Breakthrough in Baldness? Blocking the Prostaglandin D2 Pathway May be the Answer

We know that balding in men is due to a complex interplay of genetics and hormones. But recently there has been some exciting research looking at the role of "stem cells" in male balding.  Hair follicle stem cells are cells that theoretically can give rise to massive numbers of new hairs. This stem cell research is important since male balding affects nearly 50 % of men by age 50 and 80 % of men by age 70.

A few months ago, I wrote a blog about exciting  research discoveries  by Dr. George Cotsarelis and his group at the University of Pennsylvania.   At that time, the researchers showed that "bald" scalp surprisingly contains the same number of stem cells as "non bald" areas of the scalp. What was different was that bald areas of the scalp had fewer progenitor cells (or cells derived from stem cells that actually develop into new hair follicles).

With this discovery presented to the medical world, the researchers then set out to ask the next key question:

 Why do bald areas have fewer progenitor cells?

 Is it because something inhibits them from developing?

 or is it because they can’t be properly activated?

Last week, Dr. Cotsarelis and his team published some new reserach in the journal Science Translational Medicine.  Like the previous study, this was a major breakthrough in our understanding of the balding process.

What did the researchers find?

The  researchers again compared areas of balding scalp to areas of hairy (non-balding) scalp.  They found that the bald tissue had elevated levels of a protein called “Prostaglandin D2.”  In fact, when they studied 17 men with balding, they found that PGD2 protein levels were 3 times higher in bald areas than non-bald areas. In further experiments, it was shown that prostaglandin D2 was extremely important – in fact, when PGD2 was added to hair follicles in a petrie dish, the hairs stopped growing.  Moreover, Dr. Cotsarelis’ group identified the exact receptor that Prostaglandin D2 needs to bind to in order to produce it’s effects (a receptor called GP44).

So can we block the PGD2 protein and cure male baldness?

That answer is not know but one of the real exicting aspects of Dr. Cotsarelis’ study is that drugs that block PGD2 are already in development. In fact, the Merck company has a drug to treat facial flushing called "laropiprant" that blocks the protein and Actelion has a drug called "setipiprant"  to treat allergies that also affects the protein.  

What is the next step in developing new hair loss drugs?

There is no doubt that drugs that block PGD2 (or the GP44 receptor) will now be studied more intensively. But whether such drugs will help stop or reverse the balding process is not yet known. It’s also not known if such drugs would have benefit in women with genetic hair loss because only men were studied in Dr. Cotsarelis’ study. We know that the process of genetic balding in women is more complex than in men, so it may or may not have the same benefits.

I think we’ll be seeing more and more research about the role of prostaglandins in hair loss. A drug analogue of Prostaglandin F2 alpha (marketed under the name Latisse) is known to improve eyelash growth in women and may also help some individuals with eyebrow loss too. Now we have evidence that blocking prostaglandin D2 might also help hair growth. The prostaglandin pathway may have promise for new drugs to treat hair loss!