Differences and similarities between carbon nanotubes and asbestos fibers during mesothelial carcinogenesis: Shedding light on fiber entry mechanism

Abstract

The emergence of nanotechnology represents an important milestone, as it opens the way to a broad spectrum of applications for nanomaterials in the fields of engineering, industry and medicine. One example of nanomaterials that have the potential for widespread use is carbon nanotubes, which have a tubular structure made of graphene sheets. However, there have been concerns that they may pose a potential health risk due to their similarities to asbestos, namely their high biopersistence and needle‐like structure. We recently found that despite these similarities, carbon nanotubes and asbestos differ in certain aspects, such as their mechanism of entry into mesothelial cells. In the study, we showed that non‐functionalized, multi‐walled carbon nanotubes enter mesothelial cells by directly piercing through the cell membrane in a diameter‐ and rigidity‐dependent manner, whereas asbestos mainly enters these cells through the process of endocytosis, which is independent of fiber diameter. In this review, we discuss the key differences, as well as similarities, between asbestos fibers and carbon nanotubes. We also summarize previous reports regarding the mechanism of carbon nanotube entry into non‐phagocytic cells. As the entry of fibers into mesothelial cells is a crucial step in mesothelial carcinogenesis, we believe that a comprehensive study on the differences by which carbon nanotubes and asbestos fibers enter into non‐phagocytic cells will provide important clues for the safer manufacture of carbon nanotubes through strict regulation on fiber characteristics, such as diameter, surface properties, length and rigidity. (Cancer Sci, doi: 10.1111/j.1349‐7006.2012.02326.x, 2012)

Carbon Nanotube and Asbestos Exposures Induce Overlapping but Distinct Profiles of Lung Pathology in Non-Swiss Albino CF-1 Mice

“…Globular particulates such as dust and pollen are efficiently cleared by AMs but fiber particles which deposit in the distal airspaces are known to present a challenge to the clearance processes of phagocytic uptake and subsequent AM locomotion to the mucociliary-equipped regions of the airway (Lippman, 1990). It is believed that the shape and aspect ratios of biopersistent fibers such as crocidolite asbestos cause harmful deformations of AMs attempting to take up the particles (Dörger et al, 2000, Nagai & Toyokuni, 2012) while the ends of fibers may puncture or damage cell membranes (frustrated phagocytosis). In addition to inducing mechanical strain, fiber particles have large surface areas which may affect cell and tissue environments with harmful surface reactivity such as the generation of oxidative free radicals (Shukla et al, 2003).…”

Deferasirox Induces Mesenchymal–Epithelial Transition in Crocidolite-Induced Mesothelial Carcinogenesis in Rats

“…Currently, there are several lines of hypotheses on the molecular mechanisms of asbestos-induced carcinogenesis, which include free radical generation, chromosome tangling, molecular adsorption, and chronic inflammation (9)(10)(11). We hypothesized that appropriate intervention may reduce free radical generation even after exposure to asbestos fibers.…”

Nanomechanical mechanism for lipid bilayer damage induced by carbon nanotubes confined in intracellular vesicles

“…one-dimensional nanomaterials | molecular dynamics | lysosomal permeabilization | biomembrane | lipid extraction T he interactions of low-dimensional materials with the external or plasma membrane of living cells have been the subject of prior studies due to their importance in uptake and delivery, antibacterial action, and nanomaterial safety (1)(2)(3)(4)(5)(6). Following uptake, nanomaterials may also interact with internal membranes while under confinement in intracellular vesicles (7)(8)(9)(10), but the biophysics of these geometrically constrained systems is poorly understood.…”