I am not sure how similar this is to what is done for folks with certain types of cancers, but if it is, it can be pretty extreme for a while. My sister had a friend that had her immune system basically killed and replaced with cells from a healthy donor. it was a very long and involved process during which she was at high risk for even very basic types of infections. She had a number of rejection complications and other issues during the recovery. She now has a different blood type and has to get all her childhood vaccinations again. I can see this being a good option for folks with progressive varieties of MS, but for those with very mild symptoms and not much disability, its seems a bit extreme.