Ethical and Legal Issues in Therapeutic Cloning and the Study of Stem Cells

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1 Archives of Medical Research 34 (2003) REVIEW ARTICLE Ethical and Legal Issues in Therapeutic Cloning and the Study of Stem Cells Rubén Lisker Dirección de Investigación, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMNSZ), Mexico City, Mexico Received for publication June 19, 2003; accepted June 20, 2003 (03/095). Therapeutic cloning is a new technology with great medical potential, particularly in the area of transplantation medicine. It involves the transfer of the nucleus of a patient s cell into an enucleated donor oocyte for the purpose of generating an embryo. This embryo is allowed to grow until the blastocyst stage, at which time stem cells can be obtained and differentiated into the tissue needed. Stem cells can also be obtained from adult tissues, as they seem to have sufficient plasticity to use for the stated purpose. A literature review was performed, and it is clear that the main controversy regarding the use of stem cells is the origin. Few people would object to their use if obtained from adult tissues; however, many oppose harvesting them from embryos in the blastocyst stage regardless of whether 1) they are obtained from surplus embryos donated by couples after assisted reproductive techniques, or 2) they are specially manufactured for research purposes. The central reason is the consideration that embryos should be treated as full humans from the moment of fertilization. This argument is also at the bottom of an older discussion regarding the validity of abortion. There is no consensus at the present time in this regard, and it is unlikely one will be forthcoming in the future. Arguments on both sides of the issue are presented, but emphasis is made on the need for using this technology for research purposes because of its potential value as a therapeutic tool IMSS. Published by Elsevier Inc. Key Words: Therapeutic cloning, Ethical issues, Stem cells. Introduction The word clone was coined by H.J. Webber in 1903 (1) to describe a colony of organisms derived asexually from a single progenitor. He chose this word because, among other things, it was short, easy to pronounce, and different from any other word in ordinary use, so that it would not suggest any other meaning than the one desired. However, the common perception of cloning was later changed at least in part by an influential 1970 book by Alvin Toffler (2), who predicted that... man will be able to make biological carbon copies of himself. This statement changed the concept of what clones were, from simple progeny of asexual reproduction to sophisticated products of biological engi- Address reprint requests to: Rubén Lisker, M.D., Dirección de Investigación, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga #15, Col. Sección XVI, Tlalpan, México, D.F., México. Phone: ( 52) (55) ; FAX: ( 52) (55) ; rlisker@quetzal.innsz.mx neering performed by slightly mad scientists bent on controlling nature for their own agenda. This popular but erroneous idea is well identified in the book The Boys from Brazil (3), in which clonation of many copies of Adolph Hitler is claimed. Clonation can be defined as the reproduction of fragments of DNA, genes, cells, or individuals identical to the original ones. This is a normal process in some vegetables and lower animals, and it can be said that mitosis, the cell division by which all mammals multiply their cells, is a form of clonation. In the present paper, we shall discuss human clonation, specifically what is called therapeutic clonation. Human cloning has never been convincingly achieved. It would mean human asexual reproduction, accomplished by introducing the nucleus from human somatic cells into a fertilized or unfertilized oocyte whose nuclear material has been removed or inactivated, to produce a living organism that is genetically identical (except for mitochondrial DNA) to an existing or previously existing human organism. The term somatic cell refers to a diploid cell with a complete set /04 $ see front matter. Copyright 2004 IMSS. Published by Elsevier Inc. doi: /j.arcmed

