Therapeutic Cloning

Article Reference: Nucleus, April 2001, pp8-11; Author: Peter Saunders

CMF General Secretary, Peter Saunders, brings us up to date on latest developments in the furore over therapeutic cloning, and explains why he remains opposed to the idea.

The cloning of human embryos for research is now legal in the UK. New regulations under the 1990 Human Fertilisation and Embryology Act will allow scientists to clone human embryos to produce stem cells for use in treating degenerative diseases. The legislation was passed by a 366-174 majority in the House of Commons in December, and by a 212-92 vote in the House of Lords on 22 January. Although a committee is to be set up later to look further at the issues, Parliament have effectively rubber-stamped the recommendations in the Chief Medical Officer's 'Donaldson Report' tabled last summer. The new law makes the UK the first country formally to legalise the practice.[1]

The decision followed tough opposition from a powerful alliance of pro-life campaigners and religious leaders. The European Parliament also had earlier called on the British government to shelve its plans and leaders of several other European countries had expressed disapproval. I wrote to both Commons MPs and Peers in December and January and CMF members addressed meetings at Parliament as well as speaking against the move on the media.

The implementation of the new law has meanwhile been delayed through an appeal by the Prolife Alliance who believe that the Parliamentary votes are invalid because cloned embryos do not fit the definition of 'embryo' as defined in the HFE Act (ie. requiring fertilisation). The hearing has been delayed until June (after the election), so an embargo on research will meanwhile remain.[2]

So what is therapeutic cloning and why be opposed to it, especially given that the British Medical Association and the Royal Society of Medicine have supported it?

What is therapeutic cloning?

In serious degenerative diseases (such as Parkinson's, Alzheimer's and muscular dystrophy) the dream of researchers is that by replacing cells that have been lost, sufferers from such otherwise incurable disorders might be restored to health. Two approaches have been proposed. The first is to use cloned human embryos, genetically identical to the patient, made by fusing the patient's DNA with an egg emptied of its own DNA. These cloned embryos would then generate stem cells of the required type, which would not be destroyed by the patient's immune system, to repair the damaged organ. But this would result in the embryos being destroyed. The alternative is to use adult stem cells from the patient themselves.

Why be opposed to it?

I believe that the decision to legalise embryonic stem cell cloning at this time without primary legislation or lengthy debate was irresponsible and unnecessary for four reasons: Embryo stem cell cloning is unethical because it uses embryos as a means to an end, dangerous because it creates a slippery slope to reproductive cloning, misguided because the decision has been influenced by prestige and profit and unnecessary because there is a viable ethical alternative.

  1. Embryos as a means to an end
    I have dealt in detail with the status of the embryo from a Christian perspective in a previous Nucleus article.[3] The Judaeo-Christian ethic on which UK Statute Law was originally based affirms that human life at all stages of development deserves the utmost respect. Historical medical ethical codes based on the Hippocratic Oath enshrine a similar view, recognising the power and strength of doctors. The Declaration of Geneva (1948) stipulates that doctors must 'maintain the utmost respect for human life from the time of conception'. The Declaration of Helsinki (1975) says that in biomedical research 'the interest of science and society should never take precedence over considerations related to the well-being of the subject'.
    Even the Human Fertilisation and Embryology (HFE) Act itself, whilst allowing embryo research in some circumstances, recognises that human embryos have special status and deserve legal protection. Furthermore, the HFE Authority has an obligation to determine that any proposal for research using embryos is necessary and desirable, and that all alternative pathways have been fully explored through prior research or work with animals. This has not been done.

  2. The slippery slope to reproductive cloning
    Once cloned embryos have been produced, theoretically all that is necessary for reproductive cloning to take place is for them to be implanted in a womb. This process is technically straightforward and will be impossible to police. In fact, within a fortnight of the new legislation being passed, a group of international scientists had announced their intention to set up a clinic to provide cloning services to infertile couples within 18 months.[4] With 277 attempts to produce Dolly the Sheep, how many attempts will it take to produce human clones, and how many embryos and fetuses will be disposed of along the way?

  3. Prestige and Profit
    Why was there such a hurry to get this legislation passed when new therapies are five to ten years away by even the most optimistic estimates? The government waged a powerful propaganda campaign to convince the public that delay might mean lives lost; but we should be suspicious of the way the measure was sneaked in before Christmas a few months before a general election. Was the government really concerned primarily about those with degenerative disorders or was there an element of political expediency, pride in Britain being the first, and profit for British biotechnology companies? And were the research scientists, whose salaries are paid by research grants, really able to be truly objective in their recommendations?

