KYRA PHILLIPS, CNN ANCHOR: Well, those 64 stem cell lines now used by researchers worldwide may not be enough to support future research. That's the word from the National Academy of Sciences. And CNN medical correspondent Elizabeth Cohen is here now to explain -- Elizabeth, let's start with why the scientists believe that they need more.</s>ELIZABETH COHEN, CNN CORRESPONDENT: Well, they think that there are several limitations of the stem cell lines that are out there. For example, they say that eventually they're going to get old and they could have, they could start to contain genetic mutations. Now that would be a problem because you can't make the kind of treatments that you want to make with genetic mutations. Another problem, they say, is that these 64 lines were made using mouse cells. These stem cells needed to eat something so they gave them mouse cells to eat. That also would be a problem when people want to turn these stem cells into actual medical treatments for human beings. So the National Academy of Sciences says we need more stem cell lines than just the 64 that President Bush approved for federal funding and those also need to have federal funding.</s>PHILLIPS: Elizabeth, why did Bush have a limited number anyway? These scientists told him even beforehand, right, that they would need more?</s>COHEN: Oh, absolutely. They told him that over and over, that they really needed as many as they could get. So what happened is that President Bush was under enormous pressure from both sides. Scientists said give us as many stem cell lines as we could create, which could be into the thousands. However, folks who were opposed to the destruction of embryos said scientists shouldn't be given any stem cell lines at all because for every stem cell line, an embryo had to be destroyed. The way that you make a stem cell line is you take an embryo that's sitting in a fertility clinic, you destroy it and you get the stem cells that are inside it. So folks who were against the destruction of embryos said we shouldn't have any. So this was the way that President Bush compromised.</s>PHILLIPS: All right, we'll have much more coverage on this report throughout the day. Elizabeth Cohen, thank you so much.
Stem Cell Lines Not Enough For Future Research