http://www.sciencemag.org/news/2019/01/some-multiple-sclerosis-patients-knocking-out-immune-system-might-work-better-drugs

Blood stem cells (depicted here, yellow, in bone marrow) regenerated the immune system after chemotherapy in a new trial for multiple sclerosis.

In multiple sclerosis (MS), a disease that strips away the sheaths that insulate nerve cells, the body’s immune cells come to see the nervous system as an enemy. Some drugs try to slow the disease by keeping immune cells in check, or by keeping them away from the brain. But for decades, some researchers have been exploring an alternative: wiping out those immune cells and starting over.