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Grow your own

发布时间:2019-03-08 09:11:04来源:未知点击:

By Nell Boyce in Washington DC FOR the first time, researchers have persuaded adult mice to grow new hair follicles. They say their achievement may lead to alternative treatments for hair loss. In people, the pattern of hair follicles on the skin appears early in embryonic development, and no new ones develop after birth. New hairs are created when the follicles draw on stores of undifferentiated cells, and many types of baldness occur when these stem cell reserves are eventually exhausted. Hormone creams that stimulate dormant follicles to produce hair again are already available, and doctors have carried out follicle transplants. But these treatments for baldness have only had limited success, and until now no one has been able to generate new follicles in adult skin. A few years ago, Elaine Fuchs and her colleagues at the University of Chicago discovered that embryonic cells destined to become follicles express a protein called Lef-1. They also learnt that Lef-1 had a protein partner called beta-catenin that stimulates follicle development when it accumulates in adult cells. So they wondered whether a constant surplus of beta-catenin might stimulate growth of new follicles in adults. To test this theory, they created transgenic mice that produced a truncated form of beta-catenin that hangs around in cells for longer than usual. When they reached adulthood the mice kept growing new follicles, until they became very furry and even began to develop benign follicle tumours because of the uncontrolled growth (Cell, vol 95, p 605). Their hair also grew in at odd angles. In the embryo, only one side of the cells expresses a protein that directs the growth of new hair. But the new follicles didn’t have one-sided expression, and the hair grew in all directions. Nonetheless, Fuchs stresses that this is the first time anyone has managed to create new hair follicles in adult cells. She believes that short-term treatment with a cream or a drug could make new hair follicles form in humans, leading to new hair growth. “The question then becomes, can one actually develop drugs to do that?” she asks. She and her colleagues say they are trying to find out. “It’s really an outstanding paper,” says George Cotsarelis, director of the hair and scalp clinic at the University of Pennsylvania in Philadelphia, who studies hair follicles and their stem cells. “It shows that beta-catenin is one of the earliest steps in hair follicle formation,” he says. However, Cotsarelis questions whether beta-catenin will ever be used for treating baldness. “Biologically, it’s a great finding,