Determination of cytotoxicity attributed to multiwall carbon nanotubes (MWCNT) in normal human embryonic lung cell (WI-38) line

Our plain-English summary of Determination of cytotoxicity attributed to multiwall carbon nanotubes (MWCNT) in normal human embryonic lung cell (WI-38) line, by J.S. Kim, K.S. Song, H.J. Joo, et al (Journal of Toxicology and Environmental Health. Part a, 2010).

The study

• Authors: J.S. Kim, K.S. Song, H.J. Joo, J.H. Lee, I.J. Yu
• Journal: Journal of Toxicology and Environmental Health. Part a
• Published: 2010;73(21-22):1521-9
• Cited by: 32 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Carbon nanotubes (CNT) possess beneficial physicochemical and mechanical properties; however, despite these advantages there are concerns regarding the adverse effects of CNT on lung and development of diseases, such as lung cancer and mesothelioma. According to fiber characteristics of length and diameter (aspect ratio), fibers with high aspect ratio (10-15 nm diameter and containing two different length distributions of 545 ± 230 and 10451 ± 8422 nm length) are more toxic to lung than low-aspect-ratio fibers (10-15 nm diameter and length of 192 nm). It was thus of interest to investigate the effects of multiwall carbon nanotubes (MWCNT) on the viability of normal human embryonic lung cells (WI-38) using trypan blue dye exclusion, the tetrazolium salt WST-1 (4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate) assay, and lactate dehydrogenase (LDH) activity assay. MWCNT produced cell growth inhibition and death at 12.5-200 μg/ml after 24-72 h of incubation. In addition, high-aspect-ratio MWCNT were found to produce higher incidence of cytotoxicity than low-aspect-ratio fibers at 50-200 μg/ml concentration. In the presence of less than 10% trace element content such as iron in MWCNT, the trace element exerted no marked effect on cellular viability. Data indicate that MWCNT inhibited cell proliferation and triggered cell death, and it would appear that the MWCNT fiber characteristics rather than impurities play a predominant role in the observed the cytotoxicity attributed to MWCNT.

In plain English

This was a laboratory study of cells grown in dishes. It did not test asbestos and did not involve people or animals. The authors exposed a line of normal human embryonic lung cells (WI-38) to two kinds of multiwall carbon nanotubes (MWCNT) of the same diameter, 10–15 nm. One kind was longer, called 'high-aspect-ratio', and was obtained from a manufacturer. The other was shorter, called 'low-aspect-ratio', and was made by treating the first with strong acid. Cells received 0, 12.5, 25, 50, 100 or 200 µg/ml for 24, 48 or 72 hours. Three tests measured cell growth and cell damage. In two of the tests, both nanotube types significantly reduced cell growth compared with control cells given only the dispersing solution. In the third, a marker of cell damage rose with both types. The longer nanotubes were more toxic than the shorter ones at some concentrations and times. Iron oxide, tested alone at up to 20 µg/ml to stand for impurities, had no marked effect. The authors concluded that toxicity was related to fiber aspect ratio rather than trace iron.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (in vitro) cell culture experiment
• Who was studied: Cultured normal human embryonic lung cells (WI-38 cell line) obtained from the Korean cell line bank; no human subjects or animals
• Exposure: High-aspect-ratio MWCNT (CM-95, Hanwha Nanotech, 10–15 nm diameter, two length distributions of 545 ± 230 and 10451 ± 8422 nm) and acid-oxidized low-aspect-ratio MWCNT (10–15 nm diameter), dispersed in DPPC solution, at 0, 12.5, 25, 50, 100 or 200 µg/ml for 24, 48 or 72 h. Iron oxide was tested separately at up to 20 µg/ml. Control cells received DPPC alone. No asbestos was tested.
• Main results:
  • Trypan blue test: cells treated with both high- and low-aspect-ratio MWCNT showed marked inhibition of cell growth at all concentrations after 24, 48 or 72 h
  • WST-1 test: high-aspect-ratio MWCNT were more cytotoxic than low-aspect-ratio MWCNT at 200 µg/ml at 24 h, at 25–200 µg/ml at 48 h, and at 25 and 200 µg/ml at 72 h
  • LDH test (marker of cell damage): LDH leakage increased in both the high- and low-aspect-ratio MWCNT groups compared with control, at 25–200 µg/ml in the 24-h exposure group
  • LDH increases were noted at 50–200 µg/ml in the 48-h and 72-h groups; iron oxide had no marked effect on LDH leakage
  • The highest iron oxide concentration tested was 20 µg/ml, equal to 10% of the highest MWCNT concentration
  • Carbon purity was 94.86% for the high-aspect-ratio MWCNT and 98.83% for the low-aspect-ratio MWCNT
  • The low-aspect-ratio MWCNT dispersed better than the high-aspect-ratio MWCNT
• The authors' conclusion: The authors concluded that MWCNT were cytotoxic to WI-38 lung cells, that the severity was related to fiber aspect ratio rather than trace iron at a 10% impurity level, and that aspect ratio should be considered in human and environmental risk assessment

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Mesothelioma, Aspect Ratio (Length-to-diameter ratio), Lactate Dehydrogenase (LDH).

Related studies

• Toxicogenomic comparison of multi-wall carbon nanotubes (MWCNTs) and asbestos — J.S. Kim, K.S. Song, et al. (2012)
• A comparison of acute and long-term effects of industrial multiwalled carbon nanotubes on human lung and immune cells in vitro — T. Thurnherr, C. Brandenberger, et al. (2011)
• Additional histopathologic examination of the lungs from a 3-month inhalation toxicity study with multiwall carbon nanotubes in rats — S. Treumann, L. Ma-Hock, et al. (2013)
• The role of iron impurities in the toxic effects exerted by short multiwalled carbon nanotubes (MWCNT) in murine alveolar macrophages — E. Aldieri, I. Fenoglio, et al. (2013)
• Raw single-wall carbon nanotubes induce oxidative stress and activate MAPKs, AP-1, NF-kappaB, and Akt in normal and malignant human mesothelial cells — M. Pacurari, X.J. Yin, et al. (2008)
• Genotoxicity and cytotoxicity of multi-wall carbon nanotubes in cultured Chinese hamster lung cells in comparison with chrysotile A fibers — M. Asakura, T. Sasaki, et al. (2010)

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