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Blood Vessels Hold Key To Thicker Hair Growth


MGH researchers have succeeded in growing hair faster and thicker in mice, thanks to a protein that promotes blood vessel growth in their skin. The protein-treated mouse hair follicles –  while no greater in number than those of normal mice –  are individually bigger. Collectively, they increase the total volume of hair by 70 percent. This study appeared in the Feb. 19 issue of the Journal of Clinical Investigation.

Blood vessels around hair follicles during hair growth phase in mice
 Image from Massachusetts General Hospital
If the protein has the same effects in humans, it could lead to the first angiogenic therapy for male pattern baldness. "In male pattern hair loss, it's not that the follicles are gone. They're just miniature follicles," says Michael Detmar, MD, of MGH Dermatology and lead author of the study. "If anyone could find a way to make the follicles bigger, men might grow hair again."

The discovery that increasing blood flow to the scalp helps stave off baldness may be old news to many barbers. For years, they have been advising clients to massage their scalps as a way of stimulating circulation and hair growth.

A few scientific studies have suggested that people with hair loss may have fewer blood vessels. But prior to the MGH study, no one had actually measured how closely blood vessel growth is correlated with hair growth, or what might cause scalp vessels to grow in the first place.

To explore these questions, Kiichiro Yano, a research associate in MGH Dermatology, and his colleagues compared two groups of mice, one normal and one genetically programmed to produce an abundance of VEGF, a protein known to trigger blood vessel growth. The VEGF-enhanced mice grew hair faster and thicker in the first two weeks of life than did the control mice.

The VEGF-enhanced mice also regrew hair faster. Shaved 8-week-old VEGF mice not only grew hair back sooner, they also exhibited a 30 percent increase in hair follicle diameter just 12 days after hair removal. "By overall volume, the hair was about 70 percent thicker than in wild-type mice," says Detmar.

Blood vessels located in the skin surrounding the pumped-up hair follicles were 40 percent larger in diameter than those found in normal mice, suggesting that the VEGF-mediated angiogenesis was causing the hair to grow faster and thicker.

When normal mice were treated with an antibody that blocks VEGF activity and then shaved, their hair grew back slower and was thinner than the untreated mice. Twelve days after hair removal, the VEGF-deprived mice still displayed bald spots and overall reduced hair growth. "By modulating VEGF, we can directly influence the size of the hair follicles," says Detmar.

As for how the VEGF-inspired blood vessels are plumping up the hair shafts, the researchers believe they may be delivering an extra supply of growth factors, in addition to oxygen and nutrients. Detmar and his colleagues are developing a technique to deliver VEGF topically to the scalp. "The question now is can we by this method improve hair growth in humans?" he says. "Applying it to humans will be the big challenge."

Source: Massachusetts General Hospital, February 23, 2001

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