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Etude de comportement électrique des cellules isolées HEK293 et de leurs agrégats

Abstract : The work reported in this manuscript aims at understanding the electrical properties of biological tissues in the frequency range between 10 kHz and 100 MHz. Knowing these properties is essential to assess the effects of involuntary exposure of human body to electromagnetic fields, but also to diagnose a physiological change when the tissue is exposed voluntarily. Many studies have been conducted to measure the electrical properties of different tissues but existing data are not well understood because of the complexity of tissues structure. Moreover, there is considerable variability of data among studies evaluating these properties. To better understand the electrical behavior of tissues, the original approach proposed in this manuscript consists in investigating their properties starting from the cell scale. The first part of the manuscript is dedicated to the electrical characterization of HEK 293 (HumanEmbryonic Kidney) cells by electrorotation. This technique has been used to extract the electrical properties of the membrane and the cytoplasm of HEK cells. The second part of the manuscript focuses on creating cell aggregates from isolated HEKcells. Two approaches have been proposed. The first one was based on the nature of intercellular junctions. This approach led to the formation of aggregates of irregularsize and shape. The other technique consisted in using an electric field to perform dielectrophoresis-assisted cell assembly. A microsystem comprising quadrupole electrodes was designed for this purpose. Permanent aggregates of HEK cells having a controlled size and shape could be obtained using this approach. The last part of the manuscript focuses on study of the electrical behavior of the cell aggregates through numerical simulations of electrorotation spectra. The confrontation between results obtained for a single cell and those obtained for an aggregate tend to show that the extracellular medium influences strongly the electrical response of the aggregate ; Conversely, the difference in size between the cells as well as the presence of intercellular junctions does not seem to have had a notable impact. These simulation results will have to be supported by experimental studies.
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Amal El Gaddar. Etude de comportement électrique des cellules isolées HEK293 et de leurs agrégats. Autre. Ecole Centrale de Lyon, 2015. Français. ⟨NNT : 2015ECDL0008⟩. ⟨tel-01378500⟩

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