Epithelial outgrowths from lung tissue following intrapleural injection of asbestos dust in experimental animals

Our plain-English summary of Epithelial outgrowths from lung tissue following intrapleural injection of asbestos dust in experimental animals, by J.M. Davis (International Journal of Cancer, 1971).

The study

• Author: J.M. Davis
• Journal: International Journal of Cancer
• Published: 1971;7(2):238-48
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

After the intrapleural injection of asbestos dust in experimental animals, granulomas were produced and large areas of the pleural surface became thickened with fibrous tissue. In guinea-pigs injected with chrysotile dust, alveolar epithelial cells often migrated through the lung surface and were found lining spaces in the areas of pleural fibrosis. Initially these cells exhibited the exact structure of the surfactin-secreting type of alveolar cell, but later many of the cells lost the surfactin granules from their cytoplasm and became ciliated. In some animals cystic formation occurred in the lung tissue and groups of cysts grew out from the lung to invade the areas of pleural fibrosis. These cysts were also lined with surfactin-secreting alveolar cells. The possible association of these epithelial outgrowths and the well-known difficulties of diagnosing pleural mesotheliomas are discussed.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

In this animal experiment, the author injected a single dose of chrysotile or crocidolite asbestos dust into the right pleural cavity (around the lungs) of guinea-pigs, rats and mice: 25 mg for guinea-pigs and rats, 10 mg for mice. The article does not give animal numbers. Animals were examined from 7 days to 4 years later. The dust produced granulomas, and in many guinea-pigs large areas of the pleural surface became thickened with fibrous tissue. No tumours had appeared in the body cavities of guinea-pigs, though the oldest had survived more than 4 years. In guinea-pigs given chrysotile, within 14 days clefts lined with alveolar epithelial cells (cells of the lung's air sacs) had formed outside the lung surface, growing into the fibrous tissue. Many of these cells later lost their surfactin granules and became ciliated. In a few cases, groups of cysts grew from the lung into the fibrosis. Such outgrowths were rare in crocidolite-injected guinea-pigs and in rats and mice. The author concluded that they add a complication to the already confused problem of diagnosing mesothelioma.

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: animal experiment (intrapleural injection), with light and electron microscope examination of pleural lesions
• Who was studied: guinea-pigs, rats and mice, studied at the Department of Pathology, Cambridge University, in work begun in 1965; the number of animals is not stated; animals were examined from 7 days to 4 years after injection
• Exposure: a single intrapleural injection of milled chrysotile or crocidolite asbestos dust: 25 mg in 1 ml distilled water for guinea-pigs and rats, 10 mg in 0.5 ml distilled water for mice
• Main results:
  • At the time of writing, no tumours had been produced in the body cavities of guinea-pigs, although the oldest had survived more than 4 years after injection (tumours in rats and mice were to be described separately)
  • Both dusts rapidly produced large granulomas; in guinea-pigs, in many cases large areas of the pleural surface became thickened with fibrous tissue (summarized from the author's separate publication)
  • In guinea-pigs given chrysotile, clefts lined with epithelial cells formed outside the original pleural surface within 14 days, growing into granulomas and areas of pleural thickening
  • In guinea-pigs given crocidolite, and in rats and mice given either dust, the epithelial outgrowths were rare
  • All clefts examined in the first 6 months were lined by typical alveolar epithelial cells; later many cells lost their surfactin granules and produced cilia, as seen at 33 months
  • In a few cases, from about 9 months onwards, groups of clefts enlarged into cysts, with cyst formation both inside the lung and extending into areas of pleural fibrosis
• The authors' conclusion: The author concluded that outgrowths of alveolar epithelial cells into asbestos-induced pleural fibrosis add a complication to the already confused problem of diagnosing mesotheliomas, and suggested that a malignant change in such outgrowths could produce a diffuse pleural tumour
• Limitations the authors state:
  • The outgrowths occurred with any frequency only in guinea-pigs, a species notably resistant to experimental tumour production
  • The author did not know of reports of such outgrowths in human cases of asbestosis and stated that this needs further investigation
  • The dust was sterilized by heating in water, and the author could only hope that chemical changes to the asbestos were kept to a minimum

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Granuloma, Chrysotile, Fibrosis, Pleural Mesothelioma.

Related studies

• The long term fibrogenic effects of chrysotile and crocidolite asbestos dust injected into the pleural cavity of experimental animals — J.M. Davis (1970)
• The calcification of fibrous pleural lesions produced in guinea-pigs by the injection of chrysotile asbestos dust — J.M. Davis (1971)
• An electron microscope study of the response of mesothelial cells to the intrapleural injection of asbestos dust — J.M. Davis (1974)
• Acute and chronic effects of intraperitoneal injection of two types of asbestos in rats with a study of the histopathogenesis and ultrastructure of resulting mesotheliomas — M.L. Shin, H.I. Firminger (1973)
• Histogenesis and fine structure of peritoneal tumors produced in animals by injections of asbestos — J.M. Davis (1974)
• Further observations on the ultrastructure and chemistry of the formation of asbestos bodies — J.M. Davis (1970)

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