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8-Humans: A more ethical way to harvest stem cells?



                                 PART I
------------------------------- GENET-news -------------------------------

TITLE:  A more ethical way to harvest stem cells?
        Scientists are in hot pursuit.
SOURCE: The Christian Science Monitor, USA, by Peter N. Spotts
        http://www.csmonitor.com/2005/1017/p02s01-ussc.html
DATE:   17 Oct 2005

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A more ethical way to harvest stem cells? Scientists are in hot pursuit.

Researchers cite progress in efforts to address concerns about embryo
destruction and human cloning.

For seven years, scientists have tiptoed through an ethical minefield in
their quest to see if unique cells in human embryos might some day be
harnessed to treat disease.

Now two independent teams of researchers say they have harvested these
cells, called embryonic stem cells, from mice using methods they hope may
avoid the ethical morass - if the approaches can be made to work with humans.

Their results, appearing Monday on the website of the journal Nature,
follow a study published in August that examined yet a third tack toward
harvesting embryonic stem cells in a less controversial way.

Together, these efforts represent a bid to break the stem-cell impasse in
the lab rather than in the courts or the halls of Congress.

This broad lab-based approach "is encouraging," says the Rev. Tadeusz
Pacholczyk of the National Catholic Bioethics Center in Philadelphia, who
holds a doctorate in neuroscience from Yale University. "You're using the
power of science to develop a solution that gets around a very grave
moral objection."

That objection centers on the most widely used method of harvesting stem
cells from embryos, which destroys the embryos that hosted the cells.
That method also involves cloning, although scientists insist that it is
unethical to try to allow a cloned human embryo to come to term.

Many researchers hold that an embryo at the stem-cell stage does not
constitute a human, and so its loss represents a small price to pay in
exchange for the potential medical benefits they see in using stems
cells. Indeed, they argue that it is unethical to stall or block
embryonic stem-cell research.

For those who hold that life begins at conception, however, current
harvesting techniques violate the sanctity of human life. Work on stem
cells taken from adults, they say, is evidence that embryonic stem cells
may be unnecessary for therapeutic use. (Stem-cell researchers say it's
too early to know if adult stem cells hold the same potential as
embryonic stem cells.)

Enter Alex Meissner and Rudolph Jaenisch, with the Whitehead Institute
for Biomedical Research in Cambridge, Mass. They inserted genetic
material from adult mice into mouse eggs emptied of their original
nucleus. Then they fertilized the eggs, which began to divide and make
stem cells. But before they inserted the adult DNA into the original egg,
they turned off the gene linked to the process of implanting the embryos
in a uterus. Thus, the embryo could not develop much beyond the stem-cell
stage.

After the duo extracted the stem cells from the embryos, they removed the
switch from the stem cells' genetic material, yielding cells genetically
identical to the adults from whom the DNA was originally taken.

Thus, though the embryo was destroyed in the stem-cell harvesting
process, it never could latch onto a uterus. This averts the issue of
allowing a clone to come to term, says Mr. Meissner. And to some
bioethicists, an early-stage embryo that stands no chance of forming
anything more advanced lacks a human's ethical or moral standing.

This approach was first proposed by William Hurlbut of Stanford
University's program in human biology, who is a member of President
Bush's Council on Bioethics. He saw it as a possible way of averting the
ethical stalemate over stem-cell research. He acknowledges that he's
gratified by the Whitehead team's "proof of concept" results. "We should
have started this search for a technical solution a couple of years ago,"
he says.

Meissner adds, "It gives us one potential idea for how to circumvent the
ethical dilemma that has been tearing apart Congress and everyone else."

A second group led by Robert Lanza of Advanced Cell Technology in
Worcester, Mass., took a different approach. In essence, his team
employed a technique ordinarily used in fertility clinics to gauge the
genetic condition of an embryo. When fertilized mouse eggs divided to
reach the eight-cell stage, the team removed one cell. The remaining cell
cluster could develop normally. The single cell was put in a petri dish
with an already established line of stem cells. When the newcomer was
removed and allowed to develop further on its own, it formed its own
stem-cell line.

Some of these approaches have met with resistance, even from within the
stem-cell research community.

In December, three Harvard scientists argued in the New England Journal
of Medicine that the approach Dr. Hurlbut proposed - and the Whitehead
team later executed - would yield no scientific benefit. Instead, they
were concerned that such hunts would divert resources from more mainline
embryonic stem-cell work. They added that the approach doesn't solve any
ethical dilemma because in their view it incorrectly presumes that the
ethical standing of an individual hinges on the action of a single gene.


