Preparation of dexamethasone-based cationic liposome and its application to gene delivery in vitro

Modulated cellular delivery of anti-VEGF siRNA (bevasiranib) by incorporating supramolecular assemblies of hydrophobically modified polyamidoamine dendrimer in stealth liposomes

A novel lipopolymer based system was designed and characterized for cellular delivery of anti-VEGF siRNA in SKBR-3 breast tumor cell line. Polyamidoamine (PAMAM) dendrimers of low generations (G1, G2 and G3) were incorporated into polyethylene glycol (PEG)-stabilized liposomes by following the consecutive steps: (a) synthesis of the cholesterol conjugates (40% molar ratio of cholesterol to primary amines of PAMAM), (b) incorporation of the conjugates in liposome by lipid mixing and (c) microencapsulation of the siRNA using the ethanol drop method. The cholesterol conjugates of PAMAM dendrimers (G1-Chol40%, G2-Chol40% and G3-Chol40%) formed self assembly with low CMC values (<11μg/ml). Not only did G2-Chol40% show the highest lipid mixing among the cholesterol conjugates, but also, had the lowest leakage of encapsulated carboxyfluorescein tracer. Various N(amine))/L(lipid)/P(phosphate) mole ratios were investigated for siRNA condensation by ethidium bromide dye exclusion assay. The optimum N/L/P ratio of 20:33:10 was chosen for microencapsulation of anti-VEGF siRNA by ethanol drop method, showing particle size of 130nm, zeta-potential of +4mV, siRNA loading efficiency and capacity of 96% and 13wt%, and high stability against heparin sulfate (extracellular matrix). TEM shows uniform and discrete oligo- or multi-lamellar vesicular structures. The liposome incorporating G2-Chol40% was successfully internalized into SKBR-3 cells mainly through clathrin-mediated endocytosis, which was able to escape from endosomes and showed a significantly higher sequence-specific inhibition of VEGF expression and cell growth than the respective G2-Chol40%/siRNA dendriplexes. Importantly, the cytotoxicity decreased with incorporation of G2-Chol40% in the liposomes.

Evaluation of Chitosan-Tripolyphosphate Nanoparticles as a p-shRNA Delivery Vector: Formulation, Optimization and Cellular Uptake Study

Polysaccharides (especially chitosan) have recently attracted much attention as gene therapy delivery vehicles for their unique properties such as biocompatibility, biodegradability, low toxicity, and controlled release. Nanoparticles have strong potential as a carrier of plasmid short hairpin RNA (p-shRNA). This study aimed to find the optimum conditions for obtaining Chitosan/triphosphate (TPP)/p-shRNA nanoparticles by the ionic gelation method, and investigating the cellular uptake of the optimized nanoparticles. After applying the central composite design of response surface methodology (RSM), the optimum conditions for preparation of nanoparticles with small size and high loading efficiency were: chitosan/TPP ratio = 10, pH = 5.5 and N/P ratio = 11. The resulting nanoparticles had an average size of 172.8 ± 7 nm and loading efficiency of 71.5 ± 5%. SEM images showed spherical and smooth nanoparticles. The nanoparticles complexed with p-shRNA and may protect it against nuclease digestion. Cytotoxicity studies with HeLa and PC3 human cancer cells demonstrated that chitosan/TPP nanoparticles had low toxicity. Cellular uptake studies using HeLa cells showed that the nanoparticles entered the cells (cellular uptake) and delivered DNA, probably due to their favorable Zeta potential (approximately +28 mV) and small size.

The novel albumin-chitosan core-shell nanoparticles for gene delivery: preparation, optimization and cell uptake investigation

Natural polymers and proteins such as chitosan (CS) and albumin (Alb) have recently attracted much attention both in drug delivery and gene delivery. The underlying rationale is their unique properties such as biodegradability, biocompatibility and controlled release. This study aimed to prepare novel albumin-chitosan-DNA (Alb-CS-DNA) core-shell nanoparticles as a plasmid delivery system and find the best conditions for their preparation. Phase separation method and ionic interaction were used for preparation of Alb nanoparticles and Alb-CS-DNA core-shell nanoparticles, respectively. The effects of three important independent variables (1) CS/Alb mass ratio, (2) the ratios of moles of the amine groups of cationic polymers to those of the phosphate groups of DNA (N/P ratio), and (3) Alb concentration, on the nanoparticle size and loading efficiency of the plasmid were investigated and optimized through Box-Behnken design of response surface methodology (RSM). The optimum conditions were found to be CS/Alb mass ratio = 3, N/P ratio = 8.24 and Alb concentration = 0.1 mg/mL. The most critical factors for the size of nanoparticles and loading efficiency were Alb concentration and N/P ratio. The optimized nanoparticles had an average size of 176 ± 3.4 nm and loading efficiency of 80 ± 3.9 %. Cytotoxicity experiments demonstrated that the prepared nanoparticles were not toxic. The high cellular uptake of nanoparticles (~85 %) was shown by flow cytometry and fluorescent microscopy.