A Stanford University researcher has gotten a preliminary go-ahead to create a mouse with a significant number of human brain cells -- as long as the creature behaves like a mouse, not a human. A university ethics committee studied a provocative project that transplants human neurons into the brains of mice where, surprisingly, they settle in and feel right at home. The research team, led by Stanford biologist Irving Weissman, has no immediate plans to build a mouse with an entirely human brain. But it remains a theoretical possibility. The federal government does not regulate the creation of such chimeras, named after the mythical Greek creature that is part-man, part-animal. So Stanford asked where it should draw the line. It is the first university in the nation to tackle the philosophical question: When does a chimera stop being an animal and start becoming a person, suggesting that research should end? The report foreshadows the release of guidelines on stem-cell research, including chimeras, by the National Academy of Sciences.
