Researchers say they have stimulated the growth of new hair in mice, disproving a long-held belief that it is not possible to correct baldness in adults.
Scientists say they did it through the creation of new follicles, microscopic "mini-organs" in the skin that produce hair strands.
Experts say that people lose their hair because the follicles shrink and eventually disappear with age. But they discovered they can stimulate the growth of new hair-producing follicles in mice by damaging their skin.
George Cotsarelis, an investigative dermatologist at the University of Pennsylvania School of Medicine, says researchers used an abrasive technique similar to one used on humans to remove facial acne scars, except that they used the technique on the skin of laboratory mice.
"These follicles actually form from scratch out of nowhere. They're not there and then they develop from epidermal cells that normally don't make hair follicles."
In the study, the abrasion caused wounds and the healing of the wounds triggered an embryonic state in the rodents' skin, which became receptive to instructions from a protein called WNT.
The scientists discovered they could control the amount of hair growth either by blocking the amount of WNT proteins, stopping follicle formation, or over-stimulating WNT and doubling the production of hair-producing follicles.
"That suggests that wounding creates this period of time where you can manipulate the regeneration of the follicles. So, you can actually increase the number that's formed."
The results of the study are in the journal Nature. Cotsarelis says the new hair in mice was white, because the animals have no pigment throughout their skin. Cotsarelis says humans have pigment throughout their skin so new hair would likely be colored. Cotsarelis is exploring these discoveries for a (for-profit) company he helped found to examine hair regeneration in humans.