Stem cells cloned from monkey eggs

http://www.cnn.com/2007/TECH/science/11/14/monkey.clones.ap/index.html

NEW YORK (AP) -- Gleaning stem cells from cloned monkey embryos, as a
team of Oregon researchers has done, is an impressive step. But it
probably won't lead to medical treatments any time soon.

Scientists merged skin cells of a rhesus macaque male with
unfertilized monkey eggs that had the DNA removed.

One hurdle is ethical and political. Human embryos have to be
destroyed to produce stem cells. That has aroused opposition to human
embryonic stem cell research, and it led the Bush administration to
restrict federal funding for it. Scientists say that has slowed
science in this effort.

Another hurdle is the inefficiency of the process. Even if the method
described by scientists Wednesday works in humans, it would demand
too much of a precious resource -- women's unfertilized eggs.

The promise of producing stem cells by cloning is that they can be
genetically matched to a particular patient. So theoretically,
doctors should be able to transplant tissue created from them into
that person without tissue rejection. And presumably, such
transplants could help treat such conditions as diabetes and spinal
cord injury.

The process used in the new experiment is "quite inefficient,"
Shoukhrat Mitalipov of the Oregon National Primate Research Center in
Portland told reporters Wednesday.

He and his colleagues reported getting two batches of stem cells that
required using about 150 monkey eggs apiece. That's far too many if
one hopes to use human unfertilized eggs, which are cumbersome to
obtain from women.

If further work can get that down to maybe five to 10 eggs per stem
cell batch, "we will be closer to clinical applications," Mitalipov
said.

"I am quite sure it will work in humans," he added.

But then there's another issue -- showing that such stem cells really
can be used to treat diseases safely. Mitalipov said he plans to do
diabetes studies in monkeys.

For now, he and other scientists said, the new work is valuable for
showing that stem cells can be produced through cloning in monkeys.
It's been done in mice, but scientists had long been frustrated in
their attempts in primates, where the research would be more relevant
to humans.

The new work was published online Wednesday by the scientific journal
Nature. The success was reported earlier this year at a research
meeting in Australia, where it received limited media coverage. The
results were given new attention Tuesday by a London newspaper, The
Independent.

Dr. George Daley of the Harvard Stem Cell Institute, who was familiar
with the work, told The Associated Press in an e-mail that it was
a "a very important demonstration" that the process is feasible in
primates.

Mitalipov's team merged skin cells of a 9-year-old rhesus macaque
male with unfertilized monkey eggs that had the DNA removed. The
eggs, now operating with DNA from the skin cells, grew into early
embryos in the laboratory. Stem cells were recovered from these
embryos.

The researchers have applied for a patent on their procedure.

Mitalipov said separate experiments obtained monkey stem cells from a
different process called parthenogenesis, in which an egg grows into
an early embryo without any genetic contribution from a male. The
stem cells were genetic matches to the females that produced the
eggs, he said, and early experiments suggest stem cells derived this
way may someday prove useful for treating disease in women.

Nature took the unusual step of asking a separate group of scientists
to verify Mitalipov's cloning results, and it published the
verification along with Mitalipov's paper.

In an e-mail, the journal cited the highly publicized 2004 fraud that
came out of South Korea, where researchers led by Hwang woo-Suk
claimed to have produced stem cells from a cloned human embryo.

The journal said the research to verify Mitalipov's findings didn't
signal mistrust, but noted that questions would likely be raised,
and "we view this as a relatively straightforward way of putting
these questions to rest."

The verification study, by David Cram and others at the Monash
University in Australia, used DNA analysis of the male macaque, the
two monkeys whose eggs were used to create embryos, and the stem
cells. The result "demonstrates beyond any doubt" that the stem cells
came from cloned embryos, the Australians wrote in their Nature
paper.