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Monitoring Stem Cell Research

Table of Contents

The President's Council on Bioethics
Washington, D.C.
January 2004

Chapter One


This monitoring report has its origins in President George W. Bush’s remarks to the nation on August 9, 2001. It was his first major national policy address, and the topic was unusual: federal funding of research on human stem cells.i In the speech, the President announced that after several months of deliberation he had decided to make federal funding available, for the first time, for research involving certain lines of embryo-derived stem cells. At the end of the speech the President declared his intention to

name a President’s Council to monitor stem cell research, to recommend appropriate guidelines and regulations, and to consider all of the medical and ethical ramifications of biomedical innovation. . . . This council will keep us apprised of new developments and give our nation a forum to continue to discuss and evaluate these important issues.1

In keeping with the President’s intention, the Council has been monitoring developments in stem cell research, as it proceeds under the implementation of the administration’s policy. Our desire has been both to understand what is going on in the laboratory and to consider for ourselves the various arguments made in the ongoing debates about the ethics of stem cell research and the wisdom of the current policy. Although both the policy and the research are still in their infancy, the Council is now ready to give the President and the public an update on this important and dynamic area of research.

This report is very much an “update.” It summarizes some of the more interesting and significant recent developments, both in the basic science and medical applications of stem cell research and in the related ethical, legal, and policy discussions. It does not attempt to be a definitive or comprehensive study of the whole topic. It contains no proposed guidelines and regulations, nor indeed any specific recommendations for policy change. Rather, it seeks to shed light on where we are now—ethically, legally, scientifically, and medically—in order that the President, the Congress, and the nation may be better informed as they consider where we should go in the future.

I. What Are Stem Cells, and Why Is There Contention about Them?

The term “stem cells” refers to a diverse group of remarkable multipotent cells. Themselves relatively undifferentiated and unspecialized, they can and do give rise to the differentiated and specialized cells of the body (for example, liver cells, kidney cells, brain cells). All specialized cells arise originally from stem cells, and ultimately from a small number of embryonic cells that appear during the first few days of development.ii As befits their being and functioning as progenitor cells, all stem cells share two characteristic properties: (1) the capacity for unlimited or prolonged self-renewal (that is, the capability to maintain a pool of similarly undifferentiated stem cells), and (2) the potential to produce differentiated descendant cell types. As stem cells within a developing human embryo differentiate in vivo, their capacity to diversify generally becomes more limited and their ability to generate many differentiated cell types generally becomes more restricted.

Stem cells first arise during embryonic development and exist at all developmental stages and in many systems of the body throughout life. The best described to date are the blood-forming (hematopoietic) stem cells of the bone marrow, the progeny of which differentiate (throughout life) into the various types of red, white, and other cells of the blood. It appears that some stem cells travel through the circulatory system, from their tissue of origin, to take up residence in other locations within the body, from which they may be isolated. Other stem cells may be obtained at birth, from blood contained in the newborn’s umbilical cord. Once isolated and cultured outside the body, stem cells are available for scientific investigation. Unlike more differentiated cells, stem cells can be propagated in vitro for many generations—perhaps an unlimited number—of cell-doublings.

Stem cells are of interest for two major reasons, the one scientific, the other medical. First, stem cells provide a wonderful tool for the study of cellular and developmental processes, both normal and abnormal. With them, scientists hope to be able to figure out the molecular mechanisms of differentiation through which cells become specialized and organized into tissues and organs. They hope to understand how these mechanisms work when they work well, and what goes wrong when they work badly. Second, stem cells and their derivatives may prove a valuable source of transplantable cells and tissues for repair and regeneration. If these healing powers could be harnessed, the medical benefits for humankind would be immense, perhaps ushering in an era of truly regenerative medicine. No wonder that scientists around the world are actively pursuing research with stem cells.

