Human Embryo Stem Cell Research

John B. Shea
July 24, 2005
Social Justice Review
Reproduced with Permission

For the past twenty-five years experiments have been carried out on human embryos created by the so-called 'sexual' method of in vitro fertilization (IVF) at IVF clinics. The avowed purpose of those experiments has been improvement in the technique of IVF.

In 2004, the first human being was conceived by the 'asexual' means of somatic cell nuclear transfer cloning.1 Those experiments are among many others which have demonstrated that the world is now increasingly threatened by a culture of death.

Four proposals were recently made to the President's Council on Bioethics about how to produce human embryonic stem cells without creating or destroying human embryos.2 Though, no doubt, these proposals were intended to achieve a good end, they remain a source of moral concern.

The First Proposal: Donald W. Landry and Howard A. Zucker, two Columbia University physicians, suggested that frozen in vitro fertilized embryos that have been stored for five years and were not wanted for their original reproductive purpose, be unfrozen. These embryos would be at the eight to twelve cell stage of development. It was proposed that they should be closely observed for twenty-four hours, and that those embryos that fail to develop by that time should be observed for another twenty-four hours. After the observation of several hundred embryos the time beyond which no arrested embryo resumed cell division would then be determined. Dr. Landry concluded that embryos that have not divided by this time after thawing, would not divide at any later time, and are "organismically" dead. He proposed irreversible arrest of cell division rather than death of every cell of the embryo as the criterion of "organismic" death. Although they were victims of "organismic" death, those embryos, Landry maintained, could still be used as the source of normal embryonic stem cells derived from the inner cell mass of the embryo.

How is this proposal to be morally justified? It was claimed that the organismically dead embryo had irreversibly lost all on going integrated cellular division, growth, and differentiation. This loss was said to meet the criteria for brain death, which in turn, Landry held, are based on the ad hoc Committee of the Harvard Medical School definition of coma (1968). In the early embryo each cell is involved in the differentiation of other cells and therefore in the growth and development of the whole embryo. The role of these cells was held to be similar to that of the nervous system that was said to integrate the activities of the tissues and organs of a person after the brain has developed.3, 4

The second proposal: William B. Hurlbut, a physician and a bioethicist at Stanford University, proposed a different method, which he called "assisted oocyte reprogramming." That is the epigenetic reprogramming of a somatic cell nucleus by means of the forced expression of transcription factors characteristic of embryonic stem cells in order to produce a pluripotent stem cell.

How is this to be achieved? The first assumption is that epigenetic reprogramming converts a cell of one kind into another kind of cell, in this case, from a somatic cell into a pluripotent stem cell. A gene called the "nanog" gene produces a protein ["nanog"], a transcription factor, that is assumed to function as a key regulator for maintenance of a cell's pluripotency, and to prevent that cell from becoming totipotent. Pluripotency is the potential of a cell to change into many other types of cell, but not to revert to the status of a new single cell embryo. Nanog is found first in the morula and later in greater concentration in the inner cell mass of the embryo. The nanog gene produces this protein under the influence of a messenger RNA, called mRNA.

Two practical methods were proposed. First, a somatic cell, i.e. skin cell, is subjected to transcription factors, e.g. nanog, which is assumed to influence the nucleus toward a pluripotent state. This nucleus is then transferred into an enucleated oocyte producing a pluripotent stem cell. Second, alternatively or concomitantly, mRNA for nanog or for an other transcription protein is injected into an oocyte prior to nuclear transfer. It is also assumed that the pluripotent 'stem cell' nucleus thus produced never enters or passes through a totipotent embryo stage.5 Totipotency is the ability of a cell to change into any of the over two hundred kinds of cells in the body and also to become a single-cell embryo, a zygote.

Comment on the Landry/Zucker Proposal

•The Harvard Committee implied that a person in irreversible coma should be regarded as "brain dead." It further held that a person in irreversible coma is for all practical purposes, if not in reality, actually dead. This oxymoronic idea has unfortunately been accepted in the legislatures, the academies and the courts of the western world. The Harvard Committee did not equate brain death with death.

