Stem Cells: The Ethical Debate
Inside the cell is a compartment called the nucleus. This contains the genetic information which determines who we are, what we look like and how we grow.
Stem cells are unspecialised cells at an early stage of development, which have not yet differentiated into any specific type of tissue. Stem cells are found in embryos, some types of adult tissue (e.g. bone marrow), the umbilical cord and foetal tissue. Stem cells can be influenced to turn into specific types of tissue, and used to treat patients whose tissue is diseased or damaged. Examples of their potential use include the treatment of diseased nerve tissue in patients with Parkinson's disease, strokes, or Alzheimer's disease; the treatment of damaged skin tissue in people with burns, and the treatment of blood tissue in cancer victims. In theory stem cells could be induced to grow into a replacement organ, but this is at best a very long term prospect.
Scientists consider that stem cells can be derived from a number of sources:
· From early embryos (blastocysts) created by IVF, or created specifically for research using donated eggs and sperm.
· From early embryos created by inserting the nucleus from an adult cell into an egg with its nucleus removed (cell nuclear replacement, or cloning).
· From the tissues of an aborted foetus.
· From the blood cells of the umbilical cord at the time of birth.
· From some adult tissues eg bone marrow.
· From mature adult body cells re-programmed to behave like stem cells.
Stem cells derived from early embryos have the greatest potential to develop into most types of tissue. Stem cells from other sources are more limited in this potential. Research indicates that it may be possible to re-programme adult cells to behave like stem cells, but there is a lot of work yet to be done to understand this mechanism.
Embryos created by cell nuclear replacement (cloning)
In this technique the nucleus is removed from an unfertilised egg belonging to the patient or a donor. The nucleus from an adult cell of the patient or donor is put into the "empty" egg, thus creating an embryo. If implanted in the uterus of a woman this embryo would potentially develop in the normal manner, as a child with the same genetic makeup as the person who supplied the nucleus, which was put into the egg.
For research purposes, an embryo created in this manner is allowed to develop into a ball of cells called a blastocyst. At this stage stem cells are removed from it, which destroys the embryo. This method of obtaining stem cells is attractive because using a nucleus from one of the patient's cells means the embryo will have the same genetic make-up as the patient. The use of stem cells from such an embryo avoids their rejection by the patient's immune system.
The International Perspective
On 16 August 2000 a British Expert Advisory Group considering new areas of research using human embryos, reported to the British Government. Key recommendations of the Group's report, entitled "Stem Cell Research: Medical Progress with Responsibility", include:
· Research using human embryos (whether created by in vitro fertilisation or by cell nuclear replacement), to increase understanding about human disease and disorders and their cell-based treatments, should be permitted.
· Individuals whose eggs or sperm are used to create embryos to be used in research must give specific consent for that use.
· The mixing of human adult cells with the live eggs of any animal species should not be permitted.
· The transfer of an embryo created by cell nuclear replacement (cloning) into the uterus of a woman (called "reproductive cloning") should remain a criminal offence.
· An appropriate body should be established to monitor the research involving stem cells derived from embryonic sources.
The British Government has accepted the Advisory Group's recommendations in full, and intends bringing forward legislation to implement them.
In the United States Congress is facing pressure from the National Institutes of Health and the National Bioethics Advisory Committee to lift the ban on human embryo research. Similar pressures are being applied in Japan and Australia.
In late July the Australasian Health Ministers met in Wellington, where they announced they would ban cloning humans for reproduction but might allow cloning human embryos as a source of cells for tissue repair and research. Two bills on assisted human reproduction are before the Health Select Committee, and both contain clauses prohibiting cloning. However developments in the UK highlight the inadequacy of the clauses in both bills, which simply prohibit "cloning".
Research into animal cloning in New Zealand is advanced. There appears to be little research or activity involving human embryos. Any proposed research into germ-line therapy, including reproductive or therapeutic cloning, must be reviewed by GTAC (the Gene Technology Advisory Committee, which is a committee of the Health Research Council). Currently GTAC will not approve any research on human cloning.
The use of cell nuclear replacement technology to create human embryos has been described as "therapeutic cloning", or "non-reproductive cloning", because it is being investigated for use in the treatment of illnesses, rather than for the production of new individuals. The use of the term "therapeutic cloning" disguises the fact that this form of cloning results in an embryo, which is then destroyed when stem cells are removed.
