Assessing CNS Axon Regeneration

Neurons of the central nervous system (CNS) are much less able to repair themselves after damage than are neurons of the peripheral nervous system. The causes might lie with the differences in environment and type of surrounding glia, or with the neurons themselves. Goldberg et al. (see the Perspective by McKerracher and Ellezam) have isolated retinal ganglion cells, which form part of the CNS, from the rat to study their ability to regenerate axons. RGCs isolated from embryonic rats showed a much greater capability for axon regeneration than did RGCs from early postnatal rats. The diminishing capacity for axonal regeneration correlated with developmental times at which the RGC axons would normally have reached their targets and switched from axonal growth to dendrite elaboration. The switch in growth mode was not related to intrinsic cell age but rather arose from signals from neighboring retinal cells. J. L. Goldberg, M. P. Klassen, Y. Hua, B. A. Barres, Amacrine-signaled loss of intrinsic axon growth ability by retinal ganglion cells. Science 296, 1860-1864 (2002). [Abstract] [Full Text] L. McKerracher, B. Ellezam, Putting the brakes on regeneration. Science 296, 1819-1820 (2002). [Summary] [Full Text]