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Prentice is a professor of life sciences at Indiana State University
and an adjunct professor of medical &
molecular
genetics at the Indiana University School of Medicine. Dr. Prentice
also services as an ad hoc science adviser to Kansas Republican
Senator Sam Brownback.
Kathryn Jean Lopez: What impact do
you think the Nobel
laureates' letter to President Bush urging him to feed federal
funds to human-embryo stem-cell research has had and will have?
David Prentice: I think the letter
will have primarily PR value in the media. It perpetuates a number
of misconceptions and misleading statements regarding stem-cell
research, particularly embryonic as opposed to adult stem-cell research,
and will serve to continue to cloud the issue. I believe President
Bush and his staff are well aware of the truth about embryonic versus
adult stem-cell research.
Lopez: Ultimately — ideally, practically
— who should be making these decisions anyway? Most reasonable
people will read the newspaper and see that Francis Crick —
and conservatives will see Milton Friedman — signed this letter
and will think, well, they must be right?
Prentice: An informed citizenry working
with an informed legislative branch and an informed executive branch
gives the best answer. Unfortunately, many in the public will read
about this letter, recognize some high-profile "icons" or simply
that there are a lot of "smart people" who've signed on, and think
that they know all about this scientific research. Knowledgeable
people do not always perpetuate the truth. President Bush and Congress
obviously have the final say on how our federal research dollars
will be spent. The hope is that all who are participating in this
debate are fully informed about the facts and are not swayed by
celebrities who are unfortunately ill-informed or deliberately misled,
but rather weigh both the scientific and the ethical evidence.
Lopez: There is a lot of misinformation
and deception going on in the press accounts of the "stem-cell debate,"
isn't there?
Prentice: This is probably the worst
problem in this whole
| “Human
embryonic stem-cell research is illegal, immoral, and
unnecessary.” |
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debate,
the perpetuation (innocent or not) of misleading statements which
obscure many of the real facts. The Nobel Laureate letter itself
is a prime example of the "mixmaster" treatment of the facts. What
is usually lacking from press reports are a few key "adjectives"
that clarify the situation — defining whether the cells discussed
are human or animal cells, and especially whether they are "embryonic"
or "adult" stem cells.
For example, the letter sent to President Bush says that "…insulin-secreting
cells have normalized blood glucose in diabetic mice." These experiments
were done with ADULT stem cells from mice, NOT embryonic stem cells.
In fact, there are as yet no reports of anyone being able to produce
insulin-secreting cells from human embryonic stem cells, but human
ADULT stem cells that secrete insulin HAVE been isolated.
The letter promulgates the claim (made repeatedly in NIH documents)
that adult stem cells do not have the same potential as embryonic
stem cells, which in theory can form any tissue. But studies done
with adult stem cells (studies which mirror the ones done with embryonic
stem cells) DO show that adult stem cells have the capacity to form
essentially any tissue.
The most misleading term which continues to be used is "pluripotent."
Literally, this means able to form most (but not all) tissues. This
term continues to be used incorrectly, primarily to imply that human
embryonic stem cells can form all human tissues except "trophoblast"
tissue — this is an essential outer layer of cells in the early
embryo which allows it to implant into the uterine wall and nourishes
early development. The trophoblast is also the part of the embryo
removed in its destruction to harvest the inner embryonic stem cells.
The phrase "human pluripotent stem cells" has been used to counter
the question of whether human embryonic stem cells in culture could
actually reform a human embryo, implying that this is not possible.
Yet in testimony before the Senate, then-Director of the NIH, Harold
Varmus, said that this possibility was uncertain, and that in fact
it would be unethical to attempt such an experiment to determine
whether this was possible. Enter the term pluripotent — if
the embryonic stem cells cannot form trophoblast, they cannot form
an embryo. Mouse embryonic stem cells cannot form trophoblast tissue.
BUT, as stated in Thomson's original paper in 1998, human embryonic
stem cells CAN form trophoblast in culture.
Lopez: There are other ways to get
stem cells, besides embryos, aren't there? Are they just as good?
Prentice: There are several excellent
alternatives to embryos, and they are actually better potential
sources of stem cells for numerous reasons. The best sources are
from our own organs termed "adult stem cells" or "tissue stem cells."
Another excellent source is cord blood; the small amount of blood
left in an umbilical cord after it is detached from a newborn is
rich in stem cells. In the last two years, we've gone from thinking
that we had very few stem cells in our bodies, to recognizing that
many (perhaps most) organs maintain a reservoir of these cells.
