Scientists make human embryo clones
NEW YORK (AP) - January 17, 2008 The new report documents embryos made with ordinary skin cells.
But it's not the first time human cloned embryos have been made. In
2005, for example, scientists in Britain reported using embryonic
stem cells to produce a cloned embryo. It matured enough to produce
stem cells, but none were extracted.
Stem cells weren't produced by the new embryos either, and
because of that, experts reacted coolly to the research.
"I found it difficult to determine what was substantially
new," said Doug Melton of the Harvard Stem Cell Institute. He said
the "next big advance will be to create a human embryonic stem
cell line" from cloned embryos. "This has yet to be achieved."
Dr. George Daley of the Harvard institute and Children's
Hospital Boston called the new report interesting but agreed that
"the real splash" will be when somebody creates stem cell lines
from cloned human embryos.
"It's only a matter of time before some group succeeds," Daley
said.
Korean scientist Hwang Woo-suk claimed a few years ago that he'd
created such cell lines, but that turned out to be a fraud.
Dr. Samuel Wood, a co-author of the new paper and chief
executive of Stemagen Corp. of La Jolla, Calif., said he and his
colleagues are now attempting to produce stem cell lines from the
embryos.
The work was published online Thursday by the journal Stem
Cells.
Scientists say stem cells from cloned embryos could provide a
valuable tool for studying diseases, screening drugs and, perhaps
someday, creating transplant material to treat conditions like
diabetes and Parkinson's disease.
But critics raise objections. The process "involves creating
human lives in the laboratory solely to destroy them for alleged
benefit to others," said Richard Doerflinger, spokesman for the
U.S. Conference of Catholic Bishops.
Citing the earlier work in Britain, he also said that as a
scientific advancement, the new work was "very limited."
Other objections to cloning include concerns about health risks
and exploitation if large numbers of women are asked to provide
eggs.
Those objections are one reason that an alternative route to
stem cells made headlines last November. Scientists reported a
relatively simple way to turn skin cells directly into stem cells.
This direct reprogramming carries a theoretical risk of cancer for
the recipients of tissue from these cells, however, and many
scientists have urged that work continue on the cloning technique
as well.
The cloning approach involves inserting DNA from a person into
an egg, and then growing the egg into an embryo about five days old
before extracting the stem cells. At that stage, the embryo is a
sphere of about 150 cells.
In the new work, researchers took skin cells from Wood and
another volunteer and produced three embryos with DNA matching the
men's. Further DNA testing on one of these embryos strengthened the
case that it was a clone, researchers said.
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On the Net:
Journal Stem Cells: http://stemcells.alphamedpress.org
Information on stem cells: http://stemcells.nih.gov/