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Therapeutic Cloning
Human cloning involves the production of a genetic copy of another human being. There are two ways in which clones could be created. The first involves the "splitting" of an embryo's cells very early in its development thus creating one or more clones. The second technique, generally called "cloning" but referred to technically as "cell nuclear replacement" or "somatic cell nuclear transfer," involves the removal of the nucleus from an unfertilized female egg and its replacement by the nucleus of a cell taken from a donor who would then be the genetic twin of the new clone. However, the clone thus produced would not be totally genetically identical to the donor of the cell whose nucleus was used to replace the nucleus in the female egg (oocyte). While the nuclear genes of the cell donor and the clone would be identical, their mitochondrial DNA would be different because the enucleated egg would have retained extra-nucleic material such as the mitochondria. As far as medical science is concerned, however, the advantage cell nuclear replacement has over embryo splitting is that it can produce a clone of an adult organism and it has the potential to produce many more clones.[2]
The distinction made above between cloning understood as the creation of genetically identical duplicates of human beings and the creation of clones through cell nuclear replacement has important implications. For example, on December 5, 2000, the Australian Federal Parliament passed an amendment to the Gene Technology Bill 2000 to prohibit the cloning of human beings and to prohibit placing human cells into animal eggs or the placing of human and animal cells into a human uterus. The amendment prohibited the "cloning of a whole human being" from "one original" who would be "a duplicate" or "genetically identical" to the original. The first problem with this amendment to the Gene Technology Bill is that it does not define what it means by a "full human being." Does it exclude some stages of human development such as the embryonic or fetal stage? The second problem is that it leaves open the possibility of cloning using cell nuclear replacement since it only refers to the creation of clones that are completely genetically identical duplicates of the original.
Two other terms commonly used in the cloning debate are "therapeutic cloning" and "reproductive cloning." First, therapeutic cloning means that a clone (embryo) is created for the purpose of providing human embryonic stem cells (ES cells). These are undifferentiated cells which are precursors to a number of differentiated cell types from which it is possible in theory to produce bio-medical products for use in the treatment of diseases such as Alzheimer's, Parkinson's and muscular dystrophy. While the two most widely used sources of stem cells at present are IVF embryos and aborted fetal tissue, there are however other sources such as adult bone marrow, human fat and umbilical cords saved at birth. The harvesting of human ES cells requires the destruction of the embryo, irrespective of whether it is produced through IVF or by cloning.
Secondly, reproductive cloning means that an embryo is cloned with a view to implanting it in a woman's uterus and allowing it to develop fully as a baby. Regarding the two terms — "therapeutic" and "reproductive" — it is important to note that they are used merely to distinguish between the ends for which an embryo is cloned.
The Status of the Human Embryo
In order to evaluate the moral character of therapeutic cloning, two questions that must be resolved are:
• is it ever morally licit to clone a human being? • is it ever morally licit to intentionally destroy a human embryo? For the rest of this essay, I will deal almost exclusively with the second question posed above regarding the willful destruction of human embryos. The question of the morality of IVF and cloning will be addressed towards the end of the essay.
The debate over the ethical nature of therapeutic clones overlaps with the question of the morality of procured abortion insofar as the question of the moral status of the human embryo is central. To resolve this question, it is necessary to first discern when the life of an individual human being begins. The Greeks and Romans of classical times debated this question, and it continues to be debated by philosophers, theologians and scientists today. However, with the advance of scientific understanding, it has become clear that from the moment of the fusion of the human gametes (male sperm and female egg), what we have is the initial stage of a continuous human life. The scientific knowledge regarding this newly conceived zygote permits us to be sure that it is "a new human being, different and distinct from the parents," it "has a human body with all the genetic information present in its chromosomes," and as such "there is imprinted a genetic process of 'human' development."[3] This new human life, which comes into existence with the formation of the one-cell zygote, has an inbuilt capacity to initiate, sustain, control and direct its own development.
