|  Scientists
claim to have made remarkable progress in isolating and culturing an indispensable
and unique cell type found in animals, the stem cell. The general public
accepts that stem cell research is scientifically significant and clinically
promising. It also knows that this research has generated ethical questions.
No consensus has yet emerged on which answers are the right ones. We must
therefore describe the controversies that surround questions like the
following: What value judgments are at issue? Which of these collide?
Where collisions occur, which judgment should trump?
Before
we look at the controversies involved, let us review some of the basic
terminology to set the stage. Stem cells are best described in the context
of normal human development. When an egg is fertilized by a sperm, a single
cell is created that has the potential to grow into an entire organism.
Thus the fertilized egg is termed totipotent. After several days of dividing,
the totipotent cells begin to specialize and form a group of cells termed
a blastocyst (Fig. 1).
Prior to that point, any of the totipotent cells could be implanted into
a uterus and give rise to a fully formed organism.
The
blastocyst consists of an outer layer of cells that give rise to the placenta,
and an inner mass of cells cluster together at one pole that give rise
to the organism. A single cell from the inner mass has the potential to
give rise to virtually all tissues in an organism and is termed pluripotent.
However, it is not totipotent as it is unable to generate the placental
tissues and cannot be implanted into a uterus.
Pluripotent
stem cells have been derived from two sources. The first is embryos. In
vitro fertilization clinics usually fertilize more eggs than are necessary
for eventual implantation. These fertilized eggs are allowed to grow to
the blastocyst stage before being frozen. If cells from the inner cell
mass are obtained and pluripotent stem cells are isolated, these cells
are more commonly known as embryonic stem cells. The second source is
discarded fetuses. In this technique, fetal tissue is obtained from pregnancies
that have been terminated and cells are isolated from the germ lines before
they are plated onto culture dishes.
Pluripotent
stem cells continue to divide and undergo specialization. The next type
of stem cell is termed the multipotent cell. These cells are unable to
give rise to all tissues but can differentiate to a number of different
cell types within a particular tissue. Examples would include skin stem
cells that give rise to the majority of skin cells and the blood stem
cell that gives rise to the various cells found in our blood. These multipotent
cells have been found in child and adult tissues. If in fact we could
isolate all the different types of multipotent stem cells from adult tissues,
then there would be less urgency to use embryonic tissue and considerably
less controversy.
It
turns out, however, that to date a relatively small number of multipotent
cells have been discovered in adult tissues. For example, it has proven
difficult to isolate multipotent cells from the pancreas (to treat diabetes)
or from the brain (to treat degenerative disorders). It is easier to obtain
these types of cells from either fertilized eggs or aborted fetuses.
I
sketch four areas where rival value judgments present themselves. Three
of these concern the “sources” of stem cell research. The
first centers on the “status” or “moral standing”
of embryos and aborted fetuses. Are these morally licit sources for such
research? The second centers on questions of “complicity.”
Should researchers confine themselves to embryos and aborted fetuses that
the genetic parents themselves elect to donate for research? Or may researchers
themselves create embryos in order to disaggregate them for research?
The third concerns adult stem cells. Inasmuch as no one doubts that research
on adult stem cells is morally licit, should this sort of research receive
priority in the allocation of funds? Indeed, should they be the only source
of permitted research? Or should they remain one of several acceptable
sources, without ranking any single source as preferred? The fourth area
shifts to the political and legal contexts in which stem cell research
proceeds. How should moral judgments of what is desirable mesh with political
judgments of what is viable?
I
will describe the controversies but will not try now to evaluate them.
Let us consider a spectrum of value judgments in contention. To compare
them increases understanding of where disagreements lie.
First,
the status of fetuses and embryos. Those on the “right”
side of the spectrum extend the prohibition against murder as the “direct
and intentional killing of innocent life” to fetuses and embryos.
To regard early, indisputably innocent life as a “mere means”
to other, perhaps laudable ends (benefiting third parties) makes fetuses
and embryos “instruments.” It also may jeopardize, sooner
or later, our ability to welcome children into the world and to care for
them. Those in the “middle” often distinguish conception and
individuation, and permit certain sorts of research on embryos at the
earlier stages (before the “primitive streak” develops or
implantation occurs). They believe that the embryo is a form of human
life and entitled to a certain level of respect, e.g., we should not be
allowed to buy it or sell it. Those on the “left” deny that
we should accord value to pre-viable fetuses and to embryos. They assert
that we do not harm embryos by disaggregating them for research if there
had been no expectation of transfer to the uterus.
Second,
complicity. Those on the “right” grant that a researcher
who uses fetal tissue does not necessarily support the decision to request
or perform an abortion. They do believe, however, that a researcher who
either derives or uses stem cells from embryos is directly complicit in
destroying an embryo. In the latter case, the research protocol itself
requires an act of destruction. Those in the “middle” judge
that it is morally relevant to distinguish the destruction of embryos
that already exist as “spares” in in vitro fertilization clinics
from the creation of embryos in order to destroy them solely to benefit
third parties. Complicity in the former instance looks morally less ominous.