2 608 Lisker/ Archives of Medical Research 34 (2003) of chromosomes obtained from a human body at any stage of development. Asexual reproduction means reproduction not initiated by the union of the female (oocyte) and male (sperm) gametes. If a freshly formed clone is allowed to grow for a few days under certain laboratory conditions, it can develop into an early embryo that theoretically could be employed for two purposes: first, to implant in a uterus of an animal of the same species to attain a pregnancy and hopefully a normal delivery (reproductive cloning). The present interest in clonation was initiated by the birth of Dolly (4), a sheep generated by the union of an enucleated ovum and a donor nucleus from a mammary cell of a 6-year-old pregnant ewe. The procedure was very inefficient (one of 277 tries). It has been duplicated in other mammals, with similar failure rates, which is one of the reasons why reproductive cloning is at present universally banned in humans. The second purpose is to harvest stem cells and differentiate them into different normal tissues, which is called therapeutic cloning. This term has been widely used, but to avoid the negative present connotation of the word cloning, it has been proposed that a better term is cell replacement through nuclear transfer (CRNT), which is in addition more precise. In contrast to reproductive cloning, CRNT is currently immersed in legal and ethical discussions. It employs stem cells, which are unspecialized cells at a very early stage of development that under normal conditions can divide and differentiate into the many different cell types that make up all our tissues and organs. In the laboratory, they can undergo self-renewal, which means that from a few stem cells it is possible to establish large stem cell lines that can in turn be used individually to differentiate into specialized tissues. The first evidence that established the possibility of creating immortal pluripotential (called totipotential by some) human stem cell lines was published in 1998 by groups from Johns Hopkins University (5) and the University of Wisconsin (6). Other animal research has suggested major therapeutic potential for this technology. It has been shown to produce pancreatic beta cells that make insulin (7), functional myocytes (8), and neurological tissue (9). Table 1 shows the possible therapeutic uses of tissues derived from stem cells, which would be a form of transplantation medicine. Table 1. Possible therapeutic uses of tissue derived from stem cells Cell type Diseases Stem Cell Sources Adult Tissue. Stem cells have been obtained at least from bone marrow (used successfully in the treatment of leukemia), brain, skin, and blood. The major difficulties have been 1) their unspecialized expansion as stem cells and 2) the question of their plasticity, that is, the transformation into cells different from those from the tissue from which they were obtained (10). They may be genetically compatible with the patient being treated if self-derived. Fetal Tissue. These have been collected from aborted fetuses or from the umbilical cord of newborn babies. Tissue sources are readily available, and stem cells can be successfully grown and concentrated in the laboratory. The main problem is that the resulting tissue is not genetically compatible with the person requiring the transplant, unless cord blood is stored at birth for later use. Embryonic Stem Cells. There is clear evidence that such cells obtained from early embryos can be made to differentiate into a wide range of tissues (11). In humans, they could be harvested from surplus embryos produced in the process of assisted reproduction techniques and donated for research purposes, or they could be produced specifically for the stated reasons. In any event, 5 6 days after fertilization, embryonic stem cells can be taken from the inner cell mass of the blastocyst. This structure begins to form as a cluster of cells that go on to form the placenta and fetus. The blastocysts used to obtain stem cells have approximately 128 cells, i.e., seven cell divisions after zygote formation. After this stage, the cells begin to become specialized and are no longer as suitable for differentiation into all tissues. Nuclear Replacement Technique This refers to the technique employed to create the sheep Dolly (4). It does not require sperm, as explained previously and involves inserting the nucleus of a somatic cell into an enucleated oocyte. This procedure is synonymous with cloning, which can be reproductive if after a few days the embryo is to be introduced in a uterus to attempt a pregnancy or therapeutic if the embryo is made to remove stem cells at the blastocyst stage for a specific therapeutic use. Tissues thus developed would have the advantage of being genetically compatible with the donor, increasing their value manifold. Neural Heart muscle Insulin-producing Blood Liver Skin Retinal Skeletal muscle Stroke, Parkinson s, Alzheimer s, spinal cord injury Coronary, congestive heart failure Diabetes Leukemia, genetic blood diseases Hepatitis, cirrhosis Burns Macular degeneration Muscular dystrophy Ethical Considerations Stem Cells. Few people express concern about the use in research of stem cells of tissues or from cord blood taken from adults with their informed consent. The major problem relates to the fact that the source of the stem cells, particularly the creation and use of human embryos for research, is

