Towards a New Paradigm in Nano-Genotoxicology: Facing Complexity of Nanomaterials' Cellular Interactions and Effects

A systematic quality evaluation and review of nanomaterial genotoxicity studies: a regulatory perspective

The number of publications in the field of nanogenotoxicology and the amount of genotoxicity data on nanomaterials (NMs) in several databases generated by European Union (EU) funded projects have increased during the last decade. In parallel, large research efforts have contributed to both our understanding of key physico-chemical (PC) parameters regarding NM characterization as well as the limitations of toxicological assays originally designed for soluble chemicals. Hence, it is becoming increasingly clear that not all of these data are reliable or relevant from the regulatory perspective. The aim of this systematic review is to investigate the extent of studies on genotoxicity of NMs that can be considered reliable and relevant by current standards and bring focus to what is needed for a study to be useful from the regulatory point of view. Due to the vast number of studies available, we chose to limit our search to two large groups, which have raised substantial interest in recent years: nanofibers (including nanotubes) and metal-containing nanoparticles. Focusing on peer-reviewed publications, we evaluated the completeness of PC characterization of the tested NMs, documentation of the model system, study design, and results according to the quality assessment approach developed in the EU FP-7 GUIDEnano project. Further, building on recently published recommendations for best practices in nanogenotoxicology research, we created a set of criteria that address assay-specific reliability and relevance for risk assessment purposes. Articles were then reviewed, the qualifying publications discussed, and the most common shortcomings in NM genotoxicity studies highlighted. Moreover, several EU projects under the FP7 and H2020 framework set the aim to collectively feed the information they produced into the eNanoMapper database. As a result, and over the years, the eNanoMapper database has been extended with data of various quality depending on the existing knowledge at the time of entry. These activities are highly relevant since negative results are often not published. Here, we have reviewed the NanoInformaTIX instance under the eNanoMapper database, which hosts data from nine EU initiatives. We evaluated the data quality and the feasibility of use of the data from a regulatory perspective for each experimental entry.

Mitotic and chromosomal effects induced for biosynthesized nanoparticles from three mediators on Allium cepa root cells

The genotoxicity of biogenic silver nanoparticles (AgNPs) obtained from three microbial mediators was assessed using the Allium cepa assay. Three clusters were differentiated for the highest frequency of end points of clastogenicity (stick-ends, fragments and bridges), end points of missegregation (C-metaphases and disorder anaphases), and lowest frequency of all the end points. In these clusters, the treatments were grouped respectively as I) positive control (GSF); II) silver nanoparticles form Aspergillus niger (AgNPs-An); and III) silver nanoparticles from both Cryptococcus laurentii (AgNPs-Cl) and Rhodotorula glutinis (AgNPs-Rg), Ag + , and negative control (NC). These results were in according to the principal component analisys (PCA) where treatments were associated to each component of the genotoxic effects. The statistical comparative analysis of the mitotic index (IM) and the abnormal mitosis frequency (AM) indicated that both GSF and AgNPsAn induce significant genotoxic effect. Low genotoxic effects were attributed to AgNPs-Cl and AgNPs-Rg, but mitogenic stimuli, similar to that obtained by the silver ions Ag + , were observed. Results suggested that different features of biogenic nanoparticles such as composition, size, and coating may be involved in the different cytological responses of the meristematic cells.

Aneuploidy, inflammation and diseases

This review discusses how numerical aneuploidy may trigger inflammation in somatic cells and its consequences. Therefore we: i) summarized current knowledge on the cellular and molecular pathological effects of aneuploidy; ii) considered which of these aspects are able to trigger inflammation; iii) determined the genetic and environmental factors which may modulate the link between aneuploidy and inflammation; iv) explored the rôle of diet in prevention of aneuploidy and inflammation; v) examined whether aneuploidy and inflammation are causes and/or consequences of diseases; vi) identified the knowledge gaps and research needed to translate these observations into improved health care and disease prevention. The relationships between aneuploidy, inflammation and diseases are complex, because they depend on which chromosomes are involved, the proportion of cells affected and which organs are aneuploid in the case of mosaic aneuploidy. Therefore, a systemic approach is recommended to understand the emergence of aneuploidy-driven diseases and to take preventive measures to protect individuals from exposure to aneugenic conditions.

