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STEM CELL CONTROVERSY
The status of the human embryo and
human embryonic stem cell research is a controversial issue as, with the
present state of technology, the creation of a human embryonic stem cell
line requires the destruction of a human embryo. Stem cell debates have
motivated and reinvigorated the ‘pro-life’ movement whose members have
concerned themselves with the rights and status of the embryo as an
early-aged human life. They believe that embryonic stem cell research
instrumentalizes and violates the sanctity of life and constitutes
murder . The fundamental assertion of those who oppose embryonic stem
cell research is the belief that human life is inviolable, combined with
the opinion that human life begins when a sperm cell fertilizes an egg
cell to form a single cell.
Most stem cell researchers use embryos that were created but not used in
in vitro fertility treatments to derive new stem cell lines. Most of
these embryos are slated to be destroyed, or stored indefinitely. In the
United States alone, there have been estimates of at least 400,000 such
embryos. This has led some opponents of abortion, such as Senator Orrin
Hatch, to support human embryonic stem cell research.
Medical researchers widely submit that stem cell research has the
potential to dramatically alter approaches to understanding and treating
diseases, and to alleviate suffering. In the future, most medical
researchers anticipate being able to use technologies derived from stem
cell research to treat a variety of diseases and impairments. Spinal
cord injuries and Parkinson's disease are two examples that have been
championed by high-profile media personalities (i.e. Christopher Reeve
and Michael J. Fox). The anticipated medical benefits of stem cell
research have added a certain amount of emotion and urgency to the
debates, which has been exploited by proponents of embryonic stem cell
research.
Recently, researchers at Advanced Cell Technology of Worcester, Mass.,
succeeded in obtaining stem cells from mouse embryos without killing
them (see "[Lanza] technique", below). If this technique and its
reliability are improved, it would alleviate many of the ethical
problems related to embryonic stem cell research.
Arguments
for cell research state these reasons:
(1) The utilitarianism argument
The benefits of stem cell research outweigh the cost in terms of
embryonic "life"
Embryonic stem cells have the capacity to grow indefinitely in a
laboratory environment and can differentiate into almost all types of
bodily tissue. This makes embryonic stem cells an attractive prospect
for cellular therapies to treat wide range of diseases.[4]
The social, economic, and personal costs of the diseases that embryonic
stem cells have the potential to treat, are far greater than the costs
associated with the destruction of embryos.
(2) The human
potential vs humanity argument
The value of an embryo should not be placed on par with the value of a
child or adult
This argument often goes hand-in-hand with the utilitarian argument, and
can be presented in several forms:
Embryos, while of value, are not equivalent to human life while they are
still incapable of existing outside the womb (i.e. they only have the
potential for life).
Approximately 18% of zygotes do not implant after conception.
Thus far more embryos are lost
due to chance than are proposed to be used for embryonic stem cell
research or treatments.
Blastocysts are a cluster of human cells that have not differentiated
into distinct organ tissue, making cells of the inner cell mass no more
"human" than a skin cell .
Many scientists believe that homo-sapien life only begins when
brainwaves and heartbeats develop, which is during the 9th week of
pregnancy, so embryos are not humans.
(3) The
consequentialism argument
The ends (i.e. new treatments and cures) justify the means (i.e. the
destruction of an embryos)
This can be seen as a more extreme view of the utilitarianism argument.
(4) The efficiency
argument
If an embryo is going to be destroyed anyway, isn't it more efficient to
make practical use of it?
In vitro fertilization (IVF) generates large numbers of unused embryos
(i.e. 70,000 in Australia alone)[4]. Many of these thousands of IVF
embryos are slated for destruction. Using them for scientific research
utilizes a resource that would otherwise be wasted.
While the destruction of human embryos is required to establish a stem
cell line, no new embryos have to be destroyed to work with existing
stem cell lines. It would be wasteful not to continue to make use of
these cell lines as a resource.
Because of the laws, especially those of the United States, women are
given the right to abort their pregnancies. What will happen to this
unborn children? They will only be discarded. Why not take these
embryos, and use them for stem cell research? At least then the embryo
can possibly be used to save someone else's life, instead of being lost
and forgotten.
(5) Arguments for the
superiority of embryonic stem cells
Embryonic stem cells can be considered far more useful therapeutically
than adult stem cells
This is usually presented as a counter-argument to using adult stem
cells as an alternative that doesn't involve embryonic destruction.
Embryonic stems cells make up a significant proportion of a developing
embryo, while adult stem cells exist as minor populations within a
mature individual (e.g. in every 10,000 cells of the bone marrow, only
10 will be usable stem cells). Thus, embryonic stem cells are likely to
be easier to isolate and grow ex vivo than adult stem cells.
