Activation of Wnt/β-Catenin Signaling Is Involved in Hair Growth-Promoting Effect of 655-nm Red Light and LED in In Vitro Culture Model

In the 2018 study, researchers found that 655-nm red light and LED treatments promoted hair growth and delayed the transition to the catagen phase in an in vitro human hair follicle culture model. The most effective energy density was 0.839 J/cm² with a 5-minute exposure, which increased hair shaft elongation and the expression of key molecules in the Wnt/β-catenin signaling pathway, such as β-catenin, p-GSK3β, and Lef1. These results suggest that activating this pathway is a key mechanism by which 655-nm red light and LED treatments can promote hair growth, offering a potential therapeutic option for alopecia. The study used 18 to 20 hair follicles per treatment group and was supported by the National Natural Science Foundation of China.