Deciphering Hair Follicle Aging: Phenotypic Hallmarks, Molecular Mechanisms, and Innovative Interventions

Hair follicle aging is a prominent phenotypic and physiological hallmark of human aging. Recent studies have elucidated the key molecular mechanisms underlying this process, offering a foundation for the development of anti-aging interventions and therapeutic strategies. In this review, we first summarize the phenotypic changes in hair follicles during aging, including hair graying, hair thinning, hair follicle miniaturization, decreased hair follicle stem cell activity, and hair loss. We then review the roles of key cells, such as dermal papilla cells and hair follicle stem cells, in the aging process. Next, we explore the molecular mechanisms involved in hair follicle aging, focusing on external factors (eg, hormonal imbalances and inflammation) and internal factors (eg, oxidative stress and DNA damage). Finally, we discuss the therapeutic approaches to restore aged hair follicle function and the potential application of emerging technologies (eg, organoids) to delay aging and promote hair regeneration. This review provides a comprehensive summary of the current research on hair follicle aging, aiming to offer insights for future studies on the underlying mechanisms and potential therapeutic strategies.