Surface-Modified Biodegradable Nanoparticles' Impact on Cytotoxicity and Inflammation Response on a Co-Culture of Lung Epithelial Cells and Human-Like Macrophages

The toxicity of polymeric biodegradable nanoparticles was evaluated on a co-culture made from direct contact of human lung alveolar epithelial cells (A459) and macrophages (differentiated THP-1 monocytes). The co-culture was characterized by its phenotype and by confocal laser scanning microscopy. Cytokine secretion induced by lipopolysaccharide was synergistically increased in the co-culture confirming cell-cell interactions. Poly(lactide-co-glycolide) (PLGA)-based nanoparticles of 200 nm were prepared in presence of hydrophilic polymers commonly used as stabilizers [poly(vinyl alcohol), chitosan and poloxamer 188] through their interaction with particle surface. Stabilizer-free PLGA nanoparticles and stabilizers alone were also evaluated as controls. Selective uptake kinetics of PLGA nanoparticles by cell subpopulations, as well as apoptosis/necrosis detection, was achieved using a specific label for each cell type, while cytokine secretions were quantified in culture supernatants. Both cell subpopulations took up PLGA nanoparticles with similar profiles, and induced only little cytotoxicity (mostly necrosis). A mild inflammatory response to stabilized nanoparticles was detected (compared to well-known inflammatory compounds), slightly higher than the one observed for stabilizer free PLGA nanoparticles or stabilizing agents taken individually. These results demonstrate that although biodegradable nanoparticles can be considered as safe, they can internalize compounds such as the stabilizing agents which enhance their toxicity.