The fast-moving field of mixing animal and human DNA may need new ethical or regulatory boundaries for some experiments, a British panel says.

Friday's report from the Academy of Medical Sciences looks at the use of "animals containing human material" in biomedical research. Experiments mixing animal and human DNA is contentious. Winfried Rothermel/AP

Most experiments don't need stricter regulation, said Martin Bobrow, chair of the group that wrote the report. "But there are a small number of future experiments, which could approach social and ethically sensitive areas, which should have an extra layer of scrutiny," he told reporters in London.

Those sensitive areas include:

• Those where human brain cells might change animal brains.
• Those that could lead to the fertilization of human eggs in animals.
• Any modifications of animals that might create attributes considered uniquely human, like facial features, skin or speech.

To prepare the report, a panel considered evidence for experts in academia, government, industry, animal welfare groups and professional bodies. The authors also commissioned a public opinion poll about the animal and human research.

Some current examples of experiments involving the mixing of human and animal cells include:

• Mice implanted with sections of human tumour for cancer research to study how cancers develop and spread, and to test new drugs and therapies.
• Introducing human stem cells into rats to study the human brain's potential for repairing damage caused by stroke.
• Goats which have a human gene incorporated in their genome to produce a human protein that is used to treat blood clotting disorders.

Experts and members of the public disagreed about where to draw the line on such experiments.

Human-animal hybrids are outlawed in Canada under the Assisted Human Reproduction Act.

With files from The Associated Press