Comparison between mitomycin C and chitosan for prevention of anterior glottic steno after CO2 laser cordectomy in dogs.

OBJECTIVE: To compare the effectiveness of an immediate application of topical mitomycin C (MMC) with chitosan for prevention of anterior glottic stenosis (AGS) after microsurgical resecting of both vocal fold with CO2 laser, including the anterior commissure, in a canine model. DESIGN: Prospective randomized experimental study. METHOD: Twenty-four canine larynges were injured by a microresecting procedure of both vocal folds with a CO2 laser. The dogs were randomly divided into three groups for treatment, respectively with MMC, chitosan, or isotonic sodium chloride solution (control) for 5 minutes immediately after surgery. One week after the initial surgery, three dogs in each group were randomly selected, the ultrastructures of the fibroblasts were examined with a transmission electronic microscope, and expression of basic fibroblast growth factor (bFGF) and transforming growth factor beta1 (TGF-beta1) were evaluated by enzyme-linked immunosorbent assay (ELISA). Three weeks after surgery, the remaining dogs' glottic web were lysed and repeatedly treated with MMC, chitosan, or isotonic sodium chloride solution. The glottic wound healing and AGS formation were examined every week, and all larynges were harvested and examined histologically 6 weeks after the initial surgery. RESULTS: Results included 1) transmission electronic microscope examination of the ultrastructures of the fibroblasts indicated that both MMC and chitosan inhibited the proliferation of fibroblast; 2) the expression of bFGF and TGF-beta1 increased both in the MMC group and the chitosan group, and the expression of bFGF in the chi-tosan group was higher than in the MMC group (P = .010), while the expression of TGF-beta1 was lower (P = .000);3) the extent of AGS formation was decreased both in the MMC group and the chitosan group, while it was less in the chitosan group than in the MMC group (P = .047); 4) the grade of collagen content between the MMC group and the chitosan group was not significantly different (P = .5). CONCLUSION: Chitosan is more effective in preventing AGS after CO2 laser cordectomy than MMC.