[escepticos] Política e investigaciones con células madre

[Carlos Dominguez]

Nota del New York Times
Saludetes
Carolus
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August 24, 2006
Stem Cell News Could Intensify Political Debate
By NICHOLAS WADE

Biologists have developed a technique for establishing colonies of
human embryonic stem cells from an early human embryo without
destroying it. This method, if confirmed in other laboratories, would
seem to remove the principal objection to the research.

It could also redirect and intensify the emotional political debate
over current limits on federal financing for research on human
embryonic stem cells, which give rise to the cells and tissues of the
body and which scientists and patient advocate groups see as a
potential source for treatments for diseases like Alzheimer's,
Parkinson's and diabetes.

But the new method, reported yesterday by researchers at Advanced Cell
Technology on the Web site of the journal Nature, had little immediate
effect on longstanding objections of the White House and some
Congressional leaders yesterday. It also brought objections from
critics who warned of possible risk to the embryo and the in vitro
fertilization procedure itself, in which embryos are generated from a
couple's egg and sperm.

The new technique would be performed on a two-day-old embryo, after
the fertilized egg has divided into eight cells, known as blastomeres.
In fertility clinics, where the embryo is available outside the woman
in the normal course of in vitro fertilization, one of these
blastomeres can be removed for diagnostic tests, like for Down
syndrome.

The embryo, now with seven cells, can be implanted in the woman if no
defect is found. Many such embryos have grown into apparently healthy
babies over the 10 years or so the diagnostic tests have been used.

Up to now, human embryonic stem cells have been derived at a later
stage of development, when the embryo consists of about 150 cells.
Both this stage, called the blastocyst, and the earlier eight-cell
stage, occur before the embryo implants in the wall of the womb.
Harvesting the blastocyst-stage cells kills the embryo, a principal
objection of those who oppose the research.

"There is no rational reason left to oppose this research," Dr. Robert
Lanza, vice president of Advanced Cell Technology and leader of the
research team, said in an interview.

With the approach of midterm elections, in which some candidates are
already making the research a central theme, some scientists
speculated that President Bush might embrace the new method as meeting
his principal objection to the research and showing that he had been
right all along to wait for a better technique to turn up.

But Emily Lawrimore, a White House spokeswoman, suggested that the new
procedure would not satisfy the objections of Mr. Bush, who vetoed
legislation in July that would have expanded federally financed
embryonic stem cell research. Though Ms. Lawrimore called it
encouraging that scientists were moving away from destroying embryos,
she said: "Any use of human embryos for research purposes raises
serious ethical questions. This technique does not resolve those
concerns."

Last year, Dr. Lanza reported that embryonic stem cell cultures could
be derived from the blastomeres of mice, a finding others have
confirmed. He now says the same can be done with human blastomeres,
and that the colonies of cells behave in the same way as those derived
from blastocysts.

Although he used discarded human embryos, he said that anyone who
wished to derive human embryonic stem cells without destroying an
embryo could use a blastomere removed for the test, called
preimplantation genetic diagnosis.

"By growing the biopsied cell overnight," he said, "the resulting
cells could be used for both P.G.D. and the generation of stem cells
without affecting the subsequent chances of having a child."

Ronald M. Green, an ethicist at Dartmouth College and an adviser to
Advanced Cell Technology, said he hoped the new method "provides a way
of ending the impasse about federal funding for this research."

Professor Green said he believed the method should be seen as
compatible with the Dickey-Wicker amendment, the Congressional measure
that prohibits using federal money for any research in which a human
embryo is destroyed or exposed to undue risk.

Dr. James Battey, head of the stem cell task force at the National
Institutes of Health, said that it was not immediately clear if the
new method would be compatible with the Congressional restriction,
since removal of a blastomere subjected the embryo to some risk, but
that embryos on which the genetic test was performed seemed to be as
healthy as other babies born by in vitro fertilization.

