Rat pleural mesothelial cells adapted to serum-free medium as a model for the study of growth factor effects

Our plain-English summary of Rat pleural mesothelial cells adapted to serum-free medium as a model for the study of growth factor effects, by E. Bermudez, B. Libbus, J.B. Mangum (Cell Biology and Toxicology, 1998).

The study

• Authors: E. Bermudez, B. Libbus, J.B. Mangum
• Journal: Cell Biology and Toxicology
• Published: 1998;14(4):243-51
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Mesothelial cells are the putative progenitors of mesotheliomas and cell lines have been used as tools to study the responses of these cells to various stimuli, including growth factors. The present study was undertaken to develop a rat mesothelial cell line capable of sustained growth under serum-free conditions with the object of avoiding the possible confounding effects of undefined serum components. Responses of mesothelial cells to epidermal growth factor were shown to differ under serum-free versus low-serum culture conditions. In contrast, a cell line, SFM1, adapted to growth in serum-free medium was characterized and found to exhibit responses to growth factors similar to the responses reported for human cell lines. This new line should prove to be a useful model for the study of these cells in vitro.

In plain English

This laboratory study used rat cells grown in dishes. It did not test asbestos or other fibers. The authors gradually weaned a rat pleural mesothelial cell line, NRM2, off serum over seven weeks, creating a line called SFM1 that grows in serum-free medium. SFM1 cells doubled in 38 hours (NRM2: 40 hours) and kept typical mesothelial features, including a cobblestone shape, microvilli and tight junctions. NRM2 cells kept in 1% serum increased 2-fold in 4 days, and 4-fold when given epidermal growth factor (EGF) at 10 ng/ml. In serum-free medium, NRM2 cells did not respond to EGF. In SFM1 cells, EGF at 1 and 5 ng/ml and platelet-derived growth factor (PDGF) at 10 and 20 ng/ml gave statistically significant increases in cell numbers. Both factors together increased numbers more than either one alone. SFM1 cells carried chromosome changes and did not form tumors when injected into nude mice (5 per group). The authors concluded that SFM1 should be a useful model for studying these cells in the laboratory.

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) cell culture study developing and characterizing a serum-free rat mesothelial cell line, with a small tumor test in nude mice
• Who was studied: The rat pleural mesothelial cell line NRM2 and its serum-free-adapted derivative SFM1, studied at the Chemical Industry Institute of Toxicology, North Carolina, USA. Tumor-forming ability was tested in female CD-1 nu/nu (nude) mice, 5 animals per group, watched for 20 weeks.
• Exposure: No fibers were tested. Cells were treated with epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) at 1, 5, 10 or 20 ng/ml, alone or combined at 10 ng/ml each, in serum-free medium or in medium with 1% fetal bovine serum.
• Main results:
  • Adapting NRM2 cells to serum-free (HL-1) medium took seven weeks (5 passages). The adapted line was named SFM1.
  • Doubling times were 38 hours for SFM1 and 40 hours for NRM2.
  • NRM2 cells kept in 1% serum increased 2-fold in 4 days. With 10 ng/ml EGF they increased 4-fold (statistically significant).
  • NRM2 cells kept in serum-free medium did not double and did not respond to EGF.
  • NRM2 cells showed no growth effect from PDGF at 1, 5, 10 or 20 ng/ml.
  • SFM1 cells kept the cobblestone shape typical of mesothelial cells. They had microvilli, rough endoplasmic reticulum and tight junctions, and expressed both vimentin and keratin.
  • In SFM1 cells, cell numbers rose with EGF at 1, 5, 10 and 20 ng/ml, but only the 1 and 5 ng/ml increases were statistically significant.
  • In SFM1 cells, PDGF at 10 and 20 ng/ml significantly increased cell numbers. PDGF at 1 ng/ml was followed by a decrease in cell numbers.
  • In SFM1 cells, EGF and PDGF together (10 ng/ml each) increased cell numbers more than either factor alone (statistically significant).
  • SFM1 cells had a modal chromosome number of 43. They showed consistent abnormalities, including a duplication on chromosome 1 and a translocation between chromosomes 2 and 11.
  • SFM1 cells did not form tumors when injected under the skin of nude mice.
• The authors' conclusion: The authors concluded that SFM1 cells, adapted to serum-free medium, showed the characteristics and growth factor responses of normal rat and human mesothelial cells in culture, and should be a useful model for studying these cells in the laboratory.
• Limitations the authors state:
  • The lipid preparations used in the SF medium have undefined composition and can be toxic to SFM1 cells, so each new batch must be titrated.
  • SFM1 cells grew poorly at low density and did not form colonies.
  • The reason for the apparent fall in SFM1 cell numbers at higher EGF concentrations remains unclear.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelial Cells, Mesothelioma, Confounding.

Related studies

• Establishment and characterization of 20 human non-small cell lung cancer cell lines in a serum-free defined medium (ACL-4) — N. Masuda, M. Fukuoka, et al. (1991)
• Proteoglycans in human malignant mesothelioma. Stimulation of their synthesis induced by epidermal, insulin and platelet-derived growth factors involves receptors with tyrosine kinase activity — A. Syrokou, G.N. Tzanakakis, et al. (1999)
• Role of peptide growth factors in asbestos-related human lung cancer — B. Guillemin, Y. Zhang, et al. (1991)
• Different accumulation of activated extracellular signal-regulated kinases (ERK 1/2) and role in cell-cycle alterations by epidermal growth factor, hydrogen peroxide, or asbestos in pulmonary epithelial cells — S. Buder-Hoffmann, C. Palmer, et al. (2001)
• Expression of growth factor and growth factor receptor RNA in rat pleural mesothelial cells in culture — E. Bermudez, J. Everitt, et al. (1990)
• Differential proliferation of rat lung fibroblasts induced by the platelet-derived growth factor-AA, -AB, and -BB isoforms secreted by rat alveolar macrophages — J.C. Bonner, A.R. Osornio-Vargas, et al. (1991)

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