What Is Too Human? The ethics of human/animal chimeras

[andyjackson1828]

Esmail Zanjani, a researcher at the University of Nevada at Reno, has been able to grow mostly human livers in sheep. Zanjani achieved this by injecting into growing sheep fetuses either adult stem cells derived from bone marrow, or embryonic stem cells from one of the federally approved stem cell colonies.

The research was originally aimed at finding out if it would be possible to transplant stem cells into developing human fetuses to correct defects in utero. But Zanjani observed the human cells integrating into and then proliferating within a wide range of organs and tissues, including the pancreas, heart, skin and liver. Now, it looks like it will be possible to grow inside animals human cells, tissues and organs that might be suitable for transplants into people.

Let's say you need a new liver. Zanjani would take some of your bone marrow stem cells, and inject them into a fetal sheep at the proper moment. A few weeks later the lamb would be born with a liver made up chiefly of your cells. The lamb would be sacrificed and your new liver installed. Once installed, your immune system would eliminate the lamb's liver cells, leaving behind a brand new organ perfectly matched to your body. Providing sick people with life-saving transplants is certainly a morally worthy activity.

It is now common to place single human genes into plants and animals and even bacteria, to produce various therapeutic proteins, including insulin and human growth hormone. Few people now believe that putting a single human gene into another creature transforms that creature into a human being.

The rest at...

http://www.reason.com/rb/rb112404.shtml