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Mice created with human brain cells
(AP)
Updated: 2005-12-13 14:33 Researchers argue that co-mingling human and animal tissue is vital to
ensuring that experimental drugs and new tissue replacement therapies are safe
for people.
Others have performed similar experiments with rabbit and chicken eggs while
University of California-Irvine researchers have reported making paralyzed
rodents walk after injecting them with human nerve cells.
Doctors have transplanted pig valves into human hearts for years, and
scientists have injected human cells into lab animals for even longer. But the
brain poses an additional level of concern because some envision nightmare
scenarios in which a human mind might be trapped in an animal head.
"Human diseases, such as Parkinson's disease, might be amenable to stem cell
therapy, and it is conceivable, although unlikely, that an animal's cognitive
abilities could also be affected by such therapy," a report issued in April by
the influential National Academies of Science that sought to draw some ethical
research boundaries.
So the report recommended that such work be allowed, but with strict ethical
guidelines established.
"Protocols should be reviewed to ensure that they take into account those
sorts of possibilities and that they include ethically sensitive plans to manage
them if they arise," the report concluded.
At the same time, the report did endorse research that co-mingles human and
animal tissue as vital to ensuring that experimental drugs and new tissue
replacement therapies are safe for people.
Gage said the work published Monday in the journal Proceedings of the
National Academy of Sciences is another step in overcoming one of the biggest
technical hurdles confronting stem cell researchers: when exactly to inject the
cells into patients.
The results suggest that human embryonic stem cells, once injected into
people, will mature into the cells that surround them. No known human has ever
received an injection of embryonic stem cells because so little is known about
how those cells will mature once inside the body.
For now, Gage said his work is more geared toward understanding disease than
to finding a cure.
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