Why, then, is there public contention about stem cell research? Not because anyone questions the goals of such research, but primarily because there are, for many people, ethical issues connected to the means of obtaining some of the cells. The main source of contention arises because some especially useful stem cells can be derived from early-stage human embryos, which must be destroyed in the process of obtaining the cells. Arguments about the ethics of using human embryos in research are not new. They date back to the mid-1970s, beginning not long after in vitro fertilization (IVF) was first successfully accomplished with human egg and sperm in 1969. A decade later, after IVF had entered clinical practice for the treatment of infertility, arguments continued regarding the fate and possible uses of the so-called “spare embryos,” embryos produced in excess of reproductive needs and subsequently frozen and stored in the assisted-reproduction clinics. Although research using these embryos has never been illegal in the United States (except in a few states), the federal government has never funded it, and since 1995 Congress has enacted annual legislation prohibiting the federal government from using taxpayer dollars to support any research in which human embryos are harmed or destroyed.

Although the arguments about embryo research had been going on for twenty-five years, they took on new urgency in 1998, when the current stem cell controversy began. It was precipitated by the separate publication, by two teams of American researchers, of methods for culturing cell lines derived, respectively, from: (1) cells taken from the inner cell mass of very early embryos, and (2) the gonadal ridges of aborted fetuses.2,3 (In this report, we shall generally refer to the cell lines derived from these sources as, respectively, embryonic stem cells [or “ES cells”] and embryonic germ cells [or “EG cells”].) This work, conducted in university laboratories in collaboration with and with financial support from Geron Corporation, prompted great excitement and has already led to much interesting research, here and abroad. It has also sparked a moral and political debate about federal support for such research: Is it morally permissible to withhold support from research that holds such human promise? Is it morally permissible to pursue or publicly support (even beneficial) research that depends on the exploitation and destruction of nascent human life?

Persons interested in the debate should note at the outset that ES and EG cells are not themselves embryos; they are not whole organisms, nor can they be made (directly) to become whole organisms. Moreover, once a given line of ES or EG cells has been derived and grown in laboratory culture, no further embryos (or fetuses) need be used or destroyed in order to work with cells from that line. But it is not clear whether these lines can persist indefinitely, and only very few lines, representing only a few genetic backgrounds, have been made. Thus there is continuing scientific interest in developing new embryonic stem cell lines, and the existence of large numbers of stored cryopreserved embryos in assisted-reproduction clinics provides a potential source for such additional derivations. Complicating the debate has been the study of another group of stem cells, commonly called “adult stem cells,” derived not from embryos but from the many different tissues in the bodies of adults or children—sources exempt from the moral debate about obtaining ES and EG cells. For this reason, we often hear arguments about the relative scientific merits and therapeutic potential of embryonic and adult stem cells, arguments in which the moral positions of the competing advocates might sometimes influence their assessments of the scientific facts. Further complicating the situation are the large commercial interests already invested in stem cell research and the competition this creates in research and development not only in the United States but throughout the world. The seemingly small decision about the funding of stem cell research may have very large implications.

II. Broader Ethical Issues

While most of the public controversy has focused on the issue of embryo use and destruction, other ethical and policy issues have also attracted attention.iii Although entangled with the issue of embryos, the question of the significance and use of federal funds is itself a contested issue: Should moral considerations be used to decide what sort of research may or may not be funded? What is the symbolic and moral-political significance of providing national approval, in the form of active support, for practices that many Americans regard as abhorrent or objectionable? Conversely, what is the symbolic and moral-political significance of refusing to support potentially life-saving scientific investigations that many Americans regard as morally obligatory?

Even for those who favor embryo research, there are questions about its proper limits and the means of establishing and enforcing those limits through meaningful regulation. Under the present arrangement, with the federal government only recently in the picture, what is done with human embryos, especially in the private sector, is entirely unregulated (save in those states that have enacted special statutes dealing with embryo or stem cell research). Is this a desirable arrangement? Can some other system be devised, one that protects the human goods we care about but that does not do more harm than good? What are those human goods? What boundaries can and should we try to establish, and how?

