Partial alopecia area retains bulge hair follicle progenitor cells in Indian androgenetic alopecia patients

Androgenic alopecia (AGA) is a pathological condition characterized by the progressive decrease of scalp hair follicle density. Completely bald areas of AGA scalp still retain hair follicle stem cells but the progenitor cells are drastically decreased in number. However, it is unknown when the progenitor cells begin to diminish in number during the progression of AGA. Despite the prevalence of AGA in 58% of the Indian male population, no study to date has characterized the hair follicle stem and progenitor cell populations in AGA patients in this ethnic group. We observed that the partially bald area retains progenitor cells expressing CD34 and Sox9 but they are not present in the hair follicles in the completely bald area. Our study sheds light on the timeframe for effective therapeutic interventions based on modulating regulatory mechanisms to reinitiate the existing inactive follicle stem cells.