Characterization of a new coculture model of alveolo-capillary barrier developed to study the translocation and the toxicity of nanoparticles

One of the vital barriers in the human body is the air-blood barrier (ABB) in the lung. With an area of approximately 140 m2 the alveoli are functionally the most important element of the lung. Therefore, we developed an in vitro model that mimics the ABB in order to assess the translocation and the toxicity of nanoparticles (NP). In order to better mimic the reality, the model is composed of 3 cell types: THP-1 differentiated-macrophages and epithelial cells (A549 or NCI-H441) cultivated on the apical membrane of an insert, and HUVEC-CS endothelial cells on the basal side. Contrary to A549 cell line, NCI-H441 cells are not type II pneumocytes, but we showed that they are able to establish reliable junctional complexes. Consequently, they are good candidates to build a model of ABB. Coculture with THP-1 macrophages revealed to be essential to assess inflammatory process close to reality because 20 nm SiO2 and TiO2 NP-exposed macrophage's conditioned medium does not trigger the same inflammatory response compared to direct treatment of epithelial cells by NP. On the other hand, coculture of NCI-H441 cells with HUVEC-CS cells was tested with different coatings (collagen, elastin, fibronectin) to determine the best conditions in terms of cell differentiation. Moreover, different insert pore-sizes were tested (0.4 um; 1 um and 3 um) and optimal sizes (0.4 um and 1 um) were chosen according to NP translocation and cell growth. Therefore, the first results with our complete model underline the importance of using macrophages to assess inflammatory and translocation process on the ABB