I like the idea of chimeras and I like mice.  Wish my dog could talk. Ray
----- Original Message -----
From: "M.Schild" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, October 17, 2005 11:31 PM
Subject: human cells in mouse brain


> By Dianna Bai
> Monday, October 17, 2005
> last updated October 17, 2005 12:27 AM
>
> Can the cure to Alzheimer's, Parkinson's and a long list of other fatal
> genetic diseases be found in the mind of a mouse? It just might be
> possible
> with recent, but controversial, developments in stem cell research.
>
> Irving Weissman, director of Stanford's Institute for Stem Cell Biology
> and
> Regenerative Medicine, has worked with the transfer of human neurons to
> the
> brains of mice for several years now. He has already bred mice whose
> brains
> are composed of 1 percent human neurons, finding that transplanted human
> brain cells could successfully connect to a mouse brain.
>
>
> "Remarkably, even though humans and mice are separated by millions of
> years
> of evolution, human neurons responded to the mouse signals," Weissman
> said.
>
>
> Now, he wants to initiate a new experiment by transplanting human
> brain-stem
> cells to an inbred strain of mice whose natural brain cells die before the
> mice's birth. Human brain cells would then replace the mice's own,
> creating a
> breed of mice whose brains are composed entirely of human neurons.
>
>
> Although Weissman acknowledged that the experiment "may not even work at
> all"
> - if it were to be successful, scientists would have a way to study living
> human-brain cells in a lab animal. Researchers, according to Weissman,
> would
> then be able to experiment on diseased human neurons in lab animals in
> ways
> that they could not with human subjects due to the high risks.
>
>
> But even with the potential benefits, blurring the line between species
> has
> always brought up many ethical concerns in the scientific community, as
> well
> as negative reactions from the public.
>
>
> As part of an ethics committee gathered together by Weissman, Stanford Law
> Prof. Henry Greely has identified four ethical questions concerning the
> project. They include the use of stem cells from aborted fetuses, the
> inappropriate use of human tissue and the pain and suffering of the
> laboratory mice.
>
>
> However, the main concern, Greely said, is "running the risk of conferring
> aspects of humanness in the mice."
>
>
> In other words, the creation of a human chimera - a mouse with human
> consciousness.
>
>
> In Greek mythology, chimeras were hybrid creatures with bodies of goats,
> heads
> of lions and tails of snakes. But both Weissman and Greely agreed that the
> project in question is nowhere near so sensational.
>
>
> This past July, Sen. Sam Brownback (R-Kan.) introduced a bill to prohibit
> the
> creation of human chimeras. If passed, the new legislation would ban
> experiments like Weissman's, even making them subject to criminal penalty.
>
>
> "If passed, the legislation might make it a 10-year prison sentence to
> conduct experiments like these," Greely said.
>
>
> He also mentioned that the strongest reaction from the public to human
> chimeras is usually the "yuck factor."
>
>
> "People have talked about giving this mouse a human brain, but that would
> not
> be true," Greely said. "It would be unlikely to truly impossible for these
> mice to exhibit human ability."
>
>
> He stressed that neurons only comprise about 10 percent of the brain,
> while
> the connections between neurons are what scientist believe determine
> consciousness. Greely described neurons as the bricks that make up the
> brain.
>
>
> "A church built with red bricks instead of gray will still be a church
> because
> the framework has not changed, just as the structure of the mouse's brain
> has
> not changed," he said. "What's important is the architecture, not the
> bricks."
>
>
> Stanford students surveyed also doubted the possibility of someone
> creating a
> "Stuart Little."
>
>
> "I'd be interested to see the results of the experiment, but I don't think
> the mouse is going to get up and start talking," said freshman Jonathan
> Scrafford. "But if it did, then it would raise some issues."
>
>
> Others said they did not believe the experiment raised any serious ethical
> questions.
>
>
> "It doesn't bother me that much," said junior Daniel Jacobs. "Even if the
> worst thing happened and all the human behavior was transferred to a
> mouse,
> it wouldn't be that bad."
>
>
> Junior Andrew Liefer, the technology columnist for The Daily, said he had
> mixed feelings about the experiment.
>
>
> "All this research is good because it's helping solve a lot of problems,
> but
> it'd be nice if people thought about the ethical concerns a little more,"
> he
> said.
>
>
> Greely's recommendation to Weissman was to forge ahead step-by-step and to
> look for humanness in the structure of the mouse brain before proceeding
> further.
>
>
> "If everything looks mouse-like, go forward. If anything looks
> un-mouselike,
> stop," he said.
>
>
> But at the moment, Weissman's proposed mouse project still has not begun
> as
> he waits for the scientific community's approval after reviewing the
> ethical
> concerns raised by the experiment.
>
>
> "This project will test human neuronal cells in a mouse brain
> micro-environment as a prelude to studying stem cells that have human
> genetic
> diseases like Alzheimer's, Parkinson's, Lou Gehrig's, and cerebral palsy,"
> Weissman said.
>
>
> Weissman emphasized the urgency of his project as he asked, "Which of
> these
> diseases should we not be working on as fast as we can?"
>
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