Micronuclei Detection by Flow Cytometry as a High-Throughput Approach for the Genotoxicity Testing of Nanomaterials

Thousands of nanomaterials (NMs)-containing products are currently under development or incorporated in the consumer market, despite our very limited understanding of their genotoxic potential. Taking into account that the toxicity and genotoxicity of NMs strongly depend on their physicochemical characteristics, many variables must be considered in the safety evaluation of each given NM. In this scenario, the challenge is to establish high-throughput methodologies able to generate rapid and robust genotoxicity data that can be used to critically assess and/or predict the biological effects associated with those NMs being under development or already present in the market. In this study, we have evaluated the advantages of using a flow cytometry-based approach testing micronucleus (MNs) induction (FCMN assay). In the frame of the EU NANoREG project, we have tested six different NMs—namely NM100 and NM101 (TiO₂NPs), NM110 (ZnONPs), NM212 (CeO₂NPs), NM300K (AgNPs) and NM401 (multi-walled carbon nanotubes (MWCNTs)). The obtained results confirm the ability of AgNPs and MWCNTs to induce MN in the human bronchial epithelial BEAS-2B cell line, whereas the other tested NMs retrieved non-significant increases in the MN frequency. Based on the alignment of the results with the data reported in the literature and the performance of the FCMN assay, we strongly recommend this assay as a reference method to systematically evaluate the potential genotoxicity of NMs.

The Comet Assay as a Tool to Detect the Genotoxic Potential of Nanomaterials

The interesting physicochemical characteristics of nanomaterials (NMs) has brought about their increasing use and, consequently, their increasing presence in the environment. As emergent contaminants, there is an urgent need for new data about their potential side-effects on human health. Among their potential effects, the potential for DNA damage is of paramount relevance. Thus, in the context of the EU project NANoREG, the establishment of common robust protocols for detecting genotoxicity of NMs became an important aim. One of the developed protocols refers to the use of the comet assay, as a tool to detect the induction of DNA strand breaks. In this study, eight different NMs—TiO₂NP (2), SiO₂NP (2), ZnONP, CeO₂NP, AgNP, and multi-walled carbon nanotubes (MWCNT)—were tested using two different human lung epithelial cell lines (A549 and BEAS-2B). The comet assay was carried out with and without the use of the formamidopyrimidine glycosylase (FPG) enzyme to detect the induction of oxidatively damaged DNA bases. As a high throughput approach, we have used GelBond films (GBF) instead of glass slides, allowing the fitting of 48 microgels on the same GBF. The results confirmed the suitability of the comet assay as a powerful tool to detect the genotoxic potential of NMs. Specifically, our results indicate that most of the selected nanomaterials showed mild to significant genotoxic effects, at least in the A549 cell line, reflecting the relevance of the cell line used to determine the genotoxic ability of a defined NM.

Implementation of Safe-by-Design for Nanomaterial Development and Safe Innovation: Why We Need a Comprehensive Approach

Manufactured nanomaterials (MNMs) are regarded as key components of innovations in various fields with high potential impact (e.g., energy generation and storage, electronics, photonics, diagnostics, theranostics, or drug delivery agents). Widespread use of MNMs raises concerns about their safety for humans and the environment, possibly limiting the impact of the nanotechnology-based innovation. The development of safe MNMs and nanoproducts has to result in a safe as well as functional material or product. Its safe use, and disposal at the end of its life cycle must be taken into account too. However, not all MNMs are similarly useful for all applications, some might bear a higher hazard potential than others, and use scenarios could lead to different exposure probabilities. To improve both safety and efficacy of nanotechnology, we think that a new proactive approach is necessary, based on pre-regulatory safety assessment and dialogue between stakeholders. On the basis of the work carried out in different European Union (EU) initiatives, developing and integrating MNMs Safe-by-Design and Trusted Environments (NANoREG, ProSafe, and NanoReg2), we present our point of view here. This concept, when fully developed, will allow for cost effective industrial innovation, and an exchange of key information between regulators and innovators. Regulators are thus informed about incoming innovations in good time, supporting a proactive regulatory action. The final goal is to contribute to the nanotechnology governance, having faster, cheaper, effective, and safer nano-products on the market.