With the growing numbers of nanomaterials (NMs), there is a great demand for rapid and reliable ways of testing NM safety—preferably using in vitro approaches, to avoid the ethical dilemmas ...associated with animal research. Data are needed for developing intelligent testing strategies for risk assessment of NMs, based on grouping and read-across approaches. The adoption of high throughput screening (HTS) and high content analysis (HCA) for NM toxicity testing allows the testing of numerous materials at different concentrations and on different types of cells, reduces the effect of inter-experimental variation, and makes substantial savings in time and cost. HTS/HCA approaches facilitate the classification of key biological indicators of NM-cell interactions. Validation of in vitro HTS tests is required, taking account of relevance to in vivo results. HTS/HCA approaches are needed to assess dose- and time-dependent toxicity, allowing prediction of in vivo adverse effects. Several HTS/HCA methods are being validated and applied for NM testing in the FP7 project NANoREG, including Label-free cellular screening of NM uptake, HCA, High throughput flow cytometry, Impedance-based monitoring, Multiplex analysis of secreted products, and genotoxicity methods—namely High throughput comet assay, High throughput in vitro micronucleus assay, and γH2AX assay. There are several technical challenges with HTS/HCA for NM testing, as toxicity screening needs to be coupled with characterization of NMs in exposure medium prior to the test; possible interference of NMs with HTS/HCA techniques is another concern. Advantages and challenges of HTS/HCA approaches in NM safety are discussed. For further resources related to this article, please visit the WIREs website.
Carcinogenic chemicals, or their metabolites, can be classified as genotoxic or non-genotoxic carcinogens (NGTxCs). Genotoxic compounds induce DNA damage, which can be detected by an established
and
...battery of genotoxicity assays. For NGTxCs, DNA is not the primary target, and the possible modes of action (MoA) of NGTxCs are much more diverse than those of genotoxic compounds, and there is no specific
assay for detecting NGTxCs. Therefore, the evaluation of the carcinogenic potential is still dependent on long-term studies in rodents. This 2-year bioassay, mainly applied for testing agrochemicals and pharmaceuticals, is time-consuming, costly and requires very high numbers of animals. More importantly, its relevance for human risk assessment is questionable due to the limited predictivity for human cancer risk, especially with regard to NGTxCs. Thus, there is an urgent need for a transition to new approach methodologies (NAMs), integrating human-relevant
assays and
tools that better exploit the current knowledge of the multiple processes involved in carcinogenesis into a modern safety assessment toolbox. Here, we describe an integrative project that aims to use a variety of novel approaches to detect the carcinogenic potential of NGTxCs based on different mechanisms and pathways involved in carcinogenesis. The aim of this project is to contribute suitable assays for the safety assessment toolbox for an efficient and improved, internationally recognized hazard assessment of NGTxCs, and ultimately to contribute to reliable mechanism-based next-generation risk assessment for chemical carcinogens.
La exposición a xenobióticos durante el período prenatal puede tener implicaciones importantes sobre la salud del recién nacido, incidiendo en lo que puede ocurrir más adelante en su vida a nivel de ...ciertas enfermedades como asma, alérgias, retraso en el desarrollo neurológico, diabetes, enfermedades cardiovasculares y cáncer, entre otras. Por lo tanto, es necesario dotarnos de buenas herramientas para llevar a cabo análisis sistemáticos sobre el riesgo potencial en los niños, como consecuencia de estas exposiciones vía materna. El uso de biomarcadores de efecto genotóxico, evidencía los efectos tempranos de una sustancia tóxica sobre el material genético, siendo éste el primer paso de un variado conjunto de alteraciones de la salud. En nuestro estudio de biomonitorización, hemos utilizado el ensayo del cometa como biomarcador específico que nos permite evaluar los niveles de daño genético basal y oxidativo, así como la capacidad de reparación del DNA. Esto lo hemos podido aplicar a una población conformada por 200 parejas madres-hijos que fue reclutada entre Octubre de 2008 y Marzo de 2010 en el Hospital del Mar de Barcelona. Dado que los efectos de las exposiciones endógenas/exógenas a agentes genotóxicos, pueden verse modulados por la nutrición durante la fase de embarazo, en nuestro trabajo se han utilizado los patrones