Characterization and intraspinal grafting of EGF/bFGF-dependent neurospheres derived from embryonic rat spinal cord

Recent advances in the isolation and characterization of neural precursor c ells suggest that they have properties that would make them useful transpla nts for the treatment of central nervous system disorders. We demonstrate h ere that spinal cord cells isolated from embryonic day 13 Sprague-Dawley an d Fischer 344 rats possess characteristics of precursor cells. They prolife rate as undifferentiated neurospheres in the presence of EGF and bFGF and c an be maintained in vitro or frozen, expanded and induced to differentiate into both neurons and glia. Exposure of these cells to serum in the absence of EGF and bFGF promotes differentiation into astrocytes; treatment with r etinoic acid promotes differentiation into neurons. Spinal cord cells label ed with a nuclear dye or a recombinant adenovirus vector carrying the lacZ gene survive grafting into the injured spinal cord of immunosuppressed Spra gue-Dawley rats and non-immunosuppressed Fischer 334 rats for up to 4 month s following transplantation. Ln the presence of exogenously supplied BDNF, the grafted cells differentiate into both neurons and glia. These spinal co rd cell grafts are permissive for growth by several populations of host axo ns, especially when combined with exogenous BDNF administration, as demonst rated by penetration into the graft of axons immunopositive for 5-HT and CG RP. Thus, precursor cells isolated from the embryonic spinal cord of rats, expanded in culture and genetically modified, are a promising type of trans plant for repair of the injured spinal cord. (C) 2000 Elsevier Science B.V. All rights reserved.