Photodynamic therapy induces antifibrotic alterations in primary human vocal fold fibroblasts

Objectives/Hypothesis Photodynamic therapy (PDT) is a promising treatment modality for laryngeal dysplasia, early‐stage carcinoma, and papilloma, and was reported to have the ability to preserve laryngeal function and voice quality without clinical fibrotic response. We aimed to investigate the mechanism behind the antifibrotic effects of PDT on primary human vocal fold fibroblasts (VFFs) in vitro. Study Design In vitro analysis from one human donor. Methods Cell viability of VFFs in response to varying doses of PDT was investigated by the Cell Counting Kit‐8 method. Sublethal‐dose PDT (SL‐PDT) was used for the following experiments. Expression of genes related to vocal fold extracellular matrix formation was analyzed by real‐time polymerase chain reaction, enzyme‐linked immunosorbent assay, and Western blotting. Effects of PDT on cell migration, collagen contraction, and transforming growth factor β‐1 (TGF‐β1)‐induced myofibroblast differentiation were also analyzed. Results PDT affects the viability of VFFs in a dose‐dependent manner. SL‐PDT significantly changed the expression profile of VFFs with antifibrotic effects. It also inhibited cell migration, reduced collagen contraction, and reversed the fibroblast‐myofibroblast differentiation induced by TGF‐β1. Conclusions SL‐PDT induces antifibrotic alterations in VFFs. This could explain the low incidence of vocal fold scar associated with PDT. Moreover, PDT may be useful in treating existing vocal fold scars. Further studies should focus on the in vivo effect of PDT on vocal fold wound healing and scar remodeling. Level of Evidence NA Laryngoscope, 128:E323–E331, 2018