Researchers from Angers University Hospital, led by Arnaud Chevrollier, have recently published an innovative study about mitochondrial dynamics, conducted on CYTOO micropatterns. Their technique allows standardized quantitative analysis of mitochondrial networks and provides new insight into mitochondrial dysfunction. The method has strong potential in defining new diagnostic criteria for neurodegenerative disorders, cardiomyopathies, metabolic syndrome, cancer, and obesity.

1. “Cells spread on micropatterned coverslips
allow standardized visualization of the
mitochondrial network”
Arnaud Chevrollier, Angers University Hospital
Mitochondria dynamics in focus
Researchers from Angers University Hospital, led by Arnaud
Chevrollier, have recently published an innovative study about
mitochondrial dynamics, conducted on CYTOO micropatterns. Their
technique allows standardized quantitative analysis of mitochondrial
networks and provides new insight into mitochondrial dysfunction. The method
has strong potential in defining new diagnostic criteria for neurodegenerative
disorders, cardiomyopathies, metabolic syndrome, cancer, and obesity.
Since mitochondria are directly involved in energy production, metabolism, cell signalling, calcium homeostasis
and apoptosis, they play a crucial role in the life and death of eukaryote cells. However, the mitochondrial
networks constitutes a dynamic system, constantly adapting to cellular requirements by changing shape and
position. Their observation remained problematic, especially as no precise criteria of investigation has been
defined.
Arnaud Chevrollier took up this challenge, and used CYTOO micropatterns to normalize and standardize
mitochondrial analysis. He designed specific extralarge Y micropatterns, allowing fibroblasts to spread out
into reproductible equilateral triangular shapes, and flatten out the mitochondrial network over the full area.
Figure 1: Arnaud imaged the mitochondrial network in
control (A) and mitochondrial fusion gene OPA1 mutated
(B) fibroblasts (scale bars:10 microns). Fibroblasts settled
on coverslips with CYTOO Y-shaped micropatterns adop-
ted standardized triangular shapes. A1, B1: The mito-
chondria were labeled with MitoTracker Green and ana-
lyzed on deconvolved images with Imaris Filament Tracer.
A2, B2: The color codes highlight the different lengths of
the mitochondrial tubules between branch points. De-
tails show the tips of mitochondrial tubules in green and
the network branch points in red (Scale bars : 1 micron).
Courtesy of Arnaud Chevrollier.

2. Innovation in Cell-based Assays
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7 parvis Louis Néel, BHT,
Arnaud explored the mitochondrial dynamics of skin
BP 50 - 38040 Grenoble fibroblasts, carrying the OPA1 and MFN2 gene mutations,
FRANCE which are known to be involved in mitochondrial fusion, and
in severe pathologies like Autosomal Dominant Optic Atrophy and
Inc
Harvard Square Charcot Marie Tooth neuropathy. Combining the normalization induced by
One Mifflin Place micropatterning and Imaris Filament Tracer to automatically detect mitochondrial
Suite 400 Cambridge, filaments in three dimensions, he analyzed mitochondrial parameters in single cells and
MA 02138, USA
cell populations. He examined the total mitochondrial volume per cell, the connectivity of the
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mitochondrial network, the number of mitochondrial branch points, and general mitochondrial
organization. This complete exploration led him to conclude that the volume and cellular distribution
of mitochondria is affected by mutations in the OPA1 and MFN2 genes. He also discovered that the
volume of mitochondrial network is closely adapted to that of the cell, which means that the mitochondrial
volume, rather than being genetically determined, may depend on the size and shape adopted by the cell
according to its specific environment and anchoring points, making the use of micropatterns particularly relevant
to remove biais present in classical 2D culture. “The role of mitochondrial division and its potential as a therapeutic
target for neurodegeneration, call for the development of our approach in high throughput drug screening” finally
concluded Arnaud Chevrollier.
Michel Bornens, CSO at CYTOO, commented this article: “Arnaud Chevrollier’s work is amazing. He is the first one
who succeeded in establishing a standardized method to observe what used to be hidden! Combining micropatterns
and Imaris technology led him to discover that mitochondrial organization depends on the adhesion geometry
of the extracellular matrix, which is crucial for cell polarity. He also pinpointed a third region in mitochondrial
networks, associated with the microtubule organizing center. This unknown region could constitute a specific
mitochondrial structure, involved in anchoring the network and promoting the biogenesis and distribution of
mitochondria all though the cytoplasm. Chevrollier’s research could represent the first step in defining better
diagnostic criteria for mitochondrial diseases and bring new understanding in their mechanisms.”
Figure 2: visualization of the mitochondrial network from human skin fibroblasts.
Magnification 630 X. Red: mitotracker M7510 / Green: Phalloidin / Blue: Hoechst
Courtesy of the lab of Drs Donna McPhie and Bruce Cohen, Harvard
Medical School, MA, USA.
Further reading:
- Chevrollier A, Cassereau J, Ferré M, et al. Standardized mitochondrial analysis gives new insights into mitochondrial dynamics and OPA1
viewbox.fr
function. Int. J. Biochem. Cell Biol. 2012;44(6):980–988.
- Bitplane Case Study. Automated Analysis of Dynamic Mitochondrial Networks. 2012.