(392a) Lipoplex and Polyplex Nanoparticles Based On Cholesterol Modified Oligonucleotides for Enhanced Gene Delivery

Non-viral nanoparticles such as lipoplex and polyplex are promising vesicles to efficiently deliver oligonucleotides (ONs) such as antisense ODN (AS-ODN) and small interfering RNA (siRNA) in vivo. However, it still remains a major challenge to produce ON nanoparticles with well-defined nanostructures and high drug loading for enhanced gene delivery. In this presentation, we demonstrate that cholesterol modified ON (Chol-ON) can be readily condensed and encapsulated inside liposomes through ionic complexation between calcium ions and phosphates on the backbone of ON. In contrast to typical ?onion?-like structure, the core-shell structure of chol-ON/calcium/lipids nanoparticles was observed by cryogenic-temperature transmission electron microscopy (cryo-TEM). The resulting nanostructure was further investigated by atomic force microscopy (AFM). The changes of surface charge and particle size with/without calcium in the formulation were determined to explain the formation of this core-shell nanostructure. As an example, chol-G3139 (a 18-mer AS-ODN against Bcl-2 protein) were incorporated into liposomes containing lipids (DC-chol/EggPC/PEG-DSPE=30/68/2, molar ratio) in the presence of calcium. Comparing to regular G3139 or chol-G3139/lipids nanoparticles, the nanoparticles constructed from chol-G3139/calcium/lipids showed an increase in cell-uptake analyzed by confocal microscopy and Bcl-2 down-regulation determined by Western blotting in K562 and KB cells. This technology has also been extended to prepare chol-siRNA liposomal and chol-ON polyplex nanoparticles. The combination of calcium ions and chol-ON (eg. chol-ODN or chol-siRNA) provides a new strategy to control nanostructure of ON nanoparticles for cancer therapy.