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Mice created with human brain cells
(AP)
Updated: 2005-12-13 14:33
Add another creation to the strange scientific menagerie where animal species
are being mixed together in ever more exotic combinations.
Scientists
announced Monday that they had created mice with small amounts of human brain
cells in an effort to make realistic models of neurological disorders such as
Parkinson's disease.
Led by Fred Gage of the Salk Institute in San Diego, the researchers created
the mice by injecting about 100,000 human embryonic stem cells per mouse into
the brains of 14-day-old rodent embryos.
Those mice were each born with about 0.1 percent of human cells in each of
their heads, a trace amount that doesn't remotely come close to "humanizing" the
rodents.
"This illustrate that injecting human stem cells into mouse brains doesn't
restructure the brain," Gage said.
Still, the work adds to the growing ethical concerns of mixing human and
animal cells when it comes to stem cell and cloning research. After all, mice
are 97.5 percent genetically identical to humans.
"The worry is if you humanize them too much you cross certain boundaries,"
said David Magnus, director of the Stanford Medical Center for Biomedical
Ethics. "But I don't think this research comes even close to that."
Researchers are nevertheless beginning to bump up against what bioethicists
call the "yuck factor."
Three top cloning researchers, for instance, have applied for a patent that
contemplates fusing a complete set of human DNA into animal eggs in order to
manufacturer human embryonic stem cells.
One of the patent applicants, Jose Cibelli, first attempted such an
experiment in 1998 when he fused cells from his cheek into cow eggs.
"The idea is to hijack the machinery of the egg," said Cibelli, whose current
work at Michigan State University does not involve human material because that
would violate state law.
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