Marc Hedrick Dr. Hedrick is an associate
professor of Surgery & Pediatrics at UCLA. Dr. Hedrick has a
financial interest in technology developed at UCLA related to adult
stem cells. . Â Scott Klusendorf Dr.
Klusendorf is director of Bio-Ethics at Stand to Reason and a UCLA
alumnus..
Stem cells are the early building blocks of each of us. All 210
different types of human tissue originate from these primitive
cells. Because they have the potential to become any kind of
tissue, including brain, heart and skin, scientists believe that
these cells may be the key to unlock a new era in which organs and
body parts are “made” from scratch.
This emerging discipline is known as tissue engineering. Stem
cells can be found in human embryos as well as the human body any
time after birth. Two questions govern their proposed use: 1) Will
stem cell-based treatments be effective and 2) is the use of
embryonic stem cells ethical?
There is a scientific consensus regarding the potential
scientific and medical impact of stem cell research. In May
2000, the National Institutes of Health issued this unambiguous
statement: “Given the enormous promise of stem cells to the
development of new therapies for the most devastating diseases,
when a source of stem cells is identified, it is not too
unrealistic to say that this research will revolutionize the
practice of medicine and improve the quality and length of
life.”
Stem cell research will likely benefit society in at least two
ways: 1) it will help define how stem cells themselves can be used
to repair or regenerate diseased tissues and organs and 2) study of
the basic biology of stem cells will help contribute to a better
understanding of how humans develop in the earliest stages.
The consensus regarding stem cells deteriorates, however, when
the debate shifts to which stem cell is most promising. Embryonic
stem cells or ESCs have garnered the lion’s share of the
media attention.
These early fetal cells not only contain all the genetic
information of the individual but also contain the nascent capacity
to become any of the 200+ cells and tissues of the body. Ongoing
research suggests that these cells have tremendous scientific and
clinical potential.
However, ESCs have theoretic limitations to their use. If used
clinically they would necessarily be derived from another
“individual” ““ an embryo.
When stem cells or tissues derived from them are transplanted
into another person, toxic immune suppressing drugs may be needed
by the cell recipient to prevent rejection. In addition,
another’s cells can carry viruses or other rare but
significant diseases that can be transmitted to the recipient.
Also, ESC-like cells (e.g., teratomas) are known to form tumors.
Any tissues developed for patients from ESCs must not develop
tumors and must have the innate ability to respond to the normal
signals that tell tissues to grow, stop growing or heal.
Recently, non-embryonic or “adult” stem cells have
been identified and represent an important potential alternative to
the clinical use of ESCs. These cells reside quietly in many if not
all of our tissues, presumably waiting to respond to trauma or
other destructive disease processes so that they can heal the
injured tissue.
Emerging scientific evidence indicates that each of us carries
with us a “pool” of stem cells far more immature than
previously thought, perhaps like ESCs with the ability to become
many if not all types of cells and tissues.
Remarkably, even our fat tissue has been shown to contain stem
cells with the potential to recapitulate lost or missing tissues
such as bone, cartilage, muscle and other tissues. Because of the
availability of fat tissue through the common surgical procedure
called liposuction, these cells may represent a practically
unlimited and easily obtainable source of one’s own stem
cells.
In the near future, one could donate his or her own stem cells
which could be concentrated and replaced back in a form and number
sufficient to heal or mend a broken body part. Because these cells
are derived from the patient, there would be no possibility of
rejection, no need for immune suppressing drugs, and no risk of
disease transmission.
Fortunately, the risk of these normally quiescent cells
developing into tumors appears to be quite small.
Admittedly, stem cell science itself is in its early stages of
development. In the future, it will tell us which methods of stem
cell research will work: adult, embryonic or both. However, it
can’t tell us which methods are right.
The moral issues must also be considered.
If they are dismissed in favor of unrestrained scientific
progress, one can hardly condemn past atrocities such the Tuskegee
experiments of the 1920s in which black men suffering from syphilis
were promised treatment, only to have it denied so scientists could
study the disease.
Despite claims to the contrary, embryo stem cell research (ESCR)
is not morally complex. It comes down to just one question: Is the
embryo actually a human being?
If so, killing it to benefit others is a serious moral wrong. It
treats the distinct human being, with his or her own inherent moral
worth, as nothing more than a disposable instrument. Conversely, if
the embryos in question are not human, killing them to extract stem
cells requires no more justification than having a tooth pulled.
Why not create them solely for research that benefits others?
Scientifically, few dispute that individual human life begins at
conception. Unlike sperm and ovum, which merely contain human
genetic material, the embryo possesses the active (inherent)
capacity to develop itself into a fetus, infant, child and
adult.
It is a distinct, unified, self-integrating human organism. Dr.
Landrum Shettles, the first scientist to achieve conception in a
test tube, writes that conception not only confers life, it
“defines” life. That is to say, at no point does the
distinct organism that came into being undergo a “substantial
change” or change of nature. It is human and will remain so.
It is an immature human, as is an infant, but a human being
nonetheless.
True, embryos differ from newborns (or, for that matter,
toddlers) in terms of size, location and development, but are these
differences morally significant in the way proponents of ESCR need
them to be?
For example, everyone agrees that embryos are small ““
perhaps smaller than the dot at the end of this sentence. But since
when do rights depend on how large we are? Men are generally larger
than women, but that hardly means they deserve more rights.
Development also fails to disqualify the embryo as fully human.
A 4-year-old girl is less developed than a 14-year-old one, yet no
reasonable person would conclude that she is less than fully human
because of it. Nonetheless, many proponents of ESCR insist that
human embryos are non-sentient, non-rational clumps of cells
unworthy of the status “human being.”
However, if rationality and self-consciousness define the
morally significant person, then why shouldn’t greater
rationality make you more of a person? Consequently, the
intellectually and artistically gifted would be free to maximize
their pleasure at the expense of those less intelligent.
In reply, some argue destructive embryo research is justified
because “these embryos will be discarded anyway.” This
reasoning is problematic. One could, with equal validity, suggest
that we allow destructive research on 6-month fetuses scheduled for
partial-birth abortions or on political prisoners scheduled for
execution in China “since these humans will die
anyway.”
The fact is that we all die sometime. Do those of us who are
going to die later have the right to kill (and exploit) those who
will die sooner?
Even if an individual’s death is imminent, we still do not
have a license to use him for lethal experiments, which is why we
do not conduct experiments upon death-row prisoners or harvest
their organs without their consent.
In short, critics of ESCR argue that the practice violates the
very principle that once made political liberalism great: A basic
commitment to protect the weakest and most vulnerable members of
the human community.
Thankfully, the choice between medical progress and moral
principle is a false dilemma. New research suggests that embryonic
human beings do not need to lose their lives in order to save
ours.
There are morally acceptable ways of performing medical research
and combating disease.