James Thomson Interview (page: 5 / 8) Father of Stem Cell Research	Print Interview

Your breakthrough with adult stem cells came more quickly than you expected. So maybe there was an "Aha!" moment there?

James Thomson: Yeah, maybe a little bit more. Because right into it, that's what human embryonic stem cells look like at that point. We were pretty darn sure that they were the right thing at that point.

Were you with your post-doc when that happened?

James Thomson: No. See, there's never a moment. It takes so many weeks, and they look a little bit better. It just doesn't work that way.

You didn't get a call in the middle of the night?

James Thomson: No, it doesn't work that way. So from the time she dumps the transfectionary agents on the cells to the time you actually get a colony that looks half-way decent is like three weeks. And all the way in there you kind of have this gradation of things looking slightly better. You kind of stare at it and hope it looks good. So it's kind of a continuum rather than a moment.

How do you see the ethical implications of this work with adult stem cells?

James Thomson: I think they're huge. First of all, you have to make the caveat that it's not clear that they're equivalent to embryonic stem cells, but they really, really look like it. There's some technical things we need to do to make them more equivalent. The way we make them, genes are actually inserted into the DNA of the host cell, and that's not good. But there are ways around that.

Why isn't it good?

James Thomson: Because every time you insert a piece of DNA into the host cell, it could disrupt an endogenous gene and that can cause bad things: mutations, cancer. So it'd be better to do it in a way that it doesn't actually insert into the genome. There are several ways of doing that, and a lot of people are working on that now. But assuming that we can remove those and not have them actually integrate, it really looks to me like they're the equivalent of embryonic stem cells. Over time, I could be wrong. But my belief is that embryonic stem cells will be used less and less now, and these will be used more and more. There's a huge number of people jumping into the field right now, much more than there was ten years ago with human embryonic stem cells, given all the ethical issues.

There wouldn't be government bans on this.

James Thomson: No, George Bush likes this.

How do you harvest these skin cells?

James Thomson: We got them from a company that banks them. But normally it's just a little sponge biopsy. So it's a very simple procedure, wouldn't be a big deal.

And isn't the cost much lower?

James Thomson: Yeah. I haven't actually done it myself, but it's simpler than getting blood, 'cause blood you have to be there for quite a while, and a sponge biopsy's real fast.

I would think that would be a tremendous relief in your field.

Get the Flash Player to see this video. James Thomson: I don't know if relief -- there's a lot of excitement about it. And it's not simply that we found a replacement for embryonic stem cells from a less controversial source, but the idea that you can actually change the identity of a cell by this fairly simple manipulation is really big. And it goes beyond making embryonic stem cells. I think what you'll find over the next, say, five years is there'll be a bunch of papers showing similar screens for looking at changing cell types directly between two different cell types, not going all the way back to the ground state, but say making a skin cell directly into a liver cell, for example. And prior to this work, those screens didn't make a lot of sense, 'cause again, people thought it'd be too complex and couldn't possibly work. But my guess is there's going to be a lot of those screens done now. And people will find ways to change the basic state of your cells in your body to different fates.

You mentioned the possibility of turning one kind of cell -- say, a skin cell -- into another, such as a liver cell. What would be the medical implications of a breakthrough like that?

Get the Flash Player to see this video. James Thomson: The possible implications long-term is that when you think about a truly regenerative medicine, you don't want to transplant stuff, you want to give the body something so it repairs itself in a way it will not normally do. And that repairing in a way it will not normally do is based on cells changing their identity. And this means that an identity which is usually very stable can be changed artificially. So in a heart attack, for example, it'd be nice if your heart cells would divide and repopulate the heart and not just simply form heart tissue. This gives us an inkling that that's probably likely to be true someday.

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