CNN.com - Human clone experiment repeated successfully - Dec. 16, 2003


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            Human clone experiment repeated successfully


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            WASHINGTON (Reuters) -- The only researchers to publicly show
that they have cloned a human embryo said on Tuesday that they had
successfully repeated the experiment, growing an embryo to the 16-cell
stage.

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            Researchers at Advanced Cell Technology of Worcester,
Massachusetts, have also repeatedly created embryos using a process called
parthenogenesis -- using only a human egg cell and no sperm, and without
cloning.

            The company says the experiments, reported in the January issue
of Wired magazine, are not breakthroughs but a natural progression of its
efforts to create human embryonic stem cells to use for medical treatments.

            "It's not a scientific advance," ACT medical director Dr. Robert
Lanza said in a telephone interview.

            But he said the researchers had managed to replicate experiments
reported in late 2001, in which they used cloning technology to create a
human embryo that grew to the six-cell stage. They also created more
advanced embryos, called blastocysts, using parthenogenesis.

            Sheep, cattle and pigs have all been cloned using an egg cell
and an adult cell from another animal.

            But critics had questioned whether the cloning process known as
nuclear transfer has ever worked with humans. Lanza said the new
experiments, which began last June, suggest they were successful.

            A 'virgin birth'
            Even more successful were the parthenogenesis experiments -- in
which five of eight human eggs were coaxed into growing into blastocysts. At
this stage -- approximately 100 cells -- an embryo can be mined for its stem
cells.

            The stem cells -- nature's template for all cells -- can become
any sort of cell or tissue in the body.

            Scientists hope the cells may one day allow custom-made tissue
transplants to heal damaged hearts or cure diabetes by replacing dead
pancreatic cells.

            Opponents raise moral objections, saying that cloning technology
involved in making embryonic stem cells creates a living human being.

            The U.S. federal government refuses to fund embryonic stem cell
research beyond a few limited cultures, while Congress and some members of
the United Nations have made several failed attempts to ban so-called
therapeutic cloning outright.

            Lanza says parthenogenesis can bypass these objections.
Parthenogenesis is not known to lead to the development of a fetus in
mammals.

            "If implanted into a woman's uterus, we don't think it would
develop into a child," he said.

            But the resulting blastocyst, called a parthenote, can be a
source of embryonic stem cells. Tissue from such cells would be easier to
match with patients and less likely to be rejected, Lanza said, because they
contain only one person's DNA.

            It also would be more readily available than tissue from a
patient's cloned cells, which would take months to prepare.

            "For many therapies you don't have time to start from scratch,"
he said.

            It would take just 40 batches, or lines, of parthenote-generated
stem cells to create tissue matches for 70 percent of the U.S. public, Lanza
said. Embryonic stem cells are immortal, so it would not take many human
eggs to create several dozen lines.



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