Targeting delivery of oligonucleotide and plasmid DNA to hepatocyte via galactosylated chitosan vector.

Delivery of oligonucleotide to specific cells and maintenance of its biological function are important for nucleic acid therapy. The objective of this paper is to demonstrate that galactosylated low molecular weight chitosan (gal-LMWC) is a safe and effective vector of antisense oligonucleotide (ASO) and plasmid DNA for the hepatocyte targeting delivery. Gal-LMWC has been successfully prepared and MTT cytotoxic assay shows that cytotoxicity of gal-LMWC is lower than that of high molecular weight chitosan (HMWC) and low molecular weight chitosan (LMWC) in HepG2 cells. Using a complex coacervation process, gal-LMWC can form stable nano-complexes with plasmid DNA or with ASO by the electrostatic interaction. The morphometrics, particle size, and the zeta potential of gal-LMWC/ASO complexes and gal-LMWC/plasmid DNA complexes are very similar. The transfection efficiency by using gal-LMWC vector is significantly higher than that of naked DNA or naked ASO in HepG2 cells. Transfection efficiency of gal-LMWC/ASO complexes and gal-LMWC/plasmid DNA complexes depends on the molar ratio of the positive chitosan amino group and the negative DNA phosphate group (N/P ratio) strongly. Inhibition experiments confirm that the enhanced transfection efficiency is due to the ASGR mediated endocytosis of the gal-LMWC/ASO complexes or gal-LMWC/DNA complexes. These results suggest that gal-LMWC can be used in gene therapy to improve the transfection efficiency in vitro and in vivo.