Organ transplantation—removing a piece of one person and sewing it into another—is one of the weirder things that humans have figured out how to do. And our bodies don't necessarily like it. Immunosuppressive drugs can keep a person's body from noticing that there's a foreign object in there, for awhile, at least. But those drugs take their own toll, and eventually, the body can get wise and start to reject the organ.
Even so, actual humans organs are so good at doing their jobs that, in many cases, there isn’t a better alternative. Doctors and researchers have been trying, for instance, to develop an artificial heart for thirty-five years. The first artificial heart, implanted in 1969, kept its recipient alive for three days. On Monday, Carmat, a French biotechnology company that's created the world's newest artificial heart—the first to mix synthetic and biological materials—announced that the second of four patients participating in a trial had received their transplant.
The Carmat heart's valves are made of tissue from a cow's heart, as are the membranes that come into contact with the patient's blood. It's meant to last for up to five years, to extend the life of patients waiting for donor hearts or who aren't eligible for that sort of transplant. The Carmat's first test patient received his heart this past December and lived for 75 days; that trial was considered a success.