Metallic nanoparticles and in vitro cytotoxicity assessment

Particle and Fibre Toxicology, 2014

A standard short-term inhalation study (STIS) was applied for hazard assessment of 13 metal oxide nanomaterials and micron-scale zinc oxide.

Nanomedicine (London, England), 2014

To date, guidance on how to incorporate in vitro assays into integrated approaches for testing and assessment of nanomaterials is unavailable. In addressing this shortage, this review compares data from in vitro studies to results from in vivo inhalation or intratracheal instillation studies. Globular nanomaterials (ion-shedding silver and zinc oxide, poorly soluble titanium dioxide and cerium dioxide, and partly soluble amorphous silicon dioxide) and nanomaterials with higher aspect ratios (multiwalled carbon nanotubes) were assessed focusing on the Organisation for Economic Co-Operation and Development (OECD) reference nanomaterials for these substances. If in vitro assays are performed with dosages that reflect effective in vivo dosages, the mechanisms of nanomaterial toxicity can be assessed. In early tiers of integrated approaches for testing and assessment, knowledge on mechanisms of toxicity serves to group nanomaterials thereby reducing the need for animal testing.

Toxicological Sciences, 2007

Previous studies have reported little correlation between the relative toxicity of particle types when comparing lung toxicity rankings following in vivo instillation versus in vitro cell culture exposures. This study was designed to assess the capacity of in vitro screening studies to predict in vivo pulmonary toxicity of several fine or nanoscale particle types in rats. In the in vivo component of the study, rats were exposed by intratracheal instillation to 1 or 5 mg/kg of the following particle types: (1) carbonyl iron (CI), (2) crystalline silica (CS) (Min-U-Sil 5, a-quartz), (3) precipitated amorphous silica (AS), (4) nano-sized zinc oxide (NZO), or (5) fine-sized zinc oxide (FZO). Depending on particle type and solution state, these particles range in size from 90 to 500 nm in size. Following exposures, the lungs of exposed rats were lavaged and inflammation (neutrophil recruitment) and cytotoxicity end points (bronchoalveolar lavage [BAL] fluid lactate dehydrogenase [LDH] values) were measured at 24 h, 1 week, 1 and 3 months postexposure. For the in vitro component of the study, three different culture conditions were utilized. Cultures of (1) rat L2 lung epithelial cells, (2) primary alveolar macrophages (AMs) (collected via BAL from unexposed rats), as well as (3) AM-L2 lung epithelial cell cocultures were incubated with the particle types listed above, and the culture fluids were evaluated for cytotoxicity end points (LDH, 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan [MTT]) as well as inflammatory cytokines (macrophage inflammatory 2 protein [MIP-2], tumor necrosis factor alpha [TNF-a], and interleukin-6 [IL-6]) at one (i.e., cytokines) or several (cytotoxicity) time periods. Results of in vivo pulmonary toxicity studies demonstrated that instilled CI particles produced little toxicity. CS particles produced sustained inflammation and cytotoxicity. AS particles produced reversible and transient inflammatory responses. NZO or FZO particles produced potent but reversible inflammation which was resolved by 1 month postinstillation exposure. Results of in vitro pulmonary cytotoxicity studies demonstrated a variety of responses to the different particle types, primarily at high doses. With respect to the LDH results, L2 cells were the most sensitive and exposures to nano-or fine-sized ZnO for 4 or 24 h were more cytotoxic than exposures to CS or AS particles. Macrophages essentially were resistant and epithelial macrophage cocultures generally reflected the epithelial results at 4 and 24 h incubation, but not at 48 h incubation. MTT results were also interesting but, except for nano-and fine-sized ZnO, did not correlate well with LDH results. Results of in vitro pulmonary inflammation studies demonstrated that L2 cells did not produce MIP-2 cytokines, but CS-or AS-exposed AMs and, to a lesser degree, cocultures secreted these chemotactic factors into the culture media. Measurements of TNF-a in the culture media by particle-exposed cells demonstrated little activity. In addition, IL-6 secretion was measured in CS, AS, and nano-sized ZnO-exposed cocultures. When considering the range of toxicity end points to five different particle types, the comparisons of in vivo and in vitro measurements demonstrated little correlation, particularly when considering many of the variables assessed in this study-such as cell types to be utilized, culture conditions and time course of exposure, as well as measured end points. It seems clear that in vitro cellular systems will need to be further developed, standardized, and validated (relative to in vivo effects) in order to provide useful screening data on the relative toxicity of inhaled particle types.

