Salivary Leucocytes as In Vitro Model to Evaluate Nanoparticle-Induced DNA Damage

[Abstract] Metal oxide nanoparticles (NPs) have a wide variety of applications in many consumer products and biomedical practices. As a result, human exposure to these nanomaterials is highly frequent, becoming an issue of concern to public health. Recently, human salivary leucocytes have been proposed as an adequate non-invasive alternative to peripheral blood leucocytes to evaluate genotoxicity in vitro. The present study focused on proving the suitability of salivary leucocytes as a biomatrix in the comet assay for in vitro nanogenotoxicity studies, by testing some of the metal oxide NPs most frequently present in consumer products, namely, titanium dioxide (TiO₂), zinc oxide (ZnO), and cerium dioxide (CeO₂) NPs. Primary and oxidative DNA damage were evaluated by alkaline and hOGG1-modified comet assay, respectively. Any possible interference of the NPs with the methodological procedure or the hOGG1 activity was addressed before performing genotoxicity evaluation. Results obtained showed an increase of both primary and oxidative damage after NPs treatments. These data support the use of salivary leucocytes as a proper and sensitive biological sample for in vitro nanogenotoxicity studies, and contribute to increase the knowledge on the impact of metal oxide NPs on human health, reinforcing the need for a specific regulation of the nanomaterials use.This research was funded by Xunta de Galicia [ED431B 2019/02]; Ministerio de Ciencia e Innovación (PID2020-114908GA-I00); Ministerio de Educación, Cultura y Deporte [BEAGAL18/00142, to V.V.]; CA17140 NANO2CLINIC COST Action; NanoBioBarriers (PTDC/MED-TOX/31162/2017) funded by Operational Program for Competitiveness and Internationalisation through European Regional Development Funds (FEDER/FNR) and through national funds by the Portuguese Foundation for Science and Technology (FCT). NanoLegaTox (POCI-01-0145-FEDER-029651) funded by Operational Program for Competitiveness and Internationalisation (COMPETE 2020) through FEDER, and through national funds by the Portuguese Foundation for Science and Technology (FCT). A.T. Reis funded by FCT Grant SFRH/BPD/122112/2016Xunta de Galicia; ED431B 2019/02European Cooperation in Science and Technology; CA17140Portugal. Fundação para a Ciência e a Tecnologia; PTDC/MED-TOX/31162/2017Portugal. Fundação para a Ciência e a Tecnologia; POCI-01-0145-FEDER-029651Portugal. Fundação para a Ciência e a Tecnologia; SFRH/BPD/122112/201