Université PSL



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Microfluidic model of the platelet-generating organ: beyond bone marrow biomimetics
Antoine Blin, Anne Le Goff, Aurélie Magniez, Sonia Poirault-Chassac, Bruno Teste, Géraldine Sicot, Kim Anh Nguyen, Feriel S. Hamdi, Mathilde Reyssat & Dominique Baruch
Nature - Scientific Reports 6 21700 - DOI: 10.1038/srep21700 - 2016
We present a new, rapid method for producing blood platelets in vitro from cultured megakaryocytes based on a microfluidic device. This device consists in a wide array of VWF-coated micropillars. Such pillars act as anchors on megakaryocytes, allowing them to remain trapped in the device and subjected to hydrodynamic shear. The combined effect of anchoring and shear induces the elongation of megakaryocytes and finally their rupture into platelets and proplatelets. This process was observed with megakaryocytes from different origins and found to be robust. This original bioreactor design allows to process megakaryocytes at high throughput (millions per hour). Since platelets are produced in such a large amount, their extensive biological characterisation is possible and shows that platelets produced in this bioreactor are functional.
Massive radius-dependent flow slippage in carbon nanotubes
Eleonora Secchi, Sophie Marbach, Antoine Niguès, Derek Stein, Alessandro Siria & Lydéric Bocquet
Nature - 537 210–213 - DOI: 10.1038/nature19315 - 2016
Measurements and simulations have found that water moves through carbon nanotubes at exceptionally high rates owing to nearly frictionless interfaces1, 2, 3, 4. These observations have stimulated interest in nanotube-based membranes for applications including desalination, nano-filtration and energy harvesting5, 6, 7, 8, 9, 10, yet the exact mechanisms of water transport inside the nanotubes and at the water–carbon interface continue to be debated11, 12 because existing theories do not provide a satisfactory explanation for the limited number of experimental results available so far13. This lack of experimental results arises because, even though controlled and systematic studies have explored transport through individual nanotubes7, 8, 9, 14, 15, 16, 17, none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube11. Here we show that the pressure-driven flow rate through individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes, and no slippage in boron nitride nanotubes that are crystallographically similar to carbon nanotubes, but electronically different. This pronounced contrast between the two systems must originate from subtle differences in the atomic-scale details of their solid–liquid interfaces, illustrating that nanofluidics is the frontier at which the continuum picture of fluid mechanics meets the atomic nature of matter.
Topological defects in confined populations of spindle-shaped cells
Guillaume Duclos, Christoph Erlenkämper, Jean-François Joanny & Pascal Silberzan
Nature Physics - 16 (2014) 217–223 - DOI:10.1038/nphys3876 - 2016
Most spindle-shaped cells (including smooth muscles and sarcomas) organize in vivo into well-aligned ‘nematic’ domains1, 2, 3, creating intrinsic topological defects that may be used to probe the behaviour of these active nematic systems. Active non-cellular nematics have been shown to be dominated by activity, yielding complex chaotic flows4, 5. However, the regime in which live spindle-shaped cells operate, and the importance of cell–substrate friction in particular, remains largely unexplored. Using in vitro experiments, we show that these active cellular nematics operate in a regime in which activity is effectively damped by friction, and that the interaction between defects is controlled by the system’s elastic nematic energy. Due to the activity of the cells, these defects behave as self-propelled particles and pairwise annihilate until all displacements freeze as cell crowding increases6, 7. When confined in mesoscopic circular domains, the system evolves towards two identical +1/2 disclinations facing each other. The most likely reduced positions of these defects are independent of the size of the disk, the cells’ activity or even the cell type, but are well described by equilibrium liquid crystal theory. These cell-based systems thus operate in a regime more stable than other active nematics, which may be necessary for their biological function.
On-Chip Quantitative Measurement of Mechanical Stresses During Cell Migration with Emulsion Droplets
D. Molino, S. Quignard, C. Gruget, F. Pincet, Y. Chen, M. Piel & J. Fattaccioli
Scientific Reports - 6 29113 - DOI: 10.1038/srep29113 - 2016
The ability of immune cells to migrate within narrow and crowded spaces is a critical feature involved in various physiological processes from immune response to metastasis. Several in-vitro techniques have been developed so far to study the behaviour of migrating cells, the most recent being based on the fabrication of microchannels within which cells move. To address the question of the mechanical stress a cell is able to produce during the encounter of an obstacle while migrating, we developed a hybrid microchip made of parallel PDMS channels in which oil droplets are sparsely distributed and serve as deformable obstacles. We thus show that cells strongly deform droplets while passing them. Then, we show that the microdevice can be used to study the influence of drugs on migration at the population level. Finally, we describe a quantitative analysis method of the droplet deformation that allows measuring in real-time the mechanical stress exerted by a single cell. The method presented herein thus constitutes a powerful analytical tool for cell migration studies under confinement.
Optical volume and mass measurements show that mammalian cells swell during mitosis.
Zlotek-Zlotkiewicz E, Monnier S, Cappello G, Le Berre M, Piel M
J. Cell Biol. - 211( 4): 765-74 - DOI: 10.1016/j.jim.2015.12.005 - 2015
The extent, mechanism, and function of cell volume changes during specific cellular events, such as cell migration and cell division, have been poorly studied, mostly because of a lack of adequate techniques. Here we unambiguously report that a large range of mammalian cell types display a significant increase in volume during mitosis (up to 30%). We further show that this increase in volume is tightly linked to the mitotic state of the cell and not to its spread or rounded shape and is independent of the presence of an intact actomyosin cortex. Importantly, this volume increase is not accompanied by an increase in dry mass and thus corresponds to a decrease in cell density. This mitotic swelling might have important consequences for mitotic progression: it might contribute to produce strong pushing forces, allowing mitotic cells to round up; it might also, by lowering cytoplasmic density, contribute to the large change of physicochemical properties observed in mitotic cells.
