Long Fight Has Slowed Progress on Stem Cells
Wednesday, July 19, 2006; 1:46 PM
Editor's Note: This is an extended version of a story that appeared in the July 19 print edition.
The Senate vote is the latest skirmish in an often rancorous 8-year-old battle over the science and ethics of human embryonic stem cell research.
It started in November 1998, when James Thomson and colleagues at the University of Wisconsin in Madison announced that they had for the first time isolated and maintained long-term cultures of human embryonic stem cells -- a kind of cell that starts out nestled inside human embryos during the first few days of life. At that stage of development, the embryo is a nearly hollow sphere about the size of the period at the end of this sentence and consists of about 200 cells.
The cells forming the outside of that sphere eventually go on to become the placenta, which is the bridge of tissue connecting the developing embryo to the mother's womb. The cluster of cells inside that sphere, called the inner cell mass, goes on to form all the tissues of the developing embryo itself. Embryonic stem cells are the derived from this inner cell mass.
The great attraction of embryonic stem cells is twofold: their ability to make almost limitless copies of themselves in laboratory dishes and, under the influence of various chemical signals that scientists can add, their potential to become any kind of cell or tissue a body might need. That includes the kind of brain cells that are lost in Parkinson's disease, the heart muscle cells that die off after a heart attack or the pancreatic cells that go awry in diabetes. Those properties stand in contrast to so-called adult stem cells that can be found in the bone marrow, brains and other organs of children and adults, each of which has the capacity to become certain kinds of cells but not every kind of cell and appear unable to replicate indefinitely.
Scientist hope someday to be able to transplant embryonic stem cells (or, more precisely, brain cells, heart cells or other kinds of cells grown from embryonic stem cells) into patients who need them. They also see embryonic stem cells as powerful tools that will allow them to study diseases on the cellular level -- work they say could lead to new therapies and diagnostic tests and new insights into human development.
Thomson and his colleagues isolated their cells from human embryos donated by fertility clinic patients who no longer needed them for reproductive purposes. Other scientists and doctors immediately sought to replicate the discovery, both to confirm the Wisconsin findings and to make colonies of the cells for their own research. But that raised profound questions about the ethics of using -- indeed, destroying -- the earliest stages of human life as sources of research material.
Religious conservatives, in particular, who believe that even the earliest stages of human life are beings with moral standing, decried the science. To destroy an embryo for its cells -- even for the purpose of helping a sick adult -- is like killing a child so her organs could be donated to an ailing adult, they claimed.
Research proponents, in contrast, have allowed that human embryos deserve "respect" but have argued that it is wrong to grant them the same moral standing as a fetus in a mother's womb or a born person. In general, they have argued for the right to conduct research on embryos until 14 days of development -- the time when it is possible to first discern the beginnings of a spinal cord and nervous system.
Soon after Thomson's announcement, NIH director Harold Varmus asked the HHS Office of the General Counsel if NIH could fund research using human embryonic stem cells. The question arose because Congress had for the past several years inserted language in the NIH appropriation bill disallowing research that would destroy or harm an embryo. The General Counsel determined that NIH could not derive human embryonic stem cells, since the derivation involved destroying the embryo. But she said NIH could fund research on the stem cells, since they were not themselves embryos.
Once NIH knew it could support this research, the agency created a special panel of experts to consider how best to oversee human embryonic stem cell research. Two years later, as the Clinton administration was coming to an end, the panel settled on a set of recommended policies that would have allowed scientists to use federal grant money to study colonies of embryonic stem cells as long as certain ethics rules were followed. Central was a requirement that the embryos must have been created for fertility purposes, were no longer needed by the couple that made them, and were donated by that couple for use in research.
But before that policy went into effect, President Bush came into power and took the entire matter under consideration afresh. In the months before 9/11, Bush's pending decision on stem cell policy was among the most visible issues of his young presidency. When he made his decision, he announced it in what was his first televised address to the nation -- an address dedicated solely to the topic of stem cells. The date was Aug. 9, 2001.
In that announcement, Bush declared his policy, later spelled out in an executive order, that federal funds could only be used to study those embryonic stem cell colonies made from embryos that had already been destroyed by the time of his television appearance: 9 pm on Aug. 9. He declared that, based on information provided to him by experts at the National Institutes of Health, there were more than 60 such colonies either frozen or growing in test tubes around the world.
Most scientists following the field found that number to be surprisingly large. Much of the previous work had apparently not been publicly disclosed. Yet it grew even larger, into the low 70s, in the weeks to come, as additional laboratories let it be known that they, too, had batches of the cells they had derived before Aug. 9.
Over the months that followed, however, a number of issues arose that left scientists feeling there was less to Bush's policy than met the eye. As it turned out, cells from only a handful of cell colonies were actually available for distribution and study. Even today, that number has never exceeded 24. Moreover, it became clear that virtually all of those colonies had been maintained in culture dishes with blood products obtained from rodents, calling into question their usefulness as medical products because of the risk of animal viruses and other contaminants. Over time, it also became clear that some of the available colonies, including those developed first by Thomson in Wisconsin, were not aging well, and were accumulating mutations and other defects. For all these reasons, and also because of scientists' desire to have a more genetically diverse collection of colonies to work with, researchers using federal grant money for their studies -- the vast majority of U.S. basic researchers -- became increasingly frustrated with the limited number of cells available to them.
Although a few U.S. labs have pursued the production of additional cell colonies using private funds, they have complained that the process has required them to waste precious resources ensuring that those colonies be kept separate those that under study using federal monies. Last spring, the House of Representatives passed H.R. 810, co-sponsored by Reps. Mike Castle (R-Del.) and Diana DeGette (D-Colo.), which would expand the Bush policy to allow federal funding of research involving stem cells from spare embryos donated by couples who had finished their fertility treatments.
President Bush has repeatedly vowed to veto that bill should it pass the Senate.