A study of surface property changes in rat mesothelial cells induced by asbestos using aqueous two-phase polymer solutions

Our plain-English summary of A study of surface property changes in rat mesothelial cells induced by asbestos using aqueous two-phase polymer solutions, by M.M. Lee, F.H. Green, D.J. Demetrick, et al (Biochimica et Biophysica Acta, 1993).

The study

• Authors: M.M. Lee, F.H. Green, D.J. Demetrick, X. Jiang X, S. Schürch
• Journal: Biochimica et Biophysica Acta
• Published: 1993;1181(3):223-32
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Intraperitoneal (i.p.) injection of crocidolite asbestos was used to induce mesotheliomas in rats. The morphological changes of the mesothelial cells were studied by light and electron microscopy and by cytologic examination of peritoneal washings. After injection, the asbestos fibres stimulated an acute inflammatory response and were rapidly phagocytosed by the mesothelial cells and incorporated into the submesothelial tissues. At 7 days, the normal microvillous surface of the mesothelium was replaced with a syncytium of proliferating mesothelial cells showing extensive loss of microvilli. Nine months or so later, multifocal mesothelial tumours arose within the peritoneal cavity. The surface thermodynamic properties of normal, asbestos-stimulated mesothelial cells and of mesothelial tumour cells in culture were studied using an aqueous two-phase system containing 4% Dextran T-2000 and 4% poly (ethylene glycol) (PEG) w/w. After asbestos stimulation, there was a significant (P < 0.01) increase in contact angle between the dextran-rich phase and the mesothelial cell surface. These changes were even greater for the mesothelial tumours. The results indicate that the work of adhesion for asbestos-stimulated mesothelial cells and mesothelial tumours is lower than in normal tissue. These findings may be relevant to the process of tumour spread in the serosal cavities and to the development of distant metastases.

In plain English

This was an animal experiment in male Fischer 344 rats. The rats were injected into the abdominal (peritoneal) cavity with crocidolite asbestos or with saline alone. The 50 mg dose was used to follow tissue changes and tumour development, and the 10 mg dose to study cell surface properties. Asbestos caused intense inflammation, which was resolving by the seventh day. The first tumours were seen 9 months after injection. The authors measured the angle a droplet of a dextran-rich solution made on cell surfaces; a higher angle meant a lower work of adhesion. On the liver surface, the angle was 59.6° in normal tissue, 76.4° one week after asbestos and 64.2° at one month. Both increases were statistically significant (P less than 0.01). Cultured epithelial-type cells from one tumour averaged 83.3°, significantly higher than normal lining. The authors concluded that asbestos alters the surface properties of the mesothelial lining and that these changes persist in the tumours that develop. They also concluded that the changes were not due to a coating of fibronectin-rich exudate.

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: rats injected with crocidolite asbestos to induce mesotheliomas, with microscopy, peritoneal washings, and contact-angle measurements of cell surfaces in a dextran/PEG two-phase polymer system
• Who was studied: Male Fischer 344 rats weighing 100-150 g. Surface studies used groups of 6 animals at 0, 7 and 28 days, plus cultured cells from one biphasic mesothelioma that arose 9 months after asbestos injection
• Exposure: Intraperitoneal injection of 10 or 50 mg crocidolite asbestos in saline, or saline alone; uninoculated animals were additional controls. Fibres had a mean length of 8.0 micrometres and a mean diameter of 0.12 micrometres
• Main results:
  • In asbestos-injected rats, an acute inflammatory reaction was resolving by day 7, and the mesothelial surfaces were covered by proliferating mesothelial cells
  • Total cell counts in peritoneal washings of asbestos-injected rats peaked at 7 days and had returned to control values 14 days after injection
  • In rats given 50 mg crocidolite, the first tumours were observed 9 months after injection; they were multifocal and papillary, with biphasic differentiation
  • Contact angles on normal mesothelium were 59.6 degrees for liver and 59.9 degrees for abdominal wall
  • One week after asbestos, contact angles were significantly increased (P less than 0.01) on both liver (76.4 plus or minus 0.96, n=35) and abdominal wall (67.5 plus or minus 2.93, n=11) compared with untreated controls
  • One month after injection, the liver contact angle (64.2 plus or minus 1.15, n=33) was significantly higher than controls (P less than 0.01); the abdomen value was 63.9 plus or minus 2.02 (n=26)
  • Work of adhesion for liver mesothelium fell from 6.04 (normal) to 4.96 (1 week post-asbestos), in units of 10 to the minus 6 J per square metre
  • Cultured epithelial-type mesothelioma cells had a combined mean contact angle of 83.3 plus or minus 0.64 (n=41). Tumour cell angles were significantly greater than both normal and asbestos-treated mesothelium (P less than 0.01)
  • Contact angles of sarcomatous (spindle-shaped) tumour cells did not differ from those of epithelial-type tumour cells
  • Fibronectin-coated and albumin-coated glass gave contact angles of 129.0 and 89.0 degrees. The authors concluded that the asbestos-induced changes were not due to coating by fibronectin-rich inflammatory exudate
• The authors' conclusion: The authors concluded that asbestos exposure alters the surface thermodynamic properties of the mesothelial surface and that these alterations persist in the tumours that develop
• Limitations the authors state:
  • Scraping sarcomatous cells off culture flasks increased their contact angle by 9%, which the authors said could produce artifacts in experiments done right after harvesting

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelial Cells, Crocidolite, Mesothelioma, Mesothelium, Peritoneal Cavity.

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