Effects of Hepatocyte Growth Factor Injection and Reinjection on Healing in the Rabbit Vocal Fold

Summary Objectives/Hypothesis Hepatocyte growth factor (HGF) is a multifunctional polypeptide that plays various roles in embryogenesis and tissue regeneration and exhibits marked antifibrotic activity. The present study sought to assess the effects of HGF injection and reinjection coinciding with its peak of activity on collagen density, vessel density, inflammatory reaction in the lamina propria, and mean epithelial thickness in the injured rabbit vocal fold. Study Design Prospective, controlled, experimental animal study. Methods Fourteen rabbits were subdivided into two groups and underwent injury of the vocal folds. Immediately after injury, animals in group 1 received HGF injections into the right vocal fold (RVF), whereas those in group 2 received bilateral HGF injections and a single reinjection into the RVF 10 days after the first, to coincide with the peak of HGF activity. The left vocal folds (LVFs) served as controls in both groups. Histological assessment of laryngeal specimens was performed at 30 and 40 days, respectively. Results In both groups, collagen density was lower in the right (treated) vocal folds than in the left (control) folds ( P = 0.018). Vessel density was higher in the RVFs in group 2 ( P = 0.018). Differences were found in mean epithelial thickness and inflammatory reaction in the lamina propria but did not reach statistical significance. Conclusions In the scarred rabbit vocal fold, HGF injection is associated with decreased collagen density in the lamina propria, whereas reinjection after 10 days produces decreased collagen density and higher vessel density.