Estetrol Prolongs Anagen Ex Vivo: Does E4 Have Potential as a Novel Strategy to Treat Female Pattern Hair Loss?

The study investigates the potential of Estetrol (E4), a natural estrogen, as a treatment for female pattern hair loss (FPHL). Using hair follicles from 4 healthy female donors over 50 years old, the research found that 3μM E4 significantly prolonged the anagen phase of hair growth. This was associated with an increase in proliferating hair matrix keratinocytes and higher alkaline phosphatase activity, indicating enhanced dermal papilla (DP) inductivity. Although DP size and cell density were unaffected, E4 reduced DP stalk and dermal cup cell numbers, suggesting protection against DP fibroblast emigration. Additionally, E4 expanded the hair follicle stem cell progeny pool, as shown by an increased percentage of CD34+ cells. These results suggest that E4 could prevent hair follicle miniaturization and may be a promising treatment for FPHL.