Stem Cell Research in New Zealand
Issue 12, April 2004
A great deal of promise and excitement surrounds the new possibilities for health care heralded by increasing knowledge into the development of human cells. In New Zealand, Parliament is presently considering legislation on human assisted reproductive technology (HART Bill) that will impact directly on the sort of research able to be undertaken in this country.
In its proposed form, HART gives a Ministerial appointed Advisory Committee the scope to recommend to the Health Minister whether (or not) human stem cells might be sourced, for the purposes of research, from either surplus embryos (embryos left over from fertility treatments) or from embryos intentionally created expressly for such a use. In outlining the reasons for deciding whether or not to recommend such activities, the Bill draws attention to the potential benefits that the use of stem cells hold for the future of medical knowledge and care. Specifically, the Bill's current wording stipulates that the advisory committee must consider whether, and the extent to which, the activity is necessary or desirable for increasing scientific knowledge that, directly or indirectly, advances the prevention or treatment of human disease or disorder. (HART Bill, 2003, section 38)
This article will firstly outline the science of human stem cell research. It will then explore the ethical debate associated with the procuring of human stem cells with a view to explaining the controversy that exists regarding this exciting field of research. In particular it will offer a Catholic-Christian critique of the notion that the potential uses/benefits of human stem cell research, by itself, constitutes an adequate framework for regulating research in this area.
What are stem cells?
The human body contains trillions of cells. A collection of similar cells specialised for a particular purpose is called a tissue. For example, skin tissue is made of skin cells, muscle tissue is made up of muscle cells. Stem cells are unspecialised cells with a yet-to-be-determined future. They have not yet differentiated into particular tissue-specific cells. They possess an inherent ability to give rise to various types of more specialised cells, while at the same time retaining their ability to self-renew indefinitely. The product of a stem cell undergoing division is two cells, including at least one stem cell, that is, a cell which has the same capabilities as the original cell. (Ford and Herbert, 2003, p.12)
In theory stem cells can be influenced to turn into specific types of tissue, and used to treat patients whose tissue is diseased or damaged. Just a few examples of their potential use include the treatment of diseased nerve tissue in patients with Parkinson's disease, strokes, and Alzheimer's disease; damaged skin tissue in people with burns; blood tissue in cancer victims; insulin producing cells that could reverse diabetes; and formation of new retinal cells. In theory stem cells could be induced to grow into a replacement organ, but this is at best a very long-term prospect.
Stem cells may be classified according to their potency and according to their origins. The potency of a stem cell refers to its inherent ability to generate a variety of daughter cells. The greater a cell's ability to give rise to a range of specialised cells, the more potent is that stem cell. The fusion of sperm and egg marks the beginning of human life and results in a single cell that, in the case of a successful pregnancy, will eventually form a complete human being. Because all the cells of the new being will ultimately derive from this single cell, the cell is described as totipotent its potential is total, in other words. The single cell then goes through several cycles of cell division in the first few days of its development. These cells, being identical, are all totipotent since any of them, given the proper conditions, could develop into a fetus.
The first stage of cell differentiation occurs somewhere between four and seven days. At this point the human embryo has reached the blastocyst stage and resembles a hollow sphere with outer and inner cells. The outer cells will form the placenta while the cluster of inner cells will form the fetus. The inner cells are described as pluripotent stem cells since they can develop into any of the 200 different types of tissue found in the human body. The harvesting of these stem cells from the blastocyst, routine practice from a scientific perspective, inevitably destroys the embryo.
As development of the blastocyst continues, and approximately two weeks after fertilisation, the cells in the inner cell mass make decisions that result in a further degree of specialisation. The developing embryo now consists of three distinct layers of cells called germ-layer groups. Each germ-layer group is responsible for a particular pathway of development corresponding to different parts of the human body; either endoderm (internal organs), mesoderm (limbs and soft tissue), or ectoderm (skin, central and peripheral nervous system). Then, within each of these groups, the cells again make decisions to become stem cells for specific organs or tissue types. These cells are described as multipotent. While they have already undergone a degree of differentiation, they retain the potential to give rise to a limited number of different cell or tissue types associated with a particular organ or body function of the developing fetus. Hematopoietic or blood stem cells, for example, give rise to the various types of blood cells - red, white and platelets - in our body.
Multipotent stem cells are also the key to the ongoing replenishment of postnatal tissue cells in our bodies. Known as adult stem cells, they are found in various parts of the human body, including the peripheral blood. Other sources of multipotent stem cells are the human fetus and umbilical cord blood, i.e. fetal blood.
A further breakthrough in the last five years has been the discovery that embryonic germ cells from certain fetal tissue have the same pluripotent properties as embryonic stem cells. Prior to this it was considered that pluripotent cells, as described above, could only come from early stage embryos.
In countries permitting such research, researchers have largely relied on frozen embryos - surplus to the needs of couples on IVF programmes - as a source of pluripotent cells. An alternative source would be to create embryos by way of IVF specifically for the purpose of obtaining stem cells. Among other things this would give the option of using fresh rather than frozen and stored embryos.
