Understanding restricted functional recovery and designing efficient treatments to alleviate dysfunction after injury of the nervous system remain major challenges in neuroscience and medicine. Numerous molecules of potential significance in neural repair have been identified in vitro, but only few of these have proved to be of major importance in vivo up to now. Among the molecules involved in regeneration are several members of the immunoglobulin superfamily, most notably the neural cell adhesion molecules L1, its close homologue CHL1, and NCAM and, in particular, its polysialic acid glycan moiety. Sufficient evidence is now available to justify the statement that these molecules are major players not only in nervous system development but also in the adult during neural repair and synaptic plasticity. Importantly, insights into the functions of these molecules in promoting or inhibiting functional recovery have allowed the design and assessment of therapeutic approaches in animal models of central nervous system injury that could prove to be applicable in clinical settings.
