Transplant doctors predict pigs will become a main source of donor organs for people once the many technical problems of cross-species transplantation are resolved.
While primates such as chimpanzees and baboons might be a better match, pigs are cheaper, more plentiful and easier to breed, says Dr. Hugh Auchincloss Jr., assistant professor of surgery at Harvard University."What could change, I suppose, is that we could become better at making artificial organs than we are now. Then we wouldn't need the animal organs. But I don't see that as coming first," Auchincloss said this week at the annual meeting of the American Society of Transplant Physicians.
Only 50 to 60 chimpanzees are available in any given year for all types of research, according to Auchincloss.
"It doesn't make any sense to use chimpanzees because you're going to make such a small impact in the well-being of humans. And you'll make people so mad, because it is where they focus from the point of view of animal rights, understandably so," he said.
"If you can eat the pig, I'm not sure you can't transplant the liver," said Arthur Caplan, director of the Center for Biomedical Ethics at the University of Minnesota.
But some animal-rights activists say they oppose using animals, whether it's chimpanzees, pigs or even rodents.
"Animals aren't here to be our spare parts," said Dr. Neal Barnard, a psychiatrist who serves as president of the Physicians Committee for Responsible Medicine in Washington.
"They're putting all their energy into this high-tech, incredibly expensive use of the limited resources we have to put into health care . . . and it has maybe a one-in-10 million chance of ever working out," said Susan Stewart, head of the research investigative committee for the Last Chance for Animals in Los Angeles.
About 30 animal-to-human organ transplants have been performed worldwide, most of them in the early 1960s, according to Auchincloss.
The longest survivor was a 27-year-old woman who lived nine months with a chimpanzee's kidney she received in 1964. The latest patient, a 12-day-old girl known as Baby Fae, died 20 days after receiving a baboon's heart in 1984 at California's Loma Linda University Medical Center in California.
"If you define success as one-year survival, we still haven't gotten one," Auchincloss said. "But we've come awfully close."
About 50 cases also are known in which doctors attached pigs' livers to coma patients on a temporary basis, mostly in the 1960s.