In vivo targeted gene delivery by cationic nanoparticles for treatment of hepatocellular carcinoma.

BACKGROUND: Transgene expression in vivo for therapeutic purposes will require methods that allow for efficient gene transfer into cells. Although current vector technologies are being improved, the development of novel vector systems with improved targeting specificity, higher transduction efficiencies and improved safety is necessary. METHODS: Asialoglycoprotein receptor-targeted cationic nanoparticles for interleukin (IL)-12 encapsulation (NP1) or adsorption (NP2) have been formulated by blending poly(D,L-lactic-co-glycolic) acid (PLGA) (50 : 50) with the cationic lipid 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and the ligand asialofetuin (AF), by using a modified solvent evaporation process. RESULTS: We present a novel targeted lipopolymeric vector, which improves significantly the levels of luciferase gene expression in the liver upon i.v. administration. Targeted-NP2 particles showed a five- and 12-fold higher transfection activity in the liver compared to non-targeted (plain) complexes or naked pCMV DNA, respectively. On the other hand, BNL tumor-bearing animals treated with AF-NP1 containing the therapeutic gene IL-12, showed tumor growth inhibition, leading to a complete tumor regression in 75% of the treated mice, without signs of recurrence. High levels of IL-12 and interferon-gamma were detected in the sera of treated animals. Mice survival also improved considerably. Tumor treatment with AF-NP2 formulations lead only to a retardation in the tumor growth. CONCLUSIONS: In the present study, we have developed an efficient targeted non-viral vector for IL-12 gene transfer in hepatocellular carcinoma in vivo, by employing non-toxic cationic PLGA/DOTAP/AF nanoparticles. These results demonstrate for the first time that this cationic system could be used successfully and safely for delivery of therapeutic genes with antitumor activity into liver tumors with targeting specificity.

Targeted cationic poly(D,L-lactic-co-glycolic acid) nanoparticles for gene delivery to cultured cells.

We developed a new targeted cationic nanoparticulate system composed of poly(D,L-lactic-co-glycolic acid) (PLGA), 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and asialofetuin (AF), and found it to be a highly effective formulation for gene delivery to liver tumor cells. The nanoparticles (NP) were prepared by a modified solvent evaporation process that used two protocols in order to encapsulate (NP1 particles) or adsorb (NP2 particles) plasmid DNA. The final particles are in the nanoscale range. pDNA loaded in PLGA/DOTAP/AF particles with high loading efficiency showed a positive surface charge. Targeted asialofetuin-nanoparticles (AF-NP) carrying genes encoding for luciferase and interleukin-12 (IL-12) resulted in increased transfection efficiencies compared to free DNA and to plain (non-targeted) systems, even in the presence of 60% fetal bovine serum (FBS). The results of transfections performed on HeLa cells, defective in asialoglycoprotein receptors (ASGPr-), confirmed the receptor-mediated endocytosis mechanism. In summary, this is the first time that asialoglycoprotein receptor targeting by PLGA/DOTAP/DNA nanoparticles carrying the therapeutic gene IL-12 has been shown to be efficient in gene delivery to liver cancer cells in the presence of a very high concentration of serum, and this could be a potential system for in vivo application.

Versatility of biodegradable poly(D,L-lactic-co-glycolic acid) microspheres for plasmid DNA delivery.

In this study, we have optimized different formulations of DNA encapsulated into PLGA microspheres by correlating the protocol of preparation and the molecular weight and composition of the polymer, with the main characteristics of these systems in order to design an efficient non-viral gene delivery vector. For that, we prepared poly(D,L-lactic-co-glycolic acid) (PLGA) microparticles with an optimized water-oil-water double emulsion process, by using several types of polymers (RG502, RG503, RG504, RG502H and RG752), and characterized in terms of size, zeta potential, encapsulation efficiency (EE%), morphology, DNA conformation, release kinetics, plasmid integrity and erosion. The size of the particles ranged between 0.7 and 5.7 microm depending on the protocol of formulation and the molecular mass of the polymer used. The microspheres prepared by using in their formulation polymers of high molecular weight (RG503 and RG504) were bigger in size than in the case of using a lower molecular weight polymer (RG502). The EE (%) of plasmid DNA increased with increasing the molecular mass of the polymer and by using the most hydrophilic polymer RG502H, which contains terminal acidic groups in its structure. The plasmid could be encapsulated without compromising its structural and functional integrity. Also a protective effect of PLGA on endonuclease digestion is observed. Plasmid DNA release from microspheres composed of low molecular weight or hydrophilic polymers, like RG502H, was faster than from particles containing high molecular weight or hydrophobic polymers. These PLGA microspheres could be an alternative to the viral vectors used in gene therapy, given that may be used to deliver genes and other bioactive molecules, either very rapidly or in a controlled manner.