In this study, the novel RGD-modified stabilized cationic liposomes were developed as the delivery vehicle for siRNA targeting human MDR1 gene. The complex of cationic liposomes and siRNA, RGD-Lipo-siRNA, was prepared...In this study, the novel RGD-modified stabilized cationic liposomes were developed as the delivery vehicle for siRNA targeting human MDR1 gene. The complex of cationic liposomes and siRNA, RGD-Lipo-siRNA, was prepared with a narrow size distribution below 200 nm. It was shown that the encapsulated siRNA in the liposomes could be effectively protected from serum degradation. Also, enhanced cell binding and intracellular uptake of siRNA in the doxorubicin-resistant human ova- rian cancer cell lines SKOV3/A were found in RGD-Lipo-siRNA preparation as compared to that of unmodified cationic lipsomes （Lipo-siRNA）. Using the post-insertion method for RGD modification, lysosome release of siRNA in pRGD-Lipo-siRNA was improved. From flow cytometry, significant increase of doxorubicin accumulation was observed in the SKOV3/A cells treated with pRGD-Lipo-siRNA targeting human MDR1 gene. In vitro cytotoxicity assay showed that the significant cell growth inhibition was achieved in the SKOV3/A cells after treating with the combined use of siRNA and doxorubicin. In conclusions, postinserted RGD modified lipoplex, pRGD-Lipo-siRNA, was successfully used for siRNA transfection and achieved drug resistance reversal in human ovarian cancer SKOV3/A （doxorubicin-resistant） cells. It suggested that this liposomes might be a potential vehicle for siRNA delivery in vivo.展开更多
Five novel cationic lipids, the polar head group of which was attached to the cholesterol backbone via a tertiary carbamate linker, were synthesized and their physicochemical properties were compared to their transfec...Five novel cationic lipids, the polar head group of which was attached to the cholesterol backbone via a tertiary carbamate linker, were synthesized and their physicochemical properties were compared to their transfection efficiencies. Transfection activity of the primary amine analog was highest among the series, while the quaternary ammonium iodide salt was essentially transfection incompetent. Contrary to DC-Chol, methyl and ethyl carbamoyl derivatives of DC-Chol mediated high levels of transfection in the absence of DOPE. Ionization of the cationic assemblies in 40 mM Tris buffer pH 7.2 exactly correlated with the competitive nature of the inductive and steric effects of the methyl groups on the aliphatic nitrogen of the lipids’ polar moiety. Interestingly, the pH interaction zone of all lipid dispersions at 25°C was extended by ± 2 pH units from the pKa, while the pKa of the cationic lipids determined in mixed vesicles composed of 90 % DOPC and cholesterol was approximately 1.3 to 1.5 times higher than that of pure cationic assemblies. The interaction of cationic lipids with plasmid DNA was correlated with pKa, but not the transfection activity.展开更多
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 s...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.展开更多
基金National Natural Science Foundation of China(Grant No.30701056)Foundation of MOST(973 Program,Grant No.2007CB935801)+1 种基金Beijing Natural Science Foundation of China(Grant No.7083112)Doctoral Foundation of Ministry of Education of China(Grant No.20070001813).
文摘In this study, the novel RGD-modified stabilized cationic liposomes were developed as the delivery vehicle for siRNA targeting human MDR1 gene. The complex of cationic liposomes and siRNA, RGD-Lipo-siRNA, was prepared with a narrow size distribution below 200 nm. It was shown that the encapsulated siRNA in the liposomes could be effectively protected from serum degradation. Also, enhanced cell binding and intracellular uptake of siRNA in the doxorubicin-resistant human ova- rian cancer cell lines SKOV3/A were found in RGD-Lipo-siRNA preparation as compared to that of unmodified cationic lipsomes （Lipo-siRNA）. Using the post-insertion method for RGD modification, lysosome release of siRNA in pRGD-Lipo-siRNA was improved. From flow cytometry, significant increase of doxorubicin accumulation was observed in the SKOV3/A cells treated with pRGD-Lipo-siRNA targeting human MDR1 gene. In vitro cytotoxicity assay showed that the significant cell growth inhibition was achieved in the SKOV3/A cells after treating with the combined use of siRNA and doxorubicin. In conclusions, postinserted RGD modified lipoplex, pRGD-Lipo-siRNA, was successfully used for siRNA transfection and achieved drug resistance reversal in human ovarian cancer SKOV3/A （doxorubicin-resistant） cells. It suggested that this liposomes might be a potential vehicle for siRNA delivery in vivo.
文摘Five novel cationic lipids, the polar head group of which was attached to the cholesterol backbone via a tertiary carbamate linker, were synthesized and their physicochemical properties were compared to their transfection efficiencies. Transfection activity of the primary amine analog was highest among the series, while the quaternary ammonium iodide salt was essentially transfection incompetent. Contrary to DC-Chol, methyl and ethyl carbamoyl derivatives of DC-Chol mediated high levels of transfection in the absence of DOPE. Ionization of the cationic assemblies in 40 mM Tris buffer pH 7.2 exactly correlated with the competitive nature of the inductive and steric effects of the methyl groups on the aliphatic nitrogen of the lipids’ polar moiety. Interestingly, the pH interaction zone of all lipid dispersions at 25°C was extended by ± 2 pH units from the pKa, while the pKa of the cationic lipids determined in mixed vesicles composed of 90 % DOPC and cholesterol was approximately 1.3 to 1.5 times higher than that of pure cationic assemblies. The interaction of cationic lipids with plasmid DNA was correlated with pKa, but not the transfection activity.
基金National Natural Science Foundation of China (Grant No.30701056)Foundation of MOST(973 Program,Grant No.2007CB935801)+1 种基金Beijing Natural Science Foundation of China (Grant No.7083112)Doctoral Fund of Ministry of Education of China(Grant No.20070001813).
文摘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.
