A rabbit vocal fold laser scarring model for testing lamina propria tissue‐engineering therapies

Abstract

Objectives/Hypothesis To develop a vocal fold scarring model using an ablative laser in the rabbit as a platform for testing bioengineered therapies for missing or damaged lamina propria. Study Design Prospective controlled animal study. Methods An optimal laser energy level was first determined by assessing the depths of vocal fold injury created by a Holmium:YAG laser at various energy levels on fresh cadaveric rabbit larynges. The selected energy level was then used to create controlled unilateral injuries in vocal folds of New Zealand white rabbits, with the contralateral folds serving as uninjured controls. After 4 weeks, the larynges were harvested and subjected to excised-larynx phonation with high-speed imaging and immunohistochemical staining for collagen types I and III, elastin, and hyaluronic acid (HA) with quantitative histological analysis. Results 1.8 joules produced full-thickness injury of the lamina propria without extensive muscle injury. After 4 weeks, the injured vocal folds vibrated with reduced amplitude (P = 0.036) in excised-larynx phonation compared to normal vocal folds. The injured vocal folds contained a higher relative density of collagen type I (P = 0.004), higher elastin (P = 0.022), and lower HA (P = 0.030) compared to normal controls. Collagen type III was unchanged. Conclusions With its potential for higher precision of injury, this laser vocal fold scarring model may serve as an alternative to scarring produced by cold instruments for studying the effects of vocal fold lamina propria bioengineered therapies. Level of Evidence N/A.

An investigation of left–right vocal fold symmetry in rheological and histological properties

“…C). The results of fibrous proteins (i.e., collagen, elastin) distributions were in good agreement with those obtained by immunohistochemical staining, trichrome staining, and elastin van Gieson staining . Fig.…”

“…D). Similar Alcian blue staining pattern and the “band of hyaluronic acid” in rabbit vocal fold lamina propria had been reported. Histological examination showed that there were no appreciable differences in the morphological distributions of the key ECM constituents between the left and right vocal folds in all subjects.…”

“…Elastin staining was highly intense along the epithelium-lamina propria border, as previously reported. 28,29 To the contrary, staining for elastin was rather sparse in the lamina propria, with its intensity slightly increased in the deeper aspect (Fig. 4C).…”

“…The results of fibrous proteins (i.e., collagen, elastin) distributions were in good agreement with those obtained by immunohistochemical staining, trichrome staining, and elastin van Gieson staining. 1,4,28,29 Fig. 4E shows that Alcian blue staining was quite intense throughout the vocal fold lamina propria, except in the region bordering the epithelium, where hyaluronic acid was highly concentrated (Fig.…”

Response of an ovine laryngeal injury model to a novel fibrosis inhibitor

“…In order to investigate these processes further and develop novel targets and therapies, reliable, controlled experimental conditions are required – something difficult to achieve in human subjects. Animal models have been employed by many investigators in place of direct human trials . We have developed an ovine laryngeal injury model (Allen J, pers.…”