The Effects of Decorin and HGF-Primed Vocal Fold Fibroblasts In Vitro and Ex Vivo in a Porcine Model of Vocal Fold Scarring

Objectives: Vocal fold injury can be irreversible, leading to vocal fold scarring, with permanent functional effects and no optimal treatment. A porcine model of vocal fold scarring was used to test effects of decorin and primed vocal fold fibroblasts in vitro using a cell migration assay and immunoblotting, and by using functional measurements of porcine larynges and excised porcine vocal folds. Methods: In vitro: primary pig vocal fold fibroblasts (PVFFs) were subjected to cell migration assays (scratch) and treated with decorin 20 mu g/mL, hepatocyte growth factor (HGF) 200 ng/mL, epidermal growth factor (EGF) 1 nM, or transforming growth factor-beta 1 10 ng/mL. Cells also underwent decorin dose response testing. Scratch assays were analyzed in MetaMorph (R) Imaging; cell lysates were processed for MMP-8 and type I collagen content. Eleven pigs underwent unilateral vocal fold stripping procedures. At day 3 postoperatively, subjects underwent superficial injection into the affected vocal fold either with decorin 20 mu g/mL or 1 x 10(6) HGF-primed fibroblasts. Larynges were harvested and either used for ex vivo laryngeal testing or for rheological testing. Results: Scratch assay indicated significantly reduced cell migration in PVFFs treated with decorin or HGF. MMP-8 production was increased (P < 0.01) and collagen was decreased in cells treated with decorin at increasing doses. Viscoelastic measurements suggested somewhat increased stiffness for decorin treated samples. Ex vivo aerodynamic testing suggested improved vocal efficiency scores in decorin-treated larynges. Conclusions: Decorin has a noticeable effect on PVFF migration in vitro and appears to increase vocal fold stiffness but either does not change or slightly increases vocal efficiency.