New treatments for male pattern baldness could be on the way, as scientists identify a protein they believe inhibits growth of hair follicles.
Male pattern baldness, or androgenetic alopecia (AGA), affects 80 percent of men at some point in their lives, but very little is known about the molecular mechanisms of the condition.
The team at the University of Pennsylvania analysed which genes were expressed in samples of balding and non-balding scalp tissue from five men with AGA. They found elevated levels of the enzyme prostaglandin D2 synthase, and its product prostaglandin D2 (PGD2) in samples from bald areas, almost three times above normal levels.
Dr George Cotsarelis, the lead author of the study, explained that previous work showed the scalps of bald men retained hair follicle stem cells, but these cells were incapable of developing into mature hair follicles.
'At that time, we hypothesised there is either a lack of an activator in the scalp or the presence of an inhibitor that prevented the stem cells from generating hair', he added.
The latest research, published in Science Translational Medicine, found that healthy hair follicles treated with increasing amounts of PGD2 in the lab started to shrink, and eventually the hairs stopped growing. A similar hair loss pattern was observed in mice bred to have high levels of the protein.
Dr Cotsarelis said: 'We think if we are able to remove the inhibitory effects of PGD2 we would be able to allow the hair to grow'.
Prostaglandins are chemical messengers that regulate a variety of physiological responses in the body, such as the inflammatory response observed during infection. They work by binding to cell surface receptors on their target cells, including the GPR44 receptor on hair follicles. Blocking these receptors should inhibit the effects of this protein.
The good news is that there are already several experimental drugs in clinical trials that block the GPR44 receptor. Some of these drugs are being tested as a possible treatment for asthma, as prostaglandins have been implicated in the contraction of the airways during an asthma attack. However, when applied topically they might be able to reverse the inhibitory effects of prostaglandins on hair follicles.
'The next question is whether it can prevent further hair loss, or actually reverse hair loss and re-grow hair on a bald scalp', said Dr Cotsarelis.