Comparative toxicities of different forms of asbestos on rat pleural mesothelial cells

Our plain-English summary of Comparative toxicities of different forms of asbestos on rat pleural mesothelial cells, by M.C. Jaurand, I. Bastie-Sigeac, A. Renier, et al (Environmental Health Perspectives, 1983).

The study

• Authors: M.C. Jaurand, I. Bastie-Sigeac, A. Renier, J. Bignon
• Journal: Environmental Health Perspectives
• Published: 1983;51:153-8
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The effects of UICC crocidolite and chrysotile A, either oxalic acid-leached or unleached, on the viability, morphology and growth characteristics of rat pleural mesothelial cells (PMC) were examined; DQ12 quartz particles were also used. When asbestos fibers were added for 48 hr at the beginning of exponential growth, 20 or 50 micrograms/mL of chrysotile fibers were cytotoxic and no growth occurred; with 5 or 10 micrograms/mL a latent period was observed, and the mean population doubling time was increased. Chrysotile ingestion was associated with morphological changes (spreading, intense vacuolation); moreover, a large proportion of the cells was binucleated (more than 30% with 10 micrograms/mL). The oxalic acid-leached chrysotile inhibited growth at a concentration of 50 micrograms/mL; with 5 or 10 micrograms/mL, no spreading occurred, but a shrinkage of some cells was observed. A few large vacuoles were seen in the cytoplasm of the cells; there were fewer binucleated cells. Addition of 5 or 10 micrograms/mL of crocidolite, either leached or unleached, did not significantly change the growth rate, in spite of the presence of a large number of fibers inside the cells which persisted when the cells reached confluency. With 20 or 50 micrograms/mL, the mean population doubling time was increased in a dose-dependent manner. A slight vacuolation of the cells occurred. The sample of quartz did not modify the parameters studied in this report. The results confirm the different in vitro reactivities of the two kinds of unleached asbestos fibers. Leaching of chrysotile fibers decreased their reactivity; alternatively, leaching of crocidolite increased the effects on PMC.

In plain English

This was a laboratory experiment on cultured cells. The authors added UICC chrysotile A and crocidolite asbestos to rat pleural mesothelial cells (lining cells of the chest cavity) from six rats. Each fiber was tested untreated and oxalic-acid leached, and DQ12 quartz served as comparison. Particles were added for 48 hours at 5 to 50 micrograms per millilitre. Dividing and two-nucleus cells were counted at 48 or 72 hours, and growth was checked daily. Untreated chrysotile caused vacuoles, cell enlargement and many two-nucleus cells: at 72 hours, 29.3% at 5 and 37.3% at 10 micrograms per millilitre, against 1.7% in untreated cells. Leaching reduced this effect for chrysotile but increased crocidolite's effect. Quartz had no significant effect on growth, and no particle changed the share of dividing cells at 48 hours. The calculated concentration at which no growth would occur was 22.6 micrograms per millilitre for chrysotile, 28.8 for leached chrysotile, 51 for leached crocidolite and 237 for crocidolite. The authors concluded that the two unleached fibers reacted differently in the laboratory. They noted that size differences between fiber samples may require reconsidering the results.

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 cultured rat cells, short-term exposures
• Who was studied: Rat pleural mesothelial cells (PMC) from six different rats, used between the 6th and 17th passage in culture; laboratory in Creteil, France
• Exposure: UICC chrysotile A and crocidolite, either unleached or leached with 0.1 N oxalic acid. DQ12 quartz was the control particle. Particles were added for 48 hours at 5, 10, 20 or 50 micrograms per millilitre, 24 hours after plating. Mitosis and binucleated cells were counted after 48 or 72 hours of incubation, and cell numbers were compared with controls every day.
• Main results:
  • Cells treated with unleached chrysotile had numerous vacuoles, increased cell volume and many binucleated cells. Seventy-two hours after contact with the particles, 29.3 (plus or minus 0.2)% were binucleated at 5 micrograms per millilitre and 37.3 (plus or minus 2.5)% at 10 micrograms per millilitre. In the chrysotile control cultures the figure was 1.7 (plus or minus 0.8)%.
  • Acid-leached chrysotile produced binucleated cells, but at a lower percentage than unleached chrysotile. The difference from untreated cultures was significant at 10 micrograms per millilitre for leached chrysotile and at 5 micrograms per millilitre for unleached chrysotile.
  • Leached crocidolite had more effect than unleached crocidolite. At 10 micrograms per millilitre it significantly increased binucleated cells, whereas unleached crocidolite needed 50 micrograms per millilitre.
  • No particle type changed the percentage of cells in mitosis measured 48 hours after the particles were added.
  • DQ12 quartz had no significant effect on the mean population doubling time and did not change the morphology of the cultures.
  • A lag time in growth occurred with unleached chrysotile but not with leached chrysotile or with crocidolite, leached or unleached.
  • The calculated concentration at which no growth occurred was 22.6 micrograms per millilitre for chrysotile, 28.8 for leached chrysotile, 237 for crocidolite and 51 for leached crocidolite. Compared by weight, toxicity increased in the order crocidolite, leached crocidolite, leached chrysotile, chrysotile.
  • Cell numbers in treated and untreated cultures were compared every day with the F test.
  • Chrysotile and leached crocidolite were both effective at 5 micrograms per millilitre, but a significant effect took longer to appear with leached crocidolite.
• The authors' conclusion: The authors concluded that the results confirmed different in vitro reactivities of unleached chrysotile and crocidolite, and that leaching decreased chrysotile's reactivity but increased crocidolite's effects on these cells. Because other leached chrysotile samples had not caused mesothelioma in earlier work, they suggested that this cytotoxicity was not related to the probability of causing mesothelioma.
• Limitations the authors state:
  • The fiber samples differed in size and in the distribution of fiber numbers by size, so the results may need to be reconsidered.
  • It is not known whether the batch of leached chrysotile used here was carcinogenic.
  • Comparisons between fiber types in growing cells must be made carefully, because the shape of the dose-effect relationship can reverse an effect.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelial Cells, UICC, Crocidolite, Chrysotile.

Related studies

• Comparative toxicities of different forms of asbestos in a cell culture assay — B. Reiss, S. Solomon, et al. (1980)
• Effect of chrysotile and crocidolite on the morphology and growth of rat pleural mesothelial cells — M.C. Jaurand, I. Bastie-Sigeac, et al. (1983)
• Studies on in vitro chrysotile-pleural mesothelial cell interaction: morphological aspects and metabolism of benzo-3,4-pyrene — M.C. Jaurand, I. Bastie-Sigeac, et al. (1983)
• Induction of metaphase and anaphase/telophase abnormalities by asbestos fibers in rat pleural mesothelial cells in vitro — M. Yegles, L. Saint-Etienne, et al. (1993)
• Analysis of cell cycle disruptions in cultures of rat pleural mesothelial cells exposed to asbestos fibers — V. Levresse, A. Renier, et al. (1997)
• In vitro biodegradation of chrysotile fibres by alveolar macrophages and mesothelial cells in culture: comparison with a pH effect — M.C. Jaurand, A. Gaudichet, et al. (1984)

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