Immuno-therapeutic potential of haematopoietic and mesenchymal stem cell transplantation in MS.

In the last few years there has been extraordinary progress in the field of stem cell research. Two types of stem cells populate the bone marrow: haematopoietic stem/progenitor cells (HSC) and mesenchymal stem cells (MSC). The capacity of HSC to repopulate the blood has been known and exploited therapeutically for at least four decades. Today, haematopoietic stem cell transplantation (HSCT) holds a firm place in the therapy of some haematological malignancies, and a potential role of HSCT for treatment of severe autoimmune diseases has been explored in small-scale clinical studies. Multiple sclerosis (MS) is the noncancerous immune mediated disease for which the greatest number of transplants has been performed to date. The results of clinical studies are double-faced: on the one hand, HSCT has demonstrated powerful effects on acute inflammation, arresting the development of focal CNS lesions and clinical relapses; on the other hand, the treatment did not arrest chronic worsening of disability in most patients with secondary progressive MS, suggesting limited or no beneficial effects on the chronic processes causing progressive disability. MSC are a more recent addition to the range of experimental therapies being developed to treat MS. While interest in MSC usage was originally raised by their potential capacity to differentiate into different cell lineages, recent work showing their interesting immunological properties has led to a revised concept, envisioning their utilization for immuno-modulatory purposes. In this review we will summarize the current clinical and experimental evidence on HSC and MSC and outline some key questions warranting further investigation in this exciting research area.