Seeking an Ethical Option to Embryonic Stem Cell ResearchREV. THOMAS BERG, L.C.
There might be an ethically acceptable alternative for obtaining embryonic stem cells, says a bioethicist.Legionary
of Christ Father Thomas Berg, executive director of the Westchester
Institute, a Catholic ethics think tank located in suburban New York,
sees hope for a process known as altered nuclear transfer. He gave an overview
of the status of stem cell research in this interview with ZENIT.
Q: What is the ethical problem with embryonic
stem cell research?
Father Berg: The
problem is that the methods currently used to obtain these cells pluripotent
stem cells require researchers to kill living human embryos in the process.
In the case of so-called therapeutic cloning, which has been accomplished
twice and recently streamlined by a group of South Korean researchers, it requires
the intentional creation of human embryos precisely for their destruction in the
course of harvesting stem cells from them.
Are not human adult stem cells sufficient for all the therapeutic purposes
we could want?
Father Berg: We really
can't say enough in praising and promoting the inroads that have been made in
developing therapies from adult stem cells.
Decades of research have
yielded some 70 diverse therapies and clinical applications in treating diseases
and disorders, including heart damage, spinal injury and several kinds of blood
By contrast, the research on deriving therapies from human
embryonic stem cells is more nascent; it has only been going on in earnest for
the last four or five years. Will it yield therapies? Quite possibly that's
what scientists on both sides of the life issue tell me. It's too early to tell.
So, we should be guarded in our optimism with regard to the potential
of adult stem cells.
Q: Can you explain again the difference between
kinds of stem cells?
Father Berg: In
the case of embryos, we distinguish between pluripotent and totipotent.
Pluripotent cells can give you to use an analogy with painting all
the colors on the palette, but not the whole picture. That is to say, they give
you all the human tissues.
Totipotent cells, on the other hand, can
give you the whole picture a whole human being. It's the pluripotent cells
that are of interest to the researchers.
Human adult stem cells are
normally referred to as multipotent. There is ongoing debate as to whether certain
kinds of adult stem cells for example, MAP-Cs, or multipotent adult progenitor
cells can be coaxed to give rise to all tissue types. There are some reports
that scientists are perhaps on the right trail, but no conclusive studies yet.
Q: How does cloning relate to stem cell research?
Father Berg: Cloning is the creation
of a unique human individual through a process called somatic cell nuclear transfer.
A donor donates a body cell from which the nucleus is taken and then
transferred into an enucleated human egg. Factors in the cytoplasm of the egg
are responsible for literally reprogramming the inserted nucleus to a pristine
state, that of a one-cell human organism or zygote.
When coaxed with
electrical stimulation, this clone begins to undergo the normal process of cell
division which leads to the various stages of otherwise normal embryonic development.
So the link with stem cell research is the following.
Cloning has been
proposed as the ideal means of creating tailor-made embryonic stem cell lines.
The DNA of the clone is an exact match of the donor's. The clone is developed
to the blastocyst stage, about 6 days, at which point, its inner cell mass is
extracted killing the human clone in the process.
From the inner
cell mass of the clone are then derived in culture a new line of pluripotent stem
cells which are a perfect genetic match to the donor. These lines of stem cells
could be used to develop tissue replacement therapies for the donor should
he or she eventually need them with no risk of immune rejection because
the tissue is perfectly matched.
Q: Has anyone yet cloned a human being?
Father Berg: Yes. The South Korean team
led by Woo Suk Hwang reported, in February 2004, the first successful creation
of cloned human beings.
In 2004 they created some 30 embryos and allowed
them to develop to the blastocyst stage. They were then destroyed in order to
create lines of embryonic stem cells. On May 19 of this year, they reported that
they have now honed their technique and claim to have created 11 new lines of
human embryonic stem cells.
Are there morally acceptable means of obtaining human embryonic stem
Father Berg: If it were shown
to be feasible to obtain pluripotent stem cells by ethically acceptable means,
I would support and encourage scientific exploration of their potential therapeutic
value. The President's Council on Bioethics recently released a white paper exploring
several possible alternative means.
Can you briefly explain these alternative means for obtaining human pluripotent
stem cells as described recently by the President's Council on bioethics?
Father Berg: That
paper reported on, and gave an initial ethical evaluation of, four proposals for
obtaining pluripotent stem cells without killing human embryos. The proposals
are as follows in simple terms.
The first was proposed by Dr. Don Landry
and Dr. Howard Zucker, both of Columbia University. They would seek to obtain
embryonic stem cells from embryos that have been determined to be clinically "dead"
in IVF [in vitro fertilization] clinics and that are about to be disposed of.
The second would perform a biopsy on an eight-cell embryo to remove
an early forming stem cell, presumably without harming the embryo.
third, called altered nuclear transfer, ANT, and proposed by Dr. William Hurlbut
of Stanford University is to create a non-embryonic biological artifact akin to
a tumor that would nonetheless produce the equivalent of pluripotent stem cells.
And the fourth proposal would endeavor to convert adult cells into pluripotent
stem cells by reprogramming the nucleus of the adult cell to a pluripotent state.
While the bioethics council could not endorse the "biopsy" proposal,
it did encourage the pursuit of research on the other proposals using animal models.
Why pursue these alternative means for obtaining embryonic stem cells?
