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Scientists Create Embryonic Stem Cells from Skin

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Scientists Create Embryonic Stem Cells from Skin

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Scientists Create Embryonic Stem Cells from Skin

Scientists Create Embryonic Stem Cells from Skin

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Two teams independently discover a way to turn ordinary human skins cells into stem cells with the same characteristics as those derived from human embryos, a breakthrough that could open the door for advanced medical therapies.


Two scientific teams - one in America and one in Japan - are independently reporting a remarkable advance in stem cell research. They've found a way to make human embryonic stem cells without using human eggs or human embryos. The new technique promises to end the divisive ethical debate over embryonic stem cells that has raged in this country for a decade.

Joining us now is NPR's science correspondent, Joe Palca.

Joe, what exactly did these scientists do?

JOE PALCA: Well, John, what they did was they - instead of starting with embryos and using those to derive embryonic stem cells, they started with skin cells, or actually precursors to skin cells called fibroblast, that we all have in our skin. And they used viruses, as it happens, to insert genes into these fibroblasts. And what they found was that after a few days, these genes that they added were able to get the skin cells to start behaving just like embryonic stem cells. Now, they didn't pick these four genes out of a hat. These are the same four genes that seemed to be very active in embryonic stem cells. So they felt, well, hmm, if we can boost them in skin stem cells, maybe they'll start behaving like embryonic stem cells. And they did.

YDSTIE: Well, they act like stem cells, but are these cells really the same as embryonic stem cells?

PALCA: Well, this work in humans is very new, and there are still a lot of comparisons that have to be made between these cells and human embryonic stem cells, but there's been a lot of work in the last year. These cells were also created using mouse cells, starting with mouse skin cells, and the comparison between what you get from a mouse cell that's transformed this way and an embryonic stem cell, they look to be very similar. So there's every hope that these will be, if not perfectly identical, then identical for the purposes of studying and possibly therapy.

YDSTIE: So does this move us any closer to the day when embryonic stem cells can actually be used for therapy?

PALCA: Well, yes and no. It certainly — well, as we've been saying, it removes an unethical hurdle. So that should mean that funding for these cells, anyway, shouldn't be under any kind of restrictions. The other thing it does is it makes it extremely easy now to tailor a stem cell to an individual because all I have to do is get a few skin cells from you and then put in these magic factors, and suddenly I've got an embryonic stem cell line that's tailor made directly to you.

And then if you, for some — and if these cells do turn out to be useful for therapy and I have to transplant some of them into you, or something derived from them, they'll be yours. It will be like giving your, you know, your own blood back to you. So there won't be any chance of an immune rejection.

But even avoiding the immune problem, I mean nobody has exactly figured out how to use embryonic stem cells or these cells for therapy yet.

YDSTIE: But does this really end the whole ethical debate over stem cells?

PALCA: Well, it - I think it will in the long run, but I think there's still kind of an uncomfortable period, because I've already talked to scientists who say we cannot stop doing human embryonic stem cell research yet. These cells look very promising. Certainly the mouse work suggests that they will be able to do all the things that embryonic stem cells do, but right now we don't know.

And the other issue is that, for the moment at least, getting these magic factors into the skin cells requires using viruses, retroviruses, some other things that you don't want to put in cells. I mean, basically, there are indications that some of these things can and have caused cancer in gene therapy experiments. So right now it's not something to belittle. There are technical hurdles and they have to be worked out. But scientists are confident they will be.

YDSTIE: Thanks, Joe.

NPR's science correspondent Joe Palca.

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Scientists Produce Embryonic Stem Cells from Skin

Scientists Produce Embryonic Stem Cells from Skin

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Genetic modifications in skin cells (above) induced the cells into what scientists call a pluripotent state — a condition that is essentially the same as that of embryonic stem cells. Junying Yu/University of Wisconsin-Madison hide caption

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Junying Yu/University of Wisconsin-Madison

Two teams of scientists have independently discovered a way to turn ordinary human skin cells into stem cells with the same characteristics as those derived from human embryos, a breakthrough that could open the door for advanced medical therapies.

If the work holds true to its promise, it would largely bypass ethical issues that have dogged research on human embryonic stem cells. It could also allow scientists to tailor the cells to specific individuals, eliminating the possibility of rejection.

The crux of the discovery, published online Tuesday by the journals Cell and Science, is a "direct reprogramming" technique that adds a cocktail of four genetic factors to run-of-the-mill human skin cells.

The Cell paper is from a team led by Dr. Shinya Yamanaka of Kyoto University; the Science paper is from a team led by Junying Yu, working in the lab of stem-cell pioneer James Thomson of the University of Wisconsin-Madison.

The discovery builds on work presented in 2006 by Yamanaka in which the same technique was demonstrated for skin cells from mice.

The two teams have been able to isolate cells that look and behave like embryonic stem cells. The researchers caution that there are still many steps to take before the cells are useful for human therapies.

Yamanaka said he knew that the real payoff would be if his work on mouse cells could be translated to human cells.

"We started working on human cells more than a year ago, but in the beginning, the four factors didn't work," he told NPR.

He said it was unclear whether the cells he produced from skin were identical to embryonic stem cells, but "all I can say is they are very similar."

While Yamanaka was working on mice to find the critical factors for transforming skin cells to embryonic stem cells, Thomson was already working on human cells. His team also reports four factors that can transform skin cells, but two of them are different from those Yamanaka found.

"It does seem that there are multiple paths to the same outcome," Thomson said. "How divergent those paths are remains to seen."

Thomson, 48, made headlines in 1998 when he announced that his team had isolated human embryonic stem cells.

Since then, the research has pitted groups that question the ethics of harvesting stem cells from human embryos against those that hope the line of research could result in important medical breakthroughs. The latest announcement from the Japanese and American teams could skirt the controversy.

"It changes everything in that these are not cells derived from embryos anymore," Thomson told NPR. But "we are back at the starting point now. These biologically ... appear to be the same as embryonic stem cells, and we still have to figure out how to differentiate them into useful things."

The whole idea of stem-cell based therapies is that the stem cells could be used to replace or repair cells damaged or destroyed by disease or injury, such as new heart cells for people who have had heart attacks or new neurons for patients with Alzheimer's disease.

"This is a huge deal," said Jose Cibelli, a researcher at Michigan State University.

"Anybody can do this procedure. It's a very simple recipe," he said. "A combination of three or four genes, and in a couple of weeks, you go from a skin cell to an embryonic stem cell. It's remarkable."