Potential in vitro effects of carbon nanotubes on human aortic endothelial cells
Introduction
Engineered carbon nanomaterials, including carbon nanotubes, have elicited a significant interest due to their unique electronic and mechanical properties. However, the small size, large surface area, and high reactivity of these materials are the main factors for potential toxicity (Donaldson et al., 2006). Carbon nanotubes (CNT), including the single- and multi-walled (SWCNT and MWCNT), will have wide-spread applications in many technological fields, thus worker/consumer exposure is likely to occur, posing emerging health concerns (Donaldson et al., 2006, Maynard et al., 2006). Initial toxicological animal studies demonstrated that pulmonary deposition of SWCNT or MWCNT causes acute pulmonary inflammation as well as chronic responses such as fibrosis (Lam et al., 2004, Warheit et al., 2004, Muller et al., 2005, Shvedova et al., 2005, Mangum et al., 2006, Li et al., 2007a, Mercer et al., 2008). Furthermore, we demonstrated that CNT respiratory exposure is associated with adverse cardiovascular outcomes. Pulmonary deposition of SWCNT or MWCNT results in a rapid release of inflammatory mediators, activated blood cells, and thrombogenic proteins into the systemic circulation which may induce endothelial dysfunction (Erdely et al., 2009). Chronic SWCNT respiratory exposure triggers mitochondrial aortic alterations which may be associated with SWCNT-induced accelerated atherogenesis in apoE−/− mice, a model for human atherosclerosis (Li et al., 2007b). The CNT-related cardiovascular findings, are consistent with the current knowledge of the link between particulate matter in air pollution and the risk from cardiovascular diseases related to atherosclerosis (Brook et al., 2004).
The cardiovascular system may be affected through two main mechanisms including indirect effects, mediated by particle-induced pulmonary inflammation and dysfunction, or direct effects of particles that have traveled into the systemic circulation (Mills et al., 2007). It has been shown in animal models that some inhaled particles were located in tissues beyond the lung (Kreyling et al., 2002, Nemmar et al., 2002, Oberdorster et al., 2002). The proximity between epithelial type I and endothelial cell caveolar membrane structures might play a role in the particle translocation mechanisms (Heckel et al., 2004). The major unresolved question is whether particles translocate in sufficient numbers to exert a significant direct influence on vascular endothelial function (Mills et al., 2008a). Under both possible mechanisms of CNT-induced cardiovascular toxicity, endothelial cells are a potential target. Although many in vitro studies on CNT toxicity have been conducted (Shvedova et al., 2003, Manna et al., 2005, Monteiro-Riviere et al., 2005, Raja et al., 2007, Pacurari et al., 2008a, Pacurari et al., 2008b), the potential effects of CNT exposure on endothelial cells have not been investigated. The purpose of our studies was to evaluate potential direct toxicity of CNT on human endothelial cells, with special emphasis on the evaluation of dose-dependent effects. The dose response was select based on the hypothesis that endothelial cells are exposed to high particle concentrations at the penetration site and to low concentrations in the systemic vasculature as a result of translocation from the entrance site.
Section snippets
Reagents
Catalytically grown and purified SWCNT and MWCNT (Mitsui & Co., Ltd.) (Oberlin et al., 1976) were kindly provided by Dr. M. Endo (Shinshu University, Wakasato, Japan). Characteristics of the SWCNT (a specific surface area (BET) average 641 m2/g) and MWCNT (BET average 56 m2/g) have been described in greater detail (Kim et al., 2005, Koyama et al., 2006). Trace metal analysis by inductively coupled plasma optical emission spectrometry indicated iron content of SWCNT at 8.8% by weight and 0.27%
Cytotoxicity studies
In accordance with the recent findings on the specificity of cytotoxicity assays for CNT (Worle-Knirsch et al., 2006, Casey et al., 2008), the effects of CNT on HAEC viability was evaluated under serum-free culture conditions using both LDH and WST-1 assays. First, HAEC were exposed to SWCNT, MWCNT, or CB at a concentration of 150 μg/106 cells (4.5 μg/ml) for 3 or 24 h. The exposure of HAEC cells to either SWCNT or MWCNT resulted in elevated LDH cell release, a sign of membrane leakage, at 24 h
Discussion
The functionality of endothelial cells is fundamental for the homeostasis of the vascular system (Cai and Harrison, 2000). Due to its unique position in the vessel wall, the endothelium acts as a barrier and serves as the primary sensor for normal blood flow. The findings of this study demonstrated actin cytoskeleton disruption accompanied with altered VE-cadherin localization, reduced tubule formation, and a concomitant diminished viability of human aortic endothelial cells as a result of
Conflict of interest statement
The authors of this manuscript declare there are no conflicts of interest.
