Philadelphia - Dr. George Xu, a professor of pathology at the University of Pennsylvania, discovered a new type of adult stem cell that can be harvested from human hair follicles."These stem cells are quite different than stem cells that have been discovered before in human hair follicles... We call them 'hair spheres,'" Xu said. These hair spheres can be harvested and so far differentiated into six different cells, including neurons, adipose, and muscle tissue, among others. Xu said that they have enormous clinical application, with the possibility of treating Alzheimer's disease and muscular dystrophy.
"It's possible we can even make them into different shapes, other types of cells," Xu added.
Stem cell research has triggered a national debate, as scientists prefer to extract them from human embryos. President Bush signed an order forbidding federal funding for such research, since it involves the destruction of a potential human life.
However, Xu's research shows promise that scientists can honor such ethical concerns and still obtain the stem cells they desire, since hair follicles come from adults and are plentiful.
While embryonic stem cells grow faster and have a higher degree of differentiation, Xu says his approach has a better trade-off. He notes there is a possibility that a patient's body would reject an embryonic stem cell transplant, since they are foreign cells from another person.
"But if we can isolate the adult (hair follicle) stem cells from the same patient, and then we manipulate them in a culture medium, and then if we inject them back, since they are from the same patient, they will not cause a rejection," Xu said.
Xu's team starts with a small biopsy of the scalp, where they isolate the hair follicle, a process that only takes a day. They then proliferate the cells in a medium by adding growth factors, such as insulin, until they form into spheres, which takes four weeks. They follow by isolating the stem cells and begin the differentiation process, which takes another two-to-three weeks.
Xu said the stem cells his team discovered are similar to those discovered in mice, but scientists never knew before that they were also in human hair follicles. His hair spheres are unlike the previously discovered epithelial stem cells, which are also in hair follicles but have limited differentiation.
Xu said he worked with the scientist who discovered epithelial stem cells in the past.
"If we want to use them for therapeutic purposes, we will need lots of cells, so how to grow more and faster is what we're focusing on now," Xu said, adding that it will take another few years to speed up the process. His team of seven, which is a collaboration with the Wistar Institute, worked on the project for the last three years, but didn't make the breakthrough discovery of the new stem cell until last July. They are seeking funding from the National Institutes of Health.
Xu said his discovery hasn't yet received much attention from legislators, but has attracted venture capitalists and pharmaceutical companies.
Xu went to medical school in China, before earning his Ph.D. at Wake Forrest University and completing his residency at the University of Pennsylvania and a clinical fellowship at Harvard Medical School. Xu recently became an American citizen. "It's a land of opportunity, if you work hard you can achieve what you hope for," he said.
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