Mice with human-derived livers, goats with human blood cells, and other animals that contain human genes or cells are arguably valuable tools for medical research, but they also can raise tricky ethical questions and trigger public controversy. Acknowledging this reality, a report  issued today by the British Academy of Medical Sciences recommends that the U.K. government establish an expert commission to help regulate certain types of experiments involving "animals containing human material."
The report's authors hope that early public discussion of potentially controversial work—before it is undertaken—will help to encourage wider acceptance of such research. "We are trying to get this issue out there before anything has happened," says geneticist Martin Bobrow of the University of Cambridge, who chaired the academy's working group. "If public has heard about something, they are less likely to get irritable when something does hit the headlines."
The report proposes that experiments with animals containing human material (ACHM) should be divided into three categories: those that should be subject to the same oversight and regulation as other animal experiments, those that should undergo extra review before receiving permission to proceed, and a few that should be entirely off-limits. Areas that should undergo extra scrutiny include experiments that modify an animal's brain to make it more "human-like," experiments that place functional human germ cells in animals, experiments that could make animals' appearance or behavior more human, and experiments that add human genes or cells to nonhuman primates.
Three types of ACHM experiments should be forbidden, the report says, because they "lack compelling scientific justification or raise very strong ethical concerns."
First, breeding animals that have or could develop human germ cells in their gonads should not be allowed. Second, the report recommends banning research that attempts to transplant enough human-derived neural cells into a nonhuman primate to prompt human-like behavior. Finally, scientists should not allow embryos that mix human and nonhuman primate cells to develop beyond 14 days. Currently U.K. law forbids allowing human embryos containing animal cells from developing longer than 14 days. However, embryos that are "predominantly animal," but still contain human cells are unregulated in the United Kingdom. The report recommends closing that loophole.
"We haven't come across any scientists who want to do category three [off-limits] experiments," working group member Robin Lovell-Badge told a press conference this morning. Lovell-Badge, a stem cell biologist at the MRC National Institute for Medical Research in London, said that several types of the "category two" experiments have been proposed or are underway in Britain. For example, he says, researchers studying infertility have grafted human testis and ovary cells under the skin of animals in an effort to better understand their development. And animals with human skin, he says, could help scientists better understand sunburn and its connection to skin cancer. "There are good scientific reasons one should do it," he says. "But if it's done, it should be watched carefully."
The U.K. government is revising its animal research oversight to comply with a recent European Union directive. "We hope they will take this [report] into account," Bobrow says, and establish better cooperation between the U.K. Home Office, which regulates animal research, and the Department of Health, which oversees research with human subjects. It is especially important, he says, to close the loophole that leaves unregulated experiments with animal embryos that contain human cells.