  4. The alternative of adult stem cells
    The Donaldson Report's recommendations, now adopted, were based on an overly pessimistic belief in the capacity of adult stem cells to produce new treatments for debilitating degenerative diseases like Parkinson's and diabetes.

    There is now good evidence, growing all the time, that adult stem cells may be a simpler alternative to using embryonic stem cells without the practical and ethical problems inherent in the cloning of human embryos. Much of this recent research post-dates the Donaldson Report. Adult stem cells are cells that replace cells lost from a tissue throughout life. A single blood stem cell can replace the entire blood system in an animal whose bone marrow has been destroyed.[5] Until very recently the accepted dogma was that in adults stem cells were programmed to generate cells of a single tissue type.[6] For example, blood stem cells could generate blood cells, but not brain or muscle cells. Only embryonic stem cells were thought to have the ability to produce different tissue types. It is now clear that this is not the case.[7]

    In papers in Science published in December 2000, two research groups showed that blood stem cells could generate nerve cells in the brain, when transplanted into mice.[8],[9] The blood cells, which had been genetically engineered to fluoresce green, did not need to be injected into the brains of the animals; but migrated into the brain after intravenous injection. The authors of both papers stressed that these observations offered the hope of brain repair from adult blood stem cells.

    Similar research reported in 1999 demonstrated the potential of blood stem cells to repair damaged muscle in muscular dystrophy.[10] Mice with a similar disorder to human muscular dystrophy were treated with a bone marrow transplant. The donor blood stem cells were found to have generated muscle cells, repairing the muscle defect in the recipient of the transplant. In November 2000 Canadian researchers at the McGill University Health Centre showed that adult blood stem cells could be used to build up damaged heart muscle; again in research involving rats. Both embryonic and adult stem cell technologies share some of the same potential pitfalls. In a genetic disease like muscular dystrophy, all the cells in the patient carry the same abnormal gene, and adult stem cells from the patient would need to be genetically modified. Extensive research to achieve successful modification of blood stem cells is ongoing - with some encouraging results.[11] The adult stem cell approach has major advantages. There is very extensive clinical experience with obtaining, purifying and transplanting adult blood stem cells, for example in the treatment of leukaemia, and there are none of the technical problems of developing the new technologies of human embryonic stem cell culture and cloning.

    In reality tissue repair by either route will require extensive further research; but given the remarkable properties of adult stem cells and the experience we already have in their clinical use, it would seem both ethical and scientific arguments favour the allocation of resources to this approach over embryonic stem cell cloning. Rather than amending the HFE Act prematurely, Parliament should have adopted this more cautious and humane approach.


References

  1. Times 2001; (21 January, 22 January)
  2. Humanity 2001; 25(1):11 (February)
  3. Saunders P. Deadly questions on the status of the embryo. Nucleus 1998; July:28-34
  4. Josefsen D. Scientists plan human cloning clinic in the United States. BMJ 2001; 322:315 (10 February)
  5. Osawa M. Long-term lymphohematopoietic reconstitution by a single CD34- low/negative hematopoietic stem cell. Science 1996; 273: 242-5.
  6. Stem cells from umbilical cord or placenta are other alternative sources.
  7. McKay R. Stem cells-hype and hope. Nature 2000; 406: 361-4.
  8. Brazelton TR et al. From marrow to brain: expression of neuronal phenotypes in adult mice. Science 2000; 290: 1775-9 (Stanford University)
  9. Mezey E et al. Turning blood into brain: cells bearing neuronal antigens generated in vivo from bone marrow. Science 2000; 290: 1779-82.(US National Institute of Neurological Disorders and Stroke)
  10. Gussoni et al. Dystrophin expression in the mdx mouse restored by stem cell transplantation. Nature 1999; 401: 390-4.
  11. Kelly PF et al. Highly efficient gene transfer into cord blood non-obese diabetic/severe combined immunodeficiency repopulating cells by onco-retroviral vector particles pseudo-typed with the feline endogenous retrovirus (RD114) envelope protein. Blood 2000; 96: 1206-14.

Acknowledgement

I am indebted to Dr Phil Jones of the CMF study group for his research and advice on adult stem cell technology.

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