Nanotoxicology, 2012

A novel method is presented which is suitable for assessing in vivo the link between the physicochemical properties of engineered nanomaterials (ENM) and their biological outcomes. The ability of the technique to generate a variety of industryrelevant, property-controlled ENM exposure atmospheres for inhalation studies was systematically investigated. The primary particle size for Fe 2 O 3 , SiO 2 , Ag and Ag/SiO 2 was controlled from 4 to 25 nm, while the corresponding agglomerate mobility diameter of the aerosol was also controlled and varied from 40 to 120 nm. The suitability of the technique to characterize the pulmonary and cardiovascular effects of inhaled ENMs in intact animal models is also demonstrated using in vivo chemiluminescence (IVCL). The IVCL technique is a highly sensitive method for identifying cardiopulmonary responses to inhaled ENMs under relatively small doses and acute exposures. It is shown that moderate and acute exposures to inhaled nanostructured Fe 2 O 3 can cause both pulmonary and cardiovascular effects.  Nanotoxicology Downloaded from informahealthcare.com by 134.174.180.146 on 08/08/11 For personal use only.  G. A. Sotiriou et al. Nanotoxicology Downloaded from informahealthcare.com by 134.174.180.146 on 08/08/11 For personal use only. In vivo toxicological characterization of inhaled ENM  Nanotoxicology Downloaded from informahealthcare.com by 134.174.180.146 on 08/08/11 For personal use only.  G. A. Sotiriou et al. Nanotoxicology Downloaded from informahealthcare.com by 134.174.180.146 on 08/08/11 For personal use only.

International journal of immunopathology and pharmacology

Engineered nanoparticles (NP) comprise various classes of technological materials with innovative properties. Although inhalation is less likely for engineered nanomaterials (NM) compared with ambient or mineral dust particles, this can happen during bulk manufacture and handling of freely dispersible NP. In this mini-review we summarize recent data on NP and CNT (carbon nanotubes) hazards, with particular emphasis on toxic effect on lung and in cell culture of lung origin. Owing to the highest deposition efficiency in the alveolar area, primary interactions of NM occur with epithelial and alveolar macrophages (AM). Scarce data are available to date on the cell mechanisms underlying NM permeability across the airway epithelium, but the absorption of NP through airways does not seem to require epithelial mediation, suggesting rather the involvement of alternative mechanisms such as AM-dependent dissemination. The relationship between toxicity and particle characteristics may be compl...

Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology, 2012

While technical and medical potential offered by nanotechnologies increase, the safety assessment of engineered nanomaterials (NMs) needs to follow this pace. Inhalation is a major route of occupational and environmental exposure, and is most relevant for most of the respective safety assessment studies. Control and generation of aerosol from the test materials for this route of administration are technically demanding, and not surprisingly, there are relatively few NMs tested in toxicokinetic, short-term, and subchronic inhalation studies. These studies were in part adapted to the peculiarities of inhaled NMs, but few were also conducted according to organization for economic co-operation and development (OECD) test guidelines. Inhalation studies on the potential to develop chronic diseases, or studies to check the potential analogy to cardiovascular diseases associated with adverse health effects from ambient air pollution, are largely missing. On the way forward, appropriate inha...

2014

Abstract: The alveolar epithelium of the lung is by far the most permeable epithelial barrier of the human body. The risk for adverse effects by inhaled nanoparticles (NPs) depends on their hazard (negative action on cells and organism) and on exposure (concentration in the inhaled air and pattern of deposition in the lung). With the development of advanced in vitro models, not only in vivo, but also cellular studies can be used for toxicological testing. Advanced in vitro studies use combinations of cells cultured in the air-liquid interface. These cultures are useful for particle uptake and mechanistic studies. Whole-body, nose-only, and lung-only exposures of animals could help to determine retention of NPs in the body. Both approaches also have their limitations; cellular studies cannot mimic the entire organism and data obtained by inhalation exposure of rodents have limitations due to differences in the respiratory system from that of humans. Simulation programs for lung depos...

Int J Mol Sci, 2014

The alveolar epithelium of the lung is by far the most permeable epithelial barrier of the human body. The risk for adverse effects by inhaled nanoparticles (NPs) depends on their hazard (negative action on cells and organism) and on exposure (concentration in the inhaled air and pattern of deposition in the lung). With the development of advanced in vitro models, not only in vivo, but also cellular studies can be used for toxicological testing. Advanced in vitro studies use combinations of cells cultured in the air-liquid interface. These cultures are useful for particle uptake and mechanistic studies. Whole-body, nose-only, and lung-only exposures of animals could help to determine retention of NPs in the body. Both approaches also have their limitations; cellular studies cannot mimic the entire organism and data obtained by inhalation exposure of rodents have limitations due to differences in the respiratory system from that of humans. Simulation programs for lung deposition in humans could help to determine the relevance of the biological findings. Combination of biological data generated in different biological models and in silico modeling appears suitable for a realistic estimation of potential risks by inhalation exposure to NPs.