Hair is a naturally regenerating mini-organ. It goes through periods of growth, then resting, shedding and regeneration. This process is controlled by a very specific group of stem-like cells at the base of the hair follicle called Dermal Papilla (DP) cells. The number of DP cells determines the thickness of the hair.
A full thickness hair on the scalp is called a terminal hair. Androgenetic alopecia, or male/female pattern hair loss, results from the number of DP cells within follicles decreasing at each hair cycle, leading to thinner hairs. Eventually, hairs become too thin to have a full cosmetic effect and are termed vellus hairs.
The pattern of hair loss is controlled by a number of factors, including inhibition by di-hydroxytestosterone (DHT). Follicles containing DP cells that are not affected by DHT remain thicker. Replacing DHT-inhibited cells with those insensitive to DHT would convert follicles and prevent further loss.
Androgenic alopecia is the most common form of hair loss and affects billions of people worldwide.