Proposing Urothelial and Muscle In Vitro Cell Models as a Novel Approach for Assessment of Long-Term Toxicity of Nanoparticles.

Matej Skočaj,Maruša Bizjak,Vladimir Boštjan Bregar,Katarina Miš,Klemen Strojan,Jasna Lojk,Peter Veranič,Mateja Erdani Kreft,Mojca Pavlin,Sergej Pirkmajer

doi:10.3390/ijms21207545

Matej Skočaj, Maruša Bizjak + Show 8 more

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https://doi.org/10.3390/ijms21207545

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Abstract

Many studies evaluated the short-term in vitro toxicity of nanoparticles (NPs); however, long-term effects are still not adequately understood. Here, we investigated the potential toxic effects of biomedical (polyacrylic acid and polyethylenimine coated magnetic NPs) and two industrial (SiO2 and TiO2) NPs following different short-term and long-term exposure protocols on two physiologically different in vitro models that are able to differentiate: L6 rat skeletal muscle cell line and biomimetic normal porcine urothelial (NPU) cells. We show that L6 cells are more sensitive to NP exposure then NPU cells. Transmission electron microscopy revealed an uptake of NPs into L6 cells but not NPU cells. In L6 cells, we obtained a dose-dependent reduction in cell viability and increased reactive oxygen species (ROS) formation after 24 h. Following continuous exposure, more stable TiO2 and polyacrylic acid (PAA) NPs increased levels of nuclear factor Nrf2 mRNA, suggesting an oxidative damage-associated response. Furthermore, internalized magnetic PAA and TiO2 NPs hindered the differentiation of L6 cells. We propose the use of L6 skeletal muscle cells and NPU cells as a novel approach for assessment of the potential long-term toxicity of relevant NPs that are found in the blood and/or can be secreted into the urine.

Highlights

In the last three decades, various new nanomaterials and nanoparticles (NPs) have been implemented into diverse industrial and medical applications, exploiting the advantages of their small size, high reactivity, and other specific properties
The primary size and shapes of NPs in water are presented in Figure S1; it can be seen that polyacrylic acid (PAA) and PEI NPs form smaller aggregates, while SiO2 and TiO2 NPs form larger aggregates (200–300 nm) in water in agreement with dynamic −56.3 ± light scattering (DLS)
PDI values show that TiO2 and PEI NPs had more narrow size distributions in all media compared to PAA and SiO2 NPs

Summary

Introduction

In the last three decades, various new nanomaterials and nanoparticles (NPs) have been implemented into diverse industrial and medical applications, exploiting the advantages of their small size, high reactivity, and other specific properties. There are already several U.S Food and Drug Administration (FDA)-approved biomedical NP formulations that are used for drug delivery or as contrast agents for MRI (e.g., magnetic NPs) [2]. Every new type of NP has to be appropriately characterized in terms of its physicochemical characteristics in the relevant physiological media [3,4]. NPs can trigger adverse reactions in the cells, and it is crucial to assess potential short-term as well as long-term toxicity for both industrially relevant and biomedical NPs. Since most industrial NPs are not biodegradable and can persist and accumulate in tissues for longer time periods, some of the toxic effects of NPs might be evident only after long-time exposure, which implies the necessity for long-time studies and the need for appropriate cell culture models

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