[Repair of the mammalian central nervous system: the "spinal cord" model]

The central nervous system of adult mammals has been classically considered as structurally rigid, tightly wired, and unable to be repaired. We have shown that there exists a rather considerable degree of intrinsic plasticity due to the neurons themselves, but merely to glial cells and to multipotent stem cells. The spinal cord constitutes a good model on which we could demonstrate, with vascular and traumatic animal paradigms, that an early pharmacologic intervention could reduce significantly the extent of lesions and the subsequent functional deficit. Moreover, we showed that regeneration of severed central axons could occur, provided that the astrocytes' component of the glial scar was modified. Finally, transplants of embryonic neurons were shown to repair the axonal circuitry below a sectioned cord, and to restore reflex functions. All these data point to unprecedented perspectives of efficient therapies in acute and chronic neurological diseases.