The human body's immune system is similar to having millions, if not billions, of snipers at the ready aiming and poised to shoot any foreign invader. This is why transplanted tissues and organs are so vulnerable to rejection. But a recent discovery by MIT researchers hopes to make them more viable.
Perhaps some day, 3D printers will be spitting out replacement organs made from your own DNA, and like, they will show up in your mailbox an hour after you order them.