Accelerated transgene expression of pDNA/polysaccharide complexes by solid-phase reverse transfection and analysis of the cell transfection mechanism

Gene delivery using pDNA complexes immobilized on a substrate, termed solid-phase reverse transfection (RTF), has received increasing attention. This is because it can enhance transgene expression and localize gene delivery. However, gene carriers used in RTF are limited, and their transgene expression mechanisms are unclear. In this study, we employed pDNA/chitosan/anionic polysaccharide complexes for RTF and investigated their cell transfection mechanisms. The pDNA/chitosan/hyaluronic acid (HA) ternary complexes showed particularly higher transgene expression than other ternary complexes. Cellular uptake and intracellular trafficking pathways were analyzed using inhibitors of endocytosis and intracellular trafficking. It was revealed that pDNA/chitosan/HA complexes were taken up via macropinocytosis and released from late endosomes. Furthermore, pDNA complexes were remarkably accumulated in the nucleus in RTF compared with the conventional forward transfection (FTF) method. These results suggest that the cell transfection efficiency of the pDNA/chitosan/HA ternary complexes in RTF was enhanced by their efficient delivery to the nucleus via late endosomes.