Cytotoxic and oxidative effects induced by man-made vitreous fibers (MMVFs) in a human mesothelial cell line

Our plain-English summary of Cytotoxic and oxidative effects induced by man-made vitreous fibers (MMVFs) in a human mesothelial cell line, by D. Cavallo, A. Campopiano, G. Cardinali, et al (Toxicology, 2004).

The study

• Authors: D. Cavallo, A. Campopiano, G. Cardinali, S. Casciardi, P. De Simone, D. Kovacs, B. Perniconi, G. Spagnoli, C.L. Ursini, C. Fanizza
• Journal: Toxicology
• Published: 2004;201(1-3):219-29
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The introduction of man-made vitreous fibers (MMVFs) as a substitute for asbestos in industrial and residential applications raises concerns about their potential health hazards. The aim of our study was to assess cytotoxic and oxidative effects induced on a human mesothelial cell line (MeT-5A) by exposure to glass wool (GW), rock wool (RW) and refractory ceramic fibers (RCF) in comparison with crocidolite asbestos (CR). MeT-5A cells were exposed for 24 h to 2, 5 and 10 microg/cm2 of MMVF and crocidolite fibers and analysed by scanning electron microscope (SEM) for cell surface alterations. Cells were exposed for 2 h to 1, 2, 5 and 10 microg/cm2 of the same fibers and analysed by enzyme Fpg-modified comet test for direct and oxidative DNA damage. SEM revealed loss of microvilli in cells exposed to RCF and numerous blebs in cells exposed to higher doses of RW. Comet test showed significant direct DNA damage in cells exposed to RCF even at the lowest dose. Comet test with Fpg, that permits the detection of oxided DNA bases, showed significant oxidative DNA damage in cells exposed to higher doses of RW. The presence of DNA damage and alterations of cell surface induced by low doses of RCF and the presence of oxidative DNA damage and blebs on cell surface in cells exposed to higher dose of RW suggest possible cytotoxic, oxidative and genotoxic effects for these MMVFs.

In plain English

This laboratory study used a human mesothelial cell line (MeT-5A), not people. They exposed them to glass wool, rock wool, a Danish rock wool its manufacturer called biosoluble, and refractory ceramic fibers, with crocidolite asbestos as positive control. They examined cell surfaces by electron microscope after 24 hours at 2, 5 and 10 micrograms per square centimetre, and measured DNA damage by comet test after 2 hours at 1, 2, 5 and 10 micrograms per square centimetre. Crocidolite caused loss of microvilli (tiny surface projections), membrane holes and cracks at higher doses, and significant oxidative DNA damage even at the lowest dose. Refractory ceramic fibers caused significant direct DNA damage at the lowest dose but showed no oxidative DNA damage at any dose tested. Rock wool caused cell-surface blebs and significant oxidative DNA damage at higher doses. Glass wool and Danish rock wool caused no significant direct DNA damage and only a slight oxidative effect at the highest dose. The authors concluded that their results for refractory ceramic fibers and rock wool suggest possible cytotoxic, oxidative and genotoxic effects for these fibers.

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) experiment on a human mesothelial cell line, with crocidolite asbestos as positive control and unexposed cells as negative control
• Who was studied: A commercially available human mesothelial cell line (MeT-5A) obtained from the American Type Culture Collection; no human subjects or animals
• Exposure: Glass wool, rock wool, a Danish rock wool described by its manufacturer as biosoluble, and refractory ceramic fibers, with NIEHS crocidolite asbestos as positive control. Doses for electron microscopy were 2, 5 and 10 micrograms per square centimetre for 24 hours. Doses for the comet test were 1, 2, 5 and 10 micrograms per square centimetre for 2 hours.
• Main results:
  • After 24 hours, over 90% of cells exposed to man-made vitreous fibers and over 80% of cells exposed to crocidolite were viable
  • Crocidolite-exposed cells lost microvilli at 2 micrograms per square centimetre. At 5 to 10 they lost their shape and showed holes and cracks in the membrane.
  • At 2 micrograms per square centimetre, reduction in microvilli was widely seen in cells treated with rock wool, Danish rock wool and refractory ceramic fibers. Glass wool caused only a low reduction at this dose.
  • Several cells exposed to rock wool at 5 and 10 micrograms per square centimetre developed small and large blebs on their surface
  • Cells exposed to glass wool at 5 and 10 micrograms per square centimetre showed no evident changes in morphology, apart from blebbing in sporadic cells
  • Refractory ceramic fibers caused a statistically significant (P less than 0.001) increase in direct DNA damage compared with unexposed cells at the lowest dose (1 microgram per square centimetre), with a slight decrease at higher doses
  • For glass wool, rock wool and Danish rock wool, direct DNA damage rose with dose but was not statistically significant
  • Crocidolite caused statistically significant oxidative DNA damage even at 1 microgram per square centimetre
  • Among the man-made fibers, only rock wool caused significant oxidative DNA damage, at the higher doses (5 and 10 micrograms per square centimetre). Danish rock wool and glass wool showed only a slight effect at the highest dose.
  • For refractory ceramic fibers, the Fpg comet test did not show oxidative DNA damage at any of the doses used
• The authors' conclusion: The authors concluded that DNA damage and cell-surface changes from low doses of refractory ceramic fibers, and oxidative DNA damage and blebs from higher doses of rock wool, suggest possible cytotoxic, oxidative and genotoxic effects for these man-made vitreous fibers. They also concluded that the oxidative effect of the man-made fibers was significantly lower than that of crocidolite.
• Limitations the authors state:
  • The authors noted that the lowest dose of refractory ceramic fibers contained a high number of fibers per unit weight, especially of WHO-size fibers, which must be considered when interpreting the direct DNA damage seen at that dose

Topics

The National Library of Medicine indexes this study under subjects our site covers: Crocidolite.

Medical terms in this study, explained in our Lexicon: Vitreous, Mesothelial Cells, Crocidolite, MeT-5A Cells.

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• Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany — H. Pohlabeln, K.H. Jöckel, et al. (2000)
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