The Pontifical Academy for Life has identified the following ethical issues in relation to the creation and use of embryos for stem cell research or therapeutic use:
· It is not morally licit to create or use living human embryos for stem cell research because:
The living embryo is from the moment of conception a human subject with a well-defined identity, which from this moment begins its own coordinated, continuous and gradual development, such that at no later stage can it be considered as a simple mass of cells.
The embryo has a right to its own life, and therefore every intervention which is not in favour of the embryo violates that right.
No end believed to be good, such as therapeutic uses of stem cells, can justify an intervention of this kind. A good end does not make right an action which is in itself wrong.
The rights of the person must be recognised from the moment of conception, with the first of those inviolable rights being the right to life.
· For the same reasons it is not morally licit to engage in "therapeutic cloning" by producing cloned human embryos and then destroying them in order to produce stem cells.
· It is not morally licit to use stem cells from embryos, and the cells obtained from them, which are supplied by other researchers or are commercially obtainable.
As Pope John Paul II noted in a recent address to the International Congress of the Transplantation Society: "methods that fail to respect the dignity and value of the person must always be avoided...attempts at human cloning, in so far as they involve the manipulation and destruction of human embryos are not morally acceptable, even where their proposed goal is good in itself."
The lifting of the ban on the creation of embryos is particularly inappropriate when there is evidence cited by the Expert Advisory Group itself that "in the long term the scientific view is that it will be possible to re-programme adult cells to make them behave like stem cells with the full potential of embryonic stem cells, but without the morally more contestable need to create an embryo". However the Expert Advisory Group believes that "the potential benefit of discovering the mechanism for re-programming adult cells, and thereby providing compatible tissue for treatment, justifies this transitional research involving the creation of embryos by cell nuclear replacement."
The re-programming of adult cells to make them behave like stem cells may be a longer route to the therapeutic use of stem cells, but it avoids the serious moral issues surrounding the use of an embryo. In the same address quoted above, Pope John Paul II spoke in favour of this latter method: "Science itself points to other forms of therapeutic intervention which would not involve cloning or the use of embryonic cells but rather would make use of stem cells taken from adults. This is the direction that research must follow if it wishes to respect the dignity of each and every human being, even at the embryonic stage."
The Pontifical Academy for Life, in its "Declaration on the Production and the Scientific and Therapeutic Use of the Human Embryonic Stem Cells" speaks similarly:
"The possibility, now confirmed, of using adult stem cells to attain the same goals as would be sought with embryonic stem cells – even if many further steps in both areas are necessary before clear and conclusive results are obtained – indicates that adult stem cells represent a more reasonable and human method for making correct and sound progress in this new field of research and in the therapeutic applications which it promises. These applications are undoubtedly a source of great hope for a significant number of suffering people."
However the capabilities of adult cells re-programmed to behave as stem cells will be critical in determining further ethical issues. If these cells are only capable of producing multiple cell types then they are not equivalent to an embryo, and there are no problems with using them in the manner suggested by the Pontifical Council. However if they are capable of giving rise to a coherent organism, then adult cells re-programmed to behave as stem cells could be considered equivalent to an embryo, which will raise further ethical questions.
Pope John Paul II, "Address to the 18th International Congress of the Transplantation Society". 29 August 2000.
Pontifical Academy for Life, "Declaration on the Production and the Scientific and Therapeutic Use of Human Embryonic Stem cells". 25 August 2000.
Pontifical Academy for Life, "Notes on Cloning". August 1998.
Pontifical Academy for Life, "Reflections on Cloning". September 1997.
Chief Medical Officer's Expert Advisory Group Report to British Government, "Stem Cell Research: Medical Progress with Responsibility". Dept of Health (UK), August 2000.
"Government Response to the Recommendations made in the Chief Medical Officer's Expert Group Report". Dept of Health (UK), August 2000.
Nuffield Council on Bioethics, "Stem Cell Therapy: The Ethical Issues". April 2000.
Anne Dickinson is Director of Caritas Aotearoa New Zealand and Acting Convenor of IBAC – the Independent Biotechnology Advisory Council.
Rev Michael McCabe, PhD is Director of the Nathaniel Centre.