Father Berg: I think in light of
the fact that we now live in Brave New World, in which embryos are being created
en masse, and in which there will be a growing demand for new embryonic stem cell
lines, I believe we have a moral obligation to look seriously at alternate routes
to obtaining them through non-embryo destructive means.
Is there a down side to pursuing any of these proposals?
Berg: Potentially, and that's what makes
them complicated from the moral perspective and that's why we need to see the
animal studies done for these proposals.
With ANT, we have to be able
to arrive at the moral certainty that the product of ANT is not an embryo; it
may also run the risk of indirectly fomenting whole new avenues of human engineering.
The Zucker-Landry proposal may risk opening up a new market for the
IVF industry, since it proposes removing intact embryonic stem cells from IVF
embryos about to be discarded. But again, we may well have sufficient reason to
tolerate the chances of any of this happening.
You are on public record as supporting Dr. Hurlbut's proposal, ANT.
Is that correct?
Father Berg: Yes.
I, along with several other ethicists, have recently endorsed pursuing ANT on
animal models not with human cells especially in a more recent and
very specific rendition of ANT called oocyte assisted reprogramming.
How did you get involved with Dr. Hurlbut?
Berg: When I thought carefully about what
he was proposing, I felt we had almost a moral obligation to study his proposal
seriously, so I contacted him about the possibility of getting some scholars together
to look at the moral side of the proposal. That was last December.
Explain altered nuclear transfer and new version you referred to called
oocyte assisted reprogramming.
ANT is a broad conceptual proposal and could be accomplished in many different
ways. The steps involved in oocyte assisted reprogramming would be the following.
First, a cell is removed from a donor and the DNA in the nucleus of
that cell is "altered" in an effort to change the instructions that
this nucleus would be giving to the cell, keeping in mind that a cell's nucleus
essentially determines what kind of cell it will be.
Then, the nucleus
is removed from an oocyte, or egg cell, and this enucleated oocyte, now essentially
a sack of cytoplasm, is fused to the donor cell with the altered nucleus.
This process of cell fusion also called nuclear transfer is
the same has used in cloning, but the product would be radically different in
this case. This newly constituted cell would neither be an egg, nor an embryo,
nor would it any longer be the cell it once was.
Rather, it would now
be a hybrid that would show or express the properties programmed into it by the
changes made to the nucleus. The way the scientist in our working group have conceived
of it would suggest that the new cell would be programmed to essentially act like
and produce pluripotent stem cells.
These stem cells would be genetically
identical to the donor and could conceivably be used for research and therapeutic
purposes. So essentially, it would mean going from an adult cell to stem cells,
bypassing the creation and destruction of embryos in the process.
the long and the short of it is that a growing number of scientists are quite
confident that ANT-OAR would actively and immediately convert adult cells directly
into pluripotent stem cells without generating embryos.
So what exactly does the egg do in this process?
Berg: The egg's cytoplasm will strip the cellular type of the adult
cell nucleus, reverting to an undifferentiated, more plastic, and virginal state
as it were.
Yet, unlike cloning, the adult cell nucleus will not be
converted to a totipotent state a state that could generate a whole human
embryonic organism. Rather, should the ANT-OAR proposal work, the alterations
made to the donor nucleus will ensure that the cell produced is not an embryo,
and will immediately be able to multiply itself, producing a new line of pluripotent
Some people would wonder if ANT does not entail complicity in the evil
of human embryonic stem cell research. They might ask: Why mess with human eggs
and genetic material?
Father Berg: We
all share a sense of profound veneration and respect to be owed to those elements
human eggs, sperm, human genetic material that are the essentials
of human life.
Nonetheless, their use for human benefit is not something
intrinsically evil. In other words, while we don't go at it lightly, we have to
recognize that there can be legitimate and morally unproblematic uses for them.
As long as in using human eggs, human genetic material does not in itself
cause us to transgress some absolute moral norm, such as the norm prohibiting
the creation or destruction of embryos, and as long as it is pursued in light
of some substantial and probable benefit, then such research could proceed.
Could there be some foreseeable downside of doing this? For example, does
it contribute to a thinning out of our respect of life? That is hypothetical,
but even were that the case, I think in light of the fact that we now live in
Brave New World, in which embryos are being created en masse, and in which there
will be a growing demand for new embryonic stem cell lines, we have proportional
reason to pursue this research and to tolerate the potential negative consequences.
Thomas Berg, L.C.
Fr. Thomas Berg was born in Milwaukee, Wisconsin on
July 15, 1965. After joining the Legionaries of Christ in 1986, he served for
two years as Academic Director of the Immaculate Conception Apostolic School in
Center Harbor, New Hampshire. He later served for two years as professor of Classical
Humanities at the Legionary novitiate in Cheshire, CT. He received an M.A. in
Liberal Studies from Wesleyan University in 1997, and his Ph.D. in Philosophy
from Rome's Pontifical University Regina Apostolorum in 1999. He is currently
serving as associate professor of moral philosophy at the Center for Higher Studies
of the Legion of Christ in Thornwood, NY. His areas of specialization include
natural law theory, personhood theory, and biomedical issues dealing with the
beginning of life. He is a freelance ethics consultant, and also founder of the
Westchester Institute, a Catholic think-tank dedicated to fundamental research
on the Western moral tradition.
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