A Co-Culture Model of the Human Respiratory Tract to Discriminate the Toxicological Profile of Cationic Nanoparticles According to Their Surface Charge Density

Abstract

This study aimed at discriminating with sensitivity the toxicological effects of carbon dots (CDs) with various zeta potential (ζ) and charge density (Qek) in different cellular models of the human respiratory tract. One anionic and three cationic CDs were synthetized as follows: CD-COOH (ζ = -43.3 mV); CD-PEI600 (Qek = 4.70 µmol/mg; ζ = +31.8 mV); CD-PEHA (Qek = 3.30 µmol/mg; ζ = +29.2 mV) and CD-DMEDA (Qek = 0.01 µmol/mg; ζ = +11.1 mV). Epithelial cells (A549) and macrophages (THP-1) were seeded alone or as co-cultures with different A549:THP-1 ratios. The obtained models were characterized, and multiple biological responses evoked by CDs were assessed in the mono-cultures and the best co-culture model. With 14% macrophages, the 2:1 ratio co-culture best mimicked the in vivo conditions and responded to lipopolysaccharides. The anionic CD did not induce any effect in the mono-cultures nor in the co-culture. Among the cationic CDs, the one with the highest charge density (CD-PEI600) induced the most pronounced responses whatever the culture model. The cationic CDs of low charge density (CD-PEHA and CD-DMEDA) evoked similar responses in the mono-cultures, whereas in the co-culture, the three cationic CDs ranked according to their charge density (CD-PEI600 > CD-PEHA > CD-DMEDA), when taking into account their inflammatory effect. Thus, the co-culture system developed in this study appears to be a sensitive model for finely discriminating the toxicological profile of cationic nanoparticles differing by the density of their surface charges.

Fate of engineered nanomaterials at the human epithelial lung tissue barrier in vitro after single and repeated exposures

“…The A549 cell line has proven useful for studying cytotoxicity, oxidative stress, and/or the (pro-)inflammatory response following exposure to various (nano)materials (dos et al, 2011;Martin and Sarkar, 2017;Bisig et al, 2019). More complex co-cultures have been described in the literature to study the toxicity or biodistribution of (nano)materials, e.g., A549 cells combined with THP-1 macrophages (Arezki et al, 2021;Meindl et al, 2021), or A549 cells combined with human-monocyte derived macrophages and dendritic cells (Chortarea et al, 2018). Because we found no significant different biodistribution of 18-nm gold nanoparticles in A549 cells alone compared with A549 cells co-cultured with macrophages and dendritic cells in a previous study (Bachler et al, 2015), we decided to focus only the mono-culture system as the main objective of our work was to compare single with repeated exposure and to relate the fractional distribution to the physico-chemical properties of the NMs used.…”