Plasmid delivery in the rat brain

Neurodegenerative diseases as a class do not have effective pharmacotherapies. This is due in part to a poor understanding of the pathologies of the disease processes, and the lack of effective medications. Gene delivery is an attractive possibility for treating these diseases. For the paradigm to be effective, efficient, safe and versatile vectors are required. In this study we evaluated three plasmid delivery systems for transgene expression in the rat hippocampus. Two of these systems were designed to have enhanced intracellular biodegradability. It was hypothesized that this system would be less toxic and could increase the free (non-vector) associated plasmids within the cell, leading to increased transgene activity. Polyethylenimine (PEI) and r-AAV-2 (recombinant adeno associated virus-2) were used as positive, non-viral and viral controls respectively, in the in vivo experiments. The results from the studies indicate there is a distinct difference between the various vectors in terms of total cells transfected, type of cell transfected, and toxicity. Non-viral systems were effective at transfecting both neurons and glia cells within the hippocampus, while the r-AAV-2 transfected mainly neurons. In summary, plasmid-mediated systems are effective for transgene expression within the brain and deserve further study.