Estelle Durantie1, Dimitri Vanhecke1, Laura Rodriguez-Lorenzo1, Flavien Delhaes1, Sandor Balog1, Dedy Septiadi1, Joel Bourquin1, Alke Petri-Fink1,2 and Barbara Rothen-Rutishauser1
1BioNanomaterials Group, Adolphe Merkle Institute, Université de Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
2Chemistry Department, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland.
In this study, the biodistribution of aerosolized single and aggregated nanoparticles was investigated using a 3D model of the human epithelial tissue barrier. The cells were exposed at the air-liquid interface using the Vitrocell® Cloud exposure system. It consists of three main parts: a nebulizer, an aerosol chamber and a base module constituted of 12-well size inserts and connected to a controlled heating unit. Robust characterization was used to evaluate the exact delivered dose onto the cell surface and to determine the cellular uptake and translocation across the barrier.
Background: The lung represents the primary entry route for airborne particles into the human body. Most studies addressed possible adverse effects using single (nano)particles, but aerosolic nanoparticles (NPs) tend to aggregate and form structures of several hundreds nm in diameter, changing the physico-chemical properties and interaction with cells. Our aim was to investigate how aggregation might affect the biodistribution; cellular uptake and translocation over time of aerosolized NPs at the air-blood barrier interface using a multicellular lung system.
Results: Model gold nanoparticles (AuNPs) were engineered and well characterized to compare single NPs with aggregated NPs with hydrodynamic diameter of 32 and 106 nm, respectively. Exposures were performed by aerosolization of the particles onto the air-liquid interface of a three dimensional (3D) lung model. Particle deposition, cellular uptake and translocation kinetics of single and aggregated AuNPs were determined for various concentrations, (30, 60, 150 and 300 ng/cm2) and time points (4, 24 and 48 h) using transmission electron microscopy and inductively coupled plasma optical emission spectroscopy. No apparent harmful effect for single and aggregated AuNPs was observed by lactate dehydrogenase assay, nor pro-inflammation response by tumor necrosis factor α assessment. The cell layer integrity was also not impaired. The bio-distribution revealed that majority of the AuNPs, single or aggregated, were inside the cells, and only a minor fraction, less than 5%, was found on the basolateral side. No significant difference was observed in the translocation rate. However, aggregated AuNPs showed a significantly faster cellular uptake than single AuNPs at the first time point, i.e. 4 h.
Conclusions: Our studies revealed that aggregated AuNPs showed significantly faster cellular uptake than single AuNPs at the first time point, i.e. 4 h, but the uptake rate was similar at later time points. In addition, aggregation did not affect translocation rate cross the lung barrier model since similar translocation rates were observed for single as well as aggregated AuNPs.