Related Experiment Video
Updated: May 16, 2026
High-Resolution Fluorespirometry to Assess Dynamic Changes in Mitochondrial Membrane Potential in Human Immune Cells
Published on: May 24, 2024
Monitoring mitochondrial inner membrane potential for detecting early changes in viability of bacterium-infected
Introduction:
One of the most challenging safety issues in the manufacture of cell based medicinal products is the control of microbial risk as cell-based products cannot undergo terminal sterilization. Accordingly, sensitive and reliable methods for detection of microbial contamination are called for. As mitochondrial function has been shown to correlate with the viability and functionality of human mesenchymal stem cells (hMSCs) we have studied the use of a mitochondrial inner membrane potential sensitive dye for detecting changes in the function of mitochondria following infection by bacteria.
Methods:
The effect of bacterial contamination on the viability of bone marrow-derived mesenchymal stem cells (BMMSCs) was studied. BMMSC lines were infected with three different bacterial species, namely two strains of Pseudomonas aeruginosa, three strains of Staphylococcus aureus, and three strains of Staphylococcus epidermidis. The changes in viability of the BMMSCs after bacterial infection were studied by staining with Trypan blue, by morphological analysis and by monitoring of the mitochondrial inner membrane potential.
Results:
Microscopy and viability assessment by Trypan blue staining showed that even the lowest bacterial inocula caused total dissipation of BMMSCs within 24 hours of infection, similar to the effects seen with bacterial loads which were several magnitudes higher. The first significant signs of damage induced by the pathogens became evident after 6 hours of infection. Early changes in mitochondrial inner membrane potential of BMMSCs were evident after 4 hours of infection even though no visible changes in viability of the BMMSCs could be seen.
Conclusions:
Even low levels of bacterial contamination can cause a significant change in the viability of BMMSCs. Moreover, monitoring the depolarization of the mitochondrial inner membrane potential may provide a rapid tool for early detection of cellular damage induced by microbial infection. Accordingly, mitochondrial analyses offer sensitive tools for quality control and monitoring of safety and efficacy of cellular therapy products.
Insights
Detecting microbial contamination in cell-based therapies is crucial. Monitoring mitochondrial inner membrane potential in human mesenchymal stem cells (hMSCs) offers a rapid method for early detection of bacterial infection and cellular damage.
Area of Science:
- Cellular Biology
- Microbiology
- Biotechnology
Background:
- Cell-based medicinal products face manufacturing challenges due to microbial contamination risks, as terminal sterilization is not feasible.
- Sensitive detection methods are essential for ensuring the safety and efficacy of these products.
- Mitochondrial function correlates with human mesenchymal stem cell (hMSC) viability and functionality.
Purpose of the Study:
- To investigate the use of a mitochondrial inner membrane potential-sensitive dye for detecting changes in hMSC function after bacterial infection.
- To assess the impact of bacterial contamination on the viability of bone marrow-derived mesenchymal stem cells (BMMSCs).
Main Methods:
- BMMSC lines were infected with Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis.
- Cell viability was assessed using Trypan blue staining and morphological analysis.
- Mitochondrial inner membrane potential was monitored using a sensitive dye.
Main Results:
- Even low bacterial inocula caused complete BMMSC loss within 24 hours.
- Significant pathogen-induced damage was observed after 6 hours of infection.
- Early changes in mitochondrial inner membrane potential were detected after 4 hours, preceding visible viability loss.
Conclusions:
- Low-level bacterial contamination significantly impacts BMMSC viability.
- Monitoring mitochondrial inner membrane potential depolarization is a rapid tool for early detection of microbial-induced cellular damage.
- Mitochondrial analyses provide sensitive tools for quality control and safety monitoring of cellular therapy products.
