ABSTRACT
Plasmid-based gene delivery systems utilize synthetic gene carriers to condense and protect plasmid DNA (pDNA) from premature degradation during storage and transportation from the site of administration to the site of gene expression.1-3 Plasmid DNA is condensed into a highly organized structure through a complex self-assembly process. Commonly utilized synthetic gene carriers are cationic lipids, polymers, and peptides that condense pDNA by virtue of their electrostatic interactions with the anionic phosphate backbone of the nucleic acid chain. Cationic copolymers synthesized by grafting polyethylenimine (PEI) with nonionic polymers, such as poly(ethylene oxide) (PEO) or Pluronic 123 have also been used for gene delivery.4 However, noncondensing polymers, such as poloxamers and polyvinyl pyrrolidone (PVP), are also being investigated for gene delivery to muscle and tumor tissues5,6 and will be discussed in a Chapters 19 and 20.
