Fate Tracing of DNA-Damaged Hair Follicle Stem Cells and Their Seno-Differentiation Clearance Out of the Niche

The study investigates the fate of DNA-damaged hair follicle stem cells (HFSCs) and their clearance from the niche, particularly in the context of aging and chemotherapy-induced alopecia. Using mouse models that induce DNA double-strand breaks (DSBs) in a small number of stem cells, the researchers observed that DNA-damaged HFSCs are cleared from the epidermal layer, suggesting a transdermal exit. These cells exhibited markers of DNA damage and oxidative stress but did not show typical senescent cell markers like SAβ-gal and p16. The findings suggest a tissue-autonomous mechanism in the hair follicle niche that discards stressed cells, potentially leading to hair follicle miniaturization and hair loss.