With increasing knowledge of the molecular mechanisms of endogenous RNA interference,systemic delivery of small interfering RNA（siRNA） via targeted nanoparticles has emerged as a potential strategy for cancer gene therapy.In this study,a novel formulation[liposome-protamine-chondroitin sulfate nanoparticles（LPC-NP）]was developed for siRNA delivery by self-assembling with charge-charge interaction.The LPC-NP was further modified by DSPE-PEG_（2000） and DSPE-PEG_（2000）-T7 by the post-insertion method.T7,a transferrin-like seven-amino acid peptide,is a targeting ligand for transferrin receptor-overexpressed MCF-7 breast cancer cells.The particle size and zeta potential of LPC-NP were approximately 90 nm and ＋35 mV,respectively. It was shown that PEG modification could significantly decrease aggregation of LPC-NP in serum,and T7 peptide modified LPC-NP could significantly increase the cellular uptake and the gene-silencing effect of siRNA.In vitro cytotoxicity assay exhibited that significant cell growth inhibition was achieved in MCF-7 cells after the delivery of anti-EGFR siRNA.Our encouraging results suggested that T7-modified LPC-NP might be a promising carrier for RNAi-based tumor therapy.
This study aimed to investigate the effects of cationic liposomes containing different cationic lipids （DC-Chol and DOTAP） and different pegylation ratios on siRNA transfection in human U251 glioma cells. The data showed that the transfection efficiency of DOTAP was much higher than that of DC-Chol and PEG at 2 mol% enhanced cellular uptake of siRNA. Cationic liposome-siRNA complexes with particle size around 100 nm were prepared. PEG modification could efficiently stabilize the liposome in the presence of serum, which might protect the siRNA from serum degradation and prolong the circulation time in vivo. Efficient intracellular uptake and lysosome release of siRNA in human U251 glioma cells were observed for pegylated DOTAP-based lipososomes compared with the control transfection reagent lipofectamine 2000. The results demonstrated that this cationic liposome might be a potential vehicle for the in vivo delivery of siRNA.