•Dr. Landry assumes that an embryo which shows irreversible arrest of cell division due to lack of a system of chemical communication and surface recognition among the cells, therefore lacks integrative unity and is organismically dead. This state he assumes has the moral significance of brain death. What then is the moral significance of brain death?

•Pope John Paul II, in August 2000, in his address to the thirteenth International Congress of the Transplantation Society, implied that there were "clearly determined parameters, commonly held by the scientific community, which allow a physician to declare a person 'brain dead', and by implication, dead.6 On February 3, 2005, he observed that from the Christian perspective, "the moment of death of a person consists in the definitive loss of the constitutive unity of body and spirit ... the death of the person, understood in this primary sense, is an event which no scientific techniques or empirical methods can identify directly."7 He cited his predecessor, Pope Pius XII, who said, " is for the doctor to give a clear and precise definition of death and of the moment of death." Pope John Paul II stated that, in considering the definition of brain death scientists could count on the support of the Congregation of the Doctrine of the Faith. Bishop Marcelo Sanchez Sorondo, Chancellor of the Academy, stated that Pope John Paul II called the 2005 meeting "in order to re-study the signs of death and verify, at a purely scientific level, the validity of the criterion of brain death."8

•In point of fact there is no agreement at present among doctors on "a clear and precise definition of death". E. Wijdics found no global consensus on diagnostic criteria.9 W. Haupt and J. Rudolf found that guidelines for determining brain death in all European countries were different in various countries.10 Michael Wang et al. showed poor compliance with accepted guidelines in their institution.11 American physicians assume that complete loss of the entire brain and brain-stem functions is necessary before death can be declared. In Britain, brain death is defined as complete and irreversible loss only of brain-stem function. In Canada, Neil Lazar et al. state that brain death as a criterion for declaring the death of a person "is perhaps a justification in the context of organ donation and transplantation." They did not state that brain death criteria determine the "death of a person."12 The New England Journal of Medicine published an article in 2001 stating that the consensus in regard to the equation of brain death with actual death is not free of metaphysical, cultural, legal, and medical controversy. D. Alan Shewmon questions whether it is possible in medical practice to determine in physical terms what constitutes the 'organism as a whole', especially in the dying phase.13

•One should question the meaning of the assumption that the arrest of cell division renders an embryo "organismically dead." The biological mechanisms integrating the development of a single-cell embryo through to an estimated fifty to the hundred trillion cell adult stage is of stupendous complexity. Billions of biochemical interactions occur every fraction of a second in this process. How can one at the present time realistically claim to know with adequate precision and moral certainty, just when integrative unity has been lost in so complex an organism? Loss of coordinated cell division may represent only a disordered process in a still living organism that may indeed precede the death of the organism, but not indicate that its death has already occurred.

•The assumption that the brain is responsible for the integrative unity of the body is open to serious question. Many persons declared brain dead have retained free-water homeostasis vasopressin, which controls the body's ability to secrete water. The brain is the only source of vasopressin. The brain does not integrate absorption of materials, elimination and detoxification of water or gestation of a fetus. Brain dead women have given birth months after the diagnosis of brain death.14

Comment on the Hurlbut Proposal

•Despite the fact that nanog, as Hurlbut says, is found in the morula and in the inner cell mass, many of the cells in these structures remain totipotent. They are not all merely pluripotent. Nanog's presence may be irrelevant because it cannot be assumed that insertion of nanog or mRNA into the cytoplasm will reprogram all cells to become pluripotent. Most of the cells of the early developing human embryo, both in vivo and in vitro, whether derived from sexual or asexual reproduction, are totipotent, not pluripotent. That means that those cells may, by the process of regulation, be capable of reverting to the status of a zygote, a single cell embryo.15, 16 The proof is found in the empirical fact of "twinning" which can occur up to fourteen days after fertilization or cloning.

