The controversial use of human DNA in animal experiments is the focus of a study by scientists with the Academy of Medical Sciences in England who plan to examine the issue and recommend boundaries.
This type of research -- such as growing human organs in animals or swapping animal genes with human genes -- has gone on for years, but rules about how much human DNA can be put into an animal are vague, the Associated Press reported.
"It sounds yucky, but it may be well worth doing if it's going to lead to a cure for something horrible," study group member Robin Lovell-Badge, a stem cell expert at Britain's National Institute for Medical Research, said at a media briefing in London.
"We are trying to work out what is reasonable," said study group chairman Martin Bobrow, who added that he and his colleagues recognize that experiments where animals are given human features or brain cells would upset some people.
"This is a classic example of science going too fast," David King, director of the independent watchdog group Human Genetics Alert, told the AP. "If you cannot firmly say exactly what it is you're creating, you should not do it."