Target gene delivery from targeting ligand conjugated chitosan–PEI copolymer for cancer therapy

• Targeting ligand/poly(ethylene glycol)/O-carboxymethyl chitosan/low molecular weight polyethylenimine (HPOCP) was synthesized for gene delivery.
• HPOCP/siRNA polyplexes formed spherical shape and have particles sized from 100 to 300 nm.
• HPOCP/siRNA polyplexes showed increased cellular uptake more than untargeted systems.
• The cell viability of HPOCP polyplexes with VEGF siRNA or BCL2 siRNA was investigated in SK-Br3 cells.

In this study, we designed a novel carrier which was having low cytotoxicity, site-specific target function, and high transfection efficiency using low molecular weight water soluble O-carboxymethyl chitosan (OCMCh), branched low molecular weight poly(ethyleneimine) (bPEI), and targeting ligand (epitope type, HER-2/neu). OCMCh/bPEI/targeting ligand, HPOCP copolymer, and targeting ligand-modified polyamphoteric polymer, and were prepared by chemical reaction and characterized by 1H NMR and FT-IR. The binding affinity, protecting efficiency, and releasing ability of gene/HPOCP polyplex were confirmed by gel retardation assay. The pDNA(pEGFP)/HPOCP polyplexes showed high gene transfection efficiency in HCT 119 cell. In addition, siRNA/HPOCP polyplexes formed spherical shape and have particle sizes from 100 to 300 nm. The siRNA/HPOCP polyplexes have lower cytotoxicity than PEI in the all of siRNA concentrations ranging from 0 to 2 μg/μL in HEK 293 cells. The cell viability of siRNA/HPOCP polyplexes was performed in SK-Br3 cells with VEGF siRNA or BCL2 siRNA. In addition, confocal laser-scanning microscopy and flow cytometry assay were performed for cellular localization and cellular uptake efficiency of siRNA/HPOCP polyplexes. The results of the present study demonstrate that HPOCP copolymer is a good candidate as gene delivery carriers for gene delivery system or gene therapy.