Actin Flows Mediate a Universal Coupling between Cell Speed and Cell Persistence.
Maiuri P, Rupprecht J-F, Wieser S, Ruprecht V, Bénichou O, Carpi N, Coppey M, De Beco S, Gov N, Heisenberg C-P, Lage Crespo C, Lautenschlaeger F, Le Berre M, Lennon-Dumenil A-M, Raab M, Thiam H-R, Piel M, Sixt M, Voituriez R
Cell - 161(2) 374-86 - DOI: 10.1016/j.cell.2015.01.056 - 2015
Cell movement has essential functions in development, immunity, and cancer. Various cell migration patterns have been reported, but no general rule has emerged so far. Here, we show on the basis of experimental data in vitro and in vivo that cell persistence, which quantifies the straightness of trajectories, is robustly coupled to cell migration speed. We suggest that this universal coupling constitutes a generic law of cell migration, which originates in the advection of polarity cues by an actin cytoskeleton undergoing flows at the cellular scale. Our analysis relies on a theoretical model that we validate by measuring the persistence of cells upon modulation of actin flow speeds and upon optogenetic manipulation of the binding of an actin regulator to actin filaments. Beyond the quantitative prediction of the coupling, the model yields a generic phase diagram of cellular trajectories, which recapitulates the full range of observed migration patterns.
A computational mechanics approach to assess the link between cell morphology and forces during confined migration.
Aubry D, Thiam H, Piel M, Allena R
Biomech Model Mechanobiol - 14(1): 143-57 - DOI: 10.1016/bs.mcb.2014.11.007 - 2015
Confined migration plays a fundamental role during several biological phenomena such as embryogenesis, immunity and tumorogenesis. Here, we propose a two-dimensional mechanical model to simulate the migration of a HeLa cell through a micro-channel. As in our previous works, the cell is modelled as a continuum and a standard Maxwell model is used to describe the mechanical behaviour of both the cytoplasm (including active strains) and the nucleus. The cell cyclically protrudes and contracts and develops viscous forces to adhere to the substrate. The micro-channel is represented by two rigid walls, and it exerts an additional viscous force on the cell boundaries. We test four channels whose dimensions in terms of width are i) larger than the cell diameter, ii) sub-cellular, ii) sub-nuclear and iv) much smaller than the nucleus diameter. The main objective of the work is to assess the necessary conditions for the cell to enter into the channel and migrate through it. Therefore, we evaluate both the evolution of the cell morphology and the cell-channel and cell-substrate surface forces, and we show that there exists a link between the two, which is the essential parameter determining whether the cell is permeative, invasive or penetrating.
Confinement and low adhesion induce fast amoeboid migration of slow mesenchymal cells.
Liu Y-J, Le Berre M, Lautenschlaeger F, Maiuri P, Callan-Jones A, Heuzé M, Takaki T, Voituriez R, Piel M
Cell - 160( 4): 659-72 - DOI: 10.1016/j.cell.2015.01.007 - 2015
The mesenchymal-amoeboid transition (MAT) was proposed as a mechanism for cancer cells to adapt their migration mode to their environment. While the molecular pathways involved in this transition are well documented, the role of the microenvironment in the MAT is still poorly understood. Here, we investigated how confinement and adhesion affect this transition. We report that, in the absence of focal adhesions and under conditions of confinement, mesenchymal cells can spontaneously switch to a fast amoeboid migration phenotype. We identified two main types of fast migration-one involving a local protrusion and a second involving a myosin-II-dependent mechanical instability of the cell cortex that leads to a global cortical flow. Interestingly, transformed cells are more prone to adopt this fast migration mode. Finally, we propose a generic model that explains migration transitions and predicts a phase diagram of migration phenotypes based on three main control parameters: confinement, adhesion, and contractility.
Laser induced wounding of the plasma membrane and methods to study the repair process.
Jimenez AJ, Maiuri P, Lafaurie-Janvore J, Perez F, Piel M
Methods Cell Biol. - 5.2083333333 391-408 - DOI: 10.1016/bs.mcb.2014.11.007 - 2015
Cells are constantly exposed to agents that can trigger the perforation of their plasma membrane. This damage occurs naturally, and the frequency and intensity depends on how much cells are exposed to damaging threats. The following protocol is a simple and powerful method to damage the plasma membrane using laser ablation. It allows the induction of a single and localized wound at the plasma membrane of cultured cells, which can be followed with fast time-lapse imaging. The first part of the protocol describes simple cell culture techniques and the material ideal to make the experiments. A second part of the protocol gives advice about the procedures to make effective wounds in cells while ensuring a good survival rate. We also propose different ways to follow the opening and closure of the plasma membrane. Finally, we describe the procedure to efficiently analyze the data acquired after single cell photodamage to characterize the wounding process.
Cell migration and antigen capture are antagonistic processes coupled by myosin II in dendritic cells.
Chabaud M, Heuzé ML, Bretou M, Vargas P, Maiuri P, Solanes P, Maurin M, Terriac E, Le Berre M, Lankar D, Piolot T, Adelstein RS, Zhang Y, Sixt M, Jacobelli J, Bénichou O, Voituriez R, Piel M, Lennon-Duménil A-M
Nat Commun - 0.25 7526 - DOI: 110.1016/j.jim.2015.12.005 - 2015
The immune response relies on the migration of leukocytes and on their ability to stop in precise anatomical locations to fulfil their task. How