Metabolism and Organelles Unveiled with Nanolive’s 3D Label-free Live Cell Imaging Microscope

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 (~0.02 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.

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.

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). Objective magnification is 60x. On the bottom panels we progressively zoom into the cells to better appreciate all details of these interactions (2x = 120x; 4x = 240x; 8x = 480x). 

The following two movies want to drive your attention to mitochondria dynamics. Dynamic details of fusions, fissions and mitochondrial network remodeling are highlighted.

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.

Live imaging of mouse pre-adipocytes for 48 hours. 1 image per minute.

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 on the bottom, mitochondria are displayed for identification at different time points. On the right panel we reported an static TEM image of mitochodria.

  1. 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).
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