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Published on: August 6, 2013
A Low-Serum Culture System for Prolonged in Vitro Toxicology Experiments on a Macrophage System
Bastien Dalzon1, Anaelle Torres1, Julie Devcic1
1Chemistry and Biology of Metals, Université Grenoble Alpes, CNRS UMR5249, CEA, IRIG-DIESE-LCBM-ProMIT, Grenoble, France.
Insights
This study developed an improved in vitro method for studying how macrophages respond to persistent toxicants like asbestos and silica. The new protocol better mimics real-world occupational exposure by allowing longer cell culture periods and maintaining macrophage functions.
Area of Science:
- Immunotoxicology
- Cell Biology
- Materials Science
Background:
- Immunotoxicology encompasses immune cell toxicity and reactions to toxicants.
- Macrophages are key immune cells responding to particulate materials like asbestos and silica.
- Existing in vitro systems often fail to model chronic, low-dose occupational exposures.
Purpose of the Study:
- To develop an improved in vitro system for studying macrophage responses to persistent toxicants.
- To address limitations of acute exposure models in current in vitro toxicology.
- To investigate the effects of chronic, low-dose exposures on macrophages.
Main Methods:
- Modified cell culture techniques for the murine macrophage cell line J774A.1.
- Reduced animal serum concentration and switched to adult serum to limit proliferation.
- Maintained macrophage differentiated functions (phagocytosis, inflammatory response) over several days.
- Preserved protein corona formation on particulate materials.
Main Results:
- Achieved prolonged macrophage cultures (several days) simulating chronic exposure.
- Significantly reduced cell proliferation, better reflecting resident macrophage behavior.
- Sustained key macrophage functions, including phagocytosis and inflammatory responses.
- Demonstrated the importance of serum for cell viability and protein corona formation.
Conclusions:
- The modified culture protocol enables realistic in vitro modeling of chronic toxicant exposure on macrophages.
- This system is valuable for assessing the immunotoxicological effects of persistent particulate materials.
- The findings have implications for occupational health and safety regarding materials like silica and asbestos.
Abstract:
Immunotoxicology sensu lato comprises not only toxicity toward immune cells, but also biological reactions from immune cells exposed to toxicants, reactions that may have deleterious effects at the organismal level. Within this wide frame, a specific case of interest is represented by the response of macrophages to particulate materials, with the epitome examples of asbestos and crystalline silica. For such toxicants that are both persistent and often encountered in an occupational setting, i.e. at low but repeated doses, there is a need for in vitro systems that can take into account these two parameters. Currently, most in vitro systems are used in an acute exposure mode, i.e., with a single dose and a readout made shortly if not immediately after exposure. We describe here how adequate changes of the culture methods applied to the murine macrophage cell line J774A.1 enable longer periods of culture (several days), which represents a first opportunity to address the persistence and dose-rate issues. To respond to this, the protocol uses a reduction in the concentration of the animal serum used for cell culture, as well as a switch from fetal to adult serum, which is less rich in proliferation factors. By doing so, we have considerably reduced cell proliferation, which is a problem with cell lines when they are supposed to represent slowly-dividing cells such as resident macrophages. We also succeeded in maintaining the differentiated functions of macrophages, such as phagocytosis or inflammatory responses, over the whole culture period. Furthermore, the presence of serum, even at low concentrations, provides excellent cell viability and keeps the presence of a protein corona on particulate materials, a feature that is known to strongly modulate their effects on cells and is lost in serum-free culture. Besides data showing the impact of these conditions on macrophages cell line cultures, illustrative examples are shown on silica- and cobalt-based pigments.