Although well-established therapies based on transplantation of stem cell-derived tissues are still largely in the future, concern has already been expressed (as it has been about other aspects of health care in the United States) about access to any realized benefits and about research priorities: Will these benefits be equitably available, regardless of ability to pay? How should the emergence of the new field of stem cell research alter the allocation of our limited resources for biomedical research? How, in a morally and politically controverted area of research, should the balance be struck between public and private sources of support? As with any emerging discovery, how can we distinguish between genuine promise and “hype,” and between the more urgent and the less urgent medical needs calling out for assistance?4

There are also sensitive issues regarding premature claims of cures for diseases that are not scientifically substantiated and the potential exploitation of sick people and their families. Some advocates of stem cell research have made bold claims about the number of people who will be helped should the research go forward, hoping to generate sympathy for increased research funding among legislators and the public. A few advocates have gone so far as to blame (in advance) opponents of embryonic stem cell research for those who will die unless the research goes forward today. At the same time, other scientists have cautioned that the pace of progress will be very slow, and that no cures can be guaranteed in advance. Which of these claims and counterclaims is closer to the truth cannot be known ahead of time. Only once the proper scientific studies are conducted will we discover the potential therapeutic value of stem cells from any source. How, then, in the meantime should we discuss these matters, offering encouragement but without misleading or exploiting the fears and hopes of the desperately ill?

Finally, questions are raised by some about the social significance of accepting the use of nascent human life as a resource for scientific investigation and the search for cures. Such questions have been raised even by people who do not regard an early human embryo as fully “one of us,” and who are concerned not so much about the fate of individual embryos as they are about the character and sensibilities of a society that comes to normalize such practices.5 What would our society be like if it came to treat as acceptable or normal the exploitation of what hitherto were regarded as the seeds of the next generation? Conversely, exactly analogous questions are raised by some about the social significance of refusing to use these 150-to-200-cell early human embryos as a resource for responsible scientific investigation and the search for cures. What would a society be like if it refused, for moral scruples about (merely) nascent life, to encourage every thoughtful and scientifically sound effort to heal disease and relieve the suffering of fully developed human beings among us?6

It is against the background of such moral-political discussion and argument that the Council has taken up its work of monitoring recent developments in stem cell research. We are duly impressed with the difficulty of the subject and the high stakes involved. All the more reason to enable the debate to proceed on the basis of the best knowledge available, both about science and medicine and about ethics, law, and policy. Before proceeding to the results of our monitoring, we complete this introduction with some additional comments on the different types of stem cells, a few terminological observations and clarifications, and an overview of the report as a whole.

III. Types of Stem Cells: An Introduction

Although we shall report later (in Chapter 4) on recent developments in basic and clinical research using various types of stem cells, we think the following introduction to the “cast of characters” would be useful at the start.iv

A. Embryonic Stem (ES) Cells

As noted above, ES cells are derived from the inner cell mass of embryos at the blastocyst stage, roughly five to nine days after fertilization—after the zygote has divided enough times to result in about 200 cells, but before it has undergone gastrulation and differentiation into the three primary germ layers (see Appendix A).v The inner cell mass is the part of the blastocyst-stage embryo whose cells normally go on to become the body of the new individual. The outer cells of the blastocyst-stage embryo (the trophoblast cells) normally (that is, in vivo) go on to become the fetal contribution to the placenta and other structures that connect the developing individual to the mother’s bloodstream and that otherwise support the embryo’s further development. Collecting the cells of the inner cell mass results in the destruction of the developing organism. The embryos from which human stem cells can be derived are available (so far) only from in vitro fertilization (IVF): they have been conceived by a combination of egg and sperm, occurring outside the

B. Embryonic Germ (EG) Cells

EG cells are stem cells that are isolated from the gonadal ridge of a developing fetus. These are the cells that ultimately give rise to sperm cells or egg cells, depending on the sex of the fetus. The EG cells are collected from the bodies of five-to-nine-week-old fetuses that have been donated after induced abortions.vii In federally funded research, collection of the EG cells is governed by existing federal regulations for fetal-tissue donation, designed (among other things) to ensure the separation of the decision to terminate pregnancy from the decision to donate the fetal tissue for research.7

Cell lines established from either of these two sources (ES and EG cells, from embryos and fetal gonads, respectively) have demonstrated two important properties: great ability to multiply and form stable lines that can be characterized, and great flexibility and plasticity. Their progeny can differentiate in vitro into cells with characteristics of those normally derived from all three embryonic germ layers (ectoderm, endoderm, and mesoderm), which layers (in vivo) give rise in turn to all the different types of cells in the body. Because they are so flexible, it also seems likely that they could be used to produce cell preparations that could then be transplanted (assuming that the recipient’s immune response could be managed) to repopulate a part of the body such as the pancreas or spinal cord that has lost function due to disease or injury. As with stem cells derived from the various tissues of the adult body, ES cells and EG cells seem to hold out hope for an era of regenerative medicine.

