Background: A hot new topic in medical treatment is the use of mesenchymal stem cells (MSC) in therapy. The low frequency of this subpopulation of stem cells in bone marrow (BM) necessitates their in vitro expansion prior to clinical use. We evaluated the effect of long term culture on the senescence of these cells.

Despite updating knowledge and a growing number of medications for multiple sclerosis (MS), no definite treatment is available yet for patients suffering from progressive forms of the disease. Autologous bone marrow derived mesenchymal stem cell (BM-MSC) transplantation is a promising method proposed as a therapy for MS. Although the safety of these cells has been confirmed in hematological, cardiac and inflammatory diseases, its efficacy in MS treatment is still under study. Patients with progressive MS (expanded disability status scale score: 4.0 –6.50) unresponsive to conventional treatments were recruited for this study. Twenty-five patients [f/m: 19/6, mean age: 34.7±7] received a single intrathecal injection of ex-vivo expanded MSCs (mean dose: 29.5×106 cells). We observed their therapeutic response for 12 months. Associated short-term adverse events of injection consisted of transient low-grade fever, nausea /vomiting, weakness in the lower limbs and headache. No major delayed adverse effect was reported. 3 patients left the study for personal reasons. The mean (SD) expanded disability status scale (EDSS) score of 22 patients changed from 6.1 (0.6) to 6.3 (0.4). Clinical course of the disease (measured by EDSS) improved in 4, deteriorated in 6 and had no change in 12 patients. In MRI evaluation, 15 patients showed no change, whereas 6 patients showed new T2 or gadolinium enhanced lesions (1 lost to follow-up). It seems that MSC therapy can improve/stabilize the course of the disease in progressive MS in the first year after injection with no serious adverse effects. Repeating the study with a larger sample size, booster injections and longer follow-up using a controlled study design is advised.

This study suggests that injection of MSC can be a suitable method, especially for secondary-progressive patients. It seems that reinjection of these stem cells can be safe and sustaining it positively increases the effects of this therapeutic approach.

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