The fiery debate about stem cell research spins on one central issue: Whether or not scientists should be allowed to destroy human embryos in order to save human lives.

It’s a debate that has befuddled policy makers for years. But if George Xu is successful in his current line of research, it’s a debate that also may one day be a thing of the past.
Xu, a Penn assistant professor of pathology, recently made headlines in the science world when he and his research team announced they had identified a new source of adult stem cells: Human hair follicles.

According to Xu’s research, the stem cells in hair follicles share with embryos the all-important ability to “differentiate” into different cell types. That means these hair follicles could eventually become a noncontroversial, readily available source of human cell types that could then be used to treat health care issues ranging from spinal cord injuries to Parkinson’s disease. “The application for these cells would be limitless,” Xu says.

Researchers have known for years that hair follicles could be a source of adult stem cells, but Xu and his team—which also included Hong Yu, Suresh M. Kumar, and Geza Acs of Penn and Dong Fang, Ling Li, Thiennga K. Nguyen, and Meenhard Herlyn of the Wistar Institute—are the first to isolate and grow a new variety of multipotent stem cell.

Beyond the potential use of these cells in cell replacement therapy—stem cells might be used, for instance, to “grow” organs for organ replacement surgeries—the scientific community also believes studying stem cells could help them better understand the basic cell functions that make humans work—and also cause human illness.

Embryos have generally been believed to be the best source for stem cells because of their ability to be differentiated into different cell types, but some have opposed their use on moral grounds. President Bush in August of 2001 ordered severe limits on the use of embryos for this research, an order that many in the scientific community continue to oppose.

But Xu’s research sidesteps the moral issue and hints that hair follicles could prove to be just as useful as embryos.

Xu and his team managed to grow these new “multipotent stem cells” by first growing large masses of cells, what they call “hair spheres.” After growing these spheres, Xu and his team were then able to differentiate the cells into various cell types, including nerve cells, skin pigment cells and smooth muscle cells, in the same way that embryo stem cells can be used.

Each of these differentiated cells then began to demonstrate functions appropriate for the “new” cell type. “These cells actually start to behave more like differentiated cells,” Xu says. “We showed these cells not only expressed these [characteristics], but also acquired some function.”
Xu says the research is exciting because it suggests very strongly that human hair follicles could become an accessible—and morally neutral—source of stem cells.

“They are adult stem cells, so you don’t have to worry about ethical issues,” Xu says. “Even better, you can [get the cells] from the same person … so you wouldn’t have to worry about the body rejecting them. There’s no rejection to your own cells—and I think that would actually be the most important point.”

There’s just one hurdle left to overcome: Though the research is promising, and though Xu has proved that these hair follicles are a viable source for stem cells, Xu says the team has to find a way to grow the cells faster, and in greater numbers. Failing that, their use could be limited. Xu says with his lab and other researchers working on the problem it’s a hurdle that can—and will—be overcome.

Originally published on October 5, 2006.