Embryonic stem cells have been the hottest source of controversy in the news for the last month. The Pope warned against using them for research and on Aug. 9 President Bush gave the scientific community a compromise on their use, allowing the 60 or so stem-cell lines in existence for federally funded research to be used. Yet the public remains largely uneducated about the cells and why they are so useful and so controversial.
Cells in a developed human have already been given an assignment. Some will be nerves, some muscle, and some bone, and when a cell is assigned, it cannot form any other kind of tissue. Embryonic stem cells, however, have a clean slate. They can theoretically form any adult cell when aided by the right chemicals. Given this, and the fact that stem cells can multiply and grow indefinitely in culture, a world of opportunity opens for their use.
The most apparent use of embryonic stem cells is to test chemicals and drugs that may have a medical use. It is hard to test experimental drugs on humans, because side effects are unknown and testing can take years. Testing drugs on animals often yields insubstantial results, along with a clash of moral issues. But stem cells can be grown into the specific tissue on which the chemical needs to be tested, cutting time and eliminating use of and risk to test subjects.
A more advanced use of embryonic stem cells could be to grow tissues and organs to replace those that are damaged or diseased. Tissues such as bone marrow, neural tissue and muscle could be grown to help cure diFseases such as Parkinson's or juvenile onset diabetes. New tissues could also be injected into failing organs to induce new growth.
In 1998, when James Thomson, assistant professor at the Primate Research Center, first saw the power of his finding, he focused on this issue.
'Although a great deal of basic research needs to be done before these cells can lead to human therapies,' Thomson said in a statement at the time. 'I believe that, in the long run, they will revolutionize many aspects of transplantation medicine.'
Another use of stem cells can be found by studying their differentiation into new tissues. This could unlock secrets of human development that are otherwise difficult to observe. Normally, scientists have to observe tissue
development in a living organism, or kill the organism to observe specific stages of development. With embryonic stem cells, individual tissue development can be created an indefinite number of times without the presence of an organism, allowing far more opportunity for observation.F
A UW-Madison team of scientists led by Thomson succeeded in isolating embryonic stem cells in 1995, but those stem cells were from a nonhuman primate.
Three years later, in 1998, Thomson and his colleagues were able to isolate the first human embryonic stem cells, but to do so they had to use fertilized human embryos that had grown for a week. At that point the stem cells are completely undifferentiated and ready for harvest. Once the stem cells are isolated, the embryos are disposed of. This is where the controversy lies.
The utility of embryonic stem cells is still in the stage of discovery, but despite their promising future, the cells have drawn fire on moral and religious grounds, and the source of the controversy lies in the way in which the cells are obtained from the embryo.
The UW Institutional Review Board approved the actions taken in Madison, after carefully considering the ethics behind stem- cell isolation. But those who oppose embryonic stem-cell use claim it is fundamentally wrong to kill a week-old embryo. With organizations like the Conference of Catholic Bishops and right-to-life groups, killing any embryo equates with abortion.
As an alternative, some suggest using adult stem cells, but these are more difficult to obtain and use. Some important tissues in the body maintain stem cells into adulthood, but these stem cells are specific to their tissue, so nerve stem cells can only form nerves, and muscle stem cells can only form muscle. This, combined with the fact that these cells have to be harvested from a fully developed human, could make the adult stem cells impractical compared to embryonic stem cells.
Despite the controversy, a majority of Americans support embryonic stem-cell research, according to an ABC News poll. While 39 percent of respondents oppose any research, 54 percent support research and the creation of more cells for research.
Their usefulness is as-of-yet unknown, but embryonic stem- cell research will continue to run into opposition. As the public becomes more informed of the facts of stem cells, their future will be more certain.
Thomson's lab continues to work with its five stem-cell lines now eligible for federal research dollars, and continues to pave the way for stem-cell research worldwide from right here in Madison.
