Male baldness, long considered the bane in men around the globe, can become a thing of history after researchers found a biological clue that may raise the prospect of stopping and maybe even reversing hair loss.

The researchers, from University of Pennsylvania’s Perelman School of Medicine, have identified an abnormal sum of proteins called Prostaglandin D2 (PGD2) within the bald scalp of men with male pattern baldness. Lab studies were conducted using mice and cultured human hair follicles.

In both human and animal models, they discovered that PGD2 and it is derivative, 15-dPGJ2, inhibit hair growth. The inhibition occurred via a receptor called GPR44, that could be a promising therapeutic strategy to androgenetic alopecia in both women and men with thinning hair.

Among men with androgenetic alopecia (AGA), bald scalp tissue had elevated amounts of PGD2 compared with hair-covered tissue in the same individual, said George Cotsarelis, MD and colleagues.

The researchers reported yesterday (March 21) in the journal Science Translational Medicine that drugs are already being developed that concentrate on the pathways related to hair loss. The hope is that the findings result in a remedy for baldness.

Most men begin to suffer hair loss in mid-life, with nearly 80 % of men experiencing a minimum of some hair loss by age 70. In males, testosterone plays a significant role in hair thinning, as do genetic factors, causing follicles of hair to shrink and eventually becoming so small they’re invisible, leading to the look of baldness.

“Our findings should lead straight to new treating the most common reason for hair thinning in males, androgenic-alopecia,” the team wrote.

However, it remains unclear if blocking the GPR44 receptor would allow hair to regrow after balding, or if it would just prevent further balding. Additionally, it remains unclear whether inhibiting the receptor would have any effect in humans at all.

To explore that possibility, Cotsarelis and the colleagues examined scalp tissue in 22 white men between 40 and 65 who underwent hair transplantation for male pattern baldness. No men had to have either of two approved medications for baldness minoxidil and finasteride.

The researchers found through genetic analysis that levels of PGD2 were 3 times higher in bald scalp tissue compared to hair-covered scalp.

To further test the possibilities and comprehend the significance of their finding, they turned to experimental studies involving mice. In normal mice, they found a connection between the rise in PGD2 and the regression of hair follicles during normal hair cycling.

In mice engineered to have elevated of PGD2 in the skin, they developed alopecia, miniaturization of follicles, and sebaceous gland hyperplasia all characteristics associated in human baldness.

“The next phase is always to screen for compounds affecting this receptor and to also find out whether blocking that receptor would reverse balding or simply prevent balding a question that will require sometime to determine,” Cotsarelis told Helen Briggs of BBC News.

“Although another prostaglandin was known to increase hair regrowth, 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 regrowth, according to our earlier work taking a look at hair follicle stem cells,” he added.

Prostaglandins are very well characterized for their role in lots of bodily functions, including controlling cell growth and dilating smooth muscle tissue. It had been shocking to locate that PGD2 inhibited hair regrowth while prostaglandin F2alpha is known to increase hair regrowth.

“The issue of whether similar changes in PGD2 levels are located within the affected scalp of ladies with androgenic-alopecia must also be addressed,” the team wrote. Future studies, potentially testing topical treatments that could target GPR44, can determine whether targeting prostaglandins may benefit woman with AGA as well.

Cotsarelis´ study was funded by the National Institutes of Health, the Skin Disease Research Center, the Pennsylvania Department of Health, the Edwin and Fannie Gray Hall Center for Human Appearance at University of Pennsylvania Clinic, the American Skin Association, the Dermatology Foundation, and L´Oreal.

Cotsarelis is also a co-inventor of the patent owned by UPenn describing the PGD2 pathway like a target for inhibiting hair loss, among other claims.