A further method of producing embryos is through the process of Somatic Cell Nuclear Transfer. Used to create Dolly the cloned sheep, the method involves taking nuclear DNA from a cell and inserting it into either an embryo or an egg that has previously been stripped of its own nucleus. The resulting embryo is then induced to behave like a fertilised egg. For the purposes of embryonic research, development is stopped at the blastocyst stage and stem cells removed to develop new stem cell lines. In February of 2004 a South Korean team reported successfully getting 30 cloned human embryos to the blastocyst stage, a world first.
This method of obtaining stem cells is generally referred to as Therapeutic Cloning because of their use in the treatment of illnesses. It is distinguished from Reproductive Cloning which is defined as the creation of embryos for the express purpose of implantation and bringing to birth. Therapeutic cloning is attractive to researchers for at least two key reasons. Firstly stem cells obtained this way would have the same nuclear genetic makeup as the patient, thus avoiding problems of rejection by the patient's immune system. Secondly, the embryo at its earliest stages has not yet developed the markers or signatures that identify tissue as coming from a particular individual. Therefore embryonic tissue is unlikely to provoke the same foreign tissue reactions as tissue from an adult individual. 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 desire to understand and mimic the development of stem cells into a variety of tissues and even whole organs - as happens naturally in the development from embryo to fetus - has created a forceful imperative for research. Because multipotent stem cells are, by definition, more restricted in their ability to differentiate than the pluripotent or totipotent stem cells found in embryos, many researchers have regarded embryos as the more promising source of stem cells. That has resulted in considerable pressure being put on governments around the world, and now in New Zealand, to make human embryos available for such research in the name of huge health benefits for humankind. Thus the New Zealand Herald (16 February 2004) reports: New Zealand researchers want the right to destroy human embryos in order to grow stem cells that might one day provide cures for conditions such as Parkinson's disease. The fact that embryonic stem cell harvesting results in the destruction of the embryo poses one of the major ethical issues surrounding stem cell research.
It does not follow that persons who are in favour of destructive research on human embryos have no respect for its dignity. They may in fact have a considerable degree of respect for pre-nascent human life. Rather, they employ a particular philosophical approach to determining what is ethical. This approach, a consequentialist one, involves a balancing strategy. Respect for the embryo can be outweighed by factors outside or extrinsic to the embryo, nominally the usefulness (or utility) of the outcome of the research, in this case the promise of new therapies for serious diseases. The consequences of the research in conjunction with the intention of the researchers carry the burden of moral weight in their calculation of what is right. For such persons, embryos are not intrinsically valuable their right to life is non-absolute.
The Catholic-Christian perspective, in contrast, grounded in an alternative philosophical position, holds that the living embryo is, from the moment of fertilisation, a human being with an absolute right to life. Every intervention not in favour of the embryo violates its right to life. This claim rests on the notion that human dignity derives ultimately from God as giver of life and is, of its nature, intrinsic. The dignity of an embryo remains, in other words, unaffected by factors extrinsic to itself, including intention and consequences. It is not acceptable to deliberately sacrifice the life of any human being, even if this is done in order to relieve the health problems of other human beings. (World Federation of Catholic Medical Associations, 2004) Research on embryos is only moral if it is designed to protect the life and health of the specific embryo being treated. Some have advanced the argument that it is acceptable to use spare embryos left over from treatments for infertility 'because they are going to die anyway'. This is equally immoral from a Catholic perspective because it confers a second class status on these embryos and once again ignores the intrinsic value each human life has by its very nature.
Recent significant breakthroughs in research which point to multipotent (adult) stem cells being able to change their developmental fate have added a new dimension to the ethical debate surrounding stem cell research. The three distinctive germ-layer groups (see above) have traditionally been thought of as organised hierarchical systems within which cell differentiation was restricted to its organ or tissue-specific pathway. However, a number of researchers have highlighted evidence that, while not yet conclusive, suggests multipotent stem cells retain a previously unrecognised degree of developmental plasticity that allows them to differentiate across boundaries of lineage, tissue and germ layer. [Therefore] the hierarchical view no longer seems correct. (Korbling & Estrov p. 570) A number of studies have indicated that bone marrow cells, for example, can contribute to liver, skin, lung, and gut tissue.
Why is this an important issue? If the broader developmental potential of adult stem cells can be proven it would be, in Ford and Herbert's words, enormously significant: it would imply that tissue-specific adult stem cells harbour much, if not all, of the potential of embryonic stem cells. This would render the technique of deriving [pluripotent or totipotent] stem cells from embryos obsolete, thus overcoming many of the political and ethical barriers to human embryonic stem cell therapy. (2003, p. 21) This line of reasoning features prominently in the rhetoric of those who are opposed to research on embryos. Consequently, an intense debate about the merits of adult vs. embryonic stem cell research has developed. This debate has been variously described as manipulating the promise of adult stem cell research (Parker, 2003, p.10) and as surrounding studies on adult stem cells with silence (World Federation of Catholic Medical Associations, 2004) .
