CE30 - Physique de la matière condensée et de la matière diluée

Volumetric optical Imaging of viscoelastic properties for Scoliosis and Cancer Observation – VISCO

Submission summary

Obtaining a precise quantitative measurement of viscoelastic properties of cells and their microenvironment is of major interest for fundamental biology, medical diagnosis, and physics of wave propagation. Nonetheless, there is no imaging technique available to perform such measurements at the cellular scale. The VISCO project aims to develop 3D label free optical measurement of viscoelastic properties in thick biological tissues at the cellular scale, and combine this measurement with cell physiology. We will build a new optical microscope, based on a high speed volumetric spectral domain full field optical coherence tomography system, to obtain fast 3D displacement maps and reconstruct the local elasticity and viscosity at the cellular scale. We will use this microscope to improve the diagnosis ability of histopathology, including in the case of human tumor breast samples, and evaluate the role of differential muscle elasticity in a zebrafish idiopathic scoliosis model.

More precisely, full field optical coherence tomography relies on 2D recordings of a low coherence interference between the light backscattered by the sample and a reference arm. The low coherence enables to localize the interferences, so that only the signal backscsattered at a given depth can interfere, and be measured. When the spectral dependency of these interference patterns is also measured, the axial information can be recovered by a simple Fourier transform. The VISCO project aims to create a microscope based on such principle, and that will be able to switch between a high resolution configuration and a high speed configuration. Ultimately, acquisitions at 20, 000 volumes/s will be achieved at a resolution of 2x2x4µm3 .

This microscope will achieve high speed and high resolution volumetric optical coherence tomography. The analysis of the signal temporal fluctuations will enable to reveal living cells inside scattering tissue, because the active transport mechanisms inside the cells create fast and organized fluctuations. Such analysis therefore permits to obtain a contrast related with cell metabolism and physiology, which regulate the active transport mechanisms. The VISCO project will demonstrate the first simultaneous 3D dynamic full field optical coherence tomography.

Moreover, acquiring volumetric scattering data enable to measure induced local deformations, giving access to the viscoelastic properties of tissues. The transverse deformations will be measured by 2D image correlations, while nanometric axial deformations will be measurable via the phase differences between successive planes.

Therefore, various mechanical stresses will be applied on the samples, either using large scale shearing, or by generating shear waves. The local mechanical strain tensor will then be measured using the new microscope in order to measure rheological properties of biological tissues at the cellular scale. Thanks to the 3D measurements, the full strain tensor will be accessible, for various applied stresses, enabling to test new models of tissue biomechanics.

The developed microscope will allow correlating the tissue architecture, cell properties, as well as tissue and cell viscoelastic properties, hence to study the relationship between these metrics. One of the essential biophysics questions that will be addressed by the VISCO project is how the viscoelastic properties of tissues can modify, or enable biological signal transduction. Several pathological cases will be studied, including the case of invasive tumor development, and body axis abnormal development, in the case of idiopathic scoliosis.

Project coordination

Olivier THOUVENIN (Institut Langevin Ondes et Images)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Institut Langevin Institut Langevin Ondes et Images

Help of the ANR 383,544 euros
Beginning and duration of the scientific project: October 2021 - 42 Months

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