Abstract 599: Development of poly(Asp-DET) cationic polymers for nonviral gene delivery

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Cationic polymers have received much attention as promising non-viral vectors for gene transfer. However, identification of polymers able to systemically deliver nucleic acids continues to be a significant hurdle to the success of this methodology. The purpose of this study was to develop a new biocompatible and biodegradable cationic polymer system as a non-viral gene delivery agent for plasmid DNA. Poly-aspartate-diethylene triamine (“P(Asp-DET)”) polymers were synthesized and utilized to complex plasmid DNA. The resulting polymer/DNA complexes, also known as “polyplexes,” were further modified by covalent coupling with polyethylene glycol (PEG), known as “PEGylation,” and characterized. Polyplexes were evaluated for efficiency of encapsulation, particle size, zeta potential and morphology by TEM. Stability of the complexed plasmid DNA was assessed by challenging polyplexes with nucleases. Efficacy of DNA delivery and gene expression was examined by performing transfection experiments using HCT-116 cells. In vivo DNA delivery was also investigated using tumor-bearing nude mice. Asp-DET polymers were found to bind to plasmid DNA with polymer to DNA (+/-) charge ratios of above 1.5. In addition, these polymers formed polyplex particles of approximately 50-150 nm with zeta potentials between neutral and +40 mV. TEM showed that the polyplexes were uniform and spherical in shape. It was also demonstrated that the polyplexes maintained the structural integrity of DNA following incubation in nucleases. The polyplexes were also capable of transfecting HCT-116 culture cells, with non-PEG complexes having significantly higher GFP and luciferase expression. Tail vein injections of post-PEGylated polyplexes into tumor bearing nude mice did not reveal any observable toxicities. Notably, nucleic acid accumulation was found in tumors with expression detected in lymph nodes. P(Asp-DET) cationic polymers show enormous potential as non-viral drug delivery agents. Further, the surface modification of described polyplexes with PEG allowed for systemic delivery of nucleic acids to tumors. The characterization of post-PEGylated Asp-DET/DNA polyplexes provides insights that can be used to design vectors for targeted nucleic acid delivery. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 599.