Sister-chromatid exchange and cell kinetics in CHO-K1 cells, human fibroblasts and lymphoblastoid cells exposed in vitro to asbestos and glass fibre

Our plain-English summary of Sister-chromatid exchange and cell kinetics in CHO-K1 cells, human fibroblasts and lymphoblastoid cells exposed in vitro to asbestos and glass fibre, by G. Casey (Mutation Research, 1983).

The study

• Author: G. Casey
• Journal: Mutation Research
• Published: 1983;116(3-4):369-77
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Possible mutagenic activity of the asbestos dusts crocidolite and chrysotile, and fine and coarse glass, was assessed in CHO-K1 cells, human fibroblasts and human lymphoblastoid cells using the sister-chromatid exchange assay and by examining the effects on cell kinetics. Asbestos caused no dose-related increase in sister-chromatid exchange levels in any of the cell types. However, mitotic delay was induced in CHO-K1 cells and human fibroblasts. The order of magnitude of induced delay in CHO-K1 cells was chrysotile greater than fine glass greater than crocidolite greater than coarse glass. Mitotic inhibition was more pronounced in these cells if they were still in suspension when initially exposed to the dusts compared with 1 h after plating.

In plain English

This laboratory study tested whether two types of asbestos, crocidolite and chrysotile, and two glass dusts (fine glass and coarse glass) affected cells grown in culture. The cells were CHO-K1 cells, a Chinese hamster line; human fibroblasts grown from foreskin biopsies of a healthy 2-year-old boy; and two human lymphoblastoid cell lines, one from a patient with ataxia telangiectasia. The main test counted sister-chromatid exchanges, a proposed indicator of DNA damage. Neither asbestos type caused a dose-related rise in exchanges. No significant differences from unexposed cultures were found in human fibroblasts or lymphoblastoid cells. The dusts did slow cell division (mitotic delay) in CHO-K1 cells and human fibroblasts, but no difference was found in lymphoblastoid cells. In CHO-K1 cells the delay was greatest with chrysotile, followed by fine glass, crocidolite and coarse glass. The delay was stronger when the dusts were added while the cells were still in suspension. The author concluded that asbestos does not appear to act primarily as a mutagen in these cells, if the exchange test is a valid indicator of mutagenic activity.

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 laboratory experiment: cultured cells exposed to asbestos and glass dusts, assessed with the sister-chromatid exchange (SCE) assay (a proposed indicator of DNA damage) and by examining cell kinetics (mitotic delay)
• Who was studied: Cultured cells, not people: CHO-K1 cells (Chinese hamster cells); human fibroblasts from foreskin biopsies of a healthy 2-year-old boy; two human lymphoblastoid cell lines, LIZ (from a normal female with glandular fever) and 1526 (from a female patient with ataxia telangiectasia). Work done at the MRC Human Biochemical Genetics Unit, University College, London.
• Exposure: UICC crocidolite, SFA chrysotile, fine glass (code 100) and coarse glass (code 110), at concentrations of 0.001, 0.01 and 0.05 mg/ml in CHO-K1 cells, and 0.01 mg/ml in human fibroblasts and lymphoblastoid cells. Control cultures received the same volume of sterile phosphate-buffered saline.
• Main results:
  • CHO-K1 cells, with dusts added 1 h after plating: there were no consistently significant differences in SCE levels between exposed and unexposed cultures at any concentration, and no dose-related effect.
  • CHO-K1 cells, with dusts added while the cells were in suspension (0.01 mg/ml): SCE levels in the crocidolite cultures (12.5 per cell) and chrysotile cultures (12.8 per cell) were significantly higher (p less than 0.05) than in the coarse glass cultures (10.5 per cell). They were not significantly higher than in the fine glass cultures or the unexposed cultures (11.1 per cell).
  • CHO-K1 cells, mitotic delay: the order of magnitude of induced delay was chrysotile, then fine glass, then crocidolite, then coarse glass.
  • CHO-K1 cells, with dusts added 1 h after plating at 0.01 mg/ml: second-metaphase cells were 77% (fine glass), 85% (coarse glass), 84% (crocidolite) and 76% (chrysotile) of the unexposed control level. The text states that all dusts significantly (p less than 0.001) increased mitotic delay compared with the unexposed mean control, "but not the coarse glass (110)".
  • CHO-K1 cells, with dusts added while the cells were in suspension (0.01 mg/ml): second-metaphase cells were 42% (fine glass), 82% (coarse glass), 67% (crocidolite) and 34% (chrysotile) of control. The crocidolite, chrysotile and fine glass cultures had significantly (p less than 0.001) fewer second-metaphase cells than both the unexposed and the coarse glass cultures.
  • CHO-K1 cells at the highest dose (0.05 mg/ml): too few cells survived in the chrysotile and fine glass cultures to assess mitotic delay or SCE frequency.
  • Human fibroblasts (0.01 mg/ml): no significant differences in SCE levels between the dusts and the unexposed control. Exposure soon after plating severely reduced the mitotic index in all exposed cultures.
  • Human lymphoblastoid cells (0.01 mg/ml): no significant differences in SCE levels between unexposed and exposed cultures in either cell line, and no differences in the proportions of first, second and third metaphases.
  • The SCE frequency of cell line 1526 (ataxia telangiectasia) was significantly lower (p less than 0.02) than that of LIZ in all exposed cultures. The author stated the significance of this was unclear.
• The authors' conclusion: The author concluded that the lack of effect on SCE suggests asbestos does not act primarily as a mutagen in these cells, if the SCE technique can be used as an indicator of mutagenic activity. The author also stated that the results emphasise the need to use a series of tests and cell types to identify potentially mutagenic or carcinogenic agents.
• Limitations the authors state:
  • It is not yet established whether SCE induction consistently correlates with mutagenic activity.
  • No results were available for higher dust concentrations in CHO-K1 cells because too few metaphase cells were present at harvesting.
  • Formal cell kinetics studies were not possible in human fibroblasts because their mitotic indices were too low.
  • Mitotic delay in lymphoblastoid cells may have been masked because continuously dividing suspension cultures are asynchronous.

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: Fibroblast, Crocidolite, Chrysotile.

Related studies

• A comparison of the cytogenetic response to asbestos and glass fibre in Chinese hamster and human cell lines. Demonstration of growth inhibition in primary human fibroblasts — A.M. Sincock, J.D. Delhanty, et al. (1982)
• Sister chromatid exchanges in rat pleural mesothelial cells treated with crocidolite, attapulgite, or benzo 3-4 pyrene — S. Achard, M. Perderiset, et al. (1987)
• Sister chromatid exchange frequency in inhabitants exposed to asbestos in Turkey — H. Dönmez, Y. Ozkul, et al. (1996)
• In vitro response of rat pleural mesothelial cells to talc samples in genotoxicity assays (sister chromatid exchanges and DNA repair) — S. Endo-Capron, A. Renier, et al. (1993)
• Cytotoxic and genotoxic effects of calcium silicates on human lymphocytes in vitro — M. Aslam, N. Fatima, et al. (1993)
• The in vitro genetic effects of fibrous erionite and crocidolite asbestos — K.T. Kelsey, E. Yano, et al. (1986)

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