Multiple sclerosis is a chronic debilitating disease of the CNS. The relapsing remitting form of the disease is driven by CNS directed inflammation. However, in the progressive forms of the disease, inflammation has abated and the underlying pathology is less well understood. In this paper, we show that chronic lesions in progressive MS are associated with fibrotic changes, a type of pathology that has previously not thought to occur in the CNS. In an animal model of chronic MS, late stage

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... se contains no inflammatory infiltrates and is instead characterized by collagen deposition that is histologically similar to fibrosis. In human MS samples, chronic, but not acute lesions, are devoid of inflammatory infiltrates and instead contain significant collagen deposition. Furthermore, we demonstrate that both mouse and human astrocytes are the cellular source of collagen. These results suggest that anti-fibrotic therapy may be beneficial in the treatment of progressive MS.