In experiments with mice, Yamanaka's team reprogrammed adult mouse liver and stomach lining cells into iPS cells. Using a retrovirus, the scientists were able to transplant these cells into mice. Moreover, Yamanaka's team found that these reprogrammed cells avoided sites that are known to trigger tumors. In fact, mice that received the iPS remained tumor-free for six months.
Creating embryonic-like stem cells from adult cells may resolve an ethical dilemma, but whether these cells will act like real embryonic stem cells is yet to be determined.
"Using adult cells to create what appeared to be embryonic stem cells solves the ethical dilemma that some people have in creating or destroying embryos to create stem cells," Taylor said.
"The one thing we can't say yet is that whether these stem cells generated in this way will have the full potential that embryonic stem cells have," Taylor said. "They probably won't. But exactly where that line will be drawn isn't known. If they do almost everything that embryonic stem cells do, that'll be wonderful. If they don't, we may still need to consider using embryonic stem cells."
Another expert thinks this is an important step forward, but it's going to take a long time before cells generated this way can be used to treat people.
"They're one step closer to solving the problem," said Paul Sanberg, director of the University of South Florida Center for Aging and Brain Repair in Tampa. "Now they're going to have to grow the cells, implant them in animals, and show that they work for diseases," he said. "There's a lot of experiments to do between making these cells and putting them in people."
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