New York, NY - Animal-to-human transplantation of hearts is far too risky despite the desperate need for donor organs, with about 1200 patients dying each year while waiting for heart and lung transplants, according to an international transplant group, according to media reports on December 15, 2000.
Clinical trials in humans should not be considered until researchers can get 60% of pig-heart transplants to survive for at least 3 months in nonhuman primates.
"Despite years of intensive research, pig hearts implanted into nonhuman primates only survive about a month at best," reports Boston Globe staff writer Richard Saltus, who notes that the handful of humans who have received animal organs, including baboon-heart recipient Baby Fae in 1984, all died within 20 days. "Clinical trials in humans should not be considered until researchers can get 60% of pig-heart transplants to survive for at least 3 months in nonhuman primates," says a report in the Journal of Heart and Lung Transplantation, according to the Globe.
"There are two major concerns - one is, can we get the immunology right, can we get the science right," former transplant surgeon Dr David Cooper (Massachusetts General Hospital and President of the International Xenotransplantation Association) told Reuters. "The other major concern is, are we going to do any harm by transferring infectious agents to the patient...then infect the community."
Serious concerns remain about pig organs passing along infections, reports the Globe: "Pig cells can harbor retroviruses that could be transferred in transplanted organs, although scientists don't know whether the viruses would pose a danger."
"We wanted to add our weight to the fact that we felt (pig xenotransplantation) should not be considered safe and at the moment there is not enough information about it," Cooper told Reuters, which adds that "scientists fear that not only could the patient be infected but that the viruses could change in their bodies, become more dangerous and then spread to the population at large."That's all, folks (for now)
Pigs are thought to be the best donor animals "because of their size, anatomical similarity to humans, rapid breeding time, and availability," reports the Globe, adding that researchers have implanted organs from sheep, pigs, baboons, and chimpanzees into people since the 1960s. The journal report acknowledges that "both mechanical hearts and xenotransplants have their advantages, and both should be pursued for a 'medium-term' solution to the shortage of donor human hearts," according to the newspaper.
Cooper fears reports of pig xenografts might lead to fewer donations of organs, reports Reuters: "It has got to be made clear to the public that we are not ready for xenotransplants at the present time."
Heartwire from Medscape © 2000
Cite this: Pig-heart xenografts still too risky - Medscape - Dec 15, 2000.