Scientists look at creating a human-mouse embryo

By CAROLYN ABRAHAM
From Thursday's Globe and Mail

North American scientists are considering whether to implant stem cells from a human embryo into a mouse embryo — a controversial experiment that could result in a mouse-human mix reminiscent of mythological monsters.

The chimera proposal, a chimera being a creature born of at least two different species, might, in theory, allow scientists to test if human embryonic stem cells do indeed have the power to grow into every tissue type in the body.

But if it works, the experiment also raises the eerie, and ethically charged prospect of creating a mouse with troubling human features — anything from a human brain to human sperm and eggs.

"If it really did work, then you'd have this very uncomfortable creature to work with," said Janet Rossant, one of Canada's leading stem cell researchers and an opponent of the chimera experiment. "Do you generate a human brain in a mouse . . . where do you draw the line?"

Dr. Rossant, a senior scientist at Toronto's Mount Sinai Hospital, was among a select group of researchers and observers who attended a closed meeting in New York on Nov. 13, where the chimera experiment, among other things, was debated.

Sponsored by Rockefeller University and the New York Academy of Science, the day-long meeting was held to discuss ways to evaluate the power and versatility of the lines of human embryonic stem cells now being grown in labs around the world.

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