post-RLN transection on days 7 and 28. Histopathology analysis via immunohistochemistry (IHC) and genetic analysis via quantitative polymerase chain reaction (qPCR) were utilized to characterize reinnervation and gene expression changes within the harvested larynges. Results: Both biomolecule treatment groups had enhanced reinnervation of the adductor complex, as indicated by higher stimulated L-EMG area under the curve (p < 0.001), adduction during stimulation (p < 0.002), midline resting position (p < 0.002), and the presence of innervated neuromuscular junctions on IHC. qPCR results suggest both biomolecule treatments resulted in elevated neurotrophic and angiogenic factor expression from the injected muscle. Conclusions: Injectable biomolecule-infused gelatin may serve as a novel long-term therapeutic for glottic functional restoration by redirecting existing mechanisms of synkinesis via site-specific neurotrophic factor release.