Their work should lead directly to the creation of new treatments for the most common cause of hair loss in men, known as male pattern baldness. The problem of male pattern baldness is seen to varying degrees in 8 of 10 men under 70 years old. It causes hair follicles to shrink and produce microscopic hairs. These grow for a shorter duration than normal follicles, meaning that follicles just don't replace at the fast enough rate for the loss of normal ones.
The prostaglandin, known as PGD2 and its derivative, 15-dPGJ2, have been shown to inhibit hair growth in both human and animal models. The PGD2-related inhibition is associated with a receptor: GPR44, which is now looking as though it will be a promising therapeutic target for androgenetic alopecia (AGA) in both men and women with hair loss and thinning.
George Cotsarelis, MD, chair and professor of Dermatology, and senior author on the studies, explains how his work is building on a previous study from Penn. University published in the Journal of Clinical Investigation last year :
"Although a different prostaglandin was known to increase hair growth, our findings were unexpected, as prostaglandins haven't been thought about in relation to hair loss, yet it made sense that there was an inhibitor of hair growth, based on our earlier work looking at hair follicle stem cells."
More importantly, and giving hope to millions of bald people everywhere, it appears that the underlying hair follicle stem cells are intact. This seems to suggest that the scalp is either lacking an activator or has been inhibited from creating new follicle growth. In the past, general thinking was that the follicles had died permanently, hence leading baldness treatments have involved using new follicles taken from elsewhere on the scalp.
Researchers write that they took an unbiased approach when searching for possible biological causes of baldness. They looked in scalp tissue from balding and non-bald spots from men with male pattern baldness. They then cross-checked their findings in mouse models, where levels of PGD2 were elevated in bald scalp tissue at levels 3 times greater than what was found in comparative haired scalp of men with androgenetic alopecia.
When PGD2 was added to cultured hair follicles, PGD2-treated hair was significantly shortened, while PGD2's derivative, 15-dPGJ2, completely inhibited hair growth.
Prostaglandins are well understood in their role in many bodily functions. They control cell growth, constrict and dilate smooth muscle tissue, and a different prostaglandin (F2alpha) has been seen to increase hair growth. PGD2 on the other hand, inhibits hair growth.
The researchers also make note that prostaglandins may represent a common pathway shared by both men and women with AGA, although so far, they have only looked at male test results. A topical treatment to target GPR44, will determine whether focusing on prostaglandins will benefit women with AGA as well.
Written by Rupert Shepherd