Researchers in Pennsylvania say they've found a way to combat hair loss with stem cells.

The approach employs stem cells to regenerate missing or dying hair follicles in the scalp. Until recently, it wasn't possible to generate enough hair-follicle-generating stem cells to make a difference.

But now, a research team at the University of Pennsylvania's Perelman School of Medicine reports a new method for converting adult cells into epithelial stem cells (EpSCs), which, when implanted into laboratory mice, regenerated the different cell types of human skin and hair follicles and produced structurally-recognizable hair shafts.

The National Institute of Arthritis and Musculoskeletal and Skin Diseases funded the study, which appears in Nature Neuroscience.

Study lead Xiaowei Xu, an associate professor of pathology, laboratory medicine and dermatology at the university, said he and his team began the experimentation process with human skin cells called dermal fibroblasts.

By adding three genes to the cells, they converted them into induced pluripotent stem cells (iPSCs), which have the capability to differentiate into any cell types in the body.

Xu and his colleagues then converted the iPSCs into epithelial stem cells, typically found at the bulge of hair follicles.

Xu's team further demonstrated that, by carefully controlling the time and other factors of the cell growth process, they could force the iPSCs to generate large numbers of epithelial stem cells.

The researchers eventually succeeded in turning over 25 percent of the iPSCs into epithelial stem cells in 18 days.

When they compared the development of the iPSC-derived epithelial stems cells they had grown with natural stem cells taken from a human head, they realized they had accomplished what they wanted to do.

"This is the first time anyone has made scalable amounts of epithelial stem cells that are capable of generating the epithelial component of hair follicles," Xu said, adding that those cells have many potential applications including wound healing, the development of cosmetics, and, of course, hair regeneration.

When the researchers mixed the lab-generated cells with dermal cells from mice then grafted them onto the skin of the lab mice, which had compromised immune systems, they produced functional human skin cells and follicles that were indeed structurally similar to human hair follicles.

Xu says it will still be some time before the new approach leaves bald heads with thick new manes, since a lot of added research needs to be done.

"When a person loses hair, they lose both types of cells." Xu said. "We have solved one major problem, the epithelial component of the hair follicle. We need to figure out a way to also make new dermal papillae cells."

No one, he said, "has figured that part out yet."