For many multiple sclerosis patients, the approval over the past 30 years of a lengthy list of immunomodulatory therapies has helped to reduce the frequency of relapses and to slow disease progression. However, there has been little parallel progress in the development of remyelination therapies, to tackle the other key pathophysiological dimension of the disease. Patients still have no therapies that can help to repair at least some of the damage that results from flare-ups, and the resulting neuronal loss contributes to further disease progression and disability. Rewind Therapeutics NV, of Leuven, Belgium, is one of a small clutch of firms attempting to tackle this problem.