Stem cell transplantation in multiple sclerosis: multiple choices and multiple challenges

Multiple sclerosis (MS) is generally considered as an autoimmune disease of the central nervous system. This concept has led to the idea that profound immunosuppression followed by transplantation of stem cell grafts would stop, or at least slow down, disease activity. Supported by the positive effects of hematopoietic stem cell transplantation (HSCT) on experimental autoimmune encephalomyelitis and by anecdotal reports on the beneficial effect of HSCT on MS patients with concomitant malignant disease, HSCT programs for MS have been initiated worldwide. At this stage, it is impossible to draw general conclusions from the preliminary data reported and therefore overenthusiastic expectations should be tempered. The follow-up periods are too short, the groups are too small, the selected patients and protocols too heterogeneous, and publication bias on positive results cannot be excluded. However, there is ample evidence that HSCT is a technically feasible approach in MS, not more dangerous than in the hemato-oncological diseases. For every step in the HSCT procedure, there are many different options. The time has come for a systematic analysis of the safety and efficacy associated with the different methodologies.