HSCT has been harnessed for more than 40 years in the clinic as an effective therapeutic approach. In 1995, the first transplantation of hematopoietic stem cells (HSCs) was suggested as a treatment for MS after hypothesizing that an immune-mediated attack on myelin causes pathologic events in MS [9]. Two years later in the United States, HSCT was performed in 15 MS patients with a progressive form [10]. HSCs capable of self-renewal when effectively transplanted and engrafted in the human can differentiate into all of the cells found in the hematopoietic system. They are divided into two different types: long-term (LT) and short-term (ST) subtypes (Fig. 1). LT-HSCs have the ability to self-renew and provide all hematopoietic lineages during the life of an individual. ST-HSCs, as the name suggests, are incapable of long-term self-renewal under normal conditions, but they do provide the ability to reconstitute hematopoiesis of certain lineages over a finite period