C. Adult (or Non-embryonic) Stem Cells

Adult stem cells are more differentiated than ES or EG cells, but not yet fully differentiated. Like stem cells of embryonic origin, they can give rise to lineages of cells that are more specialized than themselves. The term “adult” is a bit of a misnomer (“non-embryonic” would be more accurate): these cells are found in various tissues in children as well as adults (and in fetuses as well), and they have been isolated from umbilical cord blood at the time of delivery. Despite its inaccuracy regarding the origin of the cells, the term “adult” helpfully emphasizes that the cells have been partially differentiated. Although they can give rise to various cell types, these non-embryonic stem cells are generally all within the same broad type of tissue (for example, muscle stem cells, adipose stem cells, neural stem cells). For this reason, it had long been thought that they are less flexible than those derived from embryos or fetal gonads. Yet this presumption has been disputed in recent years by those who think that certain forms of adult stem cells may be equally or nearly as plastic as non-adult stem cells. Indeed, possible exceptions to the generalization that adult stem cells give rise only to cell types found within their own broad type of tissue have recently been reported (though most of these cells may well be shorter-lived than ES cells, and, if so, potentially less useful in therapy). This finding has ignited a debate about the relative merits of embryonic stem cells and adult stem cells: which is more valuable, both for research and (especially) for clinical treatment?viii

Research involving adult stem cells raises few difficult ethical concerns, beyond the usual need to secure free and fully informed consent from donors and recipients, a favorable benefit-to-risk ratio for all participants in attempts at therapy and protection of privacy. Adult stem cells are less controversial than embryonic ones, as we have noted, because the former can be collected without lasting harm to the donor.

D. Cord Blood Stem Cells

Though clearly a type of non-embryonic stem cell, cord blood stem cells deserve some special mention. Blood found in the umbilical cord can be collected at birth and hematopoietic stem cells (and other progenitor cells) isolated from it. It has been proposed that individually banked cord blood cells may, at some later time, offer a good match for a patient needing stem cell-based treatments, whether the individual cord-blood-donor himself or a close relative, and in unrelated recipients may require a less exact genetic match than adult bone marrow. ix ,x

IV. Terminology

In considering complicated or contested public questions, language matters—even more than it ordinarily does. Clear thinking depends on clear ideas, and clear ideas can be conveyed only through clear and precise speech. And fairness in ethical evaluation and judgment depends on fair framing of the ethical questions, which in turn requires fair and accurate description of the relevant facts of the case at hand. Such considerations are highly pertinent to our topic and to the arguments it generates.

Confounding the discussions of stem cell research, there are, to begin with, difficult technical concepts, referring to complicated biological entities and phenomena, that can cause confusion among all but the experts. Some of these concepts we will clarify in Chapter 4, and others are defined in the Glossary and, in some cases, illustrated in Appendix A on early embryonic development. But the more important terminological issues are those used to formulate the ethical and policy issues about which people so vigorously disagree. We pause to comment on three of them: “the embryo” (or “the human embryo”), “spare embryos,” and “the moral status of the embryo.”

Strictly speaking, 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.” Rather, the term properly intends a certain stage of development of an organism of a distinctive kind. Indeed, the very term comes from a Greek root meaning “to grow”: an embryo is, by its name and mode of being, an immature and growing organism in an early phase of its development.xi The advent of in vitro fertilization, in which living human embryos from their first moments are encountered as independent entities outside the body of a mother, before human eyes and in human hands, may also have contributed to this tendency to reify “the embryo” in its early stages (though such reification has likely always played a role in embryology). The ex vivo existence of nascent human life is genuinely puzzling and may invite terminology that can be distorting.xii

