which actually tells you more about what has already been done, what UK public opinion is, and why this came up (a research body has said we need a framework to take into account future developments), here's
Nature:
Regulations proposed for animal–human chimaeras
The increasingly sophisticated blending of different species to create chimaeras is pushing biology into a new ethical dimension. Last year, scientists used new stem-cell technologies to create a mouse with a functioning pancreas composed entirely of rat cells. So might it soon be possible to create a monkey with a brain composed entirely of human neurons? And would it think like a human?
Such an animal might be useful to researchers studying human cognition or human-specific pathogens. But it would be ethically unacceptable and should be banned, argues a government-commissioned report from the UK Academy of Medical Sciences, a body that promotes medical research.
The document, Animals Containing Human Material , says that genetic and stem-cell technologies are now so advanced that the creation of such animals is already on the horizon. But no country has yet devised a broad regulatory framework for the research. The report, released on 22 July, calls for the United Kingdom to take the lead in putting in place specific safeguards.
"We are not proposing a new tier of regulation that will hold up important research," says Robin Lovell-Badge, a developmental biologist at the Medical Research Council's National Institute for Medical Research in London, and a member of the working group that drew up the report. At the same time, he says, "we don't want scientists to cause problems for the future by overstepping the mark of what is publicly acceptable". Unlike the hypothetical monkey with a human brain, many animals containing human material (ACHMs) are likely to advance basic biology and medicine without transgressing ethical boundaries, the report concludes.
http://www.nature.com/news/2011/110721/full/475438a.html