WEDNESDAY, March 21 (HealthDay News) -- Men worried about
encroaching baldness, take heart: A genetic analysis of tissue
taken from both bald and hairier spots on men's scalps has
identified a protein involved in male pattern hair loss.
The researchers note that drugs that inhibit the protein are
already in development, and it's possible those drugs could one day
be used to help men preserve their head of hair.
In the study, researchers from the Perelman School of Medicine
at the University of Pennsylvania did an analysis of more than
25,000 genes and honed in on one that produces an enzyme that
produces a protein known as PGD2. That protein is present in much
higher levels in bald spots.
When scientists placed PGD2 on hair follicles in a petri dish,
they found the protein inhibited hair growth.
Researchers then tested the protein on mice genetically
engineered to lack a receptor for PGD2, and found that hair growth
was unaffected. But when PGD2 was applied to mice that have a
different receptor (GPR44), the mice grew less hair.
PGD2 is a type of prostaglandin, or a hormone-like substance
known to be involved in many body functions, including regulating
the contraction and relaxation of smooth muscle tissue. Drugs that
inhibit PGD2, for example, are being studied for use in preventing
airway constriction in asthma.
"Several companies have compounds in development that block the receptor for PGD2. Those compounds are being studied to treat asthma," said senior study author Dr. George Cotsarelis, chair and professor of dermatology at University of Pennsylvania School of Medicine in Philadelphia. "We think using these compounds topically . . . could slow down and possibly reverse baldness."
The study is published in the March 21 issue of the journal
Science Translational Medicine.
About 80 percent of white men have some degree of hair loss
before age 70, according to background information in the study. In
balding men, hair follicles don't disappear, but they shrink and
produce very small, even microscopic hairs, Cotsarelis
The belief is that something is inhibiting the follicle from
growing a normal hair. One of those factors seems to be PGD2, which
was found near stem cells in the follicle, which are important in
hair growth, Cotsarelis explained.
Dr. Sanusi Umar, a dermatologist in Redondo Beach, Calif. and
associate faculty at University of California, Los Angeles, said
it's long been known that prostaglandins are involved with hair
growth, while this study shows that the opposite may also be true.
For example, Latisse (bimatoprost ophthalmic solution) is a
synthetic prostaglandin (mimicking PGF2) that encourages eyelash
growth, while Rogaine (minoxidil) is thought to work by promoting
the activity of another prostaglandin, PGE2, Umar noted.
"This study tells the other side of the story," he said.
Yet, Umar urged men not to toss out their Rogaine yet. "Yes,
this may open another front from which hair loss may be treated. It
is not likely to be the panacea, however," he added.
There are likely multiple prostaglandins involved with
inhibiting or promoting hair growth, he pointed out. Steroids and
nonsteroidal anti-inflammatory drugs also inhibit PGD2 "but have
not been shown to consistently grow hair," Umar noted.
"It is more likely that a number of end factors contribute to hair loss with factors like PGD2 inhibiting hair growth and others such as PGE2 and PGF2 promoting it," he said. "PGD2 inhibition may emerge as part of a combined approach used in combination with agents that work via different mechanisms . . . as a more effective approach to hair loss treatment."
U.S. National Library of Medicine has more on hair
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