Effects of asbestos and man-made vitreous fibers on cell division in cultured human mesothelial cells in comparison to rodent cells

Our plain-English summary of Effects of asbestos and man-made vitreous fibers on cell division in cultured human mesothelial cells in comparison to rodent cells, by K. Pelin, P. Kivipensas, K. Linnainmaa (Environmental and Molecular Mutagenesis, 1995).

The study

• Authors: K. Pelin, P. Kivipensas, K. Linnainmaa
• Journal: Environmental and Molecular Mutagenesis
• Published: 1995;25(2):118-25
• Cited by: 29 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We report the effects of chrysotile and crocidolite asbestos, and glass and rock wool fibers (man-made vitreous fibers, MMVF) on the induction of binucleate cells in vitro. The response of human mesothelial cells (target cells in fiber carcinogenesis) and rodent cells was compared. Human primary mesothelial cells, MeT-5A cells (an immortalized human mesothelial cell line), and rat liver epithelial (RLE) cells were exposed to asbestos and MMVF samples of similar size range. Milled glass wool, milled rock wool, and titanium dioxide were used as non-fibrous particle controls. All four fiber types caused statistically significant increases in the amount of binucleate cells in human primary mesothelial cells and MeT-5A cells (in the dose range 0.5-5.0 micrograms/cm2). Chrysotile and crocidolite asbestos were more effective (1.3-3.0-fold increases) than thin glass wool and thin rock wool fibers (1.3-2.2-fold increases). However, when the fiber doses were expressed as the number of fibers per culture area, the asbestos and MMVF appeared equally effective in human mesothelial cells. In RLE cells, chrysotile was the most potent inducer of binucleation (2.9-5.0-fold increases), but the response of the RLE cells to crocidolite, thin glass wool, and thin rock wool fibers was similar to the response of the human mesothelial cells. No statistically significant increases in the number of bi- or multinucleate cells were observed in human primary mesothelial cells or RLE cells exposed to the non-fibrous dusts. In MeT-5A cells exposed to 5 micrograms/cm2 of milled glass wool and milled rock wool, as well as in cultures exposed to 2 and 5 micrograms/cm2 of TiO2, significant increases were, however, observed. Our results show that rodent cells respond differently to mineral fibers than human cells. The results also add evidence to the suggested importance of disturbed cell division in fiber carcinogenesis.

In plain English

In this laboratory study, the authors exposed human primary mesothelial cells, an immortalized human mesothelial cell line (MeT-5A) and rat liver epithelial cells for 48 hours to chrysotile and crocidolite asbestos and to thin glass wool and thin rock wool. Milled glass wool, milled rock wool and titanium dioxide were non-fibrous dust controls. The authors counted cells with two or more nuclei, linking them to disturbed cell division. In both human mesothelial cell types, all four fiber types significantly increased binucleate cells at doses of 0.5 to 5.0 micrograms per square centimetre. The lowest crocidolite dose (0.25) failed to increase binucleation in primary mesothelial cells. By weight, asbestos was more effective. By fiber number, the four types acted similarly in primary mesothelial cells. In rat cells, chrysotile gave the largest increases (2.9-5.0-fold). The non-fibrous dusts had no significant effect in primary mesothelial or rat cells, but did at higher doses in MeT-5A cells. The authors concluded that rodent and human cells respond differently, and that the four fiber types can cause bi- and multinucleation at low, non-toxic doses in human mesothelial cells.