Mr. Bush has allowed federal financing for research on human embryonic
stem cells, provided they were established before Aug. 9, 2001.
Although that might seem to rule out any new cell lines derived from
blastomeres, Dr. Battey said that was not clear because the embryo
would not be destroyed, and that he would seek guidance on the point.

The federal policy does not affect privately financed stem cell
research, like that done by Advanced Cell.

Critics have a range of objections to deriving human embryonic cell
lines with the new method. The United States Conference of Catholic
Bishops, in particular, oppose both in vitro fertilization and
preimplantation genetic diagnosis, and therefore still object to the
research.

Richard Doerflinger, deputy director for pro-life activities at the
conference of bishops, said the church opposed in vitro fertilization
because of the high death rate of embryos in clinics and because
divorcing procreation from the act of love made the embryo seem "more
a product of manufacture than a gift."

Asked if he meant that the parents of a child conceived through in
vitro fertilization would love it less, Mr. Doerflinger said he was
referring to the clinic staff. "The technician does not love this
child, has no personal connection with the child, and with every
I.V.F. procedure he or she may get more and more used to the idea of
the child as manufacture," he said.

Dr. Leon Kass, former chairman of the President's Council on
Bioethics, said, "I do not think that this is the sought-for, morally
unproblematic and practically useful approach we need."

Dr. Kass said the long-term risk of preimplantation genetic diagnosis
was unknown and that the present technique was inefficient, requiring
blastomeres from many embryos to generate each new cell line. It would
be better to derive human stem cell lines from the body's mature
cells, he said, a method researchers are still working on.

Dr. Andrew La Barbera, scientific director of the American Society for
Reproductive Medicine, said that more than 2,000 babies had been born
in the United States after a preimplantation genetic diagnosis. There
is no sign yet that they have any greater risk of disease than other
in vitro fertilization babies, but the society needs more data to be
sure, Dr. La Barbera said.

Scientists welcomed the new development but also expressed concerns.
Dr. Irving Weissman, a stem cell expert at Stanford University, said
the new method, if confined to blastomeres derived from
preimplantation genetic testing, would not provide a highly desired
type of cell, those derived from patients with a specific disease.

Many scientists have come to regard this use of the cells, to explore
the basic mechanisms of disease, as more likely to provide new
therapies than direct use of the cells themselves.

Dr. Weissman said the new advance could lead into a "Congressional
trap" if Congress permitted new lines to be established only during
the preimplantation genetic diagnosis procedure. This test looks for
only a handful of diseases, he said, and not for Alzheimer's and the
other degenerative diseases for which better therapies are needed.

Congressional Republicans who led the resistance to the embryonic stem
cell legislation that had bipartisan support in the House and Senate
also said the new technique did not ease their opposition. Brian Hart,
a spokesman for Senator Sam Brownback, Republican of Kansas and a
prominent opponent of federal financing for embryonic stem cell
research, said Mr. Brownback's moral objection remained.

"You are creating a twin and then killing that twin," Mr. Hart said.

Dr. Lanza said, however, that twinning is a phenomenon that occurs at
a later stage of embryonic development and that there was no evidence
that a single blastomere could develop into a person.

Democrats and others who had pushed for added research using embryos
that were ultimately going to be discarded stepped up their criticism
of the president and his allies for holding back science.

"It's tragic that the current Republican Congress continues to rubber
stamp the restrictions that deny federal funding for scientists
engaged in medical research that could save or improve countless
lives," said Senator Edward M. Kennedy, Democrat of Massachusetts.

Political analysts said the new findings could elevate embryonic stem
cell research as a campaign issue by both keeping it in the news and
making it more difficult for opponents to explain their position.

"It paints the pro-life community into a corner," said Stuart
Rothenberg, a nonpartisan analyst of Congressional races. "As a rule,
you don't want to oppose scientific advances."

Gardiner Harris and Carl Hulse contributed reporting for this article.