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 body.vi
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.
_________________
Footnotes
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.
_________________
Endnotes
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 www.bioethics.gov.
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).