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[IPk] Fw: NYTimes.com Article: New Work May Provide Stem Cells
Check this out. We may see stem cell research yet!
IDDM 7+ years; MiniMed pumper 5+ years
New Work May Provide Stem Cells While Taking Baby From Equation
November 6, 2001
By ANDREW POLLACK
LOS ANGELES, Nov. 5 - In a development that may sidestep
some of the ethical issues surrounding stem cell research,
a scientist here says he has created stem cells that can
turn into nerve cells using a kind of embryo that cannot
develop into a baby.
The work, done in mice, is one of several recent
experiments that explore the usefulness of asexual
reproduction in deriving stem cells.
The researcher, Dr. Jerry L. Hall, uses chemicals to coax
an egg to grow into an embryo of sorts without being
fertilized by a male's sperm. Such embryos, even if
implanted into a womb, would not grow to become viable
babies, Dr. Hall and other experts said. But the embryos
can be grown in a laboratory for a few days, long enough to
become a source of stem cells.
Embryonic stem cells can turn into virtually all types of
the body's cells, potentially providing replacement cells
that can be transplanted into patients to cure diseases.
But opponents say such research is immoral because deriving
stem cells involves destroying embryos, which they see as
nascent human life.
Dr. Hall argues that if an "embryo" were not formed by
conception and would not be able to turn into a child, that
might make stem cell work more acceptable.
"We feel that this really could circumvent a lot of ethical
concerns," said Dr. Hall, an embryologist at the Institute
for Reproductive Medicine and Genetic Testing, a fertility
clinic here. He presented his work at the annual meeting of
the American Society for Reproductive Medicine in Orlando,
Fla., late last month.
But Richard M. Doerflinger of the United States Conference
of Catholic Bishops, said the technique was unlikely to end
the opposition the Roman Catholic Church has to embryonic
stem cell work.
The real question, he said, is whether these are really
embryos. If they are, "the fact that these beings would not
survive to birth does not answer the question," he said.
"Our teaching about the embryo does not rely on it having
been created by fertilization."
Numerous scientific questions remain as well about the
work, which has not been published in a scientific journal.
Dr. Hall, who did the research with Dr. Yan-Ling Feng of
the Center for Reproductive Research and Testing in
Rockville, Md., said they had not determined whether the
stem cells could turn into other types of cells, or even
whether the nerve cells were normal.
Dr. Hall said he had not yet tried to derive human stem
cells this way. But others are getting closer to that. The
University of Massachusetts has applied for a patent on
using the technique to derive stem cells from primates,
including humans. The work was done with Advanced Cell
Technology, a stem cell and cloning company in Worcester,
Scientists at the university and the company derived a line
of stem cells from monkeys that could be maintained for
months and that spontaneously differentiated into many
types of cells including beating heart cells, according to
the patent application, which has been published in Europe
but not yet granted.
Dr. Michael West, chief executive of Advanced Cell
Technology, would not comment when asked if the company had
tried this in humans. He also would not discuss the
company's work in detail, saying he did not want to
jeopardize an upcoming publication in a scientific journal.
The work takes advantage of a phenomenon known as
parthenogenesis. It is known that some species of flowers,
insects, lizards and snakes can reproduce asexually, with
the female's egg growing into a baby without being
fertilized by a male..
Parthenogenesis, which is from the Greek for virgin birth,
does not occur naturally in mammals. But for decades
scientists have known how to trick the eggs of mice,
rabbits and other mammals into developing as if they had
been fertilized by subjecting the eggs to various chemicals
or to temperature changes, needle pricks or electrical
shocks. The resulting embryos are called parthenotes. It
has not been reported that this has ever been done with
human eggs, however, and it would raise ethical questions.
An egg has a full number of chromosomes right up until
fertilization, when it ejects half of them and receives a
half set from the sperm. So if this ejection is suppressed,
an egg will have the full number of chromosomes.
The embryos created this way would not be clones of the
woman, Dr. Hall said, because the chromosomes in an egg are
somewhat different from the woman's set. Still, he said,
the tissues derived from stem cells from such embryos would
be close enough to a woman's own tissues that they would
not be rejected if transplanted back into the woman.
Another possible way to develop such compatible tissues is
to use stem cells made by cloning the patient's own cells.
The idea, known as therapeutic cloning, is to take genetic
material from a patient's cell and fuse it with an egg that
is missing its own nucleus, creating an embryo that is a
genetic copy of the patient. But because an embryo made
through that method would in theory be able to develop into
a person, Roman Catholic authorities and other abortion
opponents have objected.
To create the parthenotes, Dr. Hall and Dr. Feng bathed the
mouse egg cells in alcohol and then exposed them to a
chemical called cytochalasin D. About 30 percent of the
eggs were activated and 40 percent of those went on to form
a blastocyst, a several-day-old embryo from which stem
cells can be taken. The stem cells were treated with
retinoic acid to turn them into nerve cells.
Dr. Azim Surani, a professor of biology at Cambridge
University, said the work was not surprising since he and
others had derived parthenogenetic stem cells more than a
decade ago and saw evidence that they would turn into nerve
cells. But he said it was unclear how many other types of
cells could be created this way. "They don't form muscle
cells very easily," he said.
Dr. Surani also said the parthenotes and any tissues
derived from them might be abnormal. That is because in
normal embryo development, certain genes from the father
but not the mother, or vice versa, are turned on. But
parthenotes don't have genes from the father, so this
process, called imprinting, would go awry. Lack of
imprinting is also probably the reason that parthenotes do
not develop into babies, he said.
Still, Dr. West said it might be possible one day to
produce human babies through parthenogenesis. Male
parthenotes could be created, too, he said, by replacing
the DNA in an egg with the DNA from two of a male's sperm
But male and female parthenotes have shown differences,
said Dr. Jose Cibelli, vice president for research at
Advanced Cell Technology. Stem cells derived from male par
thenotes tend to turn into muscle cells, while stem cells
from female parthenotes turned more often into brain and
nerve cells, he said.
Dr. West said that if this process could be used to produce
live offspring it would open up vast new reproductive
possibilities. A woman could give birth by herself. Or two
men may be able to each contribute one sperm to have a baby
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