Those who argue that embryo manipulation and destruction is morally licit often assert that what is produced by the fusion of the human sperm and egg is not really a human embryo or human being. However, the following quotations taken from the works of recognized experts in the field of biological and embryological science do not support these assertions: • "The chromosomes of the oocyte and sperm are ... respectively enclosed within female and male pronuclei. These pronuclei fuse with each other to produce the single, diploid, 2N nucleus of the fertilized zygote. This moment of zygote formation may be taken as the beginning or zero time point of embryonic development."[4] • "The development of a human being begins with fertilization, a process by which two highly specialized cells, the spermatozoon from the male and the oocyte from the female, unite to give rise to a new organism, the zygote."[5] • "Embryo: the developing organism from the time of fertilization until significant differentiation has occurred, when the organism becomes known as a fetus."[6] • "Development of the embryo begins at Stage 1 when a sperm fertilizes an oocyte and together they form a zygote."[7] • "Embryo: An organism in the earliest stage of development; in a man, from the time of conception to the end of the second month in the uterus."[8] • "Fertilization is a sequence of events that begins with the contact of a sperm (spermatozoon) with a secondary oocyte (ovum) and ends with the fusion of their pronuclei (the haploid nuclei of the sperm and ovum) and the mingling of their chromosomes to form a new cell. This fertilized ovum, known as a zygote, is a large diploid cell that is the beginning, or primordium, of a human being."[9] • "The development of a human begins with fertilization, a process by which the spermatozoon from the male and the oocyte from the female unite to give rise to a new organism, the zygote."[10] • "The question came up of what is an embryo, when does an embryo exist, when does it occur. I think, as you know, that in development, life is a continuum. ... But I think one of the useful definitions that has come out, especially from Germany, has been the stage at which these two nuclei [from sperm and egg] come together and the membranes between the two break down."[11] • "Almost all higher animals start their lives from a single cell, the fertilized ovum (zygote)... The time of fertilization represents the starting point in the life history, or ontogeny, of the individual."[12] • "Zygote. This cell, formed by the union of an ovum and a sperm (Gr. zygotes, yoked together), represents the beginning of a human being. The common expression 'fertilized ovum' refers to the zygote."[13] From the biological facts given above regarding the beginning of human life, it is clear that from the time an ovum is fertilized, the life of a new human being has begun even though it will take time for its various capacities to develop and evolve. If it is objected that the embryo does not look like a human being, then we can reply by repeating the statement of the Ramsey Colloquium in 1995 which said: The embryo is a being; that is to say, it is an integral whole with actual existence. The being is human; it will not articulate itself into some other kind of animal. Any being that is human is a human being. If it is objected that, at five days or fifteen days, the embryo does not look like a human being, it must be pointed out that this is precisely what a human being looks like — and what each of us looked like — at five or fifteen days of development.[14] Endnotes for “Therapeutic Cloning” [2] This distinction between the two methods of cloning is explained in a University of New South Wales Department of Embryology paper titled Embryology Legal Issues UK.It can be obtained on the following website: http://anatomy.med.unsw.edu.au/CBL/Embryo/law/uk.htm. [3] Castrese Di Ciaccia and Vitaliano Mattioli. When Your Life Began: A Man or a Woman Was Conceived [Rome: International Medical Association, 1994], page 7. [4] William J. Larsen. Human Embryology. Second edition [New York: Churchill Livingstone, 1997], page 17. [5] Jan Langman. Medical Embryology. Third edition [Baltimore: Williams and Wilkins, 1975], page 3. [6] Cloning Human Beings. Report and Recommendations of the National Bioethics Advisory Commission (USA) [Rockville, Maryland: United States Government Printing Office, 1997], Appendix 2. [7] Marjorie A. England. Life Before Birth. Second Edition [London: Mosby-Wolfe, 1996], page 31. [8] Ida G. Dox, et al. The Harper Collins Illustrated Medical Dictionary [New York: Harper Perennial, 1993], page 146. [9] Keith L. Moore. Essentials of Human Embryology [Toronto: B.C. Decker, Inc, 1988], page 2. [10] T.W. Sadler. Langman's Medical Embryology. 7th Edition [Baltimore: Williams & Wilkins, 1995], page 3. [11] Jonathan Van Blerkom of the University of Colorado, expert witness on human embryology, before the NIH Human Embryo Research Panel (USA), Panel Transcript, February 2, 1994, page 63. [12] Bruce M. Carlson. Patten's Foundations of Embryology (6th edition) [New York: McGraw-Hill, 1996], page 3. [13] Keith L. Moore and T.V.N. Persaud. Before We Are Born: Essentials of Embryology and Birth Defects (4th edition) [Philadelphia: W.B. Saunders Company, 1993], page 1. This reference and the nine preceding it appear in the Pro-Life section of the US Catholic Bishops' Conference website whose address is: http://www.nccbuscc.org/prolife/issues/bioethic/fact298.htm [14] "The Inhuman Use of Human Beings: A Statement on Embryo Research by the Ramsey Colloquium." First Things, January 1995.
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