Histologic Characterization of Rat Vocal Fold Scarring

Abstract

This study aimed to clarify the characteristics of rat vocal fold scarring by examining the alteration of key components in the extracellular matrix: hyaluronic acid, collagen, and fibronectin. Under monitoring with a 1.9-mm-diameter telescope, unilateral vocal fold stripping was performed, and larynges were harvested at 2, 4, 8, and 12 weeks after operation. The vocal folds were histologically analyzed with Alcian blue stain, trichrome stain, and immunofluorescence of collagen type I, collagen type III, and fibronectin. The scarred vocal folds showed less hyaluronic acid and more collagen types I and III than did the controls at all time points. Type III was stable for 12 weeks, while type I declined until 8 weeks and thereafter remained unchanged. Fibronectin increased for 4 weeks and then decreased; it was close to the control level at 8 and 12 weeks. These results suggest that the tissue remodeling process in scarred vocal folds slows down around 2 months after wounding.

Histologic Characterization of Human Scarred Vocal Folds

“…In rabbit and canine studies, HA density showed no significant difference in scar compared with normal vocal folds at both two months and six months, 7 whereas HA was found to be significantly reduced in scarred vocal folds with a three-month rat model. 12 These results indicate variations of HA due to species differences and time between insult and evaluation of scar. The current human study also demonstrated individual differences in preservation of HA in scarred vocal folds regardless of cordectomy type.…”

E-Cadherin and Transglutaminase-1 Epithelial Barrier Restoration Precedes Type IV Collagen Basement Membrane Reconstruction following Vocal Fold Mucosal Injury

“…Vocal fold injuries were created as previously reported [Tateya et al, 2005;Ling et al, 2010]. In brief, rats underwent anesthesia induction using isoflurane inhalation (2-3% delivered at 0.8-1.5 l/min), followed by maintenance with an intraperitoneal injection of ketamine hydrochloride (90 mg/kg) and xylazine hydrochloride (9 mg/kg).…”

Current Understanding and Review of the Literature: Vocal Fold Scarring

“…4 Most basic science research has focused on better understanding the constituents of the ECM, their distribution, and density during differing stages of wound healing in the persistent scar. Clinical research has Scarred rabbit vocal fold ECM 4 Procollagen density increased analysis at 2 months Collagen and elastin densities decreased Viscosity and stiffness increased No difference in HA levels Scarred rabbit vocal fold ECM 5 Collagen density increased analysis at 6 months Elastin, procollagen and HA densities similar to controls Scarred canine vocal fold ECM 6 2 months: Procollagen increased, elastin decreased analysis at 2 and 6 months No difference in collagen and HA levels 6 months: Collagen increased, elastin decreased Procollagen and HA densities were similar to controls Scarred rat vocal fold ECM 8 Re-epithelialization complete by day 14 analysis for days [1][2][3][4][5][6][7][8][9][10][11][12][13][14] HA depressed, present by day 3 and peaking at day 5 Fibronectin and collagen I present by day 1. Collagen III present by day 3…”