•It is also a fact that nuclear transfer cloning, a process used in the Hurlbut proposal, in and of itself, can create a zygote. The subjection of a somatic cell nucleus to nanog, and the introduction of mRNA into an oocyte prior to nuclear transfer, may not necessarily prevent the production of a cloned embryo from the somatic cell, either as the direct result of reprogramming of the nucleus by the oocyte cytoplasm, or as the result of spontaneous regulation of a pluripotent cell that had been first created by the treatment with nanog and mRNA.

•The results of animal experiments are not necessarily always consistent with the results of experiments on human beings. What works in animals need not work in humans.

•The justification of obtaining oocytes from human donors by super-ovulation could be an ethical problem. Could it be justified for research purposes in light of the fact that super-ovulation must be assumed to involve some risk of causing cancer of the ovary, cancer of the breast, blood clots, electrolyte imbalance with harm to the liver and kidney, and future infertility of the donor?

•Nuclear transfer cloned cells contain mitochondrial DNA which can be rejected by the immune system of the recipient and which may require a lifetime of harmful immunosuppressive drug administration.

•Cloned cells produce tumours and other abnormalities.

The Third Proposal: Extraction of a cell, a blastomere, from a living eight-cell in vitro fertilized embryo, and its cultivation in a dish along with embryonic stem cells. It has been shown in mice that chemicals secreted by the embryonic stem cells can change blastomeres into stem cells. From those altered blastomeres more stem cells are derived. Ethical concerns include possible harm to the embryo and the fact that the extraction is not done for the good of the embryo. Recent research in mice has shown that a north and south pole of an embryo is determined as soon as the sperm penetrates the ovum resulting immediately in a new single-cell human organism 12 to 14 hours before fusion of the two pronuclei [syngamy]. Even when the embryo consists of just four cells, they are beginning to assert their identity. Researchers are worried that removal of the wrong cells could harm the ability of the embryo to develop.17 Bringing considerations of research into the process of in vitro fertilization would tend to suggest approval of that practice, which is immoral in the first place.

In addition, it must be remembered that a blastomere at the eight-cell stage can revert to the status of a single-cell human embryo.

The Fourth Proposal: To re-program somatic cells so as to restore them to the pluripotency characteristic of embryonic stem cells. This is achieved by fusing a somatic cell nucleus with an embryonic stem cell and then removing the stem cell nucleus. The somatic cell nucleus is reprogrammed by the cytoplasm of the embryonic stem cell.

A problem would arise if re-programming went so far as to produce a totipotent cell, that is a human zygote, a single cell human being, who would be killed if subjected to the processes ordinarily used in stem cell culture. It is a scientifically established fact that some embryonic stem cells can become zygotes spontaneously by a process called 'regulation', a process sometimes involved in normal twinning.18, 19 At the present time how can one be certain that this will not happen following re-programming?

Furthermore, the methods proposed to achieve re-programming involve what is essentially nuclear transfer cloning. This cloning could result in the production of stem cells but it could also result in the production of tumors and other cellular abnormalities and the creation of a single cell embryo that would be killed by the methods used to produce stem cells. Finally, cloning also produces stem cells that contain foreign mitochondrial DNA that can cause tissue rejection in the host.


Mauro Cozzoli, writing about the status of the embryo, has stated, "The uncertainty with regard to whether we are dealing with a human individual is not an abstract doubt regarding a theory, principle, or doctrinal position (dubium uris). As such, it is a doubt about a fact concerning the life of a human being, his existence here and now (dubium facti). As such a doubt, it "creates the same obligation as certainty."20 This means that one is not morally free to carry out research if there is a doubt about whether that research could harm or kill a human being.

