Object. The present study characterizes the time course and loci of gene expression induced by the administration of adenoviral vectors into spinal cord. Although a marked inflammatory response to these vectors occurred, no effect on spinal cord function was seen in the 1st postoperative week. The expression of transgenic genes delivered by viral vectors is being exploited throughout the nervous system. The present study utilized adenoviral vectors containing the Rous sarcoma virus (RSV) promoter and a nuclear localization signal to achieve transgenic expression in mammalian spinal cord.
Methods. Initial experiments utilizing the vector Ad.RSVlacZ (1012 particles/ml) injected into the region of the central canal resulted in viral gene expression stretching over approximately 1.2 cm of spinal cord. Gene expression was first detected 3 days following viral administration and lasted until postinjection Day 14 with peak expression at Day 7. A variety of cell types in both white and gray matter expressed lacZ. Transgenic expression of the neurotrophin nerve growth factor (NGF) was achieved using injections of Ad.RSVNGF. On histological examination mononuclear inflammatory infiltrate and gliosis were revealed surrounding the injection sites of spinal cords receiving adenovirus but not vehicle. To assess spinal cord function during viral gene expression, animals previously trained in an operant runway task were tested at 7 days postinjection (the peak of viral gene expression) and demonstrated no changes in spinal cord function.
Conclusions. Results of this study using adenoviral neurotrophic gene transfer indicate that it provided an effective tool for the delivery of potentially therapeutic proteins to the injured or diseased spinal cord.