Nanolipoparticles-mediated MDR1 siRNA delivery: preparation, characterization and cellular uptake

Lipid-based nanoparticles [NLP] are PEGylated carriers composed of lipids and encapsulated nucleic acids with a diameter less than 100 nm. The presence of PEG in the NLP formulation improves the particle pharmacokinetic behavior. The purpose of this study was to prepare and characterize NLPs containing MDR1 siRNA and evaluate their cytotoxicity and cellular uptake. MDR1 siRNA could be used in multidrug resistance reversal in cancer therapy. siRNAs were encapsulated into NLPs consisted of mPEG-DSPE/DOTAP/DOPE [10:50:40 molar ratio] by the detergent dialysis method. The particle diameters of NLPs and their surface charge were measured using dynamic light scattering. siRNA encapsulation efficiency was determined by an indirect method via filtration and free siRNA concentration determination. NLPs cytotoxicity was investigated by MTT assay. The ability of NLPs for siRNA delivery checked in two human cell lines [MCF-7/ADR and EPP85-181/RDB] by fluorescence microscopy and compared with oligofectamine. NLPs containing MDR1 siRNA were prepared with the stable size of 80-90 nm and the zeta potential near to neutral. The siRNA encapsulation efficacy was more than 80%. These properties are suitable for in vivo siRNA delivery. NLPs cytotoxicity studies demonstrated they were non-toxic at the doses used. NLPs improved siRNA localization in both cell lines. NLPs containing MDR1 siRNA can be a good candidate for in vivo siRNA delivery studies

Selective inhibitory effect of adenosine A1 receptor agonists on the proliferation of human tumor cell lines

In this study, the effects of three structural analogues of adenosine upon proliferation of human tumor cells were investigated. Previous research showed a cytotoxic effect of adenosine via A3 receptor and A[1] receptor and sometimes this effect was receptor independent. The researches showed a differential cytotoxic effect of adenosine and its A[3] agonists on cancerous cells, while other studies demonstrated tumor promoting effect of adenosine and its A[1] agonists. The purpose of the present study was the evaluation of the possible selective anti-tumor effect of A1 receptor agonists on cancerous cells. The substances of N6-cyclohexyl-adenosine [CHA, A[1] agonist], R-isomer of N6-phenylisopropyladenosine [R-PIA, A[1] agonist] and N5-ethylcarboxamido-adenosine [NECA, adenosine A[1]-A[2] non-specific agonist] were tested for their anti-proliferative effect using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide [MTT] assay method. Hep G2, Hep2, CACO2, ACHN and L929 cell lines were used in this assay. CHA inhibited cell proliferation in three cell lines [in concentration of 5-50 micro M] and R-isomer of R-PIA in one cell line [in concentration of 10-50 micro M]. These effects were inhibited partially by addition of 1,3-Dipropyl-8-cyclopentylxanthine [A1 antagonist]. The NECA analogue had no inhibitory effect on the cell proliferations. All of the substances had no cytotoxic effect on L929 cells [mouse connective tissue fibroblast cell line]. CHA and R-PIA had inhibitory effect on the proliferation of human tumor cell lines partially via A1 receptor, while they didn't show such effect on fibroblast cells. These results suggest that A[1] adenosine receptor agonists have a good potential of specific anti-tumor activity

Preparation, characterization and mucoadhesive evaluation of chitosan coated liposomes containing cyclosporine A

The aim of this study was to prepare and characterize chitosan coated liposomes containing cyclosporine A [CyA]. For this purpose, negatively charged liposomes containing CyA were prepared by solvent evaporation method. Liposomes were then added dropwise to chitosan solution [0.25% w/w] for coating. Morphology, mean size and encapsulation efficiency of chitosan coated liposomes were evaluated. To assess the mucoadhesive properties of this drug delivery system, percent of mucin adsorption onto the surface of coated liposomes was determined. The in vitro immunosuppressive effects of CyA encapsulated in the formulated liposomes were also determined on human T-cells by MTT [3- [4, 5- dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide] test. Liposomes were multilamellar vesicles [MLVs]. Mean diameter of chitosan coated liposomes was 2.76 micro m and zeta potential of them was positive [45.3 mV]. Encapsulation efficiency of coated liposomes was 86.11% +/- 2.36 and they were stable during two months. The average of IC50 or the half maximal inhibitory concentration for MLV liposomes was 3.08 2-10 M. According to the mucin adsorption results, this particulate system showed suitable mucoadhesive properties. From these results, it was concluded that the surface modification of liposomes by chitosan coating could increase the prospects of their usefulness as oral drug delivery systems for CyA