This trial aims is to determine the effect of the patient's own MSCs on cerebral inflammation in Multiple Sclerosis. The trial is being conducted by the Danish Blood Bank in conjunction with the Danish Multiple Sclerosis Society. The trial commenced in June 2012 and seeks to enrol 25 patients. Participants will be randomly divided into two groups. One group will receive mesenchymal stem cells, from their own bone marrow, intravenously (initial experimental group). This group will be monitored for 24 weeks in which MRI scans will be used to monitor lesions. The remaining subjects will receive the conventional therapy for Multiple Sclerosis and then after 24 weeks, they receive a similar mesenchymal stem cell infusion and monitored by MRI for a further 24 weeks. During this time the initial experimental group will receive only conventional therapy. This is a randomised, controlled, double blinded, and double group crossover clinical trial. No end date has been set for this trial.