JOHN YDSTIE, Host:
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: 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: 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: NPR's science correspondent Joe Palca.
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