Mitochondrial Impairment Induced by Sub-Chronic Exposure to Multi-Walled Carbon Nanotubes.

Giuseppa Visalli,Alessio Facciolà,Daniela Iannazzo,Angela Di Pietro,Alessandro Pistone,Vincenza La Fauci,Monica Currò,Pasqualina Laganà

doi:10.3390/ijerph16050792

Abstract

Human exposure to carbon nanotubes (CNTs) can cause health issues due to their chemical-physical features and biological interactions. These nanostructures cause oxidative stress, also due to endogenous reactive oxygen species (ROS) production, which increases following mitochondrial impairment. The aim of this in vitro study was to assess the health effects, due to mitochondrial dysfunction, caused by a sub-chronic exposure to a non-acutely toxic dose of multi walled CNTs (raw and functionalised). The A549 cells were exposed to multi-walled carbon nanotubes (MWCNTs) (2 µg mL−1) for 36 days. Periodically, cellular dehydrogenases, pyruvate dehydrogenase kinase 1 (PDK1), cytochrome c release, permeability transition pore (mPTP) opening, transmembrane potential (Δψ m), apoptotic cells, and intracellular ROS were measured. The results, compared to untreated cells and to positive control formed by cells treated with MWCNTs (20 µg mL−1), highlighted the efficiency of homeostasis to counteract ROS overproduction, but a restitutio ad integrum of mitochondrial functionality was not observed. Despite the tendency to restore, the mitochondrial impairment persisted. Overall, the results underlined the tissue damage that can arise following sub-chronic exposure to MWCNTs.

Highlights

With the growing trend in the production and applications of carbon nanotubes (CNTs), the increasing use in composite materials [1] and their exploration as innovative solutions for biomedical applications [2,3,4], there will be a corresponding increase in potential human exposures [5].Such exposures can cause substantial health issues as a result of the chemical–physical features and biological interactions of CNTs
We examined homemade raw multi-walled carbon nanotubes (MWCNTs) and functionalised MWCNTs; these two MWCNTs have been widely studied for the assessment of short-term toxicity in two different cell lines [18,19]
PMWCNTs were synthesised by catalytic chemical vapour deposition (CCVD) and subsequently purified from both free metals and carbonaceous particles, by products of the synthesis process [34,35]

Summary

Introduction

With the growing trend in the production and applications of carbon nanotubes (CNTs), the increasing use in composite materials [1] and their exploration as innovative solutions for biomedical applications [2,3,4], there will be a corresponding increase in potential human exposures [5] Such exposures can cause substantial health issues as a result of the chemical–physical features and biological interactions of CNTs. Numerous efforts have been made over the past two decades to investigate the biocompatibility and toxicological effects of CNTs, which are still poorly understood and controversial [6,7,8,9]. Public Health 2019, 16, 792; doi:10.3390/ijerph16050792 www.mdpi.com/journal/ijerph

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Results