Development of a Non-viral Vector for GDNF Gene Therapy of Parkinson’s Disease

Abstract

Glial cell line-derived neurotrophic factor (GDNF) is being pursued as a potential gene therapy approach for Parkinson’s disease.  Gene therapy to the brain currently relies upon intracerebral injections of viral vectors, which pose a great safety risk due to their potential immunogenicity and the overall invasiveness of surgical injection.  To circumvent this, we are investigating intranasal administration as a non-invasive pathway to the brain, and the use of non-viral vectors as a replacement to viral transduction.  Copernicus Therapeutics, Inc. has developed a nanoparticle vector in which single expression plasmids are compacted with polyethylene-glycol substituted lysine 30-mers (PEG-CK30), forming nanorods of 8-11 nm in diameter.  These nanoparticles are non-immunogenic, non-inflammatory and can deliver gene to cells in the brain.  We have previously shown that intranasal administration of PEG-CK30 allowed for successful transfection of enhanced green fluorescent protein (eGFP)-expressing plasmids throughout the rat brain.   The goal of this study was to create and assess a fusion plasmid (pUGG) in which the gene for eGFP was inserted upstream of the GDNF sequence.  This construct would allow eGFP to be used as a reporter for optimization and monitoring of GDNF transfection.  In vitro, transfection by pUGG was assessed in three cell culture systems.  In vivo, transfection was assessed after direct injection of the construct into rat striatum.  These results, in combination with previous studies, demonstrate that Copernicus’ vectors successfully transfect brain cells and the newly generated eGFP fusion provides a useful reporter for detection of transfection via immunohistochemistry, direct fluorescence microscopy, and ELISA.