Stem cells are cells that can be found within all
multi-cellular organisms and which have the ability divide and turn in to an
array of specialized cells. In other
words, stem cells are blank pieces waiting to be stamped with a purpose. While all human bodies contain stem cells, in
some number, the majority within the developed person lie in the bone marrow
and in afterbirth and birth-organs, though it is believed that skin cells may
someday be used as stem cells. Most
adult stem cells, which include those cells removed from juveniles, are of the
multipotent brand. Potency is the
potential for a stem cell to differentiate into different cell types. Multipotent cells are limited in that they
may only differentiate into the cells of a closely related family (Scholer
28) . So adult stem cells derived from muscle
tissue would only be able to differentiate into those cells which are closely
related to the tissue from which they were derived. However pluripotent stem cells have a much
greater potential as they are able to differentiate in to any cell of the three
major germ layers: those being the endoderm, ectoderm, and mesoderm which are
the basis of development in almost all animal groups more complex than worms (Scholer
28) . The greatest source, according to most, for
pluripotent stem cells are from the undeveloped fertilized human embryos. These embryos are often obtained from in vitro fertilization clinics due to
their excess or soon expiration and as such are planned to be destroyed anyway. “The embryos from which human embryonic stem
cells are derived are typically four or five days old and are a hollow
microscopic ball of cells called the blastocyst. The blastocyst includes three structures: the
trophoblast, which is the layer of cells that surrounds the blastocoels, a
hollow cavity inside the blastocyst; and the inner cell mass, which is a group
of cells at one end of the blastocoels that develop into the embryo proper” (U.S. DHHS) . The inner cell mass is removed to divide in a
culture dish; if successful the dish will fill and the fresh cells will be
divided up to be placed in new dishes for further ‘subculturing’. “The original [few] cells yield millions of
embryonic stem cells” (U.S. DHHS) .
The potential uses for stem cells in
medicine is virtually limitless today, however there are two that stick out as
the most important. A further
understanding for the genetic and molecular controls of cell division and
differentiation in humans can be generated by the study of stem cell
production. Many of the most serious and
lifelong diseases, such as cancers and birth defects, are the result of
abnormal cell division and differentiation.
Better insight into how these diseases arise could lead to new
strategies for therapeutics. Cell-based
therapies are perhaps the greatest potential application for stem cells:
because pluripotent stem cells can adapt to nearly any cell type in the body
they have the potential to be used in growing new organs, or in fixing
dilapidated ones in the body, and as a ‘renewable source of replacement cells
and tissues’ for treating diseases.
Among the diseases stem cells are believed to have the potential to aid
are nervous system problems such as Alzheimer’s, spinal cord injury, and
stroke, burns, heart disease, diabetes, osteaoarthritis, and rheumatoid
arthritis (U.S. DHHS ...potential..) .
The greatest obstacle for the
scientific and medical community to overcome are in the financial and practical
limitations placed by the government, especially in the U.S., rooted in
religious and moral outcry. Many
opponents of embryonic stem cell research oppose its use because they believe
that the use of fertilized eggs is somehow a violation of the sanctity, or
value of life. Many of the arguments
used against embryonic stem cell research are the same ones that have
previously been used in cases of abortion and even in in vitro fertilization at one time.
One of the most visible opponents to the research whom often enacts the
argument for the value of life is the Roman Catholic Church. While there are many protestant groups joined
together in the fight against stem cell research, the Catholic Church has a
greater number of parishioners than any other single Christian group in the
world. Most Catholics believe that human
life begins at conception: that is, when the sperm fertilizes the egg. In 2008 the U.S. Conference of Catholic
Bishops issued a treatise on the subject claiming that embryonic research is
immoral and unnecessary. The document
dismisses the utilitarian argument, restates the conception argument (though in
more scientific, less rhetorical method), and dismisses the in vitro model. “If fundamental rights such as the right to
life are based on abilities or qualities that can appear or disappear, grow or
diminish, and be greater or lesser in different human beings, then there are no
inherent human rights, no true human equality, only privileges for the strong” (O'Brien) .
