Journal of Neuroscience, Vol 7, 610-620, Copyright © 1987 by Society for Neuroscience
Nerve fiber growth in culture on tissue substrata from central and peripheral nervous systems
S Carbonetto, D Evans and P Cochard
In adult mammals, injured neurons regenerate extensively within the PNS but
poorly, if at all, within the CNS. We have studied the effect of substrata
consisting of tissue sections from various nervous systems on nerve fiber
growth in culture and correlated our results with the growth potential of
these tissues in vivo. Ganglionic explants from embryonic chicks (9-12 d)
fail to extend nerve fibers onto sections of adult rat optic nerve or
spinal cord (CNS) but do so on sciatic nerve (PNS). Dissociated DRG neurons
behave similarly whether in serum- containing or defined medium. Tissue
substrata from nervous systems that support regeneration in vivo--i.e.,
goldfish optic nerve, embryonic rat spinal cord, degenerating sciatic
nerve--also support fiber growth in culture. Within the same culture,
neurons will grow onto sciatic nerve rather than neighboring optic nerve
sections, suggesting that the responsible agent(s) is not soluble. In
addition, neurons adhere more extensively to sciatic nerve substrata than
to optic nerve. The occurrence of 3 molecules known to be involved in
neuron-substratum adhesion and nerve fiber growth in vitro has been
documented immunocytochemically in the tissue sections. One of these,
laminin, is demonstrable in all tissues tested that supported nerve fiber
growth. Immunoreactivities for fibronectin and heparan sulfate proteoglycan
are found in only some of these tissues. None of these 3 molecules can be
demonstrated in neural cells of normal adult rat CNS tissue. Our data
suggest that these molecules may be important effectors of nerve
regeneration in neural tissues.