Researchers have developed human-sheep chimeras as an avenue to addressing the growing demand for organ transplants.  Suprisingly  (to me anyway) these researchers have actually been allowed to produce a live animal, rather than stop the work at the fetal stage. So my question is at what ratio do we begin to consider an animal like this to be ‘human’ – 50%? 80%? 100%?  Note that the DNA itself has not been mixed.  Individual cells are either human or sheep.

O, what a brave new world.

Link: Now scientists create a sheep that’s 15% human.

Scientists have created the world’s first human-sheep chimera – which has the body of a sheep and half-human organs.

The
sheep have 15 per cent human cells and 85 per cent animal cells – and
their evolution brings the prospect of animal organs being transplanted
into humans one step closer.

Professor Esmail Zanjani, of the
University of Nevada, has spent seven years and £5million perfecting
the technique, which involves injecting adult human cells into a
sheep’s foetus.

He has already created a sheep liver which has a large proportion of
human cells and eventually hopes to precisely match a sheep to a
transplant patient, using their own stem cells to create their own
flock of sheep.

Aside from the animal welfare issue, there are some real risks with this sort of research. In particular, a nasty virus could find itself in a new and permissive environment:

Dr Patrick Dixon,
an international lecturer on biological trends, warned: "Many silent
viruses could create a biological nightmare in humans. Mutant animal
viruses are a real threat, as we have seen with HIV."

Animal
rights activists fear that if the cells get mixed together, they could
end up with cellular fusion, creating a hybrid which would have the
features and characteristics of both man and sheep. But Prof Zanjani
said: "Transplanting the cells into foetal sheep at this early stage
does not result in fusion at all."