If the term “the embryo” risks conveying the false notion that embryos are distinct kinds of beings or things, the term “spare embryo” risks making a difficult moral question seem easier than it is. The term is frequently used to describe those embryos, produced (each with reproductive intent, but in excess of what is needed) in assisted-reproduction clinics, that are not transferred to a woman in attempts to initiate a pregnancy. No longer needed to produce a child, they are usually frozen and stored for possible later use, should the first efforts fail. But the “spareness” of a “spare embryo” is not a property of a particular embryo itself; it bespeaks rather our attitude toward it, now that it may no longer be needed to serve the purpose for which it was initially brought into being. Calling something “spare,” or only “extra,” invites the thought that nothing much is lost should it disappear, because one already has more than enough: one has “embryos to spare.” It also abstracts from the distinct genetic individuality of each embryo and invites the view that embryos are, like commercial products, simply interchangeable—an outlook that may affect the further judgment of any embryo’s moral standing. To be sure, most of these unused embryos will die or be destroyed. To be sure, if these unused embryos are otherwise destined for destruction, a case can be made—and debated—that their unavoidable loss should be redeemed by putting them to use beforehand. But the moral question regarding their possible use and destruction should not be decided—here, as elsewhere—on terminological grounds, in this case, by the naming of the embryo “spare.” Rather it should be decided on the basis of a direct moral appraisal of the rights and goods involved: on the basis of what we owe to suffering humanity and the obligations we have to seek the means of its relief; and on the basis of the nature of human embryos, what we owe them as proper respect and regard, and whether and why such respect or regard may be overridden.xiii For many people, the moral question depends, in other words, on what some bioethicists call—and we ourselves will sometimes call—“the moral status of the embryo.” If embryos lacked all “moral status,” there would be little moral argument about their use and destruction.

Yet the notion “moral status” is problematic, even though it is easy to understand why it has come into fashion. For many people, the central ethical question regarding embryonic stem cell research is whether an embryonic organism from which cells may be removed to develop ES cells is fully “one of us,” deserving the same kind of respect and protection as a newborn baby, child, or adult. What they want to know is the moral standing of these organisms—entities that owe their existence, their extra-uterine situation, and their “spare-ness” to deliberate human agency—at such early stages of development. As we shall see, some people try to find structural or functional markers—for example, the familiar human form or the presence or absence of sensation—to decide the moral worth of a human embryo. Others use an argument from continuity of development to rebut any attempt to find a morally significant boundary anywhere along the continuum of growth and change. But, to judge from countless efforts to provide a biologically based criterion for ascribing full human worth, it seems certain that we shall never find an answer to our moral question in biology alone, even as the answers we give must take into account the truths of embryology. At least until now, philosophical attempts to draw moral inferences from the biological facts have not yielded conclusions that all find necessary or sound.

Under these circumstances, some people believe that we have no choice but to stipulate or ascribe some degree of moral “status” to the entity, based either on how it strikes us and the limited range of what we are able to know about it, or on what we wish to do with it: we confer upon it some moral status in regard to us, much as we confer one or another class of immigration status upon people.8 For this very reason, others object to the term, fearing that it enables us to beg the question of the intrinsic moral worth or dignity of the entity itself, seen in its own terms and without regard to us. Different Members of this Council hold different views of this terminological and ontological matter, but we all recognize the moral freight carried by attempts to speak about and ascribe “moral status” to human embryos in their earliest stage of development.xiv We encourage readers to be self-conscious about this and similar terms, even as we proceed ourselves to make use of them.

V. About the Report

Monitoring stem cell research can be a bit like watching Niagara Falls. Not only do scientific reports pour forth daily, as they do in many other areas of research, but a kind of mist rises up for the torrent of news flashes and editorials, making it difficult to separate knowledge from opinion and hope from hype. The underlying biology—whether viewed at the level of the gene, cell, tissue, organ, or organism—is dauntingly complex, as is all cell biology. At any of these levels, in this new and dynamic field, it is frequently difficult for even the most knowledgeable scientist to be truly certain of “what really causes what.” For example, how exactly do certain kinds of stem cells have their apparently beneficial effects on heart disease when the cells are extracted from a cardiac patient’s bone marrow or muscle, expanded in culture, and injected into the patient’s heart? Or what is responsible for the positive effects on a Parkinson Disease patient when cells from his own brain are similarly extracted, treated, and re-injected? We do not yet really know precisely what stem cell-based preparations do when put into the body.

