The Role of Poly(γ-glutamic acid) Incorporated in Chitosan-based Complexes as a Nucleic Acid Vector: Endocytotic Pathway and Intracellular Trafficking

摘要

Chitosan (CS)-based complexes have been considered as a vector for DNA and siRNA (small interfering RNA) delivery; nonetheless, their transfection efficiency is relatively low. An approach by incorporating poly(γ-glutamic acid) (γ-PGA) in either CS/DNA or CS/siRNA complexes was developed in our lab to enhance either their gene expression level or knowdown target gene; however, the detailed mechanisms remain to be understood. The study was designed to investigate the mechanisms in cellular uptake and intracellular trafficking of CS/DNA/γ-PGA complexes. TEM was used to gain directly understanding of the internalization mechanism of test complexes; these results confirmed our findings obtained in the inhibition experiments. After internalization, a less percentage of co-localization of CS/DNA/γ-PGA complexes with lysosomes was observed when compared with their CS/DNA counterparts. A greater cellular uptake together with a less entry into lysosomes might thus explain the promotion of transfection efficiency of CS/DNA/γ-PGA complexes. Knowledge of these mechanisms involving CS-based complexes containing γ-PGA is critical for the development of an efficient vector for DNA and siRNA transfection.