Quartz crystal microbalances (QCM) are suitable for real-time dosimetry in nanotoxicological studies using VITROCELL®Cloud cell exposure systems

Abstract

Background Accurate knowledge of cell−/tissue-delivered dose plays a pivotal role in inhalation toxicology studies, since it is the key parameter for hazard assessment and translation of in vitro to in vivo dose-response. Traditionally, (nano-)particle toxicological studies with in vivo and in vitro models of the lung rely on in silio computational or off-line analytical methods for dosimetry. In contrast to traditional in vitro testing under submerged cell culture conditions, the more physiologic air-liquid interface (ALI) conditions offer the possibility for real-time dosimetry using quartz crystal microbalances (QCMs). However, it is unclear, if QCMs are sensitive enough for nanotoxicological studies. We investigated this issue for two commercially available VITROCELL®Cloud ALI exposure systems. Results Quantitative fluorescence spectroscopy of fluorescein-spiked saline aerosol was used to determine detection limit, precision and accuracy of the QCMs implemented in a VITROCELL®Cloud 6 and Cloud 12 system for dose-controlled ALI aerosol-cell exposure experiments. Both QCMs performed linearly over the entire investigated dose range (200 to 12,000 ng/cm2) with an accuracy of 3.4% (Cloud 6) and 3.8% (Cloud 12). Their precision (repeatability) decreased from 2.5% for large doses (> 9500 ng/cm2) to values of 10% and even 25% for doses of 1000 ng/cm2 and 200 ng/cm2, respectively. Their lower detection limit was 170 ng/cm2 and 169 ng/cm2 for the Cloud 6 and Cloud 12, respectively. Dose-response measurements with (NM110) ZnO nanoparticles revealed an onset dose of 3.3 μg/cm2 (or 0.39 cm2/cm2) for both cell viability (WST-1) and cytotoxicity (LDH) of A549 lung epithelial cells. Conclusions The QCMs of the Cloud 6 and Cloud 12 systems show similar performance and are highly sensitive, accurate devices for (quasi-) real-time dosimetry of the cell-delivered particle dose in ALI cell exposure experiments, if operated according to manufacturer specifications. Comparison with in vitro onset doses from this and previously published ALI studies revealed that the detection limit of 170 ng/cm2 is sufficient for determination of toxicological onset doses for all particle types with low (e.g. polystyrene) or high mass-specific toxicity (e.g. ZnO and Ag) investigated here. Hence, in principle QCMs are suitable for in vitro nanotoxciological studies, but this should be investigated for each QCM and ALI exposure system under the specific exposure conditions as described in the present study.

A Custom-Made Device for Reproducibly Depositing Pre-metered Doses of Nebulized Drugs on Pulmonary Cells in vitro

“…The consistent ca. 10% SD of the deposited dose across all invested volumes tends to be higher than that of other reports from the Vitrocell ® Cloud systems ( Ding et al, 2020 ); however, it may be indicative of the fluorescent microscopy imaging technique as opposed to quartz crystal microbalance quantification. In any case, the device deposits a robust, spatially homogenous dose.…”

A Complete In Vitro Toxicological Assessment of the Biological Effects of Cerium Oxide Nanoparticles: From Acute Toxicity to Multi-Dose Subchronic Cytotoxicity Study.

“…In order to reproduce a more realistic exposure scenario, maintaining the conditions of temperature and humidity in physiological levels needed in the cell culture, the Vitrocell Cloud system coupled to AeroNeb Lab nebulizer was used for exposure of the cells to CeO2-NPs. During the exposures, Vitrocell Cloud produced a very homogeneous deposition of CeO2-NPs onto the cells similar to previous studies [43]. Thus, a multidose experiment was performed applying three sublethal doses of CeO2-NPs (100 µg/cm²; 10 µg/cm² and 1 µg/cm²) on the apical inserts every 2 weeks for 3 months.…”

“…One of the most commonly used devices is the Vitrocell Cloud (VITROCELL Systems GmbH, Waldkirch, Germany). This device was specifically designed for exposure in ALI through the nebulization of the toxicant in a controlled atmosphere, allowing high deposition rates of the toxicant, as well as robustness of results and high reproducibility [43]. This device offers the possibility to perform in vitro exposures to NPs in a much more realistic scenario.…”

Air−Liquid Interface Cultures of the Healthy and Diseased Human Respiratory Tract: Promises, Challenges, and Future Directions

“…Reproduced under the terms and conditions of the Creative Commons Attribution 4.0 International License. [ 215 ] Copyright 2020, The Authors, published by Springer Nature.…”