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Harnessing Mitochondrial Dynamics: A Breakthrough in Muscle Stem Cell Research

Explore how mitochondrial dynamics impact stem cells and muscle regeneration, the challenges of live cell metabolics, and advances in real-time cellular monitoring.

| 5 min read

In the quest to understand and enhance muscle regeneration, the focus has shifted to the intricate roles of mitochondria within stem cells. Recent research by Mireille Khacho and Matthew Triolo from the University of Ottawa highlights the influence of mitochondrial dynamics on muscle stem cell function. Their groundbreaking work uncovers how the shape and behavior of mitochondria can drive essential processes like cell-cycle entry and differentiation, offering promising avenues for treating muscle-wasting conditions and advancing regenerative medicine.

Q: Can you tell us about your research on the impacts of mitochondrial dynamics in stem cells and why this is so important?

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A: Mitochondria are typically referred to as “the powerhouse of the cell”. However, we now understand that they are far more than just an energy producing component of the cell. These organelles mediate a magnitude of intracellular signaling pathways that are required for maintaining normal cellular functions. In our lab, we study how the shape of mitochondria, which is governed by a process referred to as mitochondrial dynamics, impacts cellular functions. This could be via moderating energy production and/or cellular signaling. We have discovered that following damage to skeletal muscle, the mitochondria within resident muscle stem cells (MuSCs) undergo rapid fragmentation. Using genetic and pharmacologic models, we have further uncovered that this fragmentation of the mitochondria is required for proper MuSC function through modulating integral REDOX signaling mechanisms. These signaling processes thereby: 1) facilitate the cell-cycle entry of these normally quiescent/dormant stem cells and 2) ensure that these stem cells make appropriate fate decisions. 

Headshot of Mireille Khacho

Dr. Mireille Khacho

Furthermore, we have uncovered that elongation of mitochondria, through organelle fusion, is then required to modulate the differentiation of muscle precursor cells into functional muscle. Work of this nature is extremely important, as there is an abundance of evidence that during many pathophysiological situations (i.e., muscular dystrophy, cachexia, age-related sarcopenia etc.) mitochondrial dynamics are perturbed in both the skeletal muscle and their resident MuSCs. Ultimately, this may contribute to an inability of MuSCs to properly aid in regeneration of muscle following injury, and ultimately a deterioration of the tissue.

Q: What are some of the key challenges and best practices that scientists must keep in mind when performing live cell metabolics?

A: As with any experimental procedure, there are challenges that must be overcome. With respect to live cell respirometry, an extremely important factor for investigators to consider is establishing an environment that truly represents a physiologic setting that can be maintained throughout the experiment. As such, conditions for experiments should be chosen to minimize the manipulation of cells to avoid stress to the cells (i.e., constant temperature, low vibration / shaking, proper humidity and gas levels etc.). For example, in our laboratory, when we monitor cellular oxygen consumption, we ensure that the incubator being used is independent of other ongoing experiments. This will minimize opening/closing of the incubator door, which alters the cellular environment. Furthermore, scientists must choose equipment and design protocols to ensure that the monitoring system does not impede normal cellular functions, and thus truly reflects cell metabolism. It would be best to work with the developers of these equipment to test that cell function is maintained in the experimental apparatus.

Q: How does live cell monitoring of parameters like oxygen consumption aid live cell functional assays?

A: The ability to monitor oxygen consumption in live cells has provided an immense benefit when used in isolation to evaluate metabolic changes in cells in different experimental conditions (i.e., while cells are proliferating, during and after cellular differentiation, in response to genetic or pharmacological manipulations etc.). However, it has also advanced the field, in that this technology can be used in parallel with other measures of cellular function and/or viability. 

headshot of Dr. Matthew Triolo

Dr. Matthew Triolo 

Q: What methods and technologies does your lab employ for live cell monitoring, imaging, and cellular respiration?

