For many years a team of researchers led by Esmail Zanjani at the University of Nevada at Reno have been trying to grow humanized sheep. Their goal is to create sheep that have organs such as the liver that could be transplanted into humans without being rejected.

To get xenograftable organs the scientists inject extracts stem cells from adult bone marrow into a sheep fetus while it is still in the womb. These cells are integrated into the developing fetus. Zanjanis team has announced it has now made a sheep with roughly fifteen percent human cells. The sheep have a much higher percentage in their livers.

The goal of this form of genetic engineering is laudable. Produce transplantable organs. But the ethical objections are likely to be loud and heated.

The creation of chimeras is not something that has received sufficient attention and public debate. Groups sponsored by the European Union and the Presidents Council on Bioethics have taken a look but the public is still not really tracking this issue.

Some animal rights activists are not going to like the idea of creating animals to harvest their parts. Some are going to find the risks associated with carrying animal viruses into humans ethically daunting. And many are going to give mutton men are very high score on the yuk scale.

Making animal/human hybrids makes sense. But, in this case those with ethical concerns are right. We need some international standards in place before lambination becomes a standard part of transplantation.

-Art Caplan

Labels: cloning, reno, sheep, xenotransplantation