A team of biologists from the University of Chicago announced last night that they have grown shafts of hair where no hair has grown before.
The researchers believe they may have stimulated adult skin cells to revert to their embryonic condition from which they developed into fully functioning hair follicles, the hair-producing cells which become dormant in bald men.
In an experiment on laboratory mice the scientists were able to stimulate the growth of hair in the spaces between existing hair follicles of the skin to create a breed of super-hairy mice.
Although the scientists, led by Professor Elaine Fuchs of the university's department of molecular genetics and cell biology, emphasised that they had not as yet found a cure for baldness, they are in little doubt that their research is a major step forward.
"This is exciting because current treatments for baldness only work if there are living follicles left, or if the patient undergoes hair-transplant surgery," Professor Fuchs said.
"Our research shows that new follicles can be created from adult skin cells if certain molecular players are induced to act."
The key molecule in question is beta-catenin, a protein which plays a vital role in gluing skin cells together. It also, however, acts as a signalling system in the womb for instructing embryonic cells to become hair follicles in the skin.
"Beta-catenin can cause adult epithelial [skin] cells to revert to an embryonic-like state where they have the ability to chose to become a hair follicle," Professor Fuchs said.
Scientists discovered that beta-catenin binds to another molecule called LEF-1 which is usually found only in the cells that are destined to become hair-producing follicles. When the two molecules form a marriage, a new hair shaft is born.
Dr Uri Gat, a postdoctoral fellow in Professor Fuchs' laboratory, found a way of stimulating a form of beta-catenin that is not broken down in the skin, thereby creating fresh hair growth. The results are reported in the journal Cell.
"What we've shown is that we can induce hair development in adult mice when usually hair follicles only form in the embryo," Dr Gat said.
A lotion containing a substance which stimulates the production of beta- catenin in the scalp could theoretically generate the formation of new hair follicles and so cure baldness, he added.
Professor Fuchs warned, however, of unwanted side-effects in some of the mice, which developed benign tumours of the skin as a result of overactive hair follicles.
"If we can find a way to transiently express beta-catenin in these skin cells, just until new follicles are estalished, and then turn it off, we may be able to prevent tumour formation and still allow hair follicles to form."
The research also showed that blocking the activity of beta-catenin instead of stimulating it might prevent the growth of unwanted hair. This would be useful for women.Reuse content