579. In-Vivo Time Course of Reporter Gene Expression after Nucleic Acid Delivery to the Lateral Ventricle in Rat Brain

Abstract

Transient expression of a therapeutic protein can be accomplished by delivery of nonviral nucleic acid-cationic lipid complexes to target tissue(s). We have previously reported the successful wide spread CNS expression of Hsp70 as well as the reporter genes eGFP and firefly luciferase after delivery of nucleic acid-cationic lipid complexes to the lateral ventricle in the rat brain1, 2. We now report on the in-vivo time course of protein activity following nonviral gene delivery. Nucleic acid (cDNA or mRNA) encoding the reporter gene firefly luciferase complexed with the cationic lipid MLRI was injected into the CSF in the lateral ventricle. Time course of luciferase expression was followed using optical imaging (Xenogen IVIS). Our results show wide spread CNS expression consistent with our previously reported results. In addition, the time course of protein activity after injection of a plasmid carrying luciferase cDNA shows peak expression approximately 72 hours after vector delivery. In vitro data from CHO, NIH3T3, and primary neuronal cells transfected with the same vectors demonstrate a peak somewhat earlier, at approximately 48 hours (unpublished results). Luciferase activity in vivo drops off rapidly after 72 hours, but residual activity has been detected up to 18 days after delivery of the vector. Preliminary data after injection of mRNA-cationic lipid complex into the lateral ventricle demonstrates a more rapid increase and decay of CNS expression of luciferase. Results of the time course of expression of luciferase after cDNA or mRNA delivery will be presented as a series of sequential in vivo images, with region-of-interest (ROI) analysis.