                                 PART II
------------------------------- GENET-news -------------------------------

TITLE:  Stem Cell Test Tried on Mice Saves Embryo
SOURCE: The New York Times, USA, by Nicholas Wade
        http://www.nytimes.com/2005/10/17/health/17stem.html
DATE:   17 Oct 2005

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Stem Cell Test Tried on Mice Saves Embryo

Scientists have devised two new techniques to derive embryonic stem cells
in mice, one of which avoids the destruction of the embryo, a development
that could have the potential to shift the grounds of the longstanding
political debate about human stem cell research.

The destruction of embryos is a principal objection of anti-abortion
advocates who have strenuously opposed federal financing of the research.

The second new technique manipulates embryos so they are inherently
incapable of implanting in the uterus, what some see as a possible
ethical advantage in the proposed therapy, which converts a patient's
skin cell into embryonic cells and then new tissues to repair the body.
Both methods are described in today's online edition of Nature.

The technique for making embryonic stem cells without compromising the
embryo has yet to be adapted to people, but the two species are very
similar at this level of embryonic development. "I can't think of a
reason why the technique would not theoretically work in humans," said
Brigid L. M. Hogan, an embryologist at Duke University.

If it does work in people, which could take many months to find out, the
technique might divide the anti-abortion movement into those who accept
or reject in vitro fertilization, because the objection to deriving human
embryonic stem cells would come to rest on creating the embryos in the
first place, not on their destruction.

"This gets around all of the ethical arguments, except for that small
minority of the pro-life community that doesn't even support in vitro
fertilization," said Representative Roscoe G. Bartlett, Republican of
Maryland, whose Web site describes him as "a pro-life legislator."

Until now the only way of deriving human embryonic stem cells has been to
break open the embryo before it implants in the uterus, a stage at which
it is called a blastocyst, and take out the inner cell mass, whose cells
form all the tissues in a human body.

Although the blastocysts used in the procedure are ones that fertility
clinics have rejected for implantation, many opponents of abortion say
the destruction of any embryo is wrong. Congress has forbidden the use of
federal money for any such research, and federally supported scientists
can work with only a small number of existing lines of embryonic stem
cells that have been exempted by President Bush.

Robert Lanza and colleagues at Advanced Cell Technology, a biotechnology
company in Worcester, Mass., have developed an alternative way of
generating embryonic stem cells that leaves the embryo viable.

They let a fertilized mouse egg divide three times until it contained
eight cells, a stage just before the embryo becomes a blastocyst.
Removing one of these cells, they then coaxed it into growing in
glassware and forming cells that have all the same essential properties
as embryonic stem cells derived from the inner cell mass, Dr. Lanza's
team reports.

The seven-cell embryo was implanted in the mouse uterus and grew
successfully to term. This part of the procedure is known to work with
humans too, because it is the basis of a well-established test known as
preimplantation genetic diagnosis. In the test, one cell is removed from
each of a set of embryos and tested for any of 150 genetic defects,
giving the parents the choice of implanting an embryo that is disease free.

Dr. Lanza's technique is likely to be welcomed by many in the middle of
the debate, although it has not won over the United States Conference of
Catholic Bishops. Richard M. Doerflinger, its deputy director for pro-
life activities, dismissed the technique, saying that preimplantation
genetic diagnosis itself is unethical.

The technique "is done chiefly to select out genetically imperfect
embryos for discarding, and poses unknown risks of future harm even to
the child allowed to be born," Mr. Doerflinger said in an e-mail message.

Only a procedure that generated embryonic stem cells without creating or
destroying embryos "would address the Catholic Church's most fundamental
moral objection to embryonic stem cell research as now pursued," Mr.
Doerflinger said in testimony last December to the President's Council on
Bioethics.

Senator Sam Brownback, a Kansas Republican and a leading pro-life
advocate did not return a call to his office. Edmund D. Pellegrino, the
new chairman of the President's Council on Bioethics, said through a
spokeswoman that he had no comment.

But Markus Grompe, a leading stem cell scientist and a Roman Catholic who
supports the church's teaching on the unacceptability of destroying
embryos, praised the Lanza approach, provided that the extracted cell
could not develop into an embryo by itself. "I find it clearly less
objectionable than the outright destruction of the embryo," said Dr.
Grompe, who studies liver stem cells at the Oregon Health and Science
University.

In response to Dr. Grompe's reservation, Dr. Lanza said individual human
blastomeres, as the cells are known at this stage, had never been shown
to create viable embryos.