Disclaimer
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.
References (50)
- et al.
Single walled carbon nanotubes induce indirect cytotoxicity by medium depletion in A549 lung cells
Toxicol. Lett.
(2008) - et al.
Functional cooperation between the microtubule and actin cytoskeletons
Curr. Opin. Cell Biol.
(2000) - et al.
Adherens and tight junctions: structure, function and connections to the actin cytoskeleton
Biochim. Biophys. Acta
(2008) - et al.
Multi-walled carbon nanotubes injure the plasma membrane of macrophages
Toxicol. Appl. Pharmacol.
(2008) - et al.
Synthesis and structural characterization of thin multi-walled carbon nanotubes with a partially facetted cross section by a floating reactant method
Carbon
(2005) - et al.
Cadherin-directed actin assembly: E-cadherin physically associates with the Arp2/3 complex to direct actin assembly in nascent adhesive contacts
Curr. Biol.
(2002) - et al.
Role of systemic T-cells and histopathological aspects after subcutaneous implantation of various carbon nanotubes in mice
Carbon
(2006) - et al.
Structural and functional associations of apical junctions with cytoskeleton
Biochim. Biophys. Acta
(2008) - et al.
Multi-walled carbon nanotube interactions with human epidermal keratinocytes
Toxicol. Lett.
(2005) - et al.
Respiratory toxicity of multi-wall carbon nanotubes
Toxicol. Appl. Pharmacol.
(2005)
Filamentous growth of carbon through benzene decomposition
J. Cryst. Growth
Impact of carbon nanotube exposure, dosage and aggregation on smooth muscle cells
Toxicol. Lett.
Fibrinogen E-fragment inhibits the migration and tubule formation of human dermal microvascular endothelial cells in vitro
Cancer Res.
The potential risks of nanomaterials: a review carried out for ECETOC
Part Fibre Toxicol.
Air pollution and cardiovascular disease: a statement for healthcare professionals from the Expert Panel on Population and Prevention Science of the American Heart Association
Circulation
Endothelial dysfunction in cardiovascular diseases: the role of oxidant stress
Circ. Res.
Actin-based motility: from molecules to movement
Bioessays
Carbon nanotubes: a review of their properties in relation to pulmonary toxicology and workplace safety
Toxicol. Sci.
Cross-talk between lung and systemic circulation during carbon nanotube respiratory exposure
Potential Biomarkers Nano Lett.
Protein kinase Calpha activates c-Src and induces podosome formation via AFAP-110
Mol. Cell. Biol.
Colloidal gold particles as a new in vivo marker of early acute lung injury
Am. J. Physiol., Lung Cell. Mol. Physiol.
Branching morphogenesis
Circ. Res.
Translocation of ultrafine insoluble iridium particles from lung epithelium to extrapulmonary organs is size dependent but very low
J. Toxicol. Environ. Health
Pulmonary toxicity of single-wall carbon nanotubes in mice 7 and 90 days after intratracheal instillation
Toxicol. Sci.
Comparative study of pathological lesions induced by multiwalled carbon nanotubes in lungs of mice by intratracheal instillation and inhalation
Environ. Toxicol.
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Current affiliation: National Center for Environmental Assessment, U.S. Environmental Protection Agency, Washington, DC, USA.