Chitosan Nanocomplexes for the Delivery of ENaC Antisense Oligonucleotides to Airway Epithelial Cells.

Nanoscale drug delivery systems exhibit a broad range of applications and promising treatment possibilities for various medical conditions. Nanomedicine is of great interest, particularly for rare diseases still lacking a curative treatment such as cystic fibrosis (CF). CF is defined by a lack of Cl- secretion through the cystic fibrosis transmembrane conductance regulator (CFTR) and an increased Na+ absorption mediated by the epithelial sodium channel (ENaC). The imbalanced ion and water transport leads to pathological changes in many organs, particularly in the lung. We developed a non-viral delivery system based on the natural aminopolysaccharide chitosan (CS) for the transport of antisense oligonucleotides (ASO) against ENaC to specifically address Na+ hyperabsorption. CS-ASO electrostatic self-assembled nanocomplexes were formed at varying positive/negative (P/N) charge ratios and characterized for their physicochemical properties. Most promising nanocomplexes (P/N 90) displayed an average size of similar to 150 nm and a zeta potential of similar to+30 mV. Successful uptake of the nanocomplexes by the human airway epithelial cell line NCI-H441 was confirmed by fluorescence microscopy. Functional Ussing chamber measurements of transfected NCI-H441 cells showed significantly decreased Na+ currents, indicating successful downregulation of ENaC. The results obtained confirm the promising characteristics of CS as a non-viral and non-toxic delivery system and demonstrate the encouraging possibility to target ENaC with ASOs to treat abnormal ion transport in CF.