MESSAGE
| DATE | 2008-01-19 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [NYLXS - HANGOUT] Human Cloning
|
Mature Human Embryos Created From Adult Skin Cells
By Rick Weiss Washington Post Staff Writer Friday, January 18, 2008; A01
Scientists at a California company reported yesterday that they had
created the first mature cloned human embryos from single skin cells
taken from adults, a significant advance toward the goal of growing
personalized stem cells for patients suffering from various diseases.
Creation of the embryos -- grown from cells taken from the company's chief
executive and one of its investors -- also offered sobering evidence that
few, if any, technical barriers may remain to the creation of cloned
babies. That reality could prompt renewed controversy on Capitol Hill,
where the debate over human cloning has died down of late.
Five of the new embryos grew in laboratory dishes to the stage that
fertility doctors consider ready for transfer to a woman's womb: a degree
of development that clones of adult humans have never achieved before.
No one knows whether those embryos were healthy enough to grow into
babies. But the study leader, who is also the medical director of a
fertility clinic, said they looked robust, even as he emphasized that
he has no interest in cloning people.
"It's unethical and it's illegal, and we hope no one else does it
either," said Samuel H. Wood, chief executive of Stemagen in La Jolla,
whose skin cells were cloned and who led the study with Andrew J. French,
the firm's chief scientific officer.
The closely held company hopes to make embryos that are clones, or
genetic twins, of patients, then harvest stem cells from those embryos
and grow them into replacement tissues. When transplanted into patients,
the tissues would not be rejected because the immune system would see
them as "self."
"All our efforts are being directed toward personalized medicine and
diseases," said Wood, adding that the scientists did not try to extract
stem cells from the first embryos they made because they were focused
on proving they could make the clones.
Other stem cell scientists expressed optimism but said they want to see
the work repeated and more details presented.
"I'd really like to believe it, but I'm not sold yet," said Robert Lanza
of Advanced Cell Technology (ACT) in Worcester, Mass. He said the report
did not show the results of molecular tests that scientists typically
do to prove that the cloning process was complete. He and George Daley,
a stem cell scientist at Children's Hospital Boston, said the embryos
look only marginally healthy in photos.
The work is the latest evidence, however, that the field is recovering
from the scientific and public relations debacle of 2005, when similar
claims by South Korean scientists proved to have been fabricated.
Nevertheless, opponents of research on human embryos lashed out at
the approach.
"This study seems to confirm that human cloning . . . is technically
possible," said Richard Doerflinger of the U.S. Conference of Catholic
Bishops. "It does not show that a viable or normal embryonic stem cell
line can be derived this way, or that any such cell has 'therapeutic'
value. It does not answer the ethical or social questions about
the mass-production of developing human lives in order to destroy
them. . . . It only tells us that these questions are more urgent
than ever."
Other critics noted that scientists in Japan and Wisconsin recently
discovered a way to "reprogram" stem cells directly from skin cells,
without having to make embryos as a middle step.
"In light of the recent cell reprogramming developments, cloning-based
stem cell research is less justified than ever," said Marcy Darnovsky
of the Center for Genetics and Society in Oakland, Calif.
Wood and others countered that, for now, those approaches require the
use of gene-altered viruses, which can trigger tumor growth.
"It's hard to believe the FDA would approve the use of those cells,"
Wood said.
Criticism also arose on Capitol Hill, where enthusiasm has grown for
the newer stem cell methods that do not involve embryos.
"Human cloning is now less about the science and more about the novelty,
which makes it all the more nefarious," said Rep. Dave Weldon (R-Fla.),
who has sought to ban all kinds of human cloning.
He said he hopes to revive the legislation this year. Previous bills
have failed because Congress, though willing to ban the creation of
cloned babies, is divided on the issue of banning human embryo cloning
for research.
No law bans cloned-baby-making, but the Food and Drug Administration
has said that such experiments would require its approval.
Cloning involves fusing an ordinary body cell with a female's egg cell
whose DNA has been removed. Chemical factors inside the egg reprogram the
body cell's DNA so that the newly created cell develops into an embryo
that is a genetic twin of the person or animal that donated the body cell.
The technology has developed rapidly in animals, and scientists have
been trying to apply it to human cells. In 2001, scientists at ACT said
that they had made cloned human embryos but that they grew for only a
day or two.
In 2005, scientists in Britain grew human embryo clones to the
fully mature "blastocyst" stage that the California team described
yesterday. But the body cells they used were taken from other human
embryos, not from adults.
That approach offers no help to patients who are already born.
In the new work, the team took skin cells -- some from Wood's arm and
some from an anonymous Stemagen investor -- and fused them to eggs
from women who were donating their eggs to help infertile women. About
one-quarter of the resulting clones, or five in all, developed into
five-day-old blastocysts.
Wood said the key was that his lab is directly adjacent to a fertility
clinic with which the company has an arrangement, so his team obtained
the eggs within an hour or so of when they were retrieved from the
women's ovaries.
And although researchers are typically given the poorest quality
"leftover" eggs from fertility patients, donors in this experiment --
and the women for whom those eggs were intended -- agreed to give away
several of the best eggs because, in each case, they had far more than
were needed.
"They are the heroes in this," Wood said. "Think about it. You're
spending $25,000 [trying to get pregnant], and you're giving some of
those eggs away."
Under California law, egg donors cannot be paid for their service.
DNA tests proved definitively in one case, and less clearly in two others,
that the embryos were indeed clones. Results could not be obtained from
two of the embryos.
R. Alta Charo, a professor of law and bioethics at the University
of Wisconsin, said the approach is attractive because the egg donors
were not subjected to the medical risks of ovarian stimulation and egg
retrieval just for research.
"The protocol entailed no marginal increased health risks to the
egg donors, as they were already undergoing hormonal stimulation for
non-research purposes," Charo said.
Asked what it was like to look at embryos that were replicas of himself,
Wood said: "I have to admit, it's a very strange feeling. It is very
difficult to look at an embryo and realize it is what you were a few
decades ago. It is you, in a way."
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