Neural Progenitors in the Regenerating Spinal Cord

Patrizia Ferretti

Developmental Biology Unit, Institute of Child Health, UCL, London, UK

Much recent work has indicated the existence of neural progenitors in the central nervous system (CNS) of adult mammals, but these cells do not appear to be recruited in response to injury to replenish depleted neuronal pools. In contrast, lower vertebrates can activate neural progenitors following injury and regenerate significant parts of their CNS as adults. The amphibian spinal cord can indeed regenerate both after resection of the cord and after tail amputation. The ependymal cells lining the central canal are crucial for regeneration, though we have recently observed that also mature neurons translocating from the stump appear to be involved in the regenerative process. The mechanisms underlying recruitment of neural progenitors and the initiation of their division after spinal cord injury in amphibians are still poorly understood. We have recently suggested that FGF signaling plays a key role in regeneration of the newt spinal cord. We are currently trying to characterize the roles played by different FGF receptors (FGFRs), as they are differently regulated during spinal cord regeneration, using soluble forms of the receptors that act as dominant-negative agents. Interestingly, FGFR expression is also regulated during differentiation of cultured spinal cord progenitors from human embryos, suggesting conserved mechanisms in the control of neural progenitors proliferation in vertebrates as distant as amphibians and humans, and between development and regeneration.