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Background: Stem Cells

A background report by Susan Dentzer about the use of stem cells in scientific research.

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  • SUSAN DENTZER:

    The Shady Grove Fertility Center outside Washington, D.C., Is a useful place to begin to understand the debate over stem cell research. Here, physicians like Dr. Eric Widra treat patients struggling to have babies with techniques like in vitro fertilization, or IVF.

  • DR. ERIC WIDRA:

    When we get ready to treat a couple with IVF, The first step is to stimulate the ovaries to develop multiple eggs. So the woman takes a series of hormones that are identical to the hormones she normally produces, but we give them in excess quantity. And so what that does is cause the ovary to develop additional eggs other than the one that is typically ovulated.

  • SUSAN DENTZER:

    The eggs are retrieved from the woman and mixed with her partner's sperm. If fertilization takes place, an embryo results.

  • DR. ERIC WIDRA:

    During the first few days of life, the embryo goes through stages of division and development. This is a three-day-old embryo. This whole structure here represents the embryo, and each of these are an identical cell within the embryo, and there are approximately eight of them here. Each of these embryos is known as what's known as totipotential, meaning it can become anything, including a unique individual. And so these are in fact what people are interested in looking at. These are stem cells.

  • SUSAN DENTZER:

    In fact, at this stage, the entire embryo consists of stem cells– cells that will ultimately develop into all of the specialized cells that make up a human being. And unlocking the secrets of that development process promises to revolutionize medicine, leading to almost unimaginable cures for a range of diseases.

  • DR. ERIC WIDRA:

    We have no way of knowing why one of those cells will give rise to heart and bone and liver, and why another one will give rise to eyes and brain and hair, and how that machinery works. When we can learn what turns cells on to go down one path of development or the other, it becomes an incredibly powerful tool to understand human disease and to provide treatment.

  • SUSAN DENTZER:

    Researchers think that one day, stem cells like these could be nurtured in labs to grow into skin grafts for burn victims, nerve cells for people with spinal cord injuries, and even new organs for victims of kidney or liver disease.

  • DOCTOR:

    Hello. Tell us hello, baby.

  • SUSAN DENTZER:

    While the main business of centers like Shady Grove is producing babies, a byproduct is unused embryos– in effect, bundles and bundles of stem cells. That's because many more embryos are often generated through fertility treatments than are transferred into patients' uteruses. At three to five days of age, and when the embryos consist of anywhere from eight to two hundred cells, they're frozen and stored in liquid nitrogen in tanks like these.

  • DR. ERIC WIDRA:

    In fact, this is a problem throughout this area of medicine, that patients will be happy to freeze their embryos– they like that option– they get pregnant; they move away; we can't find them; we're storing these embryos and we're not… We don't have any direction from the patients of what they'd like to do with them, and sometimes we can't find them.

  • SUSAN DENTZER:

    And with thousands of unused embryos in cold storage at fertility centers across the country, they're a vast potential source of raw material for stem cell research. The question that now confronts policymakers is this: Since stem cell research would clearly involve destruction of these unused embryos, can it or should it be carried out with the aid of federal research dollars?

    For the better part of a decade, Congress has said no, annually renewing a ban on federal funding for research that destroys an embryo. But last year, the Clinton administration issued guidelines allowing some federal funding of stem cell research to proceed in spite of this congressional ban. The guidelines said federal dollars could not be used to actually destroy the embryos created through fertility treatments in order to get the stem cells. On the other hand, if stem cells were obtained from private companies or non-government labs that destroyed the embryos themselves, federally funded work on them could proceed.

    President Bush vowed to revisit the issue when he took office. Last May, the President wrote one right-to-life group that he: "opposed federal funding for stem cell research that destroys living human embryos." But he added that he supported other aspects of stem cell research, including work on stem cells derived from adults. These can be found in bone marrow and the brain. But there's great scientific uncertainty over whether they'll prove as capable as embryonic cells at developing into all other cells and tissues.

    The resulting tempest in a test tube over federal funding of stem cell research has divided the White House, as well as conservatives within the Republican Party. Although a decision from the President is expected within days or weeks, experts say that's unlikely to put an end to the debate.

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