Chitosan/cyclodextrin nanoparticles can efficiently transfect the airway epithelium in vitro

The main goal of the present study was to investigate the potential of a new generation of hybrid polysaccharide nanocarriers, composed of chitosan (CS) and anionic cyclodextrins (CDs), for gene delivery to the airway epithelium. More specifically, these nanocarriers were investigated with regard to their ability to enter epithelial cells and promote gene expression in the Calu-3 cell culture model. In the search for the most suitable nanocarrier composition for gene delivery, the effect of CS molecular weight (Mw) on the nanocarriers characteristics and their ability to transfect cells was investigated. Thus, hybrid CS/CD nanoparticles were prepared with two different CS Mw, medium (110 kDa) and low (10 kDa), and loaded with pSEAP (plasmid DNA model that encodes the expression of secreted alkaline phosphatase). The resulting nanoparticles presented an adequate size range (100-200 nm, depending on CS Mw), a positive surface charge (+22 to +35 mV) and very high DNA association efficiency values (>90%). Cellular uptake studies showed that the nanoparticles were effectively internalized by the cells, providing a good indication of their potential as gene carriers. The transfection efficiency of the different formulations, measured by the concentration of secreted gene product (SEAP), indicated that all the nanoparticles were able to elicit a significantly higher response than the naked DNA (control), the transfection efficiency being more important for low MwCS nanoparticles than for those composed of medium MwCS. Overall, this report is the first evidence of the potential of a new generation of safe polysaccharide nanocarriers for gene delivery to the airway epithelium.