Intrinsic Activation of Cell Growth and Differentiation in Ex Vivo Cultured Human Hair Follicles by a Transient Endogenous Production of ROS

The study demonstrated that transient, non-lethal endogenous ROS production in ex vivo cultured human hair follicles efficiently promoted the entry into the growth phase (anagen). This process involved the activation of the hair follicle stem cell niche, marked by the induction of stem cell differentiation markers (Ck15), increased cell proliferation, and sustained tissue growth. Additionally, it was associated with the expression of growth-related genes (Ccnd1) and the inhibition of Wnt signaling antagonists (Dkk1, Gsk3β). The findings suggested that ROS signaling intrinsically regulated the hair follicle stem cell niche independently of external signals.