A: Our lab utilizes multiple methods to monitor cells in their “native” environment. Firstly, using technology that has existed for a number of years, we visualize cellular processes using fluorescence microscopy in real time. This includes, but is not limited to, monitoring mitochondrial reactive oxygen species production via mitoSOX staining and evaluating lipid droplet dynamics with Bodipy staining. More recently, we have begun to utilize the Resipher Device from Lucid Scientific to monitor cellular respiration of muscle cells. This technology allows us to understand the contribution and/or requirement of mitochondria to metabolism within muscle cells. For example, our group has recently published that as muscle precursor cells (myoblasts) differentiate into mature muscle cells (myotubes), there is an elongation of the mitochondria within these cells and a consequential increase in mitochondrial respiration. This is commonly referred to as a metabolic switch. Excitingly, by using live cell monitoring of cellular respiration, we were able to show that if we prevent mitochondrial elongation, both genetically or pharmacologically, that differentiation cannot occur and there is a failure to upregulate mitochondrial respiration.

Q: What recent advancements in live cell monitoring have impacted your research most? 

A: Live cell monitoring is not an entirely new concept. As an example, tools to visualize and track cells and/or their intracellular components microscopically have been utilized for decades. Regarding metabolism, beyond monitoring whole animal metabolic changes in real time, there have been very few tools to assess live metabolism at a cellular level. Although very useful tools do exist to measure the metabolic efficiency of cells (i.e., mitochondrial respiratory capacity measurements), they do not capture real-time, dynamic, and physiologic changes. Thus, as a laboratory studying mitochondria in a variety of systems, such as in stem cells, we have benefited from being able to use tools  to monitor oxygen consumption in a live cell system.

Q: How do you see the field evolving in the next five to 10 years?

A: Presently, there seems to be a push in the development of technologies to monitor metabolic changes in cell models. These include measuring: 1) oxygen consumption for mitochondrial respiration, and 2) media glucose and lactate levels as a readout of glycolytic activity. It is plausible that the advancing technologies and biosensors will allow for measurements such as these to be made in unison.  We are hopeful that the field will continue to advance to a point in which other aspects of cellular metabolism can be monitored simultaneously in real time; for example, specific metabolite and/or substrate utilization or production by cells. We foresee this extending into animal models and humans as well, where technologies to track physiologic and metabolic properties in real-time are relatively limited. Ultimately, this would have implications for the health and well-being of our population.


Bios: Dr. Mireille Khacho joined the Faculty of Medicine at the University of Ottawa as an assistant professor in the Department of Biochemistry, Microbiology and Immunology in January 2018. She is also the Canada Research Chair Tier2 in Mitochondrial Dynamics and Regenerative Medicine. Dr. Khacho has made significant contributions to our current understanding of the role of mitochondrial shape in stem cell function and longevity. Her studies led to the discovery that mitochondria are upstream signaling centers that dictate stem cell fate. This work has far reaching implications in aging and regenerative medicine. Dr. Khacho’s future research is focused on understanding key mitochondrial signaling pathways that are crucial for stem cell maintenance during aging and degenerative diseases. 

Dr. Matthew Triolo is a postdoctoral fellow working with Dr. Mireille Khacho’s lab in the Faculty of Medicine at the University of Ottawa. Prior to his time in Dr. Khacho’s lab, Dr. Triolo completed his PhD under the supervision of Dr. David Hood as a member of the Muscle Health Research Centre at York University. During this time, he contributed to our understanding of skeletal muscle adaptations to exercise, disuse and aging. During his fellowship, Matthew has been funded by Muscular Dystrophy Canada in collaboration with the Neuromuscular Disease Network for Canada, and the Natural Science and Engineering Research Council of Canada. Dr. Triolo’s current work investigated mechanisms by which mitochondria regulate muscle stem cell homeostasis and function in both healthy and degenerative conditions.

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About the Author

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    Lauren Everett

    Lauren Everett is the managing editor for Lab Manager. She holds a bachelor's degree in journalism from SUNY New Paltz and has more than a decade of experience in news reporting, feature writing, and editing. She oversees the production of Lab Manager’s editorial print and online content, collaborates with industry experts for speaking engagements, and works with internal and freelance writers to deliver high-quality content. She has also led the editorial team to win Tabbie Awards in 2022, 2023, and 2024. This awards program recognizes exceptional B2B journalism and publications. 

    Lauren enjoys spending her spare time hiking, snowboarding, and keeping up with her two young children. She can be reached at leverett@labmanager.com.

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