“Contemporary American Religion and its Global Impact”




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“Contemporary American Religion and its Global Impact”

Collegium for Advanced Studies

University of Helsinki

20 September 2007


The Stem Cell Debate

in America and Around the Globe


by


Ted Peters *


The debate over the morality of human embryonic stem (hES) cell research is a global debate. It takes place on virtually every continent. Yet, whether the debate takes place in Washington, Singapore, Shanghai, London, or Helsinki, we all address nearly the same set of scientific as well as ethical issues. In part this is due to the sheer rapidity of electronic communication. It is also due in part to wandering money, money looking for an investment location where the scientific talent is high, the research costs are low, and the legal obstructions are minimal. Finally, it is due in part to the havoc stirred up by American religious voices raised in opposition to hES research.

One particularly American accent in the 21st century global debate over stem cells is the application of religious arguments mustered to oppose elective abortion in the 1970’s. Roman Catholics and American Evangelicals have allied to oppose hES research, depicting scientists as baby killers. While the scientific community is attempting to move forward with regenerative medicine, in the public square people are arguing about elective abortion.

I describe this as the “American accent” to a conversation that is otherwise globewide. Although the scientific breakthrough of isolating hES cells happened in America, research in regenerative medicine today is taking place everywhere a laboratory can find financial support. The theological theorizing leading to religious opposition takes place at the Vatican and is exported to America. The Roman Catholics have provided the theoretical arguments, while the evangelicals are borrowing these for their political advocacy. The American accent consists of a convergence of Vatican theology, evangelical activism, and government restrictions regarding what scientists can and cannot do in the laboratory. Well, so it would appear.


* Ted Peters is Professor of Systematic Theology at Pacific Lutheran Theological Seminary and the Graduate Theological Union in Berkeley, California, USA. He co-edits the journal, Theology and Science, published by the Center for Theology and the Natural Sciences. He is author of Uskallammeko Kohdata Tulevaisuuden? (Karas—Sana Oy, Lohja, 1980). The background research for this paper was conducted in partnership with two colleagues, Karen Lebacqz and Gaymon Bennett. For a more elaborate treatment, see: Ted Peters, Playing God? Genetic Determinism and Human Freedom (Routledge, 2nd ed., 2003) and The Stem Cell Debate (Fortress Press, 2007).


Actually, the public conversation is somewhat more complicated than I have just described. It is not merely a renewed debate focused on abortion. To the listening ear it might sound like the floor of the stock market, with voices yelling in competition with one another making it difficult to hear any single voice clearly. The Vatican voice is by no means the only voice. Many others are talking, some even shouting. In what follows, I would like to filter out the noise so that we can listen to the discrete messages.

In what follows, I will first offer a concise reminder of the significance of stem cells and the science of their derivation. I will then turn to the ethical controversy in the United States. I propose that below the din we can hear arguments from within three competing ethical frameworks that are religious in character, plus a fourth that does not appear to be religious. (1) The embryo protection framework directs our attention toward the derivation of stem cells, the disaggregation of the blastocyst. (2) The nature protection framework directs our attention toward perceived threats to our humanity in the face of advancing biotechnology, so it seeks to protect human nature from scientists playing God and our society from slipping toward Brave New World. (3) The medical benefits framework focuses on the improvement of human health and well being that the science of regenerative medicine promises. The fourth, (4) the professional standards framework, mediates between the public square and the scientific laboratory. Those working on professional standards are governmental funders who, in response to the public debate, wish to support research while minimizing moral offense. Finally, I will turn from description to prescription, suggesting three foundational rules for guiding Christian thinking about the ethics of stem cell research, rules that can be shared across ethical frameworks.

Ethical frameworks are conceptual devices used to sort through and order the various ethical questions raised by stem cell research.1 Questions asked within one framework may not be answered, or even addressed, within another framework. Indeed, some questions may be specifically excluded. Like the public generally, Christians along with Jews and Muslims often operate within these ethical frameworks without understanding fully their implications. The rhetoric flying back and forth in the public debate is often colorful, acrimonious, and mean spirited. Frequently it obfuscates, making it difficult to discern just what the central issues might be and what is really at stake. By understanding all three frameworks and their implications for ethics, we will understand better why the public debate seems to be a cacophony of voices which fail to understand one another. Conscientious ethicists within America or in other parts of the world, understanding this, can better construct moral arguments that will be more comprehensive and perhaps even more persuasive.


