Multiple Sclerosis, or MS, affects hundreds of thousands of people. It's a condition where the body's own immune system attacks a protective layer around nerve fibres called myelin. This prevents messages being conveyed quickly and faithfully through the brain producing symptoms that can include difficulty with vision, movement, speech, balance and sensation. In recent years scientists have begun to explore the use of stem cells to combat the progression of the disease. As author Stefano Pluchino, from Cambridge University, explained to Chris Smith.