Treatment of Vocal Fold Paralysis with Muscle Progenitor Cells - ABSTRACT Vocal fold paralysis (VFP) occurs when the recurrent laryngeal nerve (RLN) is injured, most frequently during thyroid surgery. This occurs in over 100,000 patients on one side and over 20,000 patients on both sides annually in the US. Unilateral paralysis of the laryngeal muscles causes hoarseness of voice and aspiration with swallowing; bilateral paralysis causes airway obstruction, with about 50% of patients needing a tracheotomy for adequate breathing. Current treatments are often unsatisfactory, usually with an implant for unilateral cases that can be malpositioned, or by cutting out a portion of one or both vocal folds for bilateral cases, which negatively impacts both voice and swallowing. Recent tissue engineering work in our lab and others has shown that adult muscle progenitor (stem) cells (MPCs) can be isolated from a healthy skeletal muscle, cultured, and implanted back into denervated laryngeal muscles. The MPCs become incorporated into the muscle (engrafted) and increase its nerve recovery as well as its strength. In this proposal, the use of MPCs for VFP is tested in an established canine model. In preliminary work, we found MPCs implanted into the vocal fold muscles resulted in a significant increase in the strength of the laryngeal muscles as well as increased nerve recovery. This project proposes further investigation of these exciting findings. In Aim 1, we will repeat our preliminary experiment, and also alter the conditions to be more typical of patients with VFP, with treatment delays of 3 months and 6 months from the time of RLN injury. We will also vary the amount of cells implanted to find the optimum number. These results will provide data needed for a possible clinical trial. To best simulate the size, volume and function of human laryngeal muscles, these experiments will utilize canine larynges. In Aim 2, we will explore the finding that the implanted MPCs cause an increase in innervation. How does implantation of muscle progenitor cells cause an increase in nerve growth? We will use bulk RNAseq and mass spec imaging (MSI) to identify peptides or other potentially neurotrophic molecules that are increased by implanting MPCs. Testing laryngeal muscles, with and without implanted MPCs, at different time points will help characterize the cellular mechanisms. These findings could lead to additional approaches to further maximize recovery of the injured RLN. These experiments will mainly use a rat RLN model, with a few canines for validation in a larger model.