The Science and Promise of Stem Cells


The human body is made up of millions of cells. The better part of these cells can be described as “highly differentiated.” That is, they have different, highly specialized, functions. Neural cells, heart cells, and liver cells are examples of highly differentiated cells. Each of these differentiated cells has a limited life span. During that span it is capable of dividing a certain number of times before it dies, that is, before it undergoes senescence. With each division, each differentiated cell produces two cells identical to it, two cells with the same specialized function.

Stem cells are unlike highly differentiated cells in three important respects. First, stem cells are less differentiated than other cells; their function is less highly specialized. Second, stem cells do not have such limited life spans; these cells are capable of prolonged self-renewal. Third, when stem cells divide, they not only reproduce themselves, but they produce “daughter cells” that are more highly specialized than they are. Stem cells are vital to the human body. These cells regenerate certain organ systems of the human body through the generation of new cells within those organ systems. For example, hematopoietic (i.e. blood) stem cells replenish our blood supply. When we donate blood, hematopoietic stem cells respond by accelerating the production of replacement blood cells. These are the cells from which others stem, so to speak.

Healing and growth depend on these stem cells. All people have stem cells in their bodies which are native to specific organ systems. For quite some time scientists have investigated the role these stem cells play in regenerating the tissues of those systems. In the last decade, however, something new has happened. Scientists have been able to derive stem cells in the laboratory that are not specific to particular organ systems. These stem cells offer the promise of regenerating any tissue in the body.

In 1998, for the first time, scientists derived stem cells from a human zygote (a fertilized egg). The 1998 breakthroughs took place at the University of Wisconsin where human embryonic stem (hES) cells were derived from a zygote;2 and at Johns Hopkins University where human embryonic germ (hEG) cells were derived from an aborted fetus.3 Both were funded by the Geron Corporation in California. Our discussion will focus here on the zygote derived pluripotent stem cells.

Working in vitro (“in glass”), University of Wisconsin scientists allowed the zygote to develop to the blastocyst stage—about five days. At this stage the zygote becomes a sphere of cells consisting of an outer layer of cells (the trophectoderm), hollow fluid filled cavity (the blastocoel), plus a cluster of cells inside this cavity (the inner cell mass). Breaking open the trophectoderm, scientists were able to isolate the inner cell mass, and, placing those cells into a culture medium, cause them to proliferate. Once they had divided fifty times without showing any signs of deterioration, they were dubbed “immortal” or “characterized.” The original four Wisconsin lines are to this day are still dividing and being used in experiments all over the world. Scientists named these isolated cells human embryonic stem cells (or hES cells).



The
Term: Human Embryonic Stem Cells


This naming has led to some unfortunate consequences. The term “embryonic stem cells” can be misleading in at least two ways. First, by reifying the term embryo, it implies that there is such as thing as “an embryo.” However, as a publication of the U.S. President’s Council on Bioethics has pointed out, in a strictly technical sense, “there is no such thing as ‘the embryo,’ if by this is meant a distinctive being (or kind of being) that deserves a common, reified name—like ‘dog’ or ‘elephant.’”4 From the Greek meaning “to grow,” the term “embryo,” used precisely, describes a stage of development—from fertilization until approximately the eighth week of gestation. Hence, properly speaking, in 1998 scientists derived stem cells from the zygote or the blastocyst, not the embryo. They might more properly have been called human blastocyst stem cells.

The term “embryonic stem cells” can be misleading for a second reason. The term “embryo” often evokes an image of an infant-formed creature in miniature, a creature with a head, arms, legs, etc. In fact, at the blastocyst stage the cells of the zygote are virtually undifferentiated, consisting of only two types of cells, the cells of the trophectoderm and the inner cell mass. That the blastocyst stage zygote does not yet “look like” a more developed human individual does not, in itself, constitute a salient ethical fact. An organism’s form does not determine its moral status. However, precise concepts are vital to sound and fair ethical reasoning. When forming our ethical arguments we should strive to work with precise language, even though the phrase “human embryonic stem cells” has become unavoidable.

Having noted these difficulties with the term “embryo” and with it “embryonic stem cells,” how should we proceed? These terms have become ubiquitous in the current discussion; so, it is virtually impossible to avoid using them. However, when we do use them, we should be aware of their imprecision, remaining attentive to the value of using alternative terms.


Pluripotency in Stem Cells


Now, let me return to our discussion of the promise and science of human embryonic stem cells. Recall that stem cells found in the body are native to specific organ systems. They have the potential to regenerate the tissues of that organ system; they have the potential to generate multiple different daughter cells. Because of this characteristic, these cells are described as “multipotent.” Recall also, that the stem cells found in the body can renew themselves for a prolonged period. It is thought that in vivo, or “in the body,” these cells can renew themselves and produce daughter cells throughout the life of the organism.





