Scientists who have helped create new hair cells on the skin of mice say hair loss may be reversible.
The team at the University of Pennsylvania say though damaged hair follicles were thought to be irreplaceable, hair growth can be encouraged using a single gene.
The human head has as many as 100,000 tiny hair follicles, from each of which grows a single hair and as the follicles are produced in the embryo stage of human development it was thought that no further replacement follicles could be produced during life.
However the Pennsylvania team have found that a particular gene important in wound healing, called wnt, appears to play a role in the production of new hair follicles.
In an experiment using mice, small sections of the outer skin layer, or epidermis, were removed from the creatures and the procedure appeared to awaken stem cell activity in the area, which included the production of a number of hair follicles.
The scientists found that if the action of the wnt gene was blocked, no hair follicles were produced, but if it was boosted, then many more hair follicles were produced, and the skin layer eventually became indistinguishable from surrounding areas.
Dr. George Cotsarelis, a dermatology professor at the University of Pennsylvania School of Medicine in Philadelphia who led the study, says the findings could lead to remedies for male-pattern baldness and other types of hair-loss.
Experts say the study provides convincing evidence that the skin has remarkable powers of regeneration, and shows that under certain conditions hair follicles can be created.
They say the study demonstrates that mammals possess greater regenerative abilities than commonly believed and the findings could prove more important in the development of better wound healing techniques.
The study is published in the journal Nature.