Human Clone Experiment Repeated Successfully

[Murray Charters <mcharters@xxxxxxxxxxxxxx>]

Human Clone Experiment Repeated Successfully
Tuesday, December 16, 2003 Posted: 11:03 AM EST (1603 GMT)

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.

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.

Reference:

Advanced Cell Technology


Stem cell - From Wikipedia, the free encyclopedia


Parthenogenesis - From Wikipedia, the free encyclopedia


SOURCE: Reuters / CNN


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