At the same time, all discussion in this area suffers from a persistent background tension. The stakes are high, or seem so, to many of the discussants, and there is much politicking involved. As noted earlier, opponents of embryo research try to tout the virtues of adult stem cells, because they regard their use as a morally permissible alternative. Proponents, for their part, often find it tempting to disparage or downplay all adult stem cell studies and to emphasize instead what they believe to be the superior potential of embryonic stem cells for successful future therapeutic use. Navigating between these tendencies in search of the full truth can be daunting, and few people are altogether immune to the partial but seductive calls from the scientific or moral side they prefer.

Yet without denying our individual differences on the ethical and policy questions at issue, the Council has sought in this monitoring report to present a fair-minded and thorough overview, both of the ethical and policy debates and of the scientific and medical results to date. To aid us in our task of monitoring, we have commissioned six review articles and heard several oral presentations on the state of research, covering studies using embryonic and studies using adult stem cells. We have commissioned a review article and heard a presentation on the problem of immune rejection, a potential major stumbling block to effective cell transplantation therapies.
We have read papers, commissioned writings, heard presentations, and debated among ourselves about the various ethical and philosophical issues involved, from “the moral status of the embryo,” to the existence of a moral imperative to do research, to the meaning of federal funding of morally controversial activities. We have read and heard public testimony from both supporters and opponents of the current policy on federal funding of ES cell research.

We have considered arguments—presented by scientists and patient-advocacy groups, and shared by some Members of the Council—that the current policy is impeding potentially life-saving research, for example, by offering researchers too few useful ES cell lines to work with, by causing a chilling effect on the whole field, or by allowing the field to be dominated by private companies, less given (than are publicly-funded academic scientists) to publishing and sharing the results of their research. We have considered arguments—presented by various critics and opponents of embryonic stem cell research, and shared by some Members of the Council—that the current policy has opened the path toward the possibility of “embryo farming” or that it risks weakening our respect for nascent life and our willingness to protect the weakest lives among us. We have heard from ethicists and scientific researchers, representatives of biopharmaceutical companies and disease research foundations, and senior government officials from such agencies as the National Institutes of Health and the Food and Drug Administration. We benefited from working papers prepared by the Council’s staff and from existing reports on stem cell research, and in particular reports by the National Bioethics Advisory Commission (1999) and the National Academies (2001).9 Holding our own personal views in abeyance, we have tried in the three chapters that follow to synthesize accurately and fairly what we have heard and learned: about current law and policy, about the state of the ethical debate, and about the current state of scientific research.

Chapter 2, “Current Federal Law and Policy,” describes and explains the current federal policy regarding stem cell research. It locates that policy in relation to previous law and policy touching this area of research and tries to make clear the ethical, legal, and prudential foundations on which the policy rests. It then describes the implementation of the policy and other relevant considerations. Our goal in that chapter is to describe and understand the present policy situation, in its legal, political, scientific, and ethical colorations, and to present accurately the various features of the current federal policy, many of which are not generally well understood.

Chapter 3, “Recent Developments in the Ethical and Policy Debates,” provides an overview of the ethical and policy debates surrounding stem cell research in the past two years. Special attention is, of course, given to arguments about what may (or may not) be done with human embryos, and why. But those arguments are also reviewed in relation to larger debates about the other ethical and policy issues mentioned earlier. Our goal in that chapter is to present the arguments and counter-arguments, faithfully and accurately, rather than finally to assess their validity.

Finally, in Chapter 4, “Recent Developments in Stem Cell Research and Therapy,” we offer an overview of some recent developments in the isolation and characterization of various kinds of stem cell preparations and a partial account of some significant research and clinical initiatives. In addition, by means of a selected case study, we consider how stem cell-based therapies might some day work to cure devastating human diseases, as well as the obstacles that need to be overcome before that dream can become a reality. Our goal in that chapter, as supplemented by several detailed commissioned review articles contained in the appendices, is to enable (especially non-scientific) readers to appreciate the reasons for the excitement over stem cell research, the complexities of working with these materials, some early intriguing research and therapeutic findings, and the difficult road that must be traveled before we can reap therapeutic and other benefits from this potentially highly fertile field of research.

