In the minds of many people the word cloning generally conjures up pictures of identical human beings, created without using normal reproductive processes. However cloning is more complex than this popular understanding.
The term cloning can be applied to the copying of pieces of DNA, forms of asexual reproduction in plants, the development of a line of cells or tissue from a single cell, sub-dividing an embryo in the early stages of development to form two embryos, as well as to the cell nuclear replaceient technique used to create the first cloned sheep, Dolly.
The Cloning Process
The cloning of mammalian embryos, such as those of sheep, is carried out by cell nuclear replacement, using a donor egg and a body (somatic) cell from the animal to be cloned. The nucleus containing the genetic material is removed from the donor egg, and replaced with the nucleus from the cell of the animal to be cloned. This creates a cloned embryo with which is then stimulated to begin dividing.
Human cloning can be carried out in the same way, using two slightly different methods. In the first, a donor human egg is used, and its nucleus is replaced with the nucleus of a cell from the person to be cloned. A second method involves using an existing embryo (usually a spare embryo from infertility treatment) instead of a donor egg. The nucleus of the embryo is removed and replaced with the nucleus of a cell from the person being cloned. Both techniques create an embryo with nuclear genetic material identical to that of the person being cloned.
The cloning of mammals has shown that there is a high failure rate in the use of these cloning technologies, and where a cloned animal is brought to birth there are many serious problems with deformities and short life spans. The question of what age the cloned animal is at birth remains to be answered, as potentially its cells may be the age of the animal which was cloned. The cloning of other mammals has clearly shown that, apart from the very serious ethical issues posed by human cloning, there are major problems with the safety of the process when it is used as a means of reproduction.
Reproductive and Therapeutic Cloning
With the development of stem cell research, the terms reproductive cloning and therapeutic cloning have emerged in relation to human cloning. Both processes involve the creation of a human embryo by cell nuclear replacement, using one of the methods described above. The purpose for which the cloned embryo has been created determines whether the cloning is described as reproductive or therapeutic. If the embryo is placed in the uterus of a woman and implants, it may potentially become a foetus and then a child. This is referred to as reproductive cloning, or cloning for reproductive purposes. Many countries have legislation which bans cloning for this purpose, and there is widespread opposition to it among scientists and the general public.
In therapeutic cloning the cloned embryo is allowed to grow into a ball of cells, but is not placed in the uterus of a woman. The embryo is used instead as a source of stem cells. Stem cells found in embryos are not specialized to form particular types of tissue, such as muscle or nerve tissue. They can be influenced to grow into tissues to replace damaged or diseased tissue, for example, in people with conditions such as Parkinson's disease and Alzheimer's disease, or in patients suffering from burns. Because the stem cells giving rise to the new tissue can come from a cloned embryo with the same genetic makeup as the patient, scientists expect that the problems of rejection usually associated with introducing new tissue into the body will not occur. Because the removal of stem cells results in the destruction of the embryo, there are serious ethical problems associated with the use of embryonic stem cells.
Stem cell technology offers startling new possibilities in medical treatment, which is why the use of cloning in obtaining stem cells is often described as therapeutic cloning. However the cloning process is the same in reproductive and therapeutic cloning, in both cases resulting in the creation of a human embryo with a genetic makeup identical to that of another person. In reproductive cloning the embryo would be allowed to develop into a child, whereas in therapeutic cloning the embryo is destroyed by the removal of stem cells. The use of the term therapeutic cloning is particularly inappropriate in these circumstances.
Catholic perspectives on Cloning
Catholic teaching opposes reproductive cloning for a number of reasons. It offends against the personal and unique identity given to each individual by God. It denies an individual the right to have two parents, and confuses family relationships. There are also serious questions concerning our right to so fundamentally alter the manner in which we come into existence, and the effects these actions could have on future generations and on individuals produced by cloning.
The Catholic Church is not alone in opposing cloning for reproductive purposes. In 1997 the European Parliament passed a resolution on cloning which stated:
"the cloning of human beings, whether experimentally, in the context of fertility treatment, pre-implantation diagnosis, tissue transplantation or for any other purposes whatsoever cannot under any circumstances be justified or tolerated by any society, because it is a serious violation of human rights, and contrary to the principle of equality of human beings as it permits a eugenic and racist selection of the human race, it offends against human dignity, and it requires experimentation on humans"
(European Parliament; Resolution on Cloning 12 March 1997)
In therapeutic cloning the same moral objections exist as in reproductive cloning, but there are also serious issues associated with the destruction of an embryo in the process of cloning, or by the removal of stem cells. If the cloned embryo is created by using an already existing embryo, two embryos are destroyed.
From the moment of its creation the living human embryo is human life with an individual identity. At conception it begins its own continuous development, and cannot be considered at any point to be merely a simple mass of cells. The embryo has its own right to life, which cannot be sacrificed even for the good end of therapeutic benefit to other persons. The end does not justify the means.
New Zealand legislation is being prepared which will cover all aspects of cloning. In its proposed form one of the possibilities being considered would allow cloning for therapeutic purposes but ban cloning for reproductive purposes, as has been done in the United Kingdom. The UK legislation allows human embryos to be created by cloning, but forbids their implantation in the uterus of a woman, and requires their destruction if they are used in stem cell research. In fact, legislation which follows this approach is not legislation against cloning, but against allowing cloned human beings to survive. This has been highlighted by The Pontifical Academy for Life in Reflections on Cloning:
A prohibition on cloning which would be limited to preventing the birth of a cloned child, but which would still permit the cloning of an embryo-foetus, would involve experimentation on embryos and foetuses and would require their suppression before birth a cruel, exploitative way of treating human beings.
The Pontifical Academy for Life writers also point out that a cloned embryo is human life, and that destroying it is an immoral act. Creating human embryos to be of use to other human beings, and enacting legislation which requires the destruction of human life are matters which would raise serious questions about our values as a society.