Integrated approach to the in vivo genotoxic effects of a titanium dioxide nanomaterial using LacZ plasmid‐based transgenic mice

Abstract

Titanium dioxide (TiO2 ) nanomaterials (NMs) are widely used in a diversity of products including cosmetics, pharmaceuticals, food, and inks, despite uncertainties surrounding the potential health risks that they pose to humans and the environment. Previous studies on the genotoxicity of TiO2 have reported discrepant or inconclusive findings in both in vitro and in vivo systems. This study explores the in vivo genotoxic potential of a well-characterized uncoated TiO2 NM with an average diameter of 22 nm (NM-102, from JRC repository) using several genotoxicity endpoints in the LacZ plasmid-based transgenic mouse model. Mice were exposed by intravenous injection to two daily doses of NM-102: 10 and 15 mg/kg of body weight/day. Micronuclei were analyzed in peripheral blood reticulocytes 42 hr after the last treatment. DNA strand breaks (comet assay) and gene mutations were determined in the spleens and livers of the same animals 28 days after the last treatment. Histopathological and cytological analyses were also performed in liver samples. Genotoxic effects were not detected in mice exposed to the nanosized TiO2 under the experimental conditions used, despite a moderate inflammatory response that was observed in the liver. Considering the biopersistence of TiO2 in mouse liver and the moderate inflammatory response, the possibility of a secondary genotoxic effect at higher doses and in conditions that result in a stronger inflammatory response, for example, within a longer time window, should be investigated further.

Thrombospondin-1 mediates multi-walled carbon nanotube induced impairment of arteriolar dilation

“…The results of this MWCNT exposure were obtained by using a powerful technique for the assessment of microvascular function in vivo combined with a well-characterized knockout model. This study also represents one of a handful of attempts to use genetically manipulated animals to investigate molecular mechanisms of nanotoxicity (Aragon et al, 2016; Bagher et al, 2011; Chen et al, 2015; Louro et al, 2014), and is the first in the area of the peripheral microcirculation.…”

Re-evaluation of titanium dioxide (E 171) as a food additive

“…In another recent in vivo study (Louro et al., ), transgenic C57B1/6 mice harbouring a plasmid containing the bacterial lacZ reporter gene were exposed to TiO 2 nanoparticles (anatase; average diameter 22 nm) with two daily intravenous injections at 10 and 15 mg/kg bw. Top dose was the maximum achievable based on concentration of stable nanoparticle dispersion and the administered volume.…”

“…Other in vivo studies have used other routes of exposure. Negative results in gene and chromosomal mutation tests were obtained in rats injected intravenously (Sadiq et al., ; Louro et al., ). A mild increase in micronuclei in bone marrow, with no concurrent DNA damage detectable by Comet assay, was reported in another recent intravenous study (Dobrzynska et al., ), but the Panel noted some inconsistencies in these results which are regarded of questionable biological significance.…”

Genotoxicity assessment of titanium dioxide nanoparticle accumulation of 90 days in the liver of gpt delta transgenic mice

“…Therefore, their genotoxicity is an important property for risk assessment. Several in vivo studies related to genotoxic effects of TiO 2 NPs have been reported, but their results are inconsistent [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Almost all of these reports analyzed the micronuclei and DNA damage by the comet assay, which reveals transient genotoxic consequences that occur shortly after exposure.…”

“…Genotoxicity is one of the key factors to assess the carcinogenic risk to humans. Several studies in mice and rats have reported conflicting results of various genotoxic endpoint analyses [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Recently, we reported that TiO 2 NPs have no genotoxic effects in the liver and erythrocytes when intravenously injected into gpt delta mice [17], but there are still reports about their positive effect [18,19].…”