ADENOVIRAL GENE-TRANSFER TO SPINAL-CORD NEURONS - INTRATHECAL VS. INTRAPARENCHYMAL ADMINISTRATION

The spinal cord is the site of many chronic, debilitating, neurologica l disorders that may be amenable to gene therapy. The present study, u sing quantitative and anatomical methods, examines the ability of repl ication deficient adenovirus to transfer a transcription cassette comp osed of the cytomegalovirus promoter driving the expression of the Lac Z reporter gene (AdCMV beta gal) to spinal-cord neurons. Rats were mic roinjected with AdCMV beta gal into the spinal-cord parenchyma or suba rachnoid space and sacrificed between 1 and 60 days post-infusion. The spinal cord was assayed for P-galactosidase (P-gal) activity fluorome trically (MUG). Intraparenchymal injection resulted in significant bet a-gal activity at day 1, which peaked at day 7, and decreased at day 1 4 (21-, 57- and 9.8-fold of control respectively). The spatial distrib ution of beta-gal activity on day 7 was confined to the l-cm section c ontaining the injection site but was detected 2 cm caudal to this sect ion by day 14. Histochemical staining and immunocytochemistry revealed a prominent reaction product in neurons, particularly motor neurons, and glia within the ventral grey matter bilaterally. Intrathecal viral injections showed comparatively modest, yet significant increases in beta-gal activity throughout the spinal cord with the greatest activit y (170% control) closest to the catheter tip. This study demonstrates that AdCMV beta gal injected into the ventral spinal cord results in e xtensive in vivo neuronal gene transfer with beta-gal activity reachin g a peak by day 7 and remaining detectable at 60 days. Intrathecal vir al injections result in greater spatial distribution but a comparative ly lower level of expression. (C) 1998 Elsevier Science B.V. All right s reserved.