Human mesenchymal stem cells abrogate experimental allergic encephalomyelitis after intraperitoneal injection, and with sparse CNS infiltration.

Multiple sclerosis is a currently incurable inflammatory demyelinating syndrome. Recent reports suggest that bone marrow derived mesenchymal stem cells may have therapeutic potential in experimental models of demyelinating disease, but various alternative mechanisms, ranging from systemic immune effects to local cell replacement, have been proposed. Here we used intraperitoneal delivery of human mesenchymal stem cells to help test (a) whether human cells can indeed suppress disease, and (b) whether CNS infiltration is required for any beneficial effect. We found pronounced amelioration of clinical disease but profoundly little CNS infiltration. Our findings therefore help confirm the therapeutic potential of mesenchymal stem cells, show that this does indeed extend to human cells, and are consistent with a peripheral or systemic immune effect of human MSCs in this model.