Eureka Alert reports on the work of Esmail Zanjani at the University of Nevada, Reno:
Providing the method really does produce normal human cells, they would not be rejected. And any stray animal cells would be killed off by the recipient's immune system. Of course, the idea of using part-human, part-animal chimeras as living factories for producing cells or organs raises a host of ethical and safety issues. There is the risk of transferring animal diseases to humans, for a start. And the creation of such chimeras has long been controversial. Is a sheep with human cells making up part of its brain no longer just a sheep?
Zanjani's team has now managed to produce sheep-human chimeras with a surprisingly high proportion of human cells in some organs. According to results presented at a conference earlier this month, in some cases between 7 and 15 per cent of all the cells in the sheep's livers are human. ... In some cases the human liver cells cluster together to form functional, fully human liver units, says Graca Almeida-Porada of the Nevada team. These units could be transplanted whole as auxiliary organs, says Zanjani.
There are, of course, still a lot of ethical questions that need to be addressed and even more scientific work that needs to be done - but we are coming tantalizingly close to some very interesting breakthroughs. But, just because we can do these things, does that mean we should? Are there dangers that outweigh the benefits?