Human embryonic stem (hES) cells can self-renew throughout the life of the organism in vivo (the life-span of these cells is considerably shorter in vitro); hES cells appear to be capable of unlimited self-renewal in their pre-differentiated state without genetic deterioration. This characteristic is referred to in scientific literature as “immortality.” In addition, whereas stem cells found in the body are multipotent, ex vivo hES cells are “pluripotent.” They have the potential to produce all cell and tissue types in the human body. 5 Hence, unlike stem cells found in the body, which regenerate the tissues of specific organ systems, hES cells hold out the promise of being able to rejuvenate any and all tissues.

If a scientist could guide stem cells to become specific tissues and develop means of transplanting these cells into the body, stem cell therapy would not merely stop deterioration of a part of our body due to disease or injury; it would regenerate tissue to levels of health and strength that represent our ‘normal’ expectations. Medical researchers hope to discover regenerative therapies for heart disease, liver disease, diabetes, spinal cord injury and paralysis, Parkinsons, Alzheimers; and in related research, nearly every type of cancer. The potential global impact of regenerative medicine is staggering.


Stem Cells and Cloning


The controversy over stem cells has been complicated by its entanglement with the controversy over cloning. The confusion engendered by this entanglement calls for clarification. The two controversies come together on the issue of immune rejection. If we were to coax hES cells to become differentiated neural cells, and if we were to implant those cells into a patient, that patient’s immune system would likely put up a blockade and fight off an invasion of what, genetically speaking, are foreign cells. This problem of immune rejection, or ‘histocompatibility,’ represents a significant technical hurdle that scientists will need to clear if the promise of hES cell transplantation is to be realized. (Our experience with organ transplants demonstrates how serious a problem histocompatibility can be.) If, however, the stem cells could be made with the exact genetic code of the recipient, then the transplant-recipient’s body would welcome the new cells as its own. The technology of cloning appears to offer the possibility to achieve just such a patient-sepcific match.





The process looks like this. The laboratory researcher would begin with a woman’s egg, an oocyte, and remove the DNA nucleus. Then using the technique of somatic cell nuclear transfer (SCNT or NT for short) developed in the Dolly experiments, a DNA nucleus taken from a skin cell or some other somatic cell in the future recipient’s body would be rendered quiescent and then transferred to this enucleated oocyte. The egg would then possess a full complement of DNA, the very DNA of the future recipient. The egg would be activated, and at five days or so the stem cells would be harvested. They would be teased into becoming heart tissue or liver tissue or whatever is needed. They would be placed into the patient’s body. The stem cells would then regenerate whatever organ welcomes them home. This technique is called “therapeutic cloning” and promises perhaps the best way to overcome the problem of immune rejection. It is generally distinguished from “reproductive” cloning, which would be the use of somatic cell nuclear transfer to generate a child.

The addition of therapeutic cloning to stem cell research, however, advances another set of ethical issues. Not only must the ethics of stem cells deal with the problem of destruction of a blastocyst, but it must also deal with the deliberate creation in the laboratory of a new “embryo” that is slated for destruction. Some people believe that the deliberate creation of an embryo with intent to destroy it is an even more serious ethical issue than the destruction of embryos that were already “slated for death” because they would not be implanted during the IVF process.

The goal of experiments with SCNT or therapeutic cloning is a patient-specific genetic match. Might there be another way? Suppose we could take a cell from the patient and reprogram it so that its DNA would become pluripotent? It is the interaction of the DNA with the cytoplasm that precipitates gene expression; so, might we be able to create just the right interaction that would lead to pluripotency? Such experiments have been successful in mice. Early in 2007 Shinya Yamanaka of Kyoto University accomplished the key reprogramming task. From a skin cell she was able to create a blastocyst and draw off a line of pluripotent cells.6

The next steps in research might go two directions. One direction would be to try cytoplasmic reprogramming on human skin cells, a parallel with what has been accomplished with mouse skin cells. The other would be to place human DNA into a mouse fibroblast, and ask the DNA to reprogram the cytoplasm so as to produce a blastocyst with an inner mass of human pluripotent cells. The latter method would involve chimerism, the mixing of tissue of a human and a nonhuman animal to make hES cells. These three directions of research—therapeutic cloning, cytoplasmic reprogramming of a patient’s own cells, and chimerism—are aimed at establishing a histocompatible cell line that will provide a genetic match for a specific patient.

This, in brief, is the science and promise of regenerative medicine. We turn now to the three ethical frameworks that have structured—and, in my view limited—the public debate in America over stem cells.

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