Pig Heart Transplant Failure: Doctors Detail Everything That Went Wrong

An anonymous reader quotes a report from Ars Technica: Earlier this year, news broke of the first experimental xenotransplantation: A human patient with heart disease received a heart from a pig that had been genetically engineered to avoid rejection. While initially successful, the experiment ended two months later when the transplant failed, leading to the death of the patient. At the time, the team didn't disclose any details regarding what went wrong. But this week saw the publication of a research paper that goes through everything that happened to prepare for the transplant and the weeks following. Critically, this includes the eventual failure of the transplant, which was triggered by the death of many of the muscle cells in the transplanted heart. But the reason for that death isn't clear, and the typical signs of rejection by the immune system weren't present. So, we're going to have to wait a while to understand what went wrong.[...]After death, the team performed an autopsy on the transplanted heart. They found that it had nearly doubled in weight, largely because of fluid (and some red blood cells) leaking out of blood vessels in the absence of clotting. There was significant death of heart muscle cells, but that was scattered across the heart, rather than being a general phenomenon. Critically, most of the indications of a strong immune rejection were missing. The presence of an apparent pig cytomegalovirus was worrying, but the researchers indicate there's some question about whether the tests that picked it up might have been recognizing a closely related human virus -- one that's often associated with organ transplant problems. So, for now, it's not clear what happened with this transplant or what the significance of the apparent viral infection is. Obviously, the team has lots of material to work with to try to figure out what went on, and there's a long, long list of potential experiments to do with it. And there are also additional xenotransplant trials in the works, so it may not be long before we have a better sense of whether this was something specific to this transplant or a general risk of xenotransplantation.

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