The effects of topical thyroid hormone application on growth factor expression in human fibroblasts

Abstract

It has long been known that thyroid hormones (TH) are essential for normal growth, development and cell metabolism. Studies have also shown that topical TH application can increase epidermal cell proliferation and accelerate the process of cutaneous wound healing. Despite these promising results, few researchers have examined the mechanisms and mediators through which TH may exert its effects on skin cells. In this study, human fibroblasts were stimulated with increasing triiodothyronine (T3) concentrations. A western blot was then conducted on the stimulated cell samples to determine whether two key growth factors – epidermal growth factor (EGF) and fibroblast growth factor (FGF-7) – that have been implicated in wound healing were upregulated due to topical T3 stimulation. It was found that while EGF (indirectly detected via the presence of the epidermal growth factor receptor (EGFR)) trended towards being upregulated at higher T3 concentrations, no such effect was observed with FGF-7. It was therefore determined that the EGF pathway may be an important mechanism through which TH exerts its effects on human fibroblasts and the process of cutaneous wound healing.