ABSTRACT
During the past century, many researchers have sought to uncover the biological principles that underlie the failure of regeneration within the adult mammalian central nervous system (CNS; reviewed in Fitch & Silver, 1999). Many theories have been proposed to explain this unfortunate response to trauma, including: the intrinsic inability of CNS neurons to regenerate, inhibitory influences of CNS myelin, mechanical obstruction created by the astrocytic glial scar, and local production of inhibitory molecules in the vicinity of a lesion. In addition to a myriad of theories which have attempted to explain regeneration failure, numerous therapeutic strategies have been proposed and tested in various models of spinal cord and brain injury. Despite occasional claims over the years of pioneering advances in the field of regeneration research, CNS trauma remains a difficult clinical problem and very few basic research findings have made their way into routine patient care (see also Brown, chapter 1 this volume).
