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Published on: March 10, 2014
Effects of cyclic strain on the morphology and phagocytosis of macrophages
1Division of Mechanical Science, Department of Systems and Human Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan. oboe@me.es.osaka-u.ac.jp
Abstract:
Morphology and phagocytosis of macrophages were studied after cultured under cyclic strain. Peritoneal macrophages obtained from 6-week old female C57BL/6J mice were attached to silicone rubber sheets, preincubated for 2 hours, and then cultured for 24 and 48 hours under cyclic strain of 5% amplitude and 1 Hz frequency (strained group) or no strain (non-strained group). Control data were obtained from 0-hour cultured cells (control group). Cell morphology was observed with optical and scanning electron microscopes, and shape index (SI) of each cell was determined from the perimeter and adhesion area. Phagocytotic activity was evaluated from the uptake of latex particles 1.5 microm in diameter. The morphology and phagocytosis of macrophages were affected by cyclic strain, although the percentage of differentiated cells was not the case. SI in the strained group was smaller than that in the non-strained group, and had a tendency of decreasing with time. Cyclic strain suppressed the phagocytosis of macrophages for latex particles, and there was a significant difference in the phagocytosis between the strained and the non-strained groups after 24-hour culture.
Insights
Cyclic strain alters macrophage morphology and significantly suppresses their phagocytosis of latex particles. This study reveals mechanical forces impact immune cell function, affecting cellular shape and particle uptake over time.
Area of Science:
- Cellular Biology
- Immunology
- Biomechanics
Background:
- Macrophages are crucial immune cells involved in phagocytosis.
- Mechanical forces, such as cyclic strain, can influence cell behavior and function.
- Understanding these mechanical effects is vital for tissue engineering and understanding inflammatory responses.
Purpose of the Study:
- To investigate the effects of cyclic strain on macrophage morphology and phagocytic activity.
- To quantify changes in macrophage shape index and latex particle uptake under mechanical stress.
Main Methods:
- Peritoneal macrophages from C57BL/6J mice were cultured on silicone sheets.
- Cells were subjected to cyclic strain (5% amplitude, 1 Hz) or maintained without strain for 24 and 48 hours.
- Morphology was assessed using light and scanning electron microscopy, and shape index (SI) was calculated.
- Phagocytosis was measured by the uptake of 1.5 µm latex particles.
Main Results:
- Cyclic strain significantly affected macrophage morphology and phagocytosis, but not differentiation.
- The shape index (SI) of macrophages decreased over time in the strained group compared to the non-strained group.
- Phagocytosis of latex particles was suppressed by cyclic strain, with a significant difference observed after 24 hours.
Conclusions:
- Cyclic strain negatively impacts macrophage phagocytic function.
- Mechanical forces play a significant role in modulating macrophage immune responses.
- These findings have implications for biomaterial design and understanding mechanobiology in immune contexts.
