"New rules urged on hybrid animal-human experiments," by Ben Hirschler on the Reuters website summarizes a a report from Britain's Academy of Medical Sciences on the use of animals containing human material.
But Martin Bobrow, a professor of medical genetics at the University of Cambridge, who led the Academy's working group, said there were three areas of particular concern.
"Where people begin to worry is when you get to the brain, to the germ (reproductive) cells, and to the sort of central features that help us recognize what is a person, like skin texture, facial shape and speech," he told reporters.
His report recommends that government should put in place a national expert body, working within the existing system for regulating animal research, to oversee such sensitive areas.
There are a lot of interesting aspects to this -- from the idea that regulation is needed in advance discovery, to the idea that humanizing animals will (necessarily?) lead to creating monsters, at least if a certain kind of humanization happens. Privileged here are: brain cells, germ cells, and that other category: "central features that help us recognize what is a person." So, something hidden, like pancreatic islet cells, might be transferred to from a human to an animal for the purpose of research without raising the problem that the animal might resemble a human too much. The potential problems seem to be: animals thinking, looking, or sounding like humans; or animals having human(-like) babies.
As odd as this sounds, speculating and even regulating in advance of discovery may be necessary. But once again, the boundary between "us" and our animal relatives is brought into question.