take away some of the genes that the organ expresses. so you have to take away some of the pig genes. you have to give it some human genes so that it appears to be more humanlike. then you have to make it work a little bit better. the pig heart, in particular, doesn t interact well with human bachelor blood in terms of preventing coagulation. there is this magical dance blood vessels do with the blood to keep the body in this sort of carefully balanced stance, so that you re not clotting too much and not bleeding too much. the pig heart doesn t do that well with human blood. you have to give it the ability to do that. you have to prevent longer term rejection with the use of certain medications. also, there s another concern. you know, pigs can harbor certain viruses which humans have never seen. you need to make sure you re not