============================================================ "Thank You So Much! You [21 North Main] people are amazing. I couldn't get this book through Amazon.com or Barnes and Noble.com and I've been looking for it for 25 years. Jetta" http://click.topica.com/caaacybb1ddNBb2HgmNb/21NorthMain ============================================================Study: Cloning with stem cells causes abnormalities in mice
By PAUL RECER
AP Science Writer
WASHINGTON (AP) — Researchers have found serious abnormalities in cloned
mice, a finding that strengthens the belief of many scientists that the
technique used to clone Dolly the sheep should not be used on humans.
The findings are based on the use of embryonic stem cells in cloning and come
as the Bush administration considers whether to allow federal funds for
non-cloning stem cell research. The research appears Friday in the journal
Science.
“This study confirms the suspicions of many of us that cloning of humans
would be really dangerous,” said Rudolf Jaenisch, senior author of the study
and a researcher at the Whitehead Institute for Biomedical Research and at
the Massachusetts Institute of Technology.
David Humpherys, first author of the study, said that many of the mice cloned
in the experiment appeared to be normal, including having normal genes, but
there was evidence that during embryonic and fetal development the genes did
not work properly.
“It is quite likely that just the animals that are most nearly normal make it
to birth (in cloning), but our study shows that doesn’t mean they are
completely normal,” said Humpherys. “There may be changes in gene expression
that could affect them later in life.”
In cloned humans, Jaenisch said the gene expression flaws could affect
personality, intelligence and other human attributes.
Humpherys said there was no evidence that the genes in the cloned animals
were altered, but that the way in which the genes made proteins was flawed
and unstable. In effect, the researchers found that even though the
biological blueprint was intact in the cloned animals, the way that the
blueprint was read and interpreted was flawed. This could result in abnormal
tissues and organs, they said.
Humpherys and Jaenisch said that a number of scientists doing cloning
experiments with mice, pigs, sheep and cattle have reported that even
apparently normal animals develop disorders later in life. Jaenisch said that
extreme obesity has developed in many cloned animals, including Dolly, the
first mammal cloned from an adult cell.
Dr. David A. Prentice, an Indiana State University professor of life
sciences, said the MIT-Whitehead study shows the hazards of the current
cloning technology.
“Development is a finely orchestrated ballet of cells forming tissues and
organs at the right place and time,” said Prentice. “It takes only one going
awry at the wrong time and place to have a seriously flawed individual.”
In the study, the researchers made the mouse clones using embryonic stem
cells, the primordial cells known to be able to form virtually any tissue in
the body. The DNA from the cells was removed and inserted into a mouse egg
that had been stripped of its DNA. The resulting embryos were then implanted
in mother mice and allowed to grow to birth.
The researchers monitored the expression, or action, of genes that play a
role in embryo and fetal development. They found that the genes, even from
nearly identical stem cells, worked differently. In fact, said Humpherys,
stem cells are unstable in gene expression even in the laboratory dish.
This instability raises the possibility that using stem cells to treat health
disorders may not work as well as some scientists have suggested, said Dr.
Joann A. Boughman, vice president of the American Society of Human Genetics.
“When we grow (embryonic stem) cells for a curative situation, we will need
to precisely control the process,” she said. “This paper shows that we’ve
got a very long way to go to fully understand this whole process.”
Some researchers have suggested that embryonic stem cells could be cloned
from a patient and used to grow cells that could be used to restore that
patient’s ailing heart or liver or other organs.
Jaenisch said that it is unlikely that genetic instability would block the
curative use of embryonic stem cells. He said in developing cells for
therapeutic use, researchers would harvest and inject into patients only
those cells that are normal.
During cloning, he said, no such selection is possible because an embryo must
use the DNA provided and cannot select only that which is perfect.
Regulations that would permit federal funding of embryonic stem cell research
have been delayed by President Bush who ordered a review of the whole issue.
Some in Congress oppose embryonic stem cell research because obtaining the
cells involves the death of a human embryo. Many scientists, however, believe
that embryonic stem cell research could relieve suffering for millions of
patients with a variety of disorders.
Copyright 2001 Associated Press. All rights reserved. This material may not
be published, broadcast, rewritten, or redistributed.
"We're not supposed to be perfect. We're supposed to be Useful."
Leonard Peltier
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