We've known for some time that bone-marrow stem cells can make more
blood, but now we know that these adult stem cells can also make
bone, muscle, cartilage, heart tissue, liver, and even brain. Interestingly
enough, we now know that our brain contains stem cells which can
be stimulated to make more neurons, or to take up different job
descriptions as muscle or blood. Bone marrow and cord blood are
already successfully being used clinically, while clinical use of
embryonic stem cells is years away. Current clinical applications
of adult stem cells include treatments for cancer, arthritis, lupus,
and making new corneas, to name a few.
One distinct advantage of using our own adult stem cells is that
there will be no transplant rejection, since it is our own tissue.
Use of human embryonic stem cells will require lifelong use of drugs
to prevent rejection of the tissue. Or, the patient will have to
be cloned (a second ethical issue!), and that embryo (the patient's
twin) sacrificed to obtain the embryonic stem cells for the tissue
(essentially creating a human being whose only purpose is to be
"harvested").
Another advantage of adult stem cells might be considered from a
manufacturing viewpoint: A 2-step manufacturing process is more
direct and has much less likelihood of a problem than a 10-step
process. Adult stem cells have shown success at forming many specific
tissues so far, certainly more than human embryonic stem cells in
the laboratory. And as one researcher noted regarding human embryonic
stem cells: "We thought from the first that problems would arise
using hPSCs [human pluripotent stem cells] to make replacement tissues,"
indicating that the early stage cells are both difficult and slow
to grow. "More important, there's a risk of tumors. If you're not
very careful when coaxing these early cells to differentiate —
to form nerve cells and the like — you risk contaminating the
newly differentiated cells with the stem cells. Injected into the
body, [embryonic] stem cells can produce tumors." No such problems
exist with adult stem cells.
Lopez: To what extent are we exploring
those options?
Prentice: Several scientists are investigating
uses of adult stem cells to form new tissues or repair damaged/diseased
tissue, such as for diabetes, Alzheimer's, Parkinson's, and stroke.
As mentioned before, others are already using bone marrow and cord
blood, as well as corneal tissue, for clinical applications. But
the number of researchers in this area is still small, as is the
amount of grant dollars needed to fund the research. And sadly,
embryonic stem cells have been held up as the panacea for disease
and a fountain of youth, despite the advantages of adult stem cells
both scientifically and ethically. Given that adult stem cells have
shown themselves to be scientifically more successful than embryonic
stem cells, and ethically palatable, much more needs to be heard
and said about adult stem cells, and much more funding needs to
go to adult stem-cell research.
Lopez: Do members of Congress understand
this debate? Are you confident that people in the administration
do — especially to offset HHS secretary Tommy Thompson, who
is personally for research on human embryos for this purpose.
Prentice: Some members of Congress
have made it a point to be well informed in the real facts of this
issue, particularly Sen. Sam Brownback. Many, however, have received
blended or deceptive information, and have been misled as to the
capabilities of adult stem cells and the scientific disadvantages
of embryonic stem cells.
Lopez: What should pro-life groups
be doing to get the real story out-about alternative sources? And,
simply, what their argument against this research is, so it isn't
simply caricatured in the press?
Prentice: First INFORM YOURSELF WITH
THE FACTS on the alternatives, as well as the facts (rather than
the hype) about embryonic stem cells. Do No Harm, the Coalition
of Americans for Research Ethics, has a wealth of articles about
the alternatives on their
website, plus links to other sources. Then tell your family,
friends, neighbors, any groups to which you belong, and especially
your Senators and your Representative. Impress on them that there
is more to the story than is usually told, and urge them to check
out the real difference in results between embryonic and adult stem
cells, the promises versus the reality. And INSIST that the media
tell the full story, complete with all of the adjectives and the
evidence.
Human embryonic stem-cell research is illegal, immoral, and unnecessary.
It is ILLEGAL regarding use of federal funds because Congress has
stated that no funds should be used for research which involves
the creation or destruction of human embryos for research purposes,
and human embryos are destroyed in the process of deriving human
embryonic stem cells.
It is IMMORAL, because human beings are killed in the process. Scientifically
there is no disputing that we are a human being even at the one-cell
stage. It has never been acceptable to sacrifice one set of human
lives for the potential benefit of others (and they are only potential
benefits at this point.) Human embryonic stem cell research assigns
different values to different human beings, designating some as
people and some as property.
It is totally UNNECESSARY. Ethical alternatives exist such as adult
stem cells which have already shown much more promise than embryonic
cells, these results for adult stem cells are fully detailed in
the scientific literature, and that adult stem cells are already
being used clinically, making good on the potential that embryonic
stem cells only promise.
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