MSCs have the remarkable ability to modulate the immune response mainly by inhibiting proliferation of T cells and to protect injured tissues through paracrine mechanisms. There is an urgent need to evaluate the real efficacy of MSC transplantation, and its possible position in the current therapeutic armamentarium. An international panel of MS neurology and stem cell experts, as well as immunologists formed an "International Mesenchymal Stem Cells Transplantation" (MSCT) Study Group with the aim to derive a consensus on what cells should be used for transplantation and develop a treatment protocol and an experimental program that will eventually attest to the efficacy of MSC transplantation and understand the mechanism that underlie the benefit. 12 patients with MS will be treated with IV injections of autologous isolated and expanded mesenchymal stem cells. Clinical and objective evaluations will be performed at baseline and during 12 months follow-up.