Chip microfluidique pour la détection du syndrome de détresse respiratoire aiguë (ARDS) – ChipCellTrap

Severe sepsis syndrome/septic shock or Acute Respiratory Distress Syndrome are clinically acute inflammatory syndromes associated with a mortality rate of 20-60% and are the leading cause of death in adult intensive care units. They are one of the many pathologies for which the underlying mechanisms remain to be unraveled. During acute inflammation the neutrophils (which represent 70% of leukocytes circulating in the blood flow) are trapped in pulmonary capillaries. An hypothesis advanced in the literature is that trapped neutrophils cause ischemia and lung injury, leading to the pathology. The mechanisms of cell trapping are however not well understood: in addition to adhesive phenomena, which are suspected but poorly described, the neutrophils stiffen under the effect of inflammatory mediators. One scenario is that the cells are thus unable to deform enough to flow in the narrow newrok pulmonary capillaries and are trapped. The cells then activate under the effect of the strain, express specific adhesion molecules and strongly adhere onto the endothelium. This scenario has however never been directly tested since no suitable experimental devices mimicking pulmonary capillaries and physiological flow were available up to now. The recent use of microfluidic tools for the study of biological questions at the cellular or sub-cellular scale is transforming the approach on these fields. In particular, microfluidic technology provides new tools to probe the 3-dimensional responses of cells advected by flows. For instance, it allows to characterize the mechanical response of cells under a 3D excitation often at high throughput and at low cost. We propose to use innovative microfluidic technologies to explore the scenario we have evoked in a integrated way and on large cell populations. We aim at understanding in a quantitative way the influence of adhesive and rheological properties of a non-activated neutrophil on its trapping probability in the pulmonary microcirculation and how inflammatory phenomena change the behaviour of living cells in pulmonary capillaries. The objective of this project is thus to conceive, microfabricate and use microfluidic chips allowing to characterize and correlate the 3D-deformability of neutrophils, their activation and their adhesion as they circulate in capillaries. Experimental developments will be associated to a fundamental study of the flow behaviour of soft particles (cells, vesicles, droplets) in the complex geometries of microchannels in order to obtain a deep knowledge of pure hydrodynamics effects o the deformation of the objects. Part of the project will bear on recent technological developments made by one of the partners. In collaboration with the clinical researchers involved in the project, the results we will obtain should allow to suggest and/or assess therapeutic strategies. One goal is that at the end of the project we propose an integrated microfluid chip suitable to perform clinical tests on the blood of patients with acute inflammation, in order to build diagnostic tools based on in vitro testing.