Abstract
Background and MethodsPulmonary deposited carbon nanotubes (CNTs) are cleared very slowly from the lung, but there is limited information on how CNTs interact with the lung tissue over time. To address this, three different multiwalled CNTs were intratracheally instilled into female C57BL/6 mice: one short (850 nm) and tangled, and two longer (4 μm and 5.7 μm) and thicker. We assessed the cellular interaction with these CNTs using transmission electron microscopy (TEM) 1, 3 and 28 days after instillation.ResultsTEM analysis revealed that the three CNTs followed the same overall progression pattern over time. Initially, CNTs were taken up either by a diffusion mechanism or via endocytosis. Then CNTs were agglomerated in vesicles in macrophages. Lastly, at 28 days post-exposure, evidence suggesting CNT escape from vesicle enclosures were found. The longer and thicker CNTs more often perturbed and escaped vesicular enclosures in macrophages compared to the smaller CNTs. Bronchoalveolar lavage (BAL) showed that the CNT exposure induced both an eosinophil influx and also eosinophilic crystalline pneumonia.ConclusionTwo very different types of multiwalled CNTs had very similar pattern of cellular interactions in lung tissue, with the longer and thicker CNTs resulting in more severe effects in terms of eosinophil influx and incidence of eosinophilic crystalline pneumonia (ECP).
Highlights
Carbon nanotubes (CNTs) have excellent mechanical and electrical properties and have been of great interest to researchers since their discovery some 50 year ago [1]
transmission electron microscopy (TEM) analysis revealed that the three carbon nanotubes (CNTs) followed the same overall progression pattern over time
CNTs were agglomerated in vesicles in macrophages
Summary
Carbon nanotubes (CNTs) have excellent mechanical and electrical properties and have been of great interest to researchers since their discovery some 50 year ago [1]. Inhaled CNTs are removed very slowly from the lung, and the half-life of CNTs in lung following inhalation in mice has been estimated to be ca. Assessment of CNT-toxicity is complicated by the wide variety of physical and chemical properties with which they can be manufactured. The number of defects in the lattice structure of CNTs plays a role in their toxicity [9], together with agglomeration level [10] and functionalization [11,12,13]. Pulmonary deposited carbon nanotubes (CNTs) are cleared very slowly from the lung, but there is limited information on how CNTs interact with the lung tissue over time. We assessed the cellular interaction with these CNTs using transmission electron microscopy (TEM) 1, 3 and 28 days after instillation
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