Organ transplants are frequently life-saving, but they remain a gamble when your body can reject the new organ well after the initial surgery. Yale researchers have discovered a clever solution to this: prevent your body from noticing the organ until it settles in. They've developed a drug delivery system that uses nanoparticles to slowly supply small interfering RNA (siRNA) that stops your body's white blood cells from attacking the organ as a foreign presence. Instead of lasting mere days, the siRNA lasts as long as 6 weeks. This won't necessarily eliminate the rejection response, but it should be far easier to control if and when it kicks in.