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Stem Cell Science

Susan Dentzer explains the president's decision and the science behind it.

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    In his televised address to the nation last night President Bush said that after much deliberation, he'd concluded that limited federal funding of stem cell research should go forward.


    Embryonic stem cell research offers both great promise and great peril. So I've decided we must proceed with great care. As a result of private research more than 60 genetically diverse stem cell lines already exist. They were created from embryos that have already been destroyed, and they have the ability to regenerate themselves indefinitely, creating ongoing opportunities for research. I have concluded that we should allow federal funds to be used in research on these existing stem cell lines, where the life and death decision has already been made.


    In singling out research on existing stem cell lines as being qualified for federal funding, the President was relying on several unique properties of stem cells, in contrast to most other types of human cells. Embryonic stem cells are building block cells derived from human embryos that are just five days old, and in some cases from certain cells of fetuses aborted at five to ten weeks of age. Researchers retrieve the cells and then culture them in a lab; then the magic of stem cells kicks in.


    Most of the cells have a very limited number of cell divisions. And these cells, though, have this property that they can divide indefinitely, so the important aspect of this means that once you establish cultures of these cells that you can just culture these cells indefinitely in a laboratory, send them to your colleagues, and collaborators, and then when you want, you can get them then to form other cell types.


    As a result, researchers can create a whole colony of genetically identical stem cells, grown from just several initial cells. Such a colony is called a line, although a National Institutes of Health report issued last month said there were roughly 30 such cell lines around the world, the NIH now says it's determined there at least twice as many. At the same time scientists say one question raised by the President's new policy is whether paying for research on just these existing cell lines will be sufficient. At a recent congressional hearing on the subject lawmakers pressed scientists on just how many lines were needed.


    Is it tens and tens or hundreds and hundreds? I mean, how do we finally figure this out?


    If we were to consult a panel of experts in this area right now, a number that people may settle on may be a number such as about one hundred; however, until we actually are involved in the science of looking and examining those cell lines, we will not know if they're sufficient for all of our activities.


    In addition to paying for research on embryonic stem cells, the President also said last night that his administration would increase funding for research on stem cells derived from alternative sources.


    I also believe that great scientific progress can be made through aggressive federal funding of research on umbilical cord, placenta, adult and animal stem cells, which do not involve the same moral dilemma. This year, your government will spend $250 million on this important research.


    NIH officials said today that should help shed light on a key scientific debate: whether these other types of stem cells will prove as capable as embryonic stem cells as growing into the various specialized cells in tissues of the body.


    Now we can really start comparing on head-to-head comparisons of the various types of stem cells with embryonic stem cells and answer the questions that have really been to us very frustrating and being unable to get some good scientific data as to what the things that are comparable and the things that are different among the different types of derived stem cells.


    Administration officials said today that federal grants under the new policy could begin flowing to researchers early next year.

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