And so it happened. “In a first, surgeons attached a pig kidney to a human, and it worked,” as the New York Times puts it. Data are scarce, however, and all the info we have is from the general media. The kidney came from a GalSafe pig, which is the only one FDA approved so far. But scientists from several companies have already developed pigs much more engineered than that (with three or four porcine genes knocked-out instead of one, and human gene additions). To get an updated picture, we highly recommend this article published in Nature Biotechnology last April.