3 Therapeutic Cloning, Ethical Issues 609 unacceptable and unethical for many people on the grounds that this is a new and unique human entitled to full human status from the moment of conception. A counterargument is that one cannot speak of human individuality at this time because twinning and chimerism can still occur until gastrulation (12,13). At the other end of the spectrum are those who consider that an early embryo is simply a collection of cells entitled to no greater rights that any other collection of human cells. In the middle ground, the special status of an embryo as a potential human being is accepted, but the respect owed to developing human life is regarded as increasing in proportion to the degree of embryo development. According to this view, the use of early embryos for research purposes to benefit others is morally justifiable. The potentiality concept is open to discussion because most things are not treated the same way in their early forms as in the fully developed stages (14,15). In the opinion of many, an egg is not a chicken, an acorn is not an oak, and early embryos that have no tissues or organs are incapable of thinking or feeling and therefore should not be considered human beings. I will offer two personal thoughts attempting to justify the middle ground view. First, the impact on the family of a loss of human life is related to the stage of development. Many spontaneous abortions are manifested by a delay of 1 or 2 days in presentation of the menstrual period and are received with almost complete indifference. In contrast, the effect on the parents of the birth of a dead newborn or worse, the loss of a 4- or 5-year-old child, is a very dramatic and sad event. My second point is that in the nuclear transfer technique, the zygote is not a true embryo, as it is not formed by the union of egg and sperm and therefore could be conceptualized as not properly human. Moreover, if it is formed with the purpose of harvesting stem cells, it also lacks the potential of developing into a human being. The concept of a clone formed exclusively to harvest stem cells can be objected to on the grounds that there is nothing to prevent someone from deviating from this objective and to proceed to implant such an embryo in a uterus to achieve a pregnancy. To avoid this possibility, some believe that it is much safer to disallow nuclear transfer at all. I have no empirical data supporting my contention of the differential effect of loss of life in relation to degree of development, and I recognize that my argument that the nuclear transfer technique is not a true embryo could be objected to, stating that its developmental potential is the same as that of naturally fertilized eggs. However, I believe my viewpoints are well taken and merit further discussion. Regardless of the pros and cons of my way of looking at these issues, I know that middle-of-the-road arguments will not convince anyone who holds the view that human life begins at conception. Moral, ethical, and religious objections center on when life begins, and there are heated arguments that arise from many camps. In all fairness, I will transcribe some ideas expressed in a recent symposium held in Houston entitled The Stem Cell Controversy (16). The participants included geneticists, scientists from the fields of clinical immunology and molecular biology, philosophers, and approximately 100 members of the Houston community. A New York Times article (December 18, 2001) was quoted, stating that scientifically... embryonic stem cells, the cells from which all body tissues grow, form about 2 days after sperm and egg unite, when the embryo is little more that a hollow blastocyst with an inner mass of stem cells. At this stage, researchers can remove these cells in hopes of using them to grow replacement tissues to treat a variety of diseases. One of the participants had this to say: Stem cell research holds forth the promise of both understanding our origins better and providing needed tissue in the future for those with organ specific diseases. Although this is a noble goal, there is much to be done... If, as I believe, life begins at conception, then the idea of harvesting stem cells from fertilized embryos is one of one life being more important than another. The extension of this may be a slippery slope when we make decisions about who should live and who should die. In April 2000, The Nuffield Council on Bioethics