The arguments against embryonic stem
cell research are not merely limited to the religious right, though that is
where the majority does lie. Another
objection is put forth by those who specialize in the research of adult stem
cells. Their belief is that adult stem
cells, which can be obtained from sources such as umbilical cord blood, can
actually produce better results than stem cells obtained from embryos, and
without the negative moral implications.
In addition to this their proponents claim that adult stem cells have
already produced therapies, while embryonic stem cells have not. Many adult stem cell therapies can actually
be made with stem cells harvested from the patient. Among the therapies of adult stem cells are
the treatment of leukemia and other bone and blood cancers through the use of
bone marrow transplants (UCSF Children's Hospital) . And as recently as 2008 the first transplant
of a human organ grown from adult stem cells was completed in Barcelona on a
Columbian woman and after four months had shown absolutely no signs of
rejection (Rose) .
The arguments for the use of
embryonic stem cell research are much more varied than those against but can be
summarized into four distinct groups: the utilitarian argument, the argument
for efficiency, the argument of superiority, and the argument from the
beginning of life. The utilitarian
argument is simple: embryonic stem cell research could possibly be unethical,
however the amount of good that it could potential cause outweighs the few
possible violations of morality. Embryos
are not human life because they do not have the viability to survive outside of
the womb, more than a third of fertilized eggs do not actually implant upon the
uterine wall and therefore far more embryos are lost due to this than to
research or treatments, and that life does not begin until the development of
the heart or brain in the fetus, are all possible utilitarian arguments. The argument for efficiency is primarily an
argument related to the mandatory destruction in vitro fertilization embryos; these embryos will be destroyed
anyway so why not make use of them for science? (The same thinking can apply
for embryos of abortions) The argument
of superiority is a claim against the argument that adult stem cells can
actually provide more benefit than embryonic. Mostly this argument is based on the fact that
there are a greater proportion of embryonic stem cells, they multiply faster,
and have a greater, less determined set of uses (Stem Cell
controversy) . The argument from the beginning of life is
based on the fact that prior to the embryo attaching to the uterine wall at
fourteen days it has the potential to split into two individuals from one egg,
or combine from two eggs into one individual.
Therefore, the argument says that there is only the potential for a person,
but not an actual person (West) .
While there is no end in sight for
the debates about the uses and morality of embryonic stem cell research, there
is a glimmer of light with the recent lifts by President Obama’s administration
on the limits for federal funding of stem cell research in America. Further research can only improve the
knowledge we have about what makes people tick and how to fix them when they’re
broken.
Bibliography
O'Brien, Nancy Frazier. "Embryonic stem-cell
research immoral, unnecessary, bishops say." 18 June 2008. American
Catholic. 13 December 2009
<http://www.americancatholic.org/NEWS/StemCell/>.
Rose, David.
"Claudia Castillo gets windpipe tailor-made from her own stem
cells." The Times (London) 19 November 2008.
Scholer, Hans.
"The Potential of Stem Cells: An Inventory." Knoepffler, Nikolaus. Humanbiotechnology
as Social Challenge. Burlington, VT: Ashgate Publishing, Ltd., 2007. 28.
"Stem Cell
controversy." 2010 January 7. Wikipedia. 13 January 2010
<http://en.wikipedia.org/wiki/Stem_cell_controversy#Objection>.
U.S. DHHS. "What
are embryonic stem cells?" 20 April 2009. National Institute of
Health. 13 December 2009
<http://stemcells.nih.gov/info/basics/basics3.asp>.
—. "What are the
potential uses of human stem cells and the obstacles that must be overcome
before these potential uses will be realized?" 28 April 2009. National
Institute of Health. 13 December 2009
<http://stemcells.nih.gov/info/basics/basics6.asp>.
UCSF Children's
Hospital. "Leukemia Treatment Options." 15 October 2009. UCSF
Children's Hospital. 13 December 2009
<http://www.ucsfchildrenshospital.org/treatments/leukemia_treatment_options/index.html>.
West, Michael D.
"Embryonic stem cell research is ethical." The Ethics of Genetic
Engineering. USA: Thomson Gale, 2005. 100-107.
This article originally written January 13th, 2010 for OU HSCI 3423 - History of Medicine.
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