Early Changes in Porcine Larynges Following Injection of Motor‐Endplate Expressing Muscle Cells for the Treatment of Unilateral Vocal Fold Paralysis

Objectives No curative injectable therapy exists for unilateral vocal fold paralysis. Herein, we explore the early implications of muscle‐derived motor‐endplate expressing cells (MEEs) for injectable vocal fold medialization after recurrent laryngeal nerve (RLN) injury. Methods Yucatan minipigs underwent right RLN transection (without repair) and muscle biopsies. Autologous muscle progenitor cells were isolated, cultured, differentiated, and induced to form MEEs. Three weeks after the injury, MEEs or saline were injected into the paralyzed right vocal fold. Outcomes including evoked laryngeal electromyography (LEMG), laryngeal adductor pressure, and acoustic vocalization data were analyzed up to 7 weeks post‐injury. Harvested porcine larynges were examined for volume, gene expression, and histology. Results MEE injections were tolerated well, with all pigs demonstrating continued weight gain. Blinded analysis of videolaryngoscopy post‐injection revealed infraglottic fullness, and no inflammatory changes. Four weeks after injection, LEMG revealed on average higher right distal RLN activity retention in MEE pigs. MEE‐injected pigs on average had vocalization durations, frequencies, and intensities higher than saline pigs. Post‐mortem, the MEE‐injected larynges revealed statistically greater volume on quantitative 3D ultrasound, and statistically increased expression of neurotrophic factors (BDNF, NGF, NTF3, NTF4, NTN1) on quantitative PCR. Conclusions Minimally invasive MEE injection appears to establish an early molecular and microenvironmental framework to encourage innate RLN regeneration. Longer follow‐up is needed to determine if early findings will translate into functional contraction. Level of Evidence NA Laryngoscope, 134:272–282, 2024 Herein, we injected autologous motor endplate expressing skeletal muscle cells (MEEs) into the vocal fold of pigs with unilateral vocal fold paralysis. Four weeks after injection, laryngeal muscle revealed continued gene expression of neurotrophic, myogenic, angiogenic, and motor endplate‐associated genes. These findings reveal the utility of MEEs to create a favorable microenvironment for recurrent laryngeal nerve regeneration into the larynx, and longer study timepoints are needed.