Developing an In Vivo Model of Reinke's Edema

Abstract

Approximately 7.5 million Americans suffer from difficulty using their voice. Phonatory difficulties are often multifactorial with Reinke's edema being a common underlying pathology. The most common cause of Reinke's edema is smoking. Reflux of stomach acids into the larynx and excessive voice use are also implicated in causing edema. There is currently no reproducible animal model of this common human laryngeal disease. We set out to determine if primary cigarette exposure could be 1) accomplished in an inhalation chamber designed for pigs; and 2) if cigarette smoke exposure could differentially affect the vocal folds of exposed pigs similarly to the human disorder of Reinke's edema. The pig was chosen as the animal model because the pig larynx offers the greatest structural, cellular, immunologic, and neuroanatomical similarity to the human larynx. Twelve Sinclair miniature pigs were randomly assigned to 2 treatment groups (baseline and high cigarette exposure). Six pigs assigned to the baseline cigarette smoke were exposed to 3 cigarettes per day for 20 days. Six pigs assigned to the high cigarette smoke were exposed to 15 cigarettes per day for 20 days. A week prior to treatment, each group of pigs was habituated to the chamber and human contact to reduce stress and ease treatment administration. Behavior modification was accomplished using positive reinforcement. Vocal fold, nasal mucosa, and trachea were examined histologically. Vocal fold ultrastructural alterations, epithelial intercellular space diameter, and microridge height were examined via transmission electron microscopy (TEM). Real‐time polymerase chain reaction was used to investigate genes associated with Reinke's edema in human beings. All animals tolerated the chamber without any signs of distress. Animals on average coughed more in the high exposure group compared with the low exposure (P<0.05). Histology and ultrastructure of the vocal fold were preserved even in the high exposure group of animals. Gene expression data is on‐going. The data obtained from this study offer a potential novel experimental methodology to simulate the development of Reinke's edema in healthy pigs where there is currently no reproducible animal model. The success of this methodology could impact future research on prevention, improving early diagnosis, and therapeutic options for Reinke's edema.Support or Funding InformationNIH R01DC011759