title: In vitro translocation of quantum dots and influence of oxidative stress.
abstract: In vivo, translocation of inhaled nanoparticles to the circulation has been demonstrated. However, the interaction of nanoparticles with the lung epithelium is not understood. In this study, we investigated, in vitro, the translocation of nano-sized quantum dots (QDs; 25 pmol/ml) through a tight monolayer of primary isolated rat alveolar epithelial cells. The influence of surface charge on translocation was examined using nonfunctionalized QDs, amine-QDs, and carboxyl-QDs. The interaction between nanoparticles and the lung epithelium was monitored by repeatedly measuring the transepithelial electrical resistance (TEER) and by examining the cell layer with confocal microscopy. The effect of oxidative stress was tested by incubating the cells with tert-butyl hydroperoxide (t-BOOH; 75 microM or 1 or 10 mM); the antioxidant N-acetyl-L-cysteine was also used to assess the role of particle-mediated oxidative stress. No translocation through a tight monolayer of primary rat alveolar epithelial cells was observed for any of the different types of QDs. In general, an increase in TEER was found after incubation with QDs. A condition of low oxidative stress did not enhance translocation. In contrast, conditions of high stress (1 or 10 mM t-BOOH or due to QDs toxicity) with disruption of the cell layer, as shown in a decreased TEER, resulted in substantial translocation. In conclusion, no translocation of QDs was found through a tight monolayer of primary rat alveolar epithelial cells, regardless of the QDs surface charge. QDs did not impair the barrier function of the epithelial cells. In conditions with disruption of the cell-cell barrier, translocation was demonstrated.
authors.affiliation: Katholieke Universiteit Leuven, Laboratory of Pneumology, Unit for Lung Toxicology, Herestraat 49 O&N1 bus 706, 3000 Leuven, Belgium.
authors.forename: Jorina
authors.initials: J
authors.lastname: Geys
authors.forename: Rita
authors.initials: R
authors.lastname: De Vos
authors.forename: Benoit
authors.initials: B
authors.lastname: Nemery
authors.forename: Peter H M
authors.initials: PH
authors.lastname: Hoet
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D017097:Electric Impedance; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010316:Particle Size; D011650:Pulmonary Alveoli / Q000166:cytology; D045663:Quantum Dots; D051381:Rats; D017208:Rats, Wistar; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
chemical_list: D016877:Oxidants; D020122:tert-Butylhydroperoxide