Mitochondria & Cell Metabolism
Cellular metabolism is a complex, integrated process that is supported by key organelles, such as lipid droplets and mitochondria, which engage in numerous energetic and signaling mechanisms.
A better understanding of the dynamics and interactions of such organelles could advance research in aging, cancer, degenerative diseases or obesity.
Non-invasive live cell imaging overcomes phototoxicity problem while imaging cellular metabolism processes
A major problem with current imaging techniques is phototoxicity that leads to the observation of perturbed dynamics. Consequently, the mitigation of phototoxicity leads to poor time resolution of time lapse approaches. This is particularly true for small organelles like mitochondria or lipid droplets that are extremely sensitive to photo-induced oxidation. Last but not least, the use of chemical or genetically-encoded fluorescent markers perturbs the targeted biological processes.
However, the 3D Cell Explorer overcomes this problematic as it injects in the sample ~100 times less energy (~0.2 nW/µm2) than light sheet microscopes (~1nW/µm2) that are the reference in the matter. With a resolution below 200 nm, it enables high resolution and high-frequency imaging even with sensitive material, giving access to organelle dynamics that were previously out of reach.
Novel movies showing lipid droplets and mitochondria fine dynamics live and at high resolution
Thanks to the 3D Cell Explorer’s live imaging capabilities, highlights of lipid droplets and mitochondria fine dynamics that were previously out of reach are clearly visible now.
The movies presented hereafter were taken at a frequency of one image per five seconds. This acquisition frequency can be reached over long periods of time thanks to the absence of phototoxicity with Nanolive’s imaging technique which allows to obtain label-free images at high spatial and temporal resolution (the 3D Cell Explorer has a unique implementation of holotomographic microscopy).
The two movies here below, obtained from the same time-lapse, show the close and mysterious relation between lipid droplets and mitochondria1. On top of sharing common dynamics and trajectories, mitochondria are reaching out towards lipid droplets, making clear contacts and moving away. LD-mitochondria contacts are seen here like never before, which opens doors towards a better understanding of LD-mitochondria interdependency in unperturbed or perturbed conditions.
- Benador, I. Y. et al. Mitochondria Bound to Lipid Droplets Have Unique Bioenergetics, Composition, and Dynamics that Support Lipid Droplet Expansion. Cell Metab. 27,869–885.e6 (2018).
PLOS Biology Publication
Researchers from EPFL demonstrated and published on PLOS Biology that mammalian cellular organelles such as lipid droplets (LDs) and mitochondria show specific RI 3D patterns. Moreover, they could observe the shape and dry mass dynamics of LDs, endocytic structures, and entire cells’ division that have so far, to the best of our knowledge, been out of reach. Finally, they could capture the motion of many organelles at the same time to report a multiorganelle spinning phenomenon and study its dynamic properties.
Video 1: On the left panel you can observe a time-lapse of pre-adipocytes imaged with the 3D Cell Explorer for 1 hour at a frequency of one image per five seconds (movie speed: 15fps). On the right panel we zoomed a portion of the field of view to better appreciate the interactions between mitochondria and lipid droplets. On the two small squares on the bottom, the two organelles are displayed for identification at different time points.
Video of label-free live cell imaging of a Preadipocyte cell with Nanolive imaging
Mitochondria DynamicsFusions, fissions and mitochondrial network remodeling
The following movies want to drive your attention to mitochondria dynamics. Dynamic details of fusions, fissions and mitochondrial network remodeling are highlighted.
Video 3: Live imaging of mouse pre-adipocytes for 48 hours. 1 image per minute.
Video 4: On the left panel you can observe a time-lapse of pre-adipocytes imaged with the 3D Cell Explorer for 1 hour at a frequency of one image per five seconds (movie speed: 15fps). On the small square in the bottom, mitochondria are displayed for identification at different time points. On the right panel we reported a static TEM image of mitochondria.
On the top panel you can observe a time-lapse video of of pre-adipocytes imaged with the 3D Cell Explorer for 1 hour at a frequency of one image per five seconds (movie speed: 15fps). On the middle panel are displayed four time point images of a mitochondrial fission happening in the cell. On the bottom panel a fusion process is displayed.
On the left panel you can observe a time-lapse of pre-adipocytes imaged with the 3D Cell Explorer for 1 hour at a frequency of one image per five seconds (movie speed: 15fps). On the right panel we zoomed a portion of the field of view to better appreciate the remodeling of the mitochondrial network. On the small squares on the bottom, four time point images are displayed.
Monitoring live and label-free effect of Khondrion’s drug KH176 with the 3D Cell Explorer
Khondrion’s drug KH176 rescues the cytotoxic effect by BSO
In collaboration with Khondrion, a leading clinical-stage pharmaceutical company focusing on small molecule therapeutics for mitochondrial diseases, we image here the effect of KH176, Khondrion’s leading drug candidate, in rescuing the cytotoxic effect induced by Buthionine sulfoximine (BSO). BSO inhibits the biosynthesis of glutathione, an endogenous molecule crucial for the maintenance of cellular redox states, progressively leading to cell death. KH176 counteracts BSO-induced cell death by targeting peroxiredoxin enzymes.
Neuronal Mitochondria Dynamics
Now neuroscience can observe the dynamics and behavior of living and completely unperturbed mitochondria inside axons, dendrites and around the nucleus.
Watch our Webinar: Mitochondria and lipid droplets in the spotlight: Label-free imaging of cell metabolism
Dr. Mathieu Frechin, Head of Quantitative Biology at Nanolive introduces you to the advantages of our holotomographic microscope for imaging key organelles supporting cellular metabolism such as mitochondria and lipid droplets. Watch how – for the first time – it is possible to image mitochondria live and completely marker free.
In particular, the following topics are being covered:
- Challenges in live cell imaging of cellular organelles
- State of the art of label-free microscopy of lipid droplets
- Highlights of our holotomographic approach on organelles live imaging
- Tracking lipid droplets in 3D
Please register here to view the webinar on-demand:
Feature Application: Cell metabolism
In this Feature Application, we show that: (1) holotomography can resolve the spatial and temporal dynamics of mitochondria, LDs and mitochondria-LD interactions in unperturbed conditions; (2) it is possible to induce mitochondrial dysfunction and then restore functioning by the addition of a specific drug and (3) it is possible to induce and then visualize the early stages of LD formation.