After these three substantive chapters—on policy, ethics, and science—we offer a Glossary and a series of appendices, beginning (in Appendix A) with a brief primer on early human embryonic development. That primer aspires to provide the basic facts and concepts that any thoughtful and public-spirited person needs to know about human development and especially about (early) human embryos if he or she is to participate intelligently in the ethical and political deliberations that are certain to continue in our society for some time. There follow the texts of President Bush’s August 9, 2001, stem cell speech and the NIH guidelines (for both the Clinton and Bush administrations) regarding the funding of embryonic stem cell research. Completing the appendices are the texts of all the papers that the Council commissioned, as revised by their authors in light of subsequent developments or comments received. These papers appear in the authors’ own words, unedited by the Council.

In all that we offer in this monitoring report, we have aspired to be careful and fair in our approach, precise in our use of language, accurate in presenting data and arguments, and thoughtful in our laying out of the various issues that remain before us. It is up to our readers to judge whether or not we have succeeded. The policy debates over stem cell research that led to the creation of this Council continue; they, and other debates on related topics, are unlikely to go away any time soon. Our hope is that our work will help to make those debates richer, fairer, and better informed.



i. Throughout this report, excluding appendices, all references to embryos, cells, or other biological materials are assumed to be of human origin unless otherwise stated.

ii. These cells are grouped together as the “inner cell mass” of the embryo, at the blastocyst stage of its development. Readers should consult the Glossary for definitions of technical terms and Appendix A for an illustrated guide to the embryonic developments referred to in this report.

iii. Introduced here, these issues and the discussions they have produced will be reviewed in Chapter 3.

iv. The remarks about embryo-derived cells presented in the next two sections apply to human embryonic stem cells, as opposed to, say, mouse embryonic stem cells (which will be referred to in several places because they have provided the basis for much of what we now know about embryonic stem cells).

v. In this report, we will not call the cells contained in the inner-cell-mass “stem cells,” so long as they remain inside the intact embryo. We reserve the term “stem cells” for those cells that are successfully cultured outside the embryo, following artful derivation, and that demonstrate the characteristic capacities of “stemness”: a capacity for self-renewal and a capacity for differentiation. Inner-cell-mass cells may or may not be identical to ES cells, though in an intact embryo the inner-cell-mass cells are still part of a nascent organic whole. Indeed, it is important to remember that the developmental fate of all cells inside the body is in part a function of their location within the larger whole and of the influences of the local embryonic environments to which they are subject.

vi. As of this writing, experiments in asexual methods of conceiving a human embryo, such as parthenogenesis or cloning, have not, to our knowledge, been successful beyond the very early stages of development. Embryos, fertilized in vivo, could also be procured for use in research by flushing them from the womb, but this procedure, though technically feasible, has a very low yield and is rarely done.

vii. Abortion is legal throughout the United States, pursuant to a series of federal Supreme Court decisions, the most important cases being Roe v. Wade (1973) and Casey v. Planned Parenthood (1992).

viii. We shall review recent work with both kinds of cells in Chapter 4. Anticipating the implications of that discussion, we may safely say that not enough is known to answer this empirical question. Work with both kinds of cells seems promising. Some people argue that research with non-embryonic stem cells, being a morally unproblematic path, should be given priority. Most researchers, meanwhile, support the advancement of work with both kinds of cells simultaneously, to explore their potential.

ix. Several companies in the United States have sprung up to offer commercial storage services for cord blood in case the child or a closely genetically-matched sibling should later need the stem cells contained in the cord blood for medical use. It is unclear whether individual banking of cord blood will turn out to be valuable. It may turn out that, for the vast majority of people, the cells are never needed, or that, when therapy is needed, the stored cells are found to be unsuitable or incapable of meeting the need in the time required. At the same time, Congress has recently allocated funds to create a national non-commercial cord blood bank potentially available to all patients. The authors of the legislation argue that a national bank would have cord blood of many different types, increasing the odds that a patient would find a match.

