Maximizing Outcome of Multiple Sclerosis Transplantation

Multiple sclerosis (MS) is at onset an immune-mediated demyelinating disease. In most cases, it starts as a relapsing-remitting disease with distinct attacks and no symptoms between flares. Over years or decades, virtually all cases transition into a progressive disease in which insidious and slow neurologic deterioration occurs with or without acute flares. Relapsing-remitting disease is often responsive to immune suppressive or modulating therapies, while immune based therapies are generally ineffective in patients with a progressive clinical course. This clinical course and response to immune suppression, as well as neuropathology and neuroimaging studies, suggest that disease progression is associated with axonal atrophy. Disability correlates better with measures of axonal atrophy than immune mediated demyelination. Therefore, immune based therapies, in order to be effective, need to be started early in the disease course while MS is predominantly an immune-mediated and inflammatory disease. While current immune based therapies delay disability, no intervention has been proven to prevent progressive disability.The investigators propose a randomized study of autologous unmanipulated peripheral blood hematopoietic stem cell transplant (HSCT) comparing two different conditioning regimens: (1) cyclophosphamide and rabbit anti-thymoglobulin (rATG) versus (2) cyclophosphamide, rATG, and Intravenous Immunoglobulin (IVIg).