Interesting article in light of the EAE discussion that goes on around here regularly -- make the mice a little more human and maybe their disease will be more like ours...
Trace of Human Stem Cells Put in Unborn Mice Brains
THE ASSOCIATED PRESS - December 13, 2005 - Scientists announced on Monday that they had created mice with small amounts of human brain cells in an effort to make realistic models of neurological disorders like Parkinson's disease.
Led by Fred H. Gage of the Salk Institute in San Diego, the researchers injected 100,000 human embryonic stem cells into the brain of each 14-day-old mouse embryo in the experiment.
Those mice were each born with about 0.1 percent of human cells in each of their heads, a trace amount that does not remotely come close to "humanizing" the rodents.
"This illustrates that injecting human stem cells into mouse brains doesn't restructure the brain," Dr. Gage said.
Previously, researchers had injected a more developed form of human stem cell, neural stem cells, into the brains of newborn mice. In those experiments, too, the human cells made up a tiny part of the mice brains.
The new work may add to ethical concerns about mixing human and animal cells in stem cell and cloning research.
"The worry is if you humanize them too much you cross certain boundaries," David Magnus, director of the Stanford Medical Center for Biomedical Ethics, said. "But I don't think this research comes even close to that."
Researchers say commingling human and animal tissue is vital to ensuring the safety of experimental drugs and new tissue replacement therapies. Researchers are nevertheless beginning to bump up against what bioethicists call the "yuck factor." Three researchers have applied for a patent that contemplates fusing a complete human DNA set in animal eggs to make human embryonic stem cells.
Pig valves have long been transplanted into human hearts, and scientists have injected human cells in laboratory animals even longer. But the brain poses an additional level of concern because some experts envision the possibility of a human mind 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," the National Academies of Science said in April. The report recommended work under strict ethical guidelines.
Dr. Gage said the new work, published in The Proceedings of the National Academy of Sciences, was a step in overcoming a major technical hurdle for stem cell research, precisely when to inject the cells in patients.
The results suggest that human embryonic stem cells, once injected, 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 them.