Developing a porcine model for study of vocal fold scar.

The porcine larynx is very similar in size and structure to that of humans, and wound healing in pigs is very similar to that of humans. However, the pig is not often used in vocal fold scar research because it is difficult to view the vocal folds endoscopically. To further assess the pig as a model for studying vocal scar, we compared the plane of surgical dissection in the mucosa of four porcine vocal folds with that in eight human cadaver larynges. The plane of dissection was quite similar in porcine and human larynges, occurring within the loose layer of the superficial lamina propria. We also compared healing of porcine vocal folds after elevation and replacement of an epithelial flap versus excision of epithelium, leaving an open wound. After 6 weeks, larynges were harvested for histologic examination. There was no significant difference between the mucosa of the normal vocal fold and that of the healed microflap. However, after healing of epithelial excision, there was a depressed scar, with average lamina propria thickness of 302 µm versus 864 µm for the normal fold (P<0.05). Finally, to document that the mucosal wave can be evaluated in the porcine larynx, we developed a preparation that removes the false vocal folds, to allow ex vivo phonation. Experimentally created scar in the porcine larynx is a favorable model for the study of vocal fold healing and for assessment of treatments for vocal fold scar.