Studying Cellular Metabolism with Label-Free 3D Live Imaging of Cells
Cellular metabolism is a complex process with intricately interwoven components in the thousands. It is kept going by many important cell organelles such as lipid droplets and mitochondria, which take part in numerous cell processes involving energy and cell signaling pathways.
A better insight into how these processes work and interact could help researchers in fields such as cancer, aging, degenerative conditions and obesity.
Using Non-Invasive Live Cell Imaging
Most imaging techniques used today cause phototoxicity and disturbs many cell processes. Thus time-lapse imaging is associated with phototoxicity-induced impairment of resolution. This is especially true when it comes to mitochondria and other small organelles, which cannot tolerate oxidation caused by light. The use of fluorescent markers which are either chemical or encoded in the genetic material also causes a disruption of the very biological processes which are being studied.
The 3D Cell Explorer solves this issue by using about one hundred times less light energy than the reference tool, light sheet microscopes, at about 0.2 nW/µm2 compared to 1nW/µm2. Since the resolution achieved is below 200 nm, it allows images to be taken at high resolution and at high frequency even of samples which are very sensitive to light energy. This brings inaccessible organelles within reach of imaging techniques.
Novel Movies that Allow Live and High-Resolution Imaging of Lipid Droplets and Mitochondrial Fine Dynamics
The 3D Cell Explorer allows fine dynamics of processes involving lipid droplets and mitochondria to be visualized. The movies attached to this article were imaged at one image/5 seconds. This frequency of acquisition is achievable for long durations because there is no phototoxicity provided that the experimenter makes use of Nanolive’s imaging techniques.
Instead, the images are label-free, and offer high temporal and spatial resolution. The device uses holotomographic microscopy in a very unique manner.
The two movies below belong to the same time-lapse and show how mitochondria and lipid droplets are related1. Not only do these organelles have the same trajectories and dynamics, but the mitochondria are shown to be groping towards the lipid droplets, coming in definite contact and moving apart.
Contacts between lipid droplets and mitochondria are seen in these movies with unparalleled clarity, which enables researchers to gain a far better knowledge of how these organelles depend on one another in unperturbed as well as in perturbed environments.
- 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).
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: 15 fps). 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 2. 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: 15 fps). 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 movies shown below are intended to focus attention on mitochondrial dynamics, including their fusions, fissions and remodeling of the mitochondrial network.
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: 15 fps).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 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: 15 fps). 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: 15 fps). 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.
The Khondrion Drug KH176 Prevents BSO-Induced Cytotoxicity
Along with Khondrion, which is among the foremost pharmaceutical firms conducting clinical stage research into therapeutic small drugs targeting mitochondrial diseases, the following movies show how KH176, a leading drug candidate from Khondrion, can rescue cells showing BSO (buthionine sulfoximine)-induced cytotoxicity. BSO prevents glutathione biosynthesis, which is a molecule produced in the body and plays a vital role in maintaining cellular redox states, which lead to the death of the cell. KH176 can prevent this by acting specifically on peroxiredoxin enzymes.
Imaging of Mitochondria and Lipid Droplets Without Labeling
The following section is by Dr. Mathieu Frechin, who is head of Quantitative Biology at Nanolive. It describes the benefits of the use of the holotomographic microscope for the imaging of important organelles that are required for cellular metabolism, including mitochondria and lipid droplets. The accompanying movie shows the first-ever label- and marker-free imaging of live mitochondria.
The topics below are among the most important to be covered in this article:
- Issues with the live cell imaging of organelles in the cell
- Cutting-edge label-free microscopic examination of lipid droplets
- The main features of Nanolive’s hototomographic microscopy in live imaging of organelles
- 3D tracking of lipid droplets
About Nanolive SA
Nanolive SA are scientists, working for scientists.
Their belief is that each and every Biologist, Researcher and Physician should be able to explore and interact instantly with living cells without damaging them.
Nanolive want to support the study of how living cells and bacteria work, evolve and react, thus building a solid base for new drugs and therapies, in order to enable breakthrough researches.
This is the reason why they have developed the 3D Cell Explorer.
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Last updated: Oct 19, 2018 at 6:51 AM
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