An alternative approach to studying the effects of ZnO nanoparticles in cultured human lymphocytes: combining electrochemistry and genotoxicity tests

Abstract

Nanoparticle use has increased radically raising concern about possible adverse effects in humans. Zinc oxide nanoparticles (ZnO NPs) are among the most common nanomaterials in consumer and medical products. Several studies indicate problems with their safe use. The aim of our study was to see at which levels ZnO NPs start to produce adverse cytogenetic effects in human lymphocytes as an early attempt toward establishing safety limits for ZnO NP exposure in humans. We assessed the genotoxic effects of low ZnO NP concentrations (1.0, 2.5, 5, and 7.5 µg mL -1 ) in lymphocyte cultures over 14 days of exposure. We also tested whether low and high-density lymphocytes differed in their ability to accumulate ZnO NPs in these experimental conditions. Primary DNA damage (measured with the alkaline comet assay) increased with nanoparticle concentration in unseparated and high density lymphocytes. The same happened with the fragmentation of TP53 (measured with the comet-FISH). Nanoparticle accumulation was significant only with the two highest concentrations, regardless of lymphocyte density. High-density lymphocytes had significantly more intracellular Zn 2+ than light-density ones. Our results suggest that exposure to ZnO NPs in concentrations above 5 µg mL -1 increases cytogenetic damage and intracellular Zn 2+ levels in lymphocytes.

High-Throughput Screening Platform for Nanoparticle-Mediated Alterations of DNA Repair Capacity

“…It is important to note here that mitochondrial activity and released LDH did not indicate acute cytotoxicity under the aforementioned conditions, although there was a doubling in the production of intracellular ROS after 4 h at 100 μg/mL. In accordance with the literature and our own previous work, a significant increase in oxidative damage and strand breaks in TK6 cells exposed to ZnO ENMs, as presented in Figure D, was demonstrated. Specifically, a significant and considerable increase (+40%, 95%CI: −42.51 to −31.36, p < 0.0001) in DNA damage was induced at 100 μg/mL over 4 h, but this effect was not present at lower concentrations.…”

In vitro assessment of the cytotoxic, DNA damaging, and cytogenetic effects of hydroquinone in human peripheral blood lymphocytes

“…Although the lymphocyte model is common in genetic toxicology testing and has been recently used in studies employing similar methods as ours (13,14,17), the fact that human lymphocytes represent a population of resting cells that do not possess intrinsic metabolic activation suggests the need for further studies using other appropriate cell lines to unequivocally prove the obtained results. Lastly, we are aware that testing a much wider range of hydroquinone concentrations and using more sophisticated methods (e.g., specific modifications of the comet assay and more accurate methods for the detection of apoptosis) would provide a more accurate explanation of the observed effects, but at the moment this was not possible due to various technical and financial constraints.…”

“…The contradictory results obtained thus far using well-established cytogenetic methods call for further studies, which motivated us to perform this investigation. Its aim was to explore the mechanisms of hydroquinone toxicity and assess the relationships between its cytotoxic, genotoxic, and cytogenetic effects tested at 8, 140, and 280 µg mL -1 in human peripheral blood lymphocytes exposed for 24 h. This experimental model was chosen since lymphocytes are primary cells with a stable genome, commonly used for genotoxicity testing in many contemporary studies (13)(14)(15)(16)(17). The outcomes of treatment were evaluated using the apoptosis/necrosis assay, the alkaline comet assay, and the cytokinesis-block micronucleus (CBMN) cytome assay.…”

In vitro safety assessment of the strawberry tree (Arbutus unedo L.) water leaf extract and arbutin in human peripheral blood lymphocytes

“…Lymphocytes were chosen as a model system as they represent a common source of primary cells with a stable genome, which makes them particularly useful for genotoxicity testing, as confirmed in many contemporary studies (Aydin et al 2015;Farhan et al 2015;Turkez et al 2015;Branica et al 2016;Valencia-Quintana et al 2016a, b;Petrović et al 2017;Qari and El-Assouli 2017;Sreejaya et al 2017). They are collected in a fairly non-invasive manner and do not entail special pre-treatment.…”