Promoting remyelination in multiple sclerosis by endogenous adult neural stem/precursor cells: Defining cellular targets

Although the treatment of multiple sclerosis has made significant strides in the last decade, the therapeutic enhancement of repair has yet to make the successful translation from laboratory to clinic. Nevertheless, advances in the biology of stem and precursor cells, particularly in relation to myelin damage, make this a realistic proposition during the next decade. Replacing lost myelin (remyelination) is currently thought to be an important clinical objective because of the role it might play in slowing or preventing axonal degeneration. Stem/precursor cell-based strategies for enhancing remyelination can be divided into those in which cells are transplanted into a patient (exogenous or cell therapies) and those in which the patient's own stem/precursor cells are mobilised to more efficiently engage in healing areas of demyelination (endogenous or pharmacological therapies). While the two approaches tend to be regarded separately they are not mutually exclusive. This article focuses on the endogenous approach and reviews the nature and nomenclature of the stem and precursor cells present within the adult CNS that engage in remyelination and that are therefore potential targets for pharmacological manipulation.