Embryonic Stem Cells
Embryonic Stem Cells
EMBRYONIC STEM CELLS
In 1998 a team of researchers reported that they had isolated and removed stem cells from the inner cell mass of human embryos that had been donated by couples undergoing fertility treatment (Thomson et al. 1998). The embryos had divided for several days to reach the blastocyst stage of approximately 100 cells. At this stage embryos have a hollow sphere in the middle, an outer layer of cells committed to forming the placenta and other cell lines, and a mass of undifferentiated cells pushed to one side (inner cell mass). The cells in the inner mass have, for a short time, the capacity to develop into all cells in the human body, and are known as embryonic stem (ES) cells. The researchers' announcement that they had isolated ES cells in human embryos generated considerable interest because it suggested that the cells could be removed, cultured, and coaxed to differentiate for use in medical therapy. Among other things, it was thought that large supplies of specialized cells could be widely available and used to replace cells destroyed by Parkinson's disease, Alzheimer's disease, neural cord injuries, and other diseases and conditions. The announcement also generated controversy because the act of removing ES cells destroys the embryo. In the years since, research has been limited to pre-clinical studies. Numerous safety issues must be addressed before clinical trials ethically can be conducted.
Of the many ethical issue raised by ES cell research, four are described here. First what is the moral status of human embryos? Some individuals argue that embryos have the same moral status as persons, which means it would be purposefully unethical to destroy embryos for any reason. Others argue that embryos are potential human beings that do not share the same rights as children and adults. For them, the destruction of embryos may be warranted under certain circumstances.
Second, independent of the particular moral status of human embryos, will ES cell research contribute to a mindset that treats embryos as commodities? Some express concern that using embryos for medical purposes will turn embryos into merchandise and diminish the dignity of humans in the process. Others counter that strict rules overseeing ES cell research protect human dignity while respecting the interests of patients who need therapies
Third, are ES cells necessary for medical therapies? Proponents of ES cell research claim that ES cells are versatile and easy to work with, and that they raise significant hope for effective medical therapies. Opponents claim that adult stem cells, found in human tissues and not requiring the destruction of human embryos, also hold the potential for medical therapies and provide a viable alternative form of research.
Fourth, what impact does the source of the embryos have on the ethics of ES cell research? The embryos used by James Thomson and his colleagues were donated for research by couples who were patients at in vitro fertilization (IVF) programs and who no longer needed stored embryos for their conception efforts. Arguably these embryos were created for an ethical purpose (reproduction) but were not needed; therefore it would be appropriate to secure some good from them before their inevitable destruction. It has also been advocated that embryos may need to be created solely for ES cell removal in order to secure a sufficient number of healthy and genetically diverse embryos to meet research and therapeutic needs. Critics, however, contend that this would be less ethical than using donated embryos, because the embryos would be created with the intention of destroying them. Still another possible source of ES cells is from the creation of embryos through a cloning technique (somatic cell nuclear transfer), in which the intended patient's nucleus would be used to create an embryo for deriving genetically compatible ES cells. Creating cells specifically for a patient would presumably eliminate the need for anti-rejection drugs. Critics, however, argue that therapeutic cloning would tempt individuals to use the embryos for reproduction rather than therapy.
Policy issues for human ES cell research have revolved around whether governments should fund studies involving ES cells. The issue became volatile immediately after the announced isolation of human ES cells in 1998. In the United States, the U.S. Congress held hearings on the question, numerous interest groups lobbied both for and against funding, and policy advisory bodies convened to make recommendations (Bonnicksen 2002). For example, the National Bioethics Advisory Commission concluded it would be ethical to fund the removal and use of ES cells from donated embryos (National Bioethics Advisory Commission 1999). A working group convened by the National Institutes of Health (NIH), however, concluded it was appropriate to fund only the use of ES cells (National Institutes of Health 1999). The removal of cells (and hence destruction of the embryo) would have to be funded privately. Both groups agreed the government should not fund research creating embryos solely for ES cell removal.
Following intense lobbying by, among others, right-to-life groups opposed to federal funding and scientific associations and patient advocacy groups supporting funding, President George W. Bush announced a limited compromise position on August 9, 2001 (Vogel 2001). Under the new policy, the federal government would consider funding a narrow range of proposals in which (a) ES cells had been removed with private funds prior to the date and time of Bush's speech, and (b) the embryos were donated with informed consent by couples in IVF programs. At the time it was thought approximately sixty ES cell lines worldwide met these conditions. Within a couple of years, however, it became clear that fewer than fifteen cell lines were available for research.
Opponents argue that the government should not fund research that many people regard as immoral. Advocates argue that governmental funding is necessary for the potential of this research to succeed and for new therapies to become available to help persons with presently untreatable illnesses. Funding also has the benefit of opening the door to federal oversight of the research. Assuming ES cell research lives up to its potential, more studies will be conducted in the future and new cell lines will be needed to meet the standards required for clinical tests of medical therapies. If funding remains strictly limited, research will be conducted with private sector funding outside the public eye. Inasmuch as ES cell issues generate intense discourse, it is ironic that ES cell research will proceed without the public scrutiny that comes with significant federal funding.
Debates over the ethics of cell research are ongoing in nations worldwide. For example, in Europe differences among nations have precluded funding for ES cell research by the European Union (Vogel 2003). Research is proceeding in individual nations with accommodating governmental policy, such as the United Kingdom where, among other things, a UK stem cell bank has been set up with government backing (nibsc.ac.uk/divisions/dbi/stemcell.html).
ANDREA L. BONNICKSEN
Bonnicksen, Andrea L. (2002). Crafting a Cloning Policy: From Dolly to Stem Cells. Washington, DC: Georgetown University Press.
Jones, Howard W., Jr., and Jean Cohen. (2004). "IFFS Surveillance 04." Fertility and Sterility 81(Supp. 4): S1–S54.
National Bioethics Advisory Commission. (1999). Ethical Issues in Human Stem Cell Research: Report and Recommendationsof the National Bioethics Advisory Commission. Rockville, MD: National Bioethics Advisory Commission.
National Institutes of Health. (1999). "Draft National Institutes of Health Guidelines for Research Involving Human Pluripotent Stem Cells." Federal Register 64(231): 67576–67579.
Ruse, Michael, and Christopher A. Pynes, eds. (2003). The Stem Cell Controversy: Debating the Issues. Amherst, NY: Prometheus Books.
Thomson, James A.; Joseph Itskovitz-Eldor; Sander S Shapiro; et al. (1998). "Embryonic Stem Cell Lines Derived from Human Blastocysts." Science 282: 1145–1147.
Vogel, Gretchen. (2001). "Bush Squeezes Between the Lines on Stem Cells." Science 293: 1242–1245.
Vogel, Gretchen. (2003). "E.U. Stem Cell Debate Ends in a Draw." Science 302: 1872–1873.