Cellular patch kit. Individual stem cells isolated from mouse hair follicles can develop into normal hair-bearing skin.

Fur-Replacement Therapy

A tuft of fur on the back of a hairless mouse may signal new hope for baldness sufferers and burn victims.

In the past few years researchers have ascertained that stem cells contained in the "bulge" of hair follicles are capable of producing both skin and hair. But it hasn't been clear whether the bulge contains many kinds of progenitor cells--each giving rise to a different tissue--or whether there are "multipotent" stem cells that are capable of generating skin, hair, or oil-producing sebaceous glands.

Now researchers at Rockefeller University in New York City say they have proven that the cells are multipotent, and that they can grow into all three kinds of structures when transplanted to a live animal. Using advanced cell-labeling techniques, a team in the lab of cell biologist Elaine Fuchs separated two populations of stem cells residing in mouse hair follicles. Then, to spotlight the talents of individual cells, they grew colonies from single cells. They then mixed these cells with skin cells from normal newborn mice and grafted them onto the backs of mice engineered to be hairless, on spots where skin had been surgically removed. Normally, skin cell grafts will not generate hair on hairless mice. But those given bulge stem cells grew tufts of hair as well as skin and sebaceous glands, the team reports in the 2 September issue of Cell.

"The results demonstrate for the first time that individual cells isolated from hair follicles can be cultured in the laboratory and retain a capacity to make multiple cell types when grafted," says Fuchs. So they supply "definitive evidence for bulge cells as bona fide stem cells."

Fuchs is optimistic about the next step, which is to locate similar cells in humans. Physician Len Zon, who studies blood development at Harvard Medical School in Boston, has hailed the research, telling Newsday the tufted mice are "incredible." Ultimately, he said, scientists may be able to use human hair stem cells to generate normal hair-bearing skin for burn victims, among others.

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Elaine Fuchs's lab