in the UK published a discussion paper on stem cell therapy (17) that arrived at different conclusions from those mentioned here previously: We conclude that the removal and cultivation of cells from a donated embryo does not indicate lack of respect for the embryo. We therefore recommend that research involving human embryos be permitted for the purpose of developing tissues to treat diseases from derived embryonic stem (ES) cells. Regarding the use of fetal tissue in the derivation of embryonic germ cells, the members of the Council believe that research should be permitted, and...we also recommend that as a safeguard to protect all embryo donors who could theoretically be identified by analysis of DNA of an ES cell line, they be specifically asked to consent to this research and any subsequent use of the cell line. The Abortion Problem. The previous discussion is reminiscent of a much older one regarding the legitimacy of abortion. The central question is at what point in its development from a newly fertilized ovum should it be considered an unequivocally mature, autonomous morally inviolable person? In other words, when does a human being acquire that nature and those attributes and thus has a right to life? (18). Killing another person, if that person is a non-aggressor, is regarded as a reprehensible action in most societies, with legal sanctions to pay. Several positions have emerged over the centuries as to when a zygote becomes a person. This is of course critical because a non-person cannot be killed. At one end of the spectrum is the position that the newly fertilized egg is a person from the moment of conception, because we cannot know precisely when it becomes ensouled, which is the theological equivalent of becoming

4 610 Lisker/ Archives of Medical Research 34 (2003) a person. This is the position of the contemporary Roman Catholic Church as expressed in its 1974 Declaration on Abortion by the Roman Congregation for the Doctrine of the Faith (19) and is shared, at least partially, by other religious communities (20,21). It is interesting that Thomas Aquinas, one of the greatest philosophers of the Roman Catholic faith, considered that ensoulment (hominization) did not occur until 40 days after conception for boys and 90 days for girls. At the other end of the spectrum, some argue that the necessary attribute to become a person is a capacity to be aware of oneself or to have autonomous thinking, which takes place some months after birth. There are several intermediate positions in this regard, such as a) 14 days after conception because at this time, the primitive streak forms; b) the time at which the pregnant woman can feel her fetus move inside her, generally approximately weeks into her first pregnancy and somewhat earlier in subsequent pregnancies; c) the development of a functional brain, which has been estimated to occur between 20 and 24 weeks, and d) the stage at which the fetus is viable, meaning that it can survive independently with adequate medical care, at approximately 22 weeks. In this regard, I believe that this is a technical point that does not take the baby into account and is difficult to accept. A final proposition in many countries including Mexico is that the moment of birth should be the unique and only criterion. Each criterion mentioned has pros and cons that can be aptly discussed by many people. But after many years, no consensus has been reached, and I suspect this will not occur in the future either because it is not a scientific problem that can be addressed rationally but a matter of values where no agreement seems possible. Legal Considerations In Mexico, we have no established legislation in these matters, but this is being discussed actively by our legislative bodies. Perhaps it will be interesting to some to review what the situation is in other countries such as the UK. In the UK, there is an established system to regulate the creation and use of embryos for treatment and research purposes under the Human Fertilization and Embryology Act of 1990 (22). This act was passed after extensive consultation by a Committee established after the birth of the first test tube baby in This previously mentioned act permits research on surplus embryos created in the course of in vitro fertilization treatment, with the patient s permission and for specific research purposes. For instance, from 1991 to 1998, 763,509 embryos were created, of which 351,617 were used for infertility treatment and 48,444 were donated for research. The research purposes allowed under the UK 1990 Act are to 1) promote advances in fertility treatment, 2) increase knowledge about congenital disease, 3) increase knowledge