Insulin pumps improve the lives of millions of people with diabetes around the world by monitoring blood sugar, delivering insulin, and preventing the need for constant finger-pricking. But there's a catch: they're temporary. And it's not only insulin pumps that have this problem, but all bodily implants. Why is that? Kaitlyn Sadtler details how our immune system reacts to foreign bodies. [Directed by Andrew Foerster, narrated by Bethany Cutmore-Scott].