In all four proposals the risks of artificially creating, and killing or harming a human embryo are not ruled out because these proposals incorrectly assume that the cells they produce are pluripotent rather than totipotent. These proposals are therefore not morally acceptable. Catholic theologians, philosophers, human embryologists and physicians, must carefully observe and assess current research and technical developments in the fields of human embryology and genetic engineering. Some proposed technical advances may prove to be truly for the common good. Some may not. It is of paramount importance to distinguish between these two. Cardinal Ratzinger, in an address on April 11, 2005, given at his reception of the Saint Benedict Award for the Promotion of Life and Family in Subiaco, Italy, stated, that "...moral force has not grown apace with the development of science, but, on the contrary, has diminished." He explained that, "...the most serious danger at this time is precisely the imbalance between technical possibilities and moral energy," and gave as an example the possibility to manipulate the origins of human life.21

The time has come for all Catholics who are morally responsible for the formation of public policy in relation to human reproduction, not only to have a thorough knowledge of Catholic moral teaching, but also a sufficient mastery of the relevant scientific facts. It is therefore imperative that human embryologists be included in all further public discussions in regard to the manipulation of human life in its origins. Finally, it should be noted that no human embryologist has been appointed to the President's Council on Bioethics by President George Bush or President Bill Clinton, and indeed they have been excluded from these public discussions for decades.


1 Hwang W.S. et al., Evidence of a pluripotent human embryonic stem cell line derived from a cloned blastocyst. Science, 2004, March 12; 303 (5664): 1669-74. [Back]

2 White Paper: Alternative Sources of Pluripotent Stem Cells. The President's Council on Bioethics, Washington, D.C., May 2005. [Back]

3 Donald W. Landry, Ronald A Zucker, Embryonic death and the creation of human embryonic stem cells. J.Clin.Invest., 2004, November 1; 114 (9): 1184-86. [Back]

4 The President's Council on Bioethics. [Back]

5 William B. Hurlbut, M.D. et al., Production of Pluripotent Stem Cells by Oocyte Assisted Reprogramming. Joint Statement, June 20, 2005. [Back]

6 Address of August 29, 2000, 4, in: AAS 92 (200), 824. [Back]

7 Letter of John Paul 11, To the Pontifical Academy of Sciences, "On Organ Donation." [Back]

8 Carol Glatz, 'Brain dead' may not be real death, The Catholic Weekly, Sydney, 13 February, 2005. [Back]

9 Widjicks EFM., Determining brain death in adults. Neurology, 1995; 45:1003-1011. [Back]

10 Haupt WF., Rudolf J., European brain death codes: a comparison of national guidelines. J. Neurol.. 1999, June; 246 (6): 432-7. [Back]

11 Wang MY, Wallace P, Gruen JP., Brain death documentation: analysis and issues. Neurosurgery, 2002; 51:731-36. [Back]

12 Neil Lazar et al., Bioethics for Clinicians: 24. Brain death. Canadian Medical Association Journal. 2001; 164(6): 833-6. [Back]

13 Advances in Experimental Medicine and Biology, vol. 550, pages 89 - 114, Brain Death and Disorders of Consciousness. Proceedings of the Fourth International Symposium on Coma and Death. Havana, March 9-12, 2004. Published by Plenum, 2004. [Back]

14 Fried D.R. et al., Maternal brain death during pregnancy. Medical and ethical issues. JAMA, Vol.260, No.6, Aug. 12, 1988. [Back]

15 Dianne N. Irving, MA, PhD., July 23, 2005. "Framing the Debates on Human Cloning and Human Embryonic Stem Cells: Pluripotent vs. TOTIPOTENT." [Back]

16 Ronan O'Rahilly, and Fabiola Muller, Human Embryology & Teratology, (3rd.ed.) New York: Wiley-Liss, 2001. [Back]

17 Magdalena Zernicke-Goetz, Development, vol. 132, pp. 479-90, Jan. 5, 2005. [Back]

18 Bruce Carlson, Human Embryology & Developmental Biology St. Louis, MO: Mosby, 1999, 2nd. Ed. pp. 44-49. [Back]

19 NIH Guidelines for Research Using Human Pluripotent Stem Cells, p. A-3. [November 21 2000]. [Back]

20 Mauro Cozzoli, The Human Embryo: Ethical and Normative Aspects, The Identity and Status of the Human Embryo, p. 271, Liberia Editrice Vaticana, 1999, second edition. [Back]

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