If Dr. Lanza's technique proves to work in humans, it could do more than
just provide researchers with a new source of cells. It might allow every
child born through preimplantation genetic testing to have its own line
of embryonic cells stored for the future. The blastomere removed at the
eight-cell stage could be allowed to divide, with one cell being used for
genetic testing and the other for growing a culture of perfectly matching
embryonic stem cells.

The cells would be available throughout the child's life for the kind of
tissue and organ repair that it is hoped stem cells will one day provide.
In many of the degenerative diseases of old age, from heart attacks to
Parkinson's, the body loses vital cells and fails to replace them, an
omission that could perhaps be overcome if embryonic cells like those
present at the beginning of life were available to generate replacement
cells artificially.

With the parents' consent these cells could also be used for research,
providing many new embryonic stem cell lines for laboratories. The
procedure might be even be offered for all embryos generated in fertility
clinics when its theoretical risk has been better assessed.

"I can see a day when every fertility clinic embryo has a cell removed
and banked for future tissue use or organ replacement," said Ronald M.
Green, an ethicist at Dartmouth.

Children born after the preimplantation diagnosis procedure have the same
incidence of birth defects as those who did not undergo the procedure. So
far, after some 10 years of experience, there is no indication that it
causes health problems in humans, said Andrew R. La Barbera, scientific
director of the American Society for Reproductive Medicine.

If Dr. Lanza's technique succeeds in generating human embryonic stem cell
lines, Dr. La Barbera said, "I suspect that indeed it will become routine
to generate stem cells for everyone who undergoes preimplantation genetic
diagnosis."

But Kathy Hudson, director of the Genetics and Public Policy Center at
Johns Hopkins University, said there was "little data that documents the
safety and efficacy" of the preimplantation diagnosis procedure, even
after 2,000 births. She urged the American Society for Reproductive
Medicine to create a national database to address the safety issue.

The other alternative method reported in Nature today addresses an
ethical objection to therapeutic cloning, the idea of treating patients
with new tissues generated from their own cells.

The cells would be obtained by taking the nucleus from a patient's skin
cell and injecting it into a human egg whose nucleus had been removed.
The egg develops into a blastocyst from which embryonic stem cells can be
derived in the usual way. Critics say this nuclear transfer technique
creates embryos only to destroy them.

To counter this objection, Alexander Meissner and Rudolf Jaenisch of the
Whitehead Institute in Cambridge, Mass., have created mouse nuclear
transfer embryos that are inherently incapable of implanting in the
uterus. They did so by switching off a gene in the donor nucleus that is
needed for the implantation process. The gene was switched back on later
because it is needed to form the intestinal tissues.

William Hurlbut, a member of the President's Council on Bioethics, has
suggested that such unimplantable embryos may satisfy those who say a
potential life is being destroyed in the nuclear transfer process. But
Mr. Doerflinger, of the bishops conference, told the council last
December that this approach did not fulfill his criterion that an embryo
should not be created. This is still his position, he says.

Scientists hope that alternative approaches to embryonic stem cell
research may ease the political obstacles in their path, but they also
wish to avoid being compelled to abandon existing approaches before new
ones have been shown to work.

Irving Weissman, a stem cell biologist at Stanford, notes in a commentary
in Nature that there have been calls in Congress for a moratorium on
generating new stem cell lines until the two new techniques have been
adapted to people, a prospect that he describes as "highly speculative."

Representative Bartlett said the Lanza method "has come at a very
propitious time" because the Senate is considering various stem cell
bills, including a counterpart to legislation he proposed in the House
advocating research into alternative ways of deriving embryonic stem cells.

It is not yet clear if human embryonic stem cells generated from
blastomeres would be eligible for federal financial support, because they
might still fall foul of the Dickey-Wicker amendment, which prohibits
federal research where human embryos are destroyed, discarded or
subjected to substantial risk.

Dr. Lanza's company, Advanced Cell Technology, is well known in the
cloning field, having accomplished solid achievements as well as some
that veered toward the merely attention getting, like letting a human
nucleus develop to very early stages in a cow's egg. The company is
headed by Michael West, who as founder of Geron initiated support for the
research that led to the first derivation of human embryonic cells.

It will take a lot more research and maybe several years before Advanced
Cell Technology and others can tell if the new method works in humans and
how applicable it may be.

In preimplantation genetic diagnosis, there is very little time before
the disease-free embryo must be implanted in the uterus, perhaps too
little to allow an embryonic stem cell line to be generated, as Dr. Lanza
hopes, some experts said.

The procedure is in any case highly inefficient at present, and may never
become practical for babies born through in vitro fertilization. "I think
it is wildly speculative to say that in the future every IVF child will
have embryonic stem cell lines made, especially if the efficiency is so
low already," said Dr. Hogan, of Duke.



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