Nanoparticle translocation across mouse alveolar epithelial cell monolayers: species-specific mechanisms.

Studies of polystyrene nanoparticle (PNP) trafficking across mouse alveolar epithelial cell monolayers (MAECM) show apical-to-basolateral flux of 20 and 120nm amidine-modified PNP is ~65 times faster than that of 20 and 100nm carboxylate-modified PNP, respectively. Calcium chelation with EGTA has little effect on amidine-modified PNP flux, but increases carboxylate-modified PNP flux ~50-fold. PNP flux is unaffected by methyl-β-cyclodextrin, while ~70% decrease in amidine- (but not carboxylate-) modified PNP flux occurs across chlorpromazine- or dynasore-treated MAECM. Confocal microscopy reveals intracellular amidine- and carboxylate-modified PNP and association of amidine- (but not carboxylate-) modified PNP with clathrin heavy chain. These data indicate (1) amidine-modified PNP translocate across MAECM primarily via clathrin-mediated endocytosis and (2) physicochemical properties (e.g., surface charge) determine PNP interactions with mouse alveolar epithelium. Uptake/trafficking of nanoparticles into/across epithelial barriers is dependent on both nanoparticle physicochemical properties and (based on comparison with our prior results) specific epithelial cell type. FROM THE CLINICAL EDITOR: In this study of polystyrene nanoparticle trafficking across mouse alveolar epithelial cell monolayers, the authors determined that uptake/trafficking of nanoparticles into/across epithelial barriers is dependent on both nanoparticle physicochemical properties and the specific type of epithelial cells.