[Paleopsych] Science News: 'Stuart Little' mouse soon to have a human brain

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'Stuart Little' mouse soon to have a human brain

[Science News]:

It will look like any ordinary mouse, but for America's scientists a
tiny animal threatens to ignite a profound ethical dilemma.

In one of the most controversial scientific projects ever conceived, a
group of university researchers in California's Silicon Valley is
preparing to create a mouse whose brain will be composed entirely of
human cells.

Researchers at Stanford University have already succeeded in breeding
mice with brains that are one per cent human cells.

In the next stage they plan to use stem cells from aborted foetuses to
create an animal whose brain cells are 100 per cent human.

Prof Irving Weissman, who heads the university's Institute of
Cancer/Stem Cell Biology, believes that the mice could produce a
breakthrough in understanding how stem cells might lead to a cure for
diseases such as Parkinson's and Alzheimer's disease.

The group is waiting for a key American government-sponsored report, due
this month, that will decide just how much science can blur the
distinction between man and beast.

Last week, however, the university's ethics committee approved the
research, under certain conditions. Prof Henry Greely, the head of the
committee, said: "If the mouse shows human-like behaviours, like
improved memory or problem-solving, it's time to stop."

He accepted that the project might seem "a little creepy", but insisted:
"It's not going to get up and say 'Hi, I'm Mickey'. Our brains are far
more complicated."

Biologists know such creatures as "chimeras", after the mythical Greek
monster that was part-lion, part-goat and part-serpent.

Prof Weissman said that there was no way of knowing whether the
"human-mice" would develop any human characteristics until after they
were born. In previous experiments, pigs with human blood have been
developed at a clinic in Minnesota. Last year, the University of Nevada
produced sheep whose livers were 80 per cent human and could one day be
used for transplants.

An inquiry into laying down rules for research using stem cells from
human embryos was launched last summer by America's National Academies
of Science. The government-sponsored report, said to be in draft form,
will govern stem cell research in the private sector. It comes at a time
of growing confusion in America over the limits of stem cell research.

President George W Bush halted government-funded research during his
first term of office but several states, including California, have
since passed laws that allow support for stem cell projects from local

At hearings in Washington last October, Prof Weissman argued strongly
against a ban on "chimera mice". He believes that the mice would behave
like any others, but said that he would monitor the experiment closely
and destroy them at the slightest suggestion of human-like brain

Supporters of stem cell research at Stanford University include the
actor Michael J Fox, who suffers from Parkinson's disease. Fox provided
the voice for Stuart Little, Hollywood's version of the "human mouse'',
who talks, has human parents and lives in a New York apartment.

Opponents of Prof Weissman's work accept that his mice are unlikely to
show such obvious human traits, but voice concerns that the brain cells
would begin to organise themselves in a way that was more human than
mouse. There is growing unease over whether human stem cells could
migrate to other parts of the animals, creating human sperm or eggs in
their reproductive systems.

Should two such "chimera mice" mate, it could lead to the nightmarish
scenario of a human embryo trapped in a mouse's womb. William Cheshire,
a neurology professor from the Mayo Clinic in Florida and a Christian
activist, has called for a ban on any research that destroys a human
embryo to create a new organism.

"We must be careful not to violate the integrity of humanity or of
animal life,'' he said. "Research projects that create human-animal
chimeras risk disturbing fragile ecosystems, endanger health and affront
species integrity.''

In a recent article for the conservative Weekly Standard magazine,
Wesley Smith, a consultant for the Centre for Bioethics and Culture
warned that "biotechnology is becoming dangerously close to raging out
of control''.

He wrote: "Scientists are engaging in increasingly macabre experiments
that threaten to mutate nature and the human condition." (Agencies)

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