Galactosylation of chitosan-graft-spermine as a gene carrier for hepatocyte targeting in vitro and in vivo

Abstract

Polyethyleneimine (PEI) has been described as a highly efcient gene carrier due to its efcient proton sponge effect within endosomes. However, many studies have demonstrated that PEI is toxic and associated with a lack of cell specicity despite high transfection efciency. In order to minimize the toxicity of PEI, we prepared chitosan-graft-spermine (CHI-g-SPE) in a previous study. CHI-g-SPE showed low toxicity and high transfection efciency. However, this compound also had limited target cell specicity. In the present study, we synthesized galactosylated CHI-g-SPE (GCS) because this modied GCS could be delivered specically into the liver due to hepatocyte-specic galactose receptors. The DNA-binding properties of GCS at various copolymer/DNA weight ratios were evaluated by a gel retardation assay. The GCS copolymer exhibited signicant DNA-binding ability and efciently protected DNA from nuclease attack. Using energy-ltered transmission electron microscopy (EF-TEM), we observed dense spherical, nano-sized GCS/DNA complexes with a homogenous distribution. Most importantly, GCS was associated with remarkably low cytotoxicity compared to PEI in HepG2, HeLa, and A549 cells. Moreover, GCS carriers specically delivered the gene-of-interest into hepatocytes in vitro as well as in vivo. Our results suggest that the novel GCS described here is a safe and highly efcient carrier for hepatocyte-targeted gene delivery.