Targeted delivery of small interfering RNA to angiogenic endothelial cells with liposome-polycation-DNA particles

Angiogenesis is an attractive target for cancer therapy, due to its central position in tumor growth and development. Vascular Endothelial Growth Factor (VEGF) and its receptors (VEGFRs) play a key role in the angiogenic process. A promising strategy for targeting VEGF-mediated angiogenesis is RNA interference (RNAi) using short interfering RNA (siRNA). However, for efficacious RNAi a well-designed siRNA delivery system is crucial. Liposome-Polycation-DNA (LPD) particles form a promising system for siRNA delivery to tumors. In order to target angiogenic endothelial cells, LPD particles may be modified with a targeting ligand, such as a cyclic Arg-Gly-Asp (RGD) peptide that specifically binds to integrins expressed on tumor-associated endothelial cells. In the current study, RGD-targeted PEGylated LPD particles containing VEGFR-2 siRNA were prepared and optimized with respect to their size and charge by varying protamine content, carrier DNA content for stronger complexation, and PEGylation density. The size of the optimized particles was around 200 nm and the ζ-potential was approximately +20 mV. The uptake and silencing efficacy of the RGD-targeted PEGylated LPD particles were evaluated in H5V cells (murine endothelial cells) and Human Umbilical Vein Endothelial cells (HUVECs). When compared to non-targeted LPD particles, enhanced uptake and silencing of VEGFR-2 expression was observed for RGD-targeted PEGylated LPD particles. In conclusion, the RGD-targeted PEGylated LPD particles containing VEGFR-2 siRNA presented here may be a promising approach for targeting VEGF-mediated angiogenesis in cancer therapy.