Kyoto Prefectural University of Medicine Kyoto, Kyoto, Japan
Objectives: Vocal fold scar remains a therapeutic challenge. Although Local injections of basic fibroblast growth factor (bFGF) or hepatocyte growth factor (HGF) have proven effective to soften the scarred vocal folds, there still were some limitations, especially for severe cases. Given that bFGF and HGF have been reported to have synergic regenerative effects, we investigated the effects of combining these growth factors for severe vocal fold scarring in vitro and in vivo.
Methods: The lamina propria of vocal folds was deeply injured down to the thyroarytenoid muscle in 26 male Sprague Dawley rats. Two months after injury, vocal fold scar fibroblasts from 6 rats were cultured with bFGF (100 ng/mL), HGF (10 ng/mL), dual growth factors (100 ng/mL bFGF and 10 ng/mL HGF), or without growth factors for 24 hours. The cells were collected and qPCR was performed to investigate the gene expression of the extracellular matrix. Remaining 20 rats were divided into 4 groups and treated with intracordal injections of bFGF (100 ng/50µL), HGF (100 ng/50µL), dual growth factors (100 ng bFGF and 100 ng HGF in 50µL), or sham group (50µL saline). Each group received four injections weekly. Histological examinations were completed 6 months after the initial surgery.
Results: qPCR revealed that the expression of hyaluronic acid synthase 2 in the combination group was significantly upregulated than in the control group. Histological examination showed significant recovery of hyaluronic acid and reduction of collagen deposition only in the combination group.
Conclusion: The current study showed that the combination therapy of bFGF and HGF might have more potential in treatment for severe vocal fold scarring.