Multiple sclerosis (MS) is a chronic neurological disease estimated to affect around 2. 3 million people worldwide. It is believed to be an autoimmune disorder, in which the immune system mistakingly attacks healthy tissue in the central nervous system (CNS). Myelin - the protective coating surrounding the nerve fibers - is damaged in the attack, as well as the cells that produce myelin, called oligodendrocytes. The underlying nerve fibers may also be damaged.