Embryonic stem cells divide more rapidly than adult stem cells,
potentially making it easier to generate large numbers of cells for
therapeutic means. In contrast, adult stem cell might not divide fast
enough to offer immediate treatment.
Embryonic stem cells have greater plasticity, allowing them to treat a
wider range of diseases.
Adult stem cells from the patient's own body might not be effective in
treatment of genetic disorders. Allogeneic embryonic stem cell
transplantation (i.e. from a healthy donor) may be more practical in
these cases than gene therapy of a patient's own cell.
DNA abnormalities found in adult stem cells that are caused by toxins
and sunlight may make them poorly suited for treatment.[4].
Embryonic stem cells have been shown to be effective in treating heart
damage in mice.
Arguments
against embryonic stem cell research
(1) Embryos are lives
An embryo contains the potential to form a human or is actually a human,
therefore it should be valued as highly as a human life.
Similar arguments are commonly voiced by the pro-life movement to
condemn abortion. This opinion is often related to religious doctrine
that purports that human life and/or soul start at conception. Based
upon this value system, the subsequent argument against embryonic stem
cell research is teleological, i.e. life (an embryo) is inherently
valuable and cannot be involuntarily destroyed to save another life.
As an extension of this, it is argued that the tendency by some
supporters of embryonic stem cell researchers to dismiss the ethical
significance of embryo destruction may act to devalue human life.
Moreover, it has been argued that "the line at which an embryo becomes a
human life remains as arbitrary as ever" .
(2) Exploring
alternative therapeutic options
Embryonic stem cells should be abandoned in favour of alternatives, such
as those involving adult stem cells.
Adult stem cell and cord blood stem cell research would be able to make
greater advances if less money and resources were channeled into
embryonic stem cell research.
It is claimed by pro-life supporters that the use of adult stem cells
from sources such as umbilical cord blood has consistently produced more
promising results than the use of embryonic stem cells. Such claims are
disputed by supporters of embryonic stem cell research.
Adult stem cells have already produced therapies, while embryonic stem
cells have not.[8] However, it should be acknowledged that scientists
have studied adult stem cells for decades, but first isolated human
embryonic stem cells only in 1998.[9]
(3) Scientific flaws
in embryonic stem cell research
Another concern with embryonic stem cell research is the tendency of
stem cells from embryos to create tumors. However, proposed treatments
will use cells derived from ESCs, not undifferentiated ESCs.
(4) Overstatement of
research potential
Scientists have long promised spectacular results from embryonic stem
cell research, and this has not yet occurred
This argument is hotly debated on both sides. Those critical of
embryonic stem cell research point to a current lack of practical
treatments, while supporters argue that advances will come with more
time and that breakthroughs cannot be predicted.
Conspicuously, some criticism has even come from researchers themselves.
For example, in November 2004, Princeton University president and
geneticist Shirley Tilghman said, "Some of the public pronouncements in
the field of stem-cell research come close to overpromising at best and
delusional fantasizing at worst." Similarly, fertility expert and
current president of the British Association for the Advancement of
Science, Lord Winston has warned of a public backlash against stem cell
research if it fails to deliver on some of the "hype" surrounding
potential treatments.
Stem cells
without embryonic destruction
Notably, a fundamental
impediment to the widespread acceptance of embryonic stem cell research
is the destruction of the embryo. Consequently, some stem cell
researchers are working to develop techniques of isolating stem cells
that are as potent as embryonic stem cells, but do not require the
destruction of a human embryo. Some believe that human somatic cells can
be coaxed to "de-differentiate" and revert to an embryonic state.
Researchers at Harvard University, led by Kevin Eggan, have attempted to
transfer the nucleus of a somatic cell into an existing embryonic stem
cell, thus creating a new stem cell line.[15] Another study published in
August 2006 also indicates that differentiated cells can be reprogrammed
to an embryonic-like state by introducing four specific factors.
Researchers at Advanced Cell Technology, led by Robert Lanza, reported
the successful derivation of a stem cell line using a process similar to
preimplantation genetic diagnosis, in which a single blastomere is
extracted from a blastocyst. It should be noted that this process has
not yet demonstrated the ability of donor blastocysts to survive to term
as well after blastomere harvesting. Nevertheless, this technique may in
future allow for the creation of stem cells without embryonic
destruction.
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What
is a stem cell?
Research history and
developments
Isolation and in vitro culture
Production of male gametes
Contamination by reagents used in cell culture
Reducing donor-host rejection
Potential method for new cell line derivation
Stem cell therapies
Controversy of
Embryonic stem cell research
Arguments for cell research state these reasons:
Arguments against embryonic stem cell research
Stem cells without embryonic destruction
Patents covering human
stem cell research
International policy
context
US policy debate
Origins of policy debate in the U.S.
Congressional response
References |