x. The possibility of therapeutic use of cord blood stem cells has raised a serious question unrelated to the ethics of stem cell research: whether parents of a sick child may morally conceive another child, of genetic make-up appropriate for providing compatible cord blood cells, primarily to treat the first child. In generating the second child, a prospective parent or parents might screen preimplantation embryos for genetic suitability to provide the cells (both compatible blood type and freedom from the genetic disease affecting the older sibling). These and other ethical questions surrounding preimplantation genetic diagnosis (PGD) go beyond our present subject and will not be considered further in this report.

xi. In classical embryology, “embryo” is the name given—somewhat arbitrarily—to the developing human organism from the time of fertilization until roughly eight weeks, the time that the first calcification of bone occurs. After that, the developing human organism is called a “fetus,” equally a reified name for a dynamic entity, an entity-in-the-process-of-becoming-more-fully-the-kind-of-organism-it-already-is.

xii. The Council is well aware of the fact that the debate about abortion shadows all these discussions about “embryos.” Yet in all of our work to date, on cloning and stem cell research, we have called attention to the fact that we face a rather different moral situation when we are dealing with embryos in the laboratory, in the absence of concerns for a pregnant woman’s life and future. Accordingly, we explore the ethical issues of embryo research by addressing what we know (and how we know) about ex vivo human embryos, separate from any issues that enter when the interests of pregnant women are engaged.

xiii. Some Members of this Council (including Alfonso Gómez-Lobo and Robert George) hold that the moral question should be decided on the basis of the prior consideration of the rightness or wrongness of intentionally destroying human beings for the sake of further goals, and then on whether or not human embryos are human beings in the relevant sense.

xiv. It is, of course, possible to hold the view that the earliest human embryos have no moral status or worth, because they are so small and undifferentiated or because they lack the ordinary human shape and form or the specifically human capacities for sensation or consciousness or the capacity to develop on their own ex vivo. Some of these arguments are reviewed in Chapter 3. Here it suffices to observe that at least one Member of this Council (Michael Gazzaniga) holds this view.



1. “Remarks by the President on Stem Cell Research,” Crawford, Texas, August 9, 2001. Text made available by the White House Press Office, August 9, 2001. (Also available in full at Appendix B of this report.)

2. Thomson, J., et al., “Embryonic stem cell lines derived from human blastocysts,” Science 282: 1145-1147 (1998).

3. Shamblott, M., et al., “Derivation of pluripotent stem cells from cultured human primordial germ cells,” Proceedings of the National Academy of Science 95: 13726-13731 (1998).

4. See, among others, Dresser, R., “Embryonic Stem Cells: Expanding the Analysis,” American Journal of Bioethics 2(1): 40-41 (2003); and the personal statements of Council Members Rebecca Dresser and William May, appended to the Council’s July 2002 report Human Cloning and Human Dignity: An Ethical Inquiry.

5. See, among others, Kass, L., “The Meaning of Life – In the Laboratory,” The Public Interest, Winter 2002; Cohen, E., “Of Embryos and Empire,” The New Atlantis 2: 3-16 (2003); and “The Moral Case against Cloning-for-Biomedical-Research” presented by some Members of the Council in the Council’s July 2002 report Human Cloning and Human Dignity: An Ethical Inquiry, Chapter 6.

6. See, for instance, “The Moral Case for Cloning-for-Biomedical-Research” presented by some Members of the Council in the Council’s July 2002 report Human Cloning and Human Dignity: An Ethical Inquiry, Chapter 6; and the personal statements of Council Members Elizabeth Blackburn, Daniel Foster, Michael Gazzaniga, and Janet Rowley appended to that report.

7. 45 C.F.R. § 46.204(h-i).

8. See, for instance, Green, R., The Human Embryo Research Debates, New York: Oxford University Press (2001). Also see the discussion of the Council in its October 17, 2003, meeting, particularly the comments of Council Member Alfonso Gómez-Lobo. A transcript of that session is available on the Council’s website at

9. National Bioethics Advisory Commission (NBAC), Ethical Issues in Human Stem Cell Research, Bethesda, MD: Government Printing Office (1999); National Research Council/Institute of Medicine (NRC/IOM), Stem Cells and the Future of Regenerative Medicine, Washington, D.C.: National Academy Press (2001).




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