The Secret to Growing More Hair? Just Ask a Wounded Mouse


 Researchers from the University of Pennsylvania have discovered an important scientific finding that offers good news to the 60-90 million men and women in North America affected with hair loss.

Humans are born with about 100,000 hairs on the scalp. At present, it is thought that the number of hair follicles an individual is born with is the maximum number of hair follicles that person will ever develop during their lifetime. For humans, it seems that it is not possible to produce new hair follicles beyond the number generated at birth. Hair loss conditions like genetic hair loss, reduce the number of follicles on the scalp.

Exciting research over the last few years has challenged the concept that new hairs can never be generated after birth.    For years, it has been recognized that when the skin of a mouse is wounded, new hair follicles can be created. This phenomenon of new hair creation after skin injury does not happen in humans -  a finding that has stumped researchers.  The answer may now have been uncovered.

New Research from UPenn

Researchers from the University of Pennsylvania showed that when the skin of mouse is injured, immune cells residing in the skin known as gamma delta T cells are triggered to produce a chemical known as Fgf9.  Fgf9 stimulates the wound repair machinery of the skin to produce additional chemicals that not only heal the skin but stimulate creation of brand new hair follicles.

Interestingly the skin of humans was shown to have much lower numbers of the gamma delta immune cells compared to mice. When skin injury occurs in humans, a wound is healed with creation of a scar, and no new hair follicles are created.

With the new discovery of the importance of the Fgf9 protein in creating new hairs, the race is on to better understand how to use this information to generate new hairs in humans and to design drugs that prompt creation of new hair follicles.  One might imagine the possibility that if a minor wound could be introduced on human scalp and FgF9 like drugs were applied to the skin, new hair follicles could theoretically be generate. This remains to be tested, but offers hopes to the millions of individuals across North America with hair loss.

SOURCE: Gay D et al. Fgf9 from dermal gamma delta T cells induces hair follicle neogenesis after wounding. Nature Medicine. Published Online June 2 2013



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Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887

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