Our bodies are full of tiny superheroes—antibodies that fight foreign invaders, cells that regenerate, and structures that ensure our systems run smoothly. One such structure is myelin, a material that forms a protective cape around the axons of our nerve cells so that they can send signals quickly and efficiently. But myelin becomes damaged in demyelinating diseases like multiple sclerosis, leaving neurons without their sheaths. Researchers from Caltech now believe they have found a way to help the brain replace damaged myelin.