The CNS lesion scar: new vistas on an old regeneration barrier.

Scar formation represents a reaction of nervous tissue to any form of physical injury. Research over the past decade has demonstrated that the scar composed of glial cells and several extracellular matrix molecules constitutes an obstacle to axon regeneration in the CNS. This review briefly summarizes the current knowledge on (a) the structural and functional features of the lesion scar and (b) the development of therapeutic interventions to override this regeneration barrier.