| These studies investigated the use of an adeno-associated virus (AAV) platform for gene transfer into the healthy and injured spinal cords of adult rats. These studies predominantly focused on in vivo gene delivery applications and the use of non-viral, CNS-specific viral vectors for improved long-term, stable transgene expression in the CNS. Making use of a unique reporter gene, the gene for the bioluminescent Green Fluorescent Protein (GFP) we found stable, robust transgene expression from 2 neuronal promoters, the neuron-specific enolase (NSE) promoter and the platelet-derived growth factor (PDGF) B-chain promoter. We saw strong expression for up to 4 months for both vectors and for up to 9 months after injection with the PDGF recombinant virus, with no evidence of toxicity or overt pathology from either the transgene or the recombinant virus. We also saw an overall improvement of transgene expression from novel CNS vectors relative to vectors containing viral promoters. We explored the potential for injured tissue to express transgenes and made use of an injury-labile promoter, the glial fibrillary acidic protein (GFAP) promoter to increase transgene expression in astrocytes following ventral root avulsion. Three weeks after injury, we found a significantly higher incidence of transgene expressing astrocytes from this promoter relative to the results from a ubiquitous housekeeping promoter. In healthy tissue we also found a higher incidence of glial transgene expression relative to the housekeeping or neuronal promoter, but found a striking and unanticipated predominance of expression in neurons by the glial promoter. Finally, the preliminary data we generated from studies of AAV-transduced progenitors would support the use of AAV and these cells as vehicles for gene transfer in transplant paradigms. |
