Under the Microscope/Prof William Reville: I recently explained my opposition to harvesting stem cells from human embryos because I believe our duty of care towards embryos enjoins us not to deliberately kill them. I also oppose harvesting stem cells for biomedical research from legally aborted human foetuses.
Embryonic and foetal stem cell research has the potential to discover cures for various human illnesses. The question then arises as to what one's attitude should be towards useful knowledge that results from such research. I believe it is ethically consistent to oppose the deliberate killing of human embryos and foetuses and to also avail of some, but not all, of the treatments and cures for human illnesses obtained through research on these cells.
Human life begins at conception when the mother's egg is fertilised by the father's sperm. The fertilised egg divides in two, these two daughter cells also divide and this process of cell division and differentiation continues for 9 months, through the birth of the baby, and thereafter until the entire process culminates in death. The product of conception is called an embryo up to the end of the second month of pregnancy, and until birth it is called a foetus.
Stem cells are undifferentiated cells that have the capacity to develop into any of the differentiated cell types that make up our individual tissues such as muscle, liver, skin, etc. Stem cells to be used for research can be harvested from the embryo - usually "spare" embryos from IVF procedures - on about the fourth day of its development. This act unfortunately kills the embryo. Stem cells can also be harvested from the aborted foetus, from umbilical cord blood and from various adult tissues. The two latter stem cell types are less flexible than embryonic or foetal stem cells but, in principle, they could yield the same useful knowledge and their use poses no ethical problems.
Research on embryonic and foetal stem cells is carried out in several countries. Stem cell research appears to offer great potential but is still in its infancy and only time will tell how useful it will be. Research on human stem cells can be carried out in 3 main ways. The primary focus is to develop ways to direct stem cells to differentiate into specific tissue cell types and thereby to act as a renewable source of replacement cells and tissues to treat diseases such as Parkinson's and Alzheimer's diseases, spinal cord injury, heart disease, diabetes, osteoarthritis, rheumatoid arthritis, strokes and burns. The cells used in this type of therapy would be directly descended from the original stem cells taken from the embryo or foetus.
Secondly, stem cells can be used to test new drugs. For example, if a new drug is targeted at the liver, stem cells would be directed to differentiate into liver cells in the laboratory and the drug would be tested on this human liver tissue. Thirdly, research on stem cells investigates how undifferentiated cells maintain their undifferentiated state and, then, how they are naturally instructed and enabled to undergo the process of differentiation. Such research could illuminate many of the complex events that occur during human development. Some very serious problems such as cancer and birth defects are caused by abnormal cell division and differentiation. Research on stem cells could show us how to prevent or reverse these conditions.
It seems to me that, if you oppose the deliberate killing of the embryo or the foetus, you could not approve or avail of cell-based therapies coming out of the first type of research on embryonic or foetal stem cells because the cells that would be used in treatment are direct descendants of the cells taken from the embryo or foetus. On the other hand, I believe that it would be acceptable to avail of useful knowledge that might arise from the other two types of research on embryonic or foetal stem cells.
I am against killing embryos and I oppose abortion except where the continuation of pregnancy endangers the life of the mother or in other medically necessary conditions. I am therefore prepared to forego the accelerated benefits that research using embryonic or foetal stem cells might bring.
However, if such research, in the limited areas I have described, is carried out elsewhere by people who do not share my views, and such work produces a cure for a disease, I would personally have no problem in using this knowledge to cure myself or others, despite the fact that, in my view, the knowledge was bought at too high a price. For example, if such research showed that drinking lemon juice every day prevented the contraction of cancer it would be foolish of me to avoid lemon juice. Knowledge in itself can be neutral even when the method of its unveiling is ethically tainted.
No ethical problems arise from harvesting and researching stem cells from umbilical cord blood or from human adult tissue. These stem cells may be more awkward to handle than embryonic or foetal stem cells, but they seem to offer the full potential of embryonic or foetal cells. More importantly, all therapies that result from work on umbilical cord and adult stem cells will be ethically acceptable to all, whereas many people will shun many of the therapies that might result from work on embryonic and foetal stem cells. Research should therefore concentrate on umbilical cord and adult human stem cells. William Reville is associate professor of
biochemistry and director of microscopy at University College Cork