Label free 3D analysis of organelles in living cells by refractive index shows pre-mitotic organelle spinning in mammalian stem cells

We are happy to make accessible our ongoing work made in collaboration with the team of Prof. Gisou van der Goot of EPFL under the format of a BioRxiv preprint publication. Sound science takes time but awesome results must be shared as fast as possible!

It all started with a very talented Master student (Christopher Tremblay) who was shared between Nanolive and Prof. Van Der Goot’s lab and ended with this amazing work where it’s demonstrated, for the very first time, how the 3D Cell Explorer allows marker-free imaging of key cell organelles in live cells and much more! 

Find the full text here: https://www.biorxiv.org/content/biorxiv/early/2018/09/04/407239.full.pdf 

Abstract

Holo-tomographic microscopy (HTM) is a label-free non-phototoxic microscopy method reporting the fine changes of a cell’s refractive indexes (RI) in 3D. By combining HTM with epifluorescence, we demonstrate that cellular organelles such as Lipid droplets and mitochondria show a specific RI signature that distinguishes them with high resolution and contrast. We further show that HTM allows to follow in unprecedented ways the dynamics of mitochondria, lipid droplets as well as that of endocytic structures in live cells over long period of time, which led us to observe to our knowledge for the first time a global organelle spinning occurring before mitosis.

Figure: Comparison of specific fluorescent signals and refractive index map. Visual and profile comparison as well as 3D view of a, HeLa cells refractive index (RI) map to mitochondria-specific fluorescent signal (mito-YFP) or b, to a lipid droplet-specific fluorescent signal (Bodipy) shows specificity and gain in resolving power. RI and fluorescent signal profiles have been normalized between 0 (background) and 1 (profile maximum).

Label-free Live Cell Imaging: Nuclear Rotation before Mitosis

You can observe a time-lapse of pre-adipocytes imaged with the 3D Cell Explorer at a frequency of one image per twenty seconds (movie speed: 20fps). You can appreciate the interactions between mitochondria and lipid droplets in a label free manner. The video shows pre-mitotic organelle spinning in mammalian stem cells; a phenomenum observed for the first time.
Objective magnification is 60x.

More information at: nanolive.ch/metabolism

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