This past March, the University announced the creation of the Center for Excellence in XenoDiagnostics, the only U.S. facility prepared to meet demands for testing of xenotransplantation techniques.
The idea of transplanting animal organs into humans is not entirely new — some of the first efforts at heart transplantation in the 1960s placed a sheep’s heart in the chest of a man — and one of the well-known cases of American medical ethics involved the unsuccessful transplant of a baboon heart into the chest of a critically ill infant who became known as Baby Fae in the late 1970s.
The major obstacle to the success of efforts at xenotransplantation, transplantation from one species into another, has been in overcoming the challenge of immunological incompatibility. The advent of powerful immunosuppressive drugs developed for and employed in human to human transplantation, and dramatic breakthroughs in genetic manipulation techniques promise the ability to create animals whose organs are immunologically compatible with humans.
Why is xenotransplantation important? Every year, thousands of people die awaiting the availability of human organs for transplantation, and xenotransplantation offers the possibility of supplying organs to nearly all that need them.
If animal organs could be made human-compatible, or human immunology made indifferent to the presence of animal organs, then the shortage of human organs could be quickly overcome. Take, for instance, the research being performed on pig organs for human transplantation. It so happens that a pig’s anatomy, in terms of the size and shape of its internal organs, is relatively similar to a human’s. If a pig liver, heart, kidney or any number of other organs could be genetically altered so that it could be successfully transplanted into a human, hog farms and meat packing plants could do double duty — they’d be raising and collecting organs for transplant as well as meat for our tables.
Yet things are never so simple. The development of xenotransplantation raises a number of ethical issues, both for individuals and the public.
Individual and public safety are real concerns when animal organs are introduced into humans. As the National Academy of Science’s Institute of Medicine concluded regarding public health risk and xenotransplantation, animals may transmit diseases to humans that can infect individuals, and in some cases be passed on to other humans. Careful screening of the animals from which organs would come, and an ongoing surveillance of those who receive animal organs should reduce the likelihood of infection. But the long-term risk of animal to human infection is unknown, and it is possible that animal infections exist that we cannot detect or test — witness the only recently discovered infectious agent for so-called Mad Cow disease and its human counterpart, Cruezfeldt-Jacob disease.
In addition to assuring safety, the challenge of achieving informed consent from the recipients of animal organs will be daunting. There is precious little information about the physical risks as well as psychological impact of xenotransplantation, and the desperation of potential recipients — and therefore likely willingness to undertake even extreme risk — make understanding difficult and increase the potential for exploitation.
The genetic modification of food animals also raises issues for the public. Experience with other “altered” food products should tell us that society is not always willing to accept technological innovation in the things we eat. Milk from cows treated with bovine growth hormone was rejected in many areas where it was marketed. How would the public react to pork products that came from pigs genetically engineered so that their organs would be useful in human transplantation? It is possible to see how these products could eventually be priced lower than pork from “regular” pigs since the use of otherwise wasted organs would make the value of individual animals greater. Would the public be enticed by cheaper meat from genetically altered, organ donating animals? If so, xenotransplantation offers a way to more efficiently use food animals. If not, we have to ask ourselves the more difficult question of whether we should raise animals expressly for the purpose of harvesting their organs — effectively creating organ farms. Some people might not have a problem with raising pigs or other traditional food animals for such a purpose, but what if the most effective organ donor animals were dogs, porpoises or chimpanzees?
The prospect of creating a way to save the lives of the thousands waiting for donor organs is enticing, and research into its eventual realization ought to go forward. But the fact that xenotransplantation raises many new ethical issues argues for careful consideration and public debate as this research proceeds so that we are not solving the organ shortage crisis at the expense of creating another.

Jeffrey Kahn is the director of the University of Minnesota Center for Bioethics.