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Researchers Keep Pig Heart Beating In Baboon Belly For 2 Years (arstechnica.com)
An anonymous reader quotes a report from Ars Technica: Researchers report Tuesday that they were able to keep pig hearts alive and beating in the abdomens of five baboons for record amounts of time -- a median of 298 days and a max of 945 days. Previous benchmarks were set at a median of 180 and a max of 500 days, respectively. Currently in the US, 22 people die every day just waiting for organs, which are in constant short supply. To help solve the problem, researchers turned to pigs years ago to see if they could lend useful organs or at least provide temporary "bridge" tissue to those on wait-lists. Pigs were a good fit mainly because their organs' sizes are similar to that of human's. In early studies, successful survival time in pig-to-primate transplants, generally called xenotransplants, were measured in minutes. The swine substitutes naturally have a molecular marker, called alpha 1-3-galactosyltransferase (gal), which triggers deadly blood clots in primates. In the new study, researchers at the National Institutes of Health and colleagues, tweaked the approach; they engineered the gal-knock out pigs to have extra anti-clotting genetic features and used an antibody to selectively shut down the part of the primate's immune system that responds to pig organs. To avoid needlessly killing the baboons and doing extensive surgery, the researchers opted to transplant the pig hearts into the baboon's abdomens, leaving the primates' hearts in place. In the abdomen, the pig tickers hooked up to circulatory system and beat for a record-breaking amount of time.
Great idea, if you never want to have kids.
One of the big problems with xeno-transplants from pigs is PERV (Porcine Endogenous RetroVirus).
We've treated a number of people with Parkinson's in the U.S. (many more in Russia, where the technique was pioneered) using fetal pig stem cells from the brains. However, we're typically worried about introducing the virus to the human genome, since it become part of the actual genome of the organism (hence "endogenous"). One of the requirements to participate in the clinical trials was an agreement to not have unprotected sex which might result in a pregnancy -- ever -- to keep it out of the human genome.