Recent findings certainly make it more difficult to argue that we need to continue with embryonic stem cell research. In the words of Tobin and Gleeson (2002): [w]hen we say that we 'need' to do something, we mean (at least) that the doing of that thing is required in order to achieve some purpose. However, it is not obvious that experimentation on embryos is required for any therapeutic purpose. Noting that current therapeutic successes all involve adult stem cells they further add that any therapeutic benefits directly obtainable from embryonic cells are a long way off [Therefore] there is no reason to think that not allowing experimentation on human embryos will delay the development of therapies in any significant way. (p.4)
Yet, despite such insistence, there are counter claims that the ability to derive cells from cloned embryos would have several potential benefits that cannot be obtained in any other way. (Bioscience News & Advocate, 2004) Even Tobin and Gleeson (2002, p.4) do not rule out that experiments on embryos have the potential to provide us with theoretical knowledge. Consequently, the most honest conclusion at this point in time is that the ethical controversies surrounding embryonic research cannot be definitively resolved by way of comparisons between the two types of research.
Then again, neither should we seek to resolve it by way of comparison. If for no other reason, it might appear (from a Catholic-Christian perspective) that we are accepting the major premise of those who promote embryonic stem cell research; i.e. the idea that outcome or consequences are a sufficient determinant for resolving the ethical desirability of this research. As Parker (2003) bluntly puts it: One wonders why, if research using embryonic stem cells is clearly wrong, there is any need to argue for, or even mention its scientific inferiority. (p.12) From a Catholic-Christian perspective, more fundamental reasons exist for resisting such research, as already noted.
Focusing on the potential (and mostly yet to be proven) therapeutic outcomes as providing the justification for embryonic stem cell research effectively wraps a cloak of humanitarianism around a philosophy of pragmatism and utilitarianism while disguising its fundamental premises. But human life and human nature are too complex to be adequately evaluated from a single narrow perspective. A more philosophically robust and broader approach recognises that an exclusive appeal to future health benefits obscures or ignores other fundamental ethical issues that are vitally important; in particular questions regarding human dignity, the current remoteness of benefits from ES cells, and profound repercussions for society. These repercussions include the further commodification of human life and the fact that any experimental cloning will help facilitate the eventuality of human reproductive cloning simply by refining the procedure.
Put most simply, the Catholic-Christian approach rests on the idea that a good end does not make right an action that is in itself wrong. This translates into the working notion that some techniques may be better left on the shelf, regardless of the touted benefits. (Ford and Herbert, 2003 p.67)
As noted above, New Zealand Parliament is presently considering legislation (HART Bill) that will regulate the type of embryo research able to be undertaken in this country. This legislation will eventually fall into one of four possible positions:
- The prohibition of all embryo research
- Research confined to the use of embryonic stem cells already in existence and extracted prior to a specified date
- The use and ongoing isolation of embryonic stem cells from surplus IVF embryos
- The creation of embryos specifically for research
Overseas, a number of countries have legislated to prohibit the future harvesting of embryonic stem cells. This move, which limits research to the use of stem-cell lines already in existence - position b) above -, recognises that embryonic research involves a degree of wrongdoing. While researchers generally regard it as a compromise solution because the use of existing cell lines has a number of drawbacks from a scientific perspective, it still appeals for a number of reasons. It offers protection to human embryos, something which positions c) and d) do not, while still allowing some research on embryonic stem cells.
The legislation around stem cell research in New Zealand needs to take shape out of a debate which is robust and honest. It will be robust in as much as it allows the broader issues and questions to be canvassed. It will be honest to the extent it strips away the ethical camouflage that disguises a simplistic and narrow appeal to potential benefits, as if consideration of benefits alone provides a sufficiently robust ethical framework.
Stem cell research holds very real promise for the prevention and treatment of serious diseases. However, legislation in New Zealand needs to take sufficient account of the moral harm associated with the destruction of human embryos, including its repercussions for the way we look at all human life. From a Catholic-Christian perspective, the absolute dignity of human life means that no outcome, no matter how noble, can justify the destruction or harming of embryos. Other promising and more ethically acceptable alternatives exist and we have a moral obligation to pursue the more ethically acceptable alternatives.
Ban reproductive cloning, successful cloners say. (2004, February 19) BioScience News & Advocate. Retrieved February 19, 2004.
Ford, N.M., & Herbert, H. (2003). Stem Cells. Strathfield, NSW: St Pauls Publication.
Stem cell scientists call for more relaxed rules. (2004, February 16) New Zealand Herald.
Korbling, M., & Estrov, Z. Adult stem cells for tissue repair a new therapeutic concept? The New England Journal of Medicine 349(6), 570-82.
Parker, M. (2003). Reasoning about embryos, cloning and stem cells: Let's get more clear and distinct. Monash Bioethics Review, 22(1), 8-17.
Tobin, B., Gleeson, G. The embryo stem cell debate. Bioethics Outlook, 13(4), 1-4.
World Federation of Catholic Medical Associations. (2004, 19 February) Human embryo cloning by Korean scientists. Press Release.
John Kleinsman teaches Moral Theology at the Wellington Catholic Education Centre and is also a part time researcher for The Nathaniel Centre.