In vivo gene delivery with non-viral carriers

Abstract

Gene delivery is an emerging therapy for treatment of many different diseases and conditions, with the first therapy recently approved for clinical use. This thesis investigates non-viral carriers for gene delivery for bone regeneration, with an emphasis on the mechanisms of plasmid DNA (pDNA) delivery and methods to improve transfection. Polyethylenimine (PEI, 2 kDa) modified with linoleic acid (PEI-LA) was found to give transfection rates comparable to viral vectors both in vitro and in vivo. The PEI-LA/pDNA complexes were found to display a decreased transfection efficiency over time, but a gelatin coating was found to prevent this loss of transfection. The gelatin-coated particles also led to increased transfection in vivo, allowing lower doses of pDNA to be used. Finally, we developed a novel quantitative PCR (qPCR) method to detect pDNA bound in a polymer complex such that the pharmacokinetics could be investigated. The pDNA delivered without a polymeric carrier was degraded very rapidly, while pDNA from PEI and PEI-LA complexes were detectable for two and four weeks respectively. For polymeric complexes, the qPCR method was in good agreement with studies tracking fluorescently labelled pDNA. Similar to in vitro results, PEI complexes gave no gene expression while PEI-LA complexes gave gene expression for at least four weeks. Although no bone regeneration was observed following delivery of complexes, these studies provide crucial information on the non-viral gene delivery in vivo.