The ethics of stem cells
Stem cells have been used in medicine for many years - bone marrow transplantation is a form of stem cell therapy. Ethical concerns have focused mainly on the use of embryonic stem cells in research and their possible application in medicine.
A core issue has been the source of embryonic stem cells. Until recently, these were obtained from embryos that were by-products of assisted fertilisation attempts; these could be voluntarily donated for use in research.
More recently, UK law was changed to allow researchers to create human embryos for use in research, so that embryonic stem cells could be extracted. The key difference here was that new human embryos were being created specifically for research. Some commentators argued that this contravened the principle that human life should never be created as a means to an end. However, embryos created for research cannot by law be implanted in the womb, so never give rise to new individuals.
A key ethical concept is the moral status of the embryo. The consensus, enshrined in the Human Fertilisation and Embryology Act in 1990, is that the embryo does have moral rights but not to the same extent as a living person. The interpretation is challenged by some groups, including the Catholic Church, which holds that new life begins at the point of conception and hence a fetus at any stage of development should hold full human rights. Others, including some other faiths, consider that the status of a fetus changes as it develops, for example as its nervous system appears.
The rights of a fetus at any a particular stage are balanced against the potentially large benefits that others may gain from research and, ultimately, stem cell-based treatments. This line of reasoning has led some to argue that use of embryonic stem cells is not justified, because alternatives are available, such as adult stem cells or, more recently, induced pluripotent stem cells. Most scientists counter that research on embryonic stem cells is still needed to clarify fundamental biological mechanisms and because it is not yet clear which types of stem cell will prove the best bet therapeutically. Use of pre-14-day embryos, still little more than a ball of cells, would therefore remain justified.
Image: Human embryonic stem cells; Annie Cavanagh, Wellcome Images
References
Daley GQ et al. Ethics. The ISSCR guidelines for human embryonic stem cell research. Science. 2007 Feb 2;315(5812):603-4. PMID: 17272706