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: In vitro (cell culture) laboratory experiment, with a separate fiber-uptake (phagocytosis) experiment
• Who was studied: Cultured cells, not people. The three cell types were: human primary mesothelial cells established from pleural effusions; MeT-5A, an immortalized, non-tumorigenic human mesothelial cell line; and rat liver epithelial (RLE) cells. The work was done at the Finnish Institute of Occupational Health, Helsinki. No study dates are given.
• Exposure: UICC standard chrysotile A and crocidolite, plus thin glass wool and thin rock wool fibers of similar size, applied for 48 hours at doses from 0.25 to 5.0 micrograms per square centimetre. Milled glass wool, milled rock wool and titanium dioxide were the non-fibrous controls. UICC amosite was used, in place of crocidolite, only in the fiber-uptake experiment, at 2 micrograms per square centimetre for 0, 6 and 24 hours.
• Main results:
  • In human primary mesothelial cells and MeT-5A cells, all four fiber types (chrysotile, crocidolite, thin glass wool, thin rock wool) caused statistically significant increases in binucleate cells in the dose range 0.5-5.0 micrograms per square centimetre.
  • At the lowest dose, 0.25 micrograms per square centimetre, results differed by fiber and cell type. Chrysotile gave a 1.2-fold increase (P less than 0.05) in mesothelial cells. Crocidolite failed to induce binucleation in primary mesothelial cells but gave a 1.2-fold increase in MeT-5A cells.
  • In the human mesothelial cells, by weight, chrysotile and crocidolite gave 1.3-3.0-fold increases (0.5-2.0 micrograms per square centimetre). Thin glass wool and thin rock wool gave 1.3-2.2-fold increases (1.0-5.0 micrograms per square centimetre).
  • When doses were expressed as number of fibers per culture area, all four fiber types induced binucleate cells similarly in primary mesothelial cell cultures.
  • The non-fibrous dusts caused no increase in binucleate primary mesothelial cells. In MeT-5A cells, however, 5.0 micrograms per square centimetre of milled glass wool and milled rock wool gave 1.3- and 1.4-fold increases, and titanium dioxide at 2.0 and 5.0 gave statistically significant increases.
  • In rat liver epithelial cells, chrysotile was the strongest inducer (2.9-5.0-fold increases). Crocidolite gave 1.7-2.4-fold increases at all three doses. Thin glass wool significantly increased binucleate cells only at its lowest dose (1 microgram per square centimetre). Milled glass wool, milled rock wool and titanium dioxide had no significant effect.
  • Fiber uptake after 6 hours, in human mesothelial cells: over 90% of amosite fibers, over 80% of thin glass wool fibers and less than 40% of chrysotile fibers were inside or attached to the cells.
  • Fiber uptake after 6 hours, in rat liver epithelial cells: 12% of amosite fibers, 13% of thin glass wool fibers and about 30% of chrysotile fibers were incorporated.
• The authors' conclusion: The authors concluded that both serpentine (chrysotile) and amphibole (crocidolite) asbestos, as well as thin glass wool and thin rock wool fibers, can induce bi- and multinucleation at low, non-toxic doses in human mesothelial cells. They also concluded that there appear to be species-specific differences between human mesothelial cells and rodent cells in how mineral fibers affect cell division.
• Limitations the authors state:
  • The glass and rock wool samples contained five to ten times more non-fibrous particles than fibers, unlike the asbestos samples.
  • Background (control) levels of binucleate cells were high and variable in MeT-5A and primary mesothelial cells (4.2-8.2%), compared with rat cells (1.5-3.0%).
  • The 48-hour exposure may be too short. Longer culture times are probably needed to detect chromosomal changes arising from further divisions of binucleate cells.
  • The authors caution that, despite these cell results for glass and rock wool, epidemiological and animal inhalation studies have not shown a link between man-made vitreous fibers and cancer.
  • Only viable cells could be analysed, because severely damaged cells detach and are lost before fixation.

Topics

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

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

Related studies

• Cytotoxic and oxidative effects induced by man-made vitreous fibers (MMVFs) in a human mesothelial cell line — D. Cavallo, A. Campopiano, et al. (2004)
• In vitro cytotoxicity of asbestos and man-made vitreous fibers: roles of fiber length, diameter and composition — G.A. Hart, L.M. Kathman, et al. (1994)
• Cytogenetic response to asbestos fibers in cultured human primary mesothelial cells from 10 different donors — K. Pelin, A. Hirvonen, et al. (1995)
• Man-made mineral fiber hazardous properties assessment using transgenic rodents: example of glass fiber testing — M.C. Bottin, J.C. Vigneron, et al. (2003)
• Cytotoxicity of oxidants and asbestos fibers in cultured human mesothelial cells — V.L. Kinnula, K. Aalto, et al. (1994)
• Cellular ingestion, toxic effects, and lesions observed in human bronchial epithelial tissue and cells cultured with asbestos and glass fibers — A. Haugen, P.W. Schafer, et al. (1982)

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