dietéticos de las madres durante el embarazo para evaluar los alimentos ingeridos en la dieta, y estimar su posible papel modulador. Además, hemos considerado a la dieta como un vehículo para ingerir distintos contaminantes ambientales con potencialidad genotóxica. Los resultados indican que los niveles del daño genético basal, los niveles de oxidación del DNA (purinas y pirimidinas oxidadas), al igual que la capacidad de reparación detectada en los linfocitos de cordón umbilical de los hijos, se encuentran correlacionados con los niveles de estos parámetros en los linfocitos de sangre de sus madres. La asociación positiva observada entre el daño genotóxico en el DNA de los linfocitos del cordón umbilical y el de las madres, sugiere la existencia de intercambios transplacentarios de los agentes involucrados en la inducción de lesiones en el DNA. Por otra parte, el ensayo del cometa es capaz de detectar alteraciones en el DNA causadas por la exposición endógena y/o exógena a compuestos genotóxicos o como resultado de la interacción con algunos factores como la edad, el indice de masa corporal, los micronutrientes, la temporada del parto, el género y otros factores ambientales. En este estudio, se ha demostrado también que los recién nacidos de mujeres expuestas a contaminantes potencialmente inductores de estrés oxidativo no presentan un mayor nivel de daño oxidativo en su DNA. Por último, los datos apoyan la hipótesis de que la exposición materna y los intercambios transplacentarios son eventos biológicos medibles y sus efectos se pueden detectar en el cordón umbilical, demostrando una posible exposición in utero. La falta de resultados que nos indiquen una asociación entre la ingesta de estos compuestos y la aparición de efectos genotóxicos, nos indican que se necesitan más estudios sobre cómo el consumo de alimentos ricos en estos contaminantes y/o sus precursores podrían relacionarse con el riesgo de efectos genotóxicos y sus consecuencias en el recién nacido.
Fetal exposure to xenobiotic agents during prenatal period may have important implications on the health of newborns, as well as adverse health diseases later in child life, such as asthma, allergies, neurologic impairment, diabetes, cardiovascular diseases and cancer, among others. Therefore, it is necessary to develop and use sensitive tools to carry out a systematic analysis of the potential risk in children resulting from exposures to genotoxic agents through the mother.
A cross-sectional study of 200 voluntary and healthy pregnant women, at the Hospital del Mar in Barcelona, was performed. Biological samples were obtained from 2008 to 2010. In our study, we have used the comet assay as a biomarker of effect, allowing to assess the level of basal and DNA oxidative damage by incorporating lesion-specific bacterial DNA repair enzymes, such as formamidopyrimidine DNA glycosylase (FPG) and endonuclease III (EndoIII), as well as to evaluate DNA repair capacity in mothers-newborns lymphocytes. Since the effect of exposure to hazardous environmental agents may be modified by diet during the pregnancy, in our work we used the dietary patterns of these mothers to assess food intake during pregnancy and their possible modulating effect. We have also considered dietary intake as a vehicle for exposure to various environmental pollutants potentially genotoxic. The results of this study indicated that the levels of basal damage, oxidative damage (oxidized purines and pyrimidines), and repair capacity measured in mothers and children are correlated. These positive associations may indicate transplacental exchange of agents involved in the induction of DNA lesions. So, the comet assay can detect DNA alterations caused by exposure to endogenous and/or exogenous genotoxic compounds, as well as interaction with factors such as age, body mass index, micronutrients, season of birth, gender and other environmental factors. In this study, we have also shown that infants born from women exposed to contaminants that may induce potentially oxidative stress, does not present higher level of oxidative damage in DNA. Finally, our data support the hypothesis that maternal exposure and transplacental exchanges are biological events measurable, and they can be detected in the umbilical cord, indicating a possible exposure in utero. The lack of results indicating an association between intake of these genotoxics compounds and the occurrence of genotoxic effects, lead us to suggest that further studies are necessary to show how the consumption of foods with high content of contaminants and/or their precursors can be related to increased risk of genotoxic effects in the newborns.
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