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By Rick Weiss
Scientists in Massachusetts said on this
past Sunday November 25 they had succeeded in creating the
world's first cloned human embryos, a controversial advance
intended to speed the development of new medical therapies
but which could also hasten the arrival of the first cloned
baby.
The cloned human embryos, made by researchers at Advanced
Cell Technology in Worcester, grew for only a few hours --
long enough to form microscopic balls containing just four
to six cells each.
The work broke new scientific and ethical ground and reignited
a long-simmering debate over human cloning that had been on
the back burner since the Sept. 11 terrorist attacks and ensuing
events.
The use of federal funds
to conduct research on human cloning is now illegal,
but privately funded scientists such as those at ACT are under
no such restriction. Several members of Congress yesterday
vowed to place the legality issue on the top of their agendas.
Michael West, ACT's chief executive, has repeatedly said he
has no interest in making cloned human babies. Rather, the
goal is to coax cloned embryos to grow for just a few days,
then isolate from them embryonic stem cells, which have the
capacity to grow into all kinds of human tissues -- a process
called therapeutic cloning.
Experiments in animals have suggested that cloned human embryonic
stem cells could launch a new era of regenerative medicine
in which replacement tissues and perhaps organs could be grown
for transplantation into aging or diseased individuals.
In August, President Bush announced a policy that allows federally
financed scientists to conduct research on human embryonic
stem cells. But those cells must be retrieved from embryos
that were created by in vitro fertilization and had been slated
for destruction at fertility clinics. Federally funded stem
cell research involving cloned embryos is precluded under
the Bush policy.
Some scientists have argued, however, that the best way to
make stem cells for transplantation into patients is to grow
them from embryos that are clones of those patients. That
way the stem cells -- and the tissues made from those stem
cells -- would be genetically identical to the patient and,
in theory, less likely to be rejected by the patient's immune
system.
But that approach has raised ethical concerns because it would
require the creation of human embryos with the sole intent
of destroying them.
The latest work does not show that stem cells can be derived
from cloned human embryos, because the clones did not live
past the six-cell stage. Typically an embryo must grow to
a mass of a few hundred cells before it gives rise to stem
cells.
But the work breaks new
scientific ground by demonstrating that a single cell taken
from a human adult can be coaxed to turn into what appears
to be a healthy young embryo -- a feat until now accomplished
only in farm animals and mice.
And it breaks new ethical ground by creating the beginnings
of a human being from a single parent -- a step that many
people have said is, at a minimum, morally precarious.
The only previous report of such an experiment was by South
Korean scientists in 1998. But that work was never published
in a scientific venue, and some experts have questioned whether
it was as successful as the scientists there had reported.
Scientists involved in the latest work said it was justified
because they and the company's ethics advisory board had concluded
that the creations did not have the same moral standing as
conventional human embryos and because the creations had such
great potential to reduce human suffering.
"This work sets the stage for
human therapeutic cloning as a potentially limitless
source of immune-compatible cells for tissue engineering and
transplantation medicine," said Robert Lanza, vice president
of medical and scientific development at ACT and a principal
scientist involved in the work, in a news release.
"Our intention is not to create cloned human beings,
but rather to make life-saving therapies for a wide range
of human disease conditions, including diabetes, strokes,
cancer, AIDS, and neurodegenerative disorders such as Parkinson's
and Alzheimer's disease."
Antiabortion religious groups spoke out against the work.
"We're moving toward artificially creating human embryos
solely to mine them for spare parts -- solely to destroy them
for their cells," said Richard Doerflinger of the US
Conference of Catholic Bishops.
Cloning involves the creation of an embryo from a single adult
cell. In the most commonly used technique -- the one used
to create Dolly the sheep, the first cloned mammal -- the
adult cell is fused with an egg cell whose own genetic material
has been removed.
Through a process that scientists have only recently begun
to understand, naturally occurring chemicals inside the egg
persuade the newly fused creation to behave like a fertilized
egg. It begins to divide, one cell into two and two into four,
until it becomes an embryo.
If that embryo is transferred to the womb of a surrogate mother
-- as has been done repeatedly in recent years with mice,
sheep, goats, cattle and pigs, that clone can develop into
a fetus and eventually a newborn -- one
that is genetically identical
to the adult that donated the original cell.
ACT had previously made cloned embryos using donated human
cells fused with cow eggs (which are more easily obtained
than human eggs), including some the firm said appeared to
produce coveted stem cells. But the cross-species combination
raised technical and ethical issues that the firm wished to
overcome.
According to details released on Act's Web site -- company
officials could not be reached for comment yesterday -- the
human embryo cloning work began earlier this year when the
company placed ads in the Boston area seeking egg donors.
Volunteers were given psychological and medical tests, and
a dozen of them were selected to donate eggs.
That process involves weeks of hormone supplements and a minor
surgical procedure, which can generate up to about 20 eggs.
Other individuals were asked to donate skin cells -- the cells
from which the clones would grow -- and in July the researchers
tried to fuse some of those cells with eggs.
After three such attempts failed to generate an early embryo,
the researchers took a tip from a University of Hawaii team
that had cloned mice using cells other than skin cells as
their donor cells. They had used a kind of cell that grows
inside the ovaries, and which appears to be amenable to being
cloned when fused with an egg.
All told, the researchers went through 71 egg cells from seven
volunteers before they got a live embryo to grow. Ultimately
they managed to get three early embryos to grow -- two that
got to the four-cell stage and one that grew to "at least"
six cells, the report said.
All three early embryos
apparently died after that. It remains unclear
whether they harbored genetic or other defects related to
the cloning process that might have prevented them from maturing.
The same research team also used a second technique to try
to clone embryos. Using chemicals, they forced some human
eggs to start dividing on their own, as though they had been
fertilized by sperm.
In those experiments, which involve a process called parthenogenesis,
the researchers got six out of 22 eggs to grow into what appeared
to be five-day-old embryos -- old enough to contain stem cells.
But for reasons that remain unclear, those embryos lacked
the inner cell mass that usually contains embryonic stem cells.
Clonaid, a second company, said yesterday it, too, had cloned
human embryos and hopes to eventually create fully-developed
human clones. Its research has not been published, and Clonaid
has not revealed the location of its lab.
Clonaid director Brigitte Boisselier told the Associated Press
that its embryos were created by injecting eggs with a variety
of other cells, but she refused to give details.
The ACT research is described in a new and relatively unknown
on-line scientific journal called E-BioMed: Journal of Regenerative
Medicine.
The company also arranged special media exclusives through
which the work is described in Monday's issue of US News &
World Report and in the lay science magazine Scientific American
-- a media-savvy arrangement that some experts criticized
as an unprofessional means of sharing new scientific data.
One ethicist interpreted the approach as evidence that the
company is engaged in a power play to gain hotly contested
intellectual property rights to the fledgling technology.
Washington Post November
26, 2001; Page A01
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