Those on the “left” hold that once we permit the obtaining
of cells from spare embryos in in vitro fertilization clinics, we may
also permit the creating of embryos for the purposes of research. In both
cases, we permit embryos to be a means to address the needs of others.
The key decision is to permit their use in research, whatever their origin.
Third,
the alternative of adult stem cells. Those on the “right”
accent the advances that researchers have made in their work on adult
stem cells. Everyone agrees that one advantage of using adult stem cells
is that we avoid the risk of tissue rejection when we treat a patient
with his or her own cells. Those in the “middle” are disposed
generally to accept (though sometimes reluctantly, particularly as research
on adult stem cells shows increasing promise) a verdict that many scientists
have reached. It is that adult stem cells are necessary but not sufficient
for obtaining the various cell types that clinically important areas of
research require. Those on the “left” insist that we have
not definitively established the case for limiting research to adult stem
cells, when we consider all of the likely consequences. Research that
is free to use any one of the three “sources” will maximize
the possibilities.
Fourth,
political and legal contexts. In the United States, we should
demarcate two levels. The first concerns controversies about federal funding
of stem cell research. These have consumed the bulk of disputants’
energies. Passions rise highest where taxpayer dollars figure centrally.
Disputants perceive that federal expenditures attest to society-wide convictions.
Those who occupy particular positions along the spectrum outlined above
each champion criteria for federal funding that support their own value
judgments about “sources.” The second level concerns the absence
of coordination between research permitted in the public and private sectors.
Many are disquieted that there is no society-wide oversight of research
projects. Others either welcome the status quo or appear resigned to it.
Some judge the current arrangements to be satisfactory as long as researchers
somewhere are free to pursue various possibilities. Liberty from
scrutiny allows those in the private sector to conduct research that holds
promise of achieving major breakthroughs that societal scrutiny might
well forestall. In light of societal pluralism, such scrutiny is likely
to be constraining, reflecting compromises. Others judge the present situation
to be ad hoc to a fault. They assert that publicly and privately funded
research should be somehow coordinated, while the realistic chances of
coordination seem to be distressingly slight.
Disputants
from all parts of the spectrum have concentrated on what federally funded
research should include. Comparatively little has been said about conduct
in the private sector, where currently a thousand research flowers bloom.
Some liberals especially look to the private sector for much of the most
promising and innovative research. As they see it, for the government
to issue and enforce rules that apply not only to federally funded research,
but also to all research, including privately funded research, would be
a poisonous gift. Such a step would curtail substantially the kinds of
research currently allowed in the private sector. They prefer to rely
instead on ethical standards that professional bodies most directly involved
propound, and on ethics advisory committees that Geron and the Advanced
Cell Technology group, for instance, have established. These matters are
beyond the scope of our inquiry. I add only that one may entertain certain
justified worries without indiscriminately attacking all free market research
undertakings. The results of privately funded research may not be immediately
or universally available to the general public, in the fashion that federally
funded research is. “Commercial organizations” are, after
all, designed to make money. Neither in their objectives nor in their
management are they designed to balance conflicting interests or to pay
homage to the distinctive noncommercial qualities of medical research
and medical care. At a minimum, the government should not ignore the lack
of coordination mentioned above or permit so many decisions to be made
by default.
As
we reflect on these four areas, it seems clear that no one engaged in
stem cell research can evade such ethical questions. We are bound to weigh
arguments about where to place ourselves along a spectrum, how far judgments
about abortion and stem cell research diverge, and so on. If we give these
enduring moral concerns short shrift, we enter the political fray with
undefended assumptions that we merely announce. To avoid such an outcome,
we must not grow weary of moral debates. They matter, and views taken
exert vast influence. Between those who regard embryos as equally valuable
human life and those who regard embryos as only “clumps of cells
in Petri dishes,” there is no peace. I close by offering one observation
that comes from inhabiting a particular region in the “middle.”
Is
it cogent to claim that abortion and embryonic stem cell research are
morally indistinguishable from murder? Posing so blunt a question concentrates
our thoughts. Yet it also encourages an unfortunate tendency to restrict
evaluative possibilities to a single either/or. Either we judge
abortion and the destruction of embryos to be treating fetuses and embryos
as mere means to other ends, or we judge the case for transparency to
omit too many morally relevant considerations, but then rush to the other
end, where we judge abortion and embryonic stem cell research as morally
indifferent actions in themselves, to be evaluated solely
by the benefits they bring to others. Beliefs in the middle lead us to
reject this simplifying restriction. Here one engages formidable arguments
from the “right” and the “left” and appropriates
as much as one consistently can, while retaining a distinctive vantage
point. From this point, one finds a position less cogent than many conservatives
do that extends without modification (morally, if not legally) the prohibition
of murder to the prohibition of abortion and embryonic stem cell research.
The middle point ascribes greater importance to fetuses and embryos
than many liberals do, an importance not reduced to the benefits that
research on them may bring to third parties. From this point, one permits
research on embryos conceived to enhance fertility, but which will never
be implanted. One excludes embryos created exclusively for research, where
we directly and intentionally create them, in order to disaggregate
them. Whether this region is the most fitting place to be, and what dangers
lie in locating ourselves there, are matters to be canvassed elsewhere.
top of page
|
