Entry of PIP3-containing polyplexes into MDCK epithelial cells by local apical-basal polarity reversal

The polarized architecture of epithelium presents a barrier to therapeutic drug/gene carriers, which is mainly due to a limited (apical) internalization of the carrier systems. The bacterium Pseudomonas aeruginosa invades epithelial cells by inducing production of apical phosphatidylinositol-3, 4, 5-triphosphate (PIP3), which results in the recruitment of basolateral receptors to the apical membrane. Since basolateral receptors are known receptors for gene delivery vectors, apical PIP3 may improve the internalization of such vectors into epithelial cells. PIP3 and nucleic acids were complexed by the cationic polymer polyethylenimine (PEI), forming PEI/PIP3 polyplexes. PEI/PIP3 polyplexes showed enhanced internalization compared to PEI polyplexes in polarized MDCK cells, while basolateral receptors were found to redistribute and colocalize with PEI/PIP3 polyplexes at the apical membrane. Following their uptake via endocytosis, PEI/PIP3 polyplexes showed efficient endosomal escape. The effectiveness of the PIP3-containing delivery system to generate a physiological effect was demonstrated by an essentially complete knock down of GFP expression in 30% of GFP-expressing MDCK cells following anti-GFP siRNA delivery. Here, we demonstrate that polyplexes can be successfully modified to mimic epithelial entry mechanisms used by Pseudomonas aeruginosa. These findings encourage the development of pathogen-inspired drug delivery systems to improve drug/gene delivery into and across tissue barriers.