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Updated: Jun 30, 2025
Polarization of M1 and M2 Human Monocyte-Derived Cells and Analysis with Flow Cytometry upon Mycobacterium tuberculosis Infection
Published on: September 18, 2020
Dielectric properties of human macrophages are altered by Mycobacterium tuberculosis infection
Matthew P Johnson1, Nira Lauterkorn2, Rebecca Lewis3
1Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, UK.
Abstract:
The analysis of cell electrophysiology for pathogenic samples at BSL3 can be problematic. It is virtually impossible to isolate infected from uninfected without a label, for example green fluorescent protein, which can potentially alter the cell electrical properties. Furthermore, the measurement of highly pathogenic organisms often requires equipment dedicated only for use with these organisms due to safety considerations. To address this, we have used dielectrophoresis to study the electrical properties of the human THP-1 cell line and monocyte-derived macrophages before and after infection with non-labelled Mycobacterium tuberculosis. Infection with these highly pathogenic bacilli resulted in changes including a raised surface conductance (associated with reduced zeta potential) and increased capacitance, suggesting an increase in surface roughness. We have also investigated the effect of fixation on THP-1 cells as a means to enable study on fixed samples in BSL1 or 2 laboratories, which suggests that the properties of these cells are largely unaffected by the fixation process. This advance results in a novel technique enabling the isolation of infected and non-infected cells in a sample without labelling.
Insights
This study introduces dielectrophoresis to analyze cell electrophysiology in Mycobacterium tuberculosis infections. The novel technique allows isolation of infected from uninfected cells without labeling, overcoming BSL3 limitations.
Area of Science:
- Cellular electrophysiology
- Microbiology
- Biophysics
Background:
- Analyzing pathogenic cell electrophysiology at BSL3 is challenging due to labeling artifacts and safety concerns.
- Isolating infected cells without altering electrical properties is difficult.
- Current methods require specialized equipment for highly pathogenic organisms.
Purpose of the Study:
- To develop a novel, label-free technique for studying cell electrophysiology in Mycobacterium tuberculosis-infected cells.
- To investigate the electrical property changes in THP-1 cells and macrophages post-infection.
- To assess the feasibility of using fixed cells for electrophysiological analysis.
Main Methods:
- Dielectrophoresis was used to measure electrical properties of THP-1 cells and macrophages.
- Cells were analyzed before and after infection with non-labeled Mycobacterium tuberculosis.
- The effect of fixation on cell properties was evaluated.
Main Results:
- Mycobacterium tuberculosis infection increased surface conductance and capacitance, indicating altered surface roughness.
- Reduced zeta potential was observed in infected cells.
- Cell fixation minimally affected electrical properties, allowing BSL1/2 lab studies.
Conclusions:
- Dielectrophoresis offers a label-free method to distinguish infected from uninfected cells.
- This technique overcomes safety and labeling limitations in BSL3 environments.
- Fixed cells can be utilized for electrophysiological studies, expanding research accessibility.
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