Toxicity and Clearance of Intratracheally Administered Multiwalled Carbon Nanotubes from Murine Lung
Carbon nanotubes (CNT) are known to have widespread industrial applications; however, several reports indicated that these compounds may be associated with adverse effects in humans. In this study, multiwalled carbon nanotubes were administered to murine lungs intratracheally to determine whether acute and chronic pulmonary toxicity occurred. In particular, pristine multiwalled carbon nanotubes (PMWCNT) and acid-treated multiwalled carbon nanotubes (TMWCNT) were used in this study. In broncheoalveolar lavage fluid (BALF) cell analysis, PMWCNT induced more severe acute inflammatory cell recruitment than TMWCNT. Histopathologically, both PMWCNT and TMWCNT induced multifocal inflammatory granulomas in a dose-dependent manner. The observed granulomas were reversible, with TMWCNT-induced granulomas diminishing faster than PMWCNT-induced granulomas. Although the area of granuloma reduced with time, hyperplasia and dysplastic characteristics such as mitotic figures, anisokaryosis, and anisocytosis were still observed. These findings demonstrate that MWCNT induces granulomatous inflammation, and the duration and pattern of inflammation seem to vary depending upon the types of MWCNT to which mice are exposed. Therefore, toxicity studies on various types of CNT are needed as the responsiveness to these compounds differs.
Available from: Nivedita Chatterjee
- "Several reports related to CNT (particularly MWCNT) toxicity at the molecular, cellular, and whole-animal levels were published (Clark et al., 2012; Tabet et al., 2009; Kim et al., 2010a; 2010b; Liang et al., 2010), but data obtained and information are still controversial (Liu et al., 2013; 2014; Jiang et al., 2013; Li et al., 2013; Coccini et al., 2010; Cavallo et al., 2012). "
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ABSTRACT: The aim of this study was to evaluate in vitro (human bronchial epithelial cells, BEAS2B cells) and in vivo (the nematode Caenorhabditis elegans, C. elegans) toxicity outcomes following exposure to pristine as well as surface-functionalized multiwalled carbon nanotubes (MWCNT) following hydroxylation-oxygenation (O(+)), amination (NH2), or carboxylation (COOH) of the carbon nanotubes (CNT). Cell viability and proliferation were measured by Ez-Cytox, trypan blue exclusion, and colony formation assays. The genotoxic potential of the MWCNT was determined by using the alkaline comet assay. In addition, survival and reproduction were used as endpoints for detection of toxicity of MWCNT in C. elegans. The carboxylated (COOH)-MWCNT was found most toxic as evidenced by cytotoxic and genotoxic among all tested compounds. The order of sensitivity was COOH > O(+) > NH2 > pristine. There were almost no marked changes in survival following exposure of C. elegans to MWCNT. It is of interest that only pristine MWCNT exerted significant reduction in reproductive capacity of C. elegans. Surface functionalization significantly influenced the bioactivity of MWCNT, which displayed species as well as target-organ specificity. The mechanisms underlying these specific modes of nano-biological interactions need to be elucidated.
Available from: Massimiliano G Bianchi
- "Interestingly, these changes were not associated with decreased cell viability or with an altered expression of tight junction proteins, while they seemed to be related to the fibre-like properties of MWCNT (Rotoli et al., 2009). In vivo, rodents receiving MWCNT by intratracheal instillation or pharyngeal aspiration showed early formation of granulomas and fibrosis at deposition sites, leading to functional respiratory impairment (Kim et al., 2010; Ravichandran et al., 2009, 2010; Reddy et al., 2010). Several reports suggest a pro-allergic effect following intratracheal instillation of MWCNT in mice, with an increased production of Th2 cytokines (such as IL-4, IL-5, and IL-10) (Park et al., 2009), exacerbation of allergic airway inflammation (Inoue et al., 2009) and increased occurrence of fibrosis (Ryman- Rasmussen et al., 2009). "
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ABSTRACT: Abstract Aggregates of multiwalled carbon nanotubes (MWCNT) impair the barrier properties of human airway cell monolayers. To resolve the mechanism of the barrier alteration, monolayers of Calu-3 human airway epithelial cells were exposed to aggregated MWCNT. At the cell-population level, trans-epithelial electrical resistance (TEER) was used as an indicator of barrier competence, caspase activity was assessed with standard biochemical assays, and cell viability was investigated by biochemical techniques and high-throughput screening (HTS) technique based on automated epifluorescence microscopy. At cell level, the response to MWCNT was investigated with confocal microscopy, by evaluating cell death (calcein/propidium iodide (PI)), proliferation (Ki-67), and apoptosis (caspase activity). At the cell-population level, exposure to aggregated MWCNT caused a decrease in TEER, which was not associated with a decrease in cell viability or onset of apoptosis even after an 8-d exposure. In contrast, confocal imaging demonstrated contact with MWCNT aggregates triggered cell death after 24 h of exposure. In the presence of a natural surfactant, both TEER decrease and contact-mediated toxicity were mitigated. With confocal imaging, increased proliferation and apoptosis were detected in Calu-3 cells next to the aggregates. Contact-mediated cytotoxicity was recorded in two additional cell lines (BEAS-2B and A549) derived from human airways. Similar results were confirmed by adopting two additional MWCNT preparations with different physico-chemical features. This indicates MWCNT caused localized damage to airway epithelial monolayers in vitro and altered the apoptotic and proliferative rate of epithelial cells in close proximity to the aggregates. These findings provide evidence on the pathway by which MWCNT aggregates impair airway barrier function, and support the use of imaging techniques as a possible regulatory-decision supporting tool to identify effects of aggregated nanomaterials not readily detected at cell population level.
Available from: Francesco Sgarrella
- "A possible reason of the large amount os studies is that this cell type is an easy long-term culturing primary immune cell population compare to T cells or natural killer cells. Additional file
3 gives an overview on the papers published in the last years on macrophage and their interaction with carbon nanotubes, carbon nanohorns, graphene and GO
[16,22,29,35,38,45,47,53-103]. The large majority of the work performed in vitro was carried out using the murine macrophage cell line RAW 264.7, which can guarantee high experimental reproducibility, it is easy to culture and, being a good transfection host, it is suitable for nanomaterial-based conjugate uptake assays. "
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ABSTRACT: It has been recently proposed that nanomaterials, alone or in concert with their specific biomolecular conjugates, can be used to directly modulate the immune system, therefore offering a new tool for the enhancement of immune-based therapies against infectious disease and cancer. Here, we revised the publications on the impact of functionalized carbon nanotubes (f-CNTs), graphene and carbon nanohorns on immune cells. Whereas f-CNTs are the nanomaterial most widely investigated, we noticed a progressive increase of studies focusing on graphene in the last couple of years. The majority of the works (56%) have been carried out on macrophages, following by lymphocytes (30% of the studies). In the case of lymphocytes, T cells were the most investigated (22%) followed by monocytes and dendritic cells (7%), mixed cell populations (peripheral blood mononuclear cells, 6%), and B and natural killer (NK) cells (1%). Most of the studies focused on toxicity and biocompatibility, while mechanistic insights on the effect of carbon nanotubes on immune cells are generally lacking. Only very recently high-throughput gene-expression analyses have shed new lights on unrecognized effects of carbon nanomaterials on the immune system. These investigations have demonstrated that some f-CNTs can directly elicitate specific inflammatory pathways. The interaction of graphene with the immune system is still at a very early stage of investigation. This comprehensive state of the art on biocompatible f-CNTs and graphene on immune cells provides a useful compass to guide future researches on immunological applications of carbon nanomaterials in medicine.
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