about the causes of miscarriage, 4) develop more effective techniques in contraception, and 5) develop techniques to identify genetic abnormalities before embryo implantation. In all cases, the researcher must apply to the Human Fertilization and Embryonic Administration for approval, which must be satisfied that the use of embryos is necessary for the purpose of the specific research. At the present time, the 1990 Act does not allow the mixing of human and animal gametes. Embryos can only be used if the individual whose eggs or sperm are employed give their consent. In addition, the Act forbids human reproductive cloning, but the production of embryos for the extraction of stem cells to develop tissue for treatment purposes is allowed. In contrast to the UK, in the U.S. there is strong congressional opposition to funding any research that involves human embryos. On August 25, 2000, the National Institutes of Health (NIH) declared that they would only fund research on stem cells harvested from surplus infertility procedures and not those created for research purposes (23). These restrictions apply to federally funded research, and presently private sector research on embryonic stem cells and cell replacement through nuclear transfer is not illegal, except in several states that have passed laws regulating research on human embryos, fetuses, and unborn children (24). To my mind, the UK legal stance is the more logical one. I believe that this research is ethically permissible and can prove to be of enormous medical benefits. References 1. Webber HJ. New horticultural and agricultural terms. Science 1903;28: Toffler A. Future shock. New York: Random House; Levin I. The Boys from Brazil. New York: Random House; Wilmut I, Schniske AE, McWhir J, Kind AJ, Campbell KH. Viable offspring derived from fetal and adult mammalian cells. Nature 1997; 385: Thomson JA, Itskovitz-Eldor J, Shapiro SS, Waknitz MA, Swiergiel JJ, Marshall SS, Jones JM. Embryonic stem cell lines derived from human blastocysts. Science 1998;282: Shamblot MJ, Axelman J, Wong S, Bugg M, Littlefield JW, Donovan PJ, Blumenthal PD, Huggins GR, Gearhart JD. Derivations of pluripotent cells from cultured human primordial germ cells. Proc Natl Acad Sci USA 1998;95: Assady S, Maor G, Amit M, Itskovitz-Eldor J, Shorecks KL, Tzukerman M, Insulin production by human embryonic stem cells. Diabetes 2001;50: Kehat I, Kenyogin-Karsenti D, Snir M, Seger H, Amit M, Gopstein A, Livne E, Binah O, Itskovitz Eldor J, Gepstein L. Human embryonic stem cells can differentiate into myocytes with structural and functional properties of cardiomyocytes. J Clin Invest 2001;108: Brazelton TR, Rossi FMV, Keshet GI, Blau HM. From marrow to brain: expression of neuronal phenotypes in adult mice. Science 2000; 290: Bjornson CR, Rietze RL, Reynolds BA, Magli MC, Vescovi AL. Turning brain into blood: a hematopoietic fate adopted by adult neural stem cells in vivo. Science 1999;283: Mayani H. A glance into somatic stem cell biology: basic principles, new concepts, and clinical relevance. Arch Med Res 2003;34:3 15.

5 Therapeutic Cloning, Ethical Issues Train L, Dean JC, Hamilton MP, Bonthron DT. A true hermaphrodite resulting from embryo amalgamation after in vitro fertilization. N Engl J Med 1998;338: Shannan JA, Walter AB. Reflections on the moral status of the preembryo. Theol Stud 1990;51: Lanza RP, Caplan AL, Silver LM, Cibelli JB, West WD, Green RM. The ethical validity of using nuclear transfer in human transplantation. JAMA 2000;284: Warren MA. On the moral and legal status of abortion. The Monist 1973;57: Knudson PL. The stem cell controversy. Arch Med Res 2002; 33: Nuffield Council on Bioethics. Stem cell therapy: the ethical issues. London: Nuffield Council on Bioethics; Gillon R. Is there a new ethics of abortion? J Med Ethics 2001;27(Suppl II): As reported in Mahonay J. Bioethics and belief. London: Shead and Ward; Goldsand G, Zahara RS, Rosenberg MG. Bioethics for clinicians. 22. Jewish bioethics. Can Med Assoc J 2001;164: Pauls M, Hutchinson RC. Bioethics for clinicians. 28. Protestant bioethics. Can Med Assoc J 2002;160: Stem cell research: medical progress with responsibility. A report from The Chief Medical Officer s Group reviewing the potential of developments in stem cell research and cell nuclear replacement to benefit human health. London: Department of Health;July Department of Health and Human Services. Public Health Service. National Institutes of Health Guidelines for Research using pluripotent stem cells. Washington, D.C., USA: 65 Federal Register, August 25, 2000: Andrews L, Elster N. International regulation of human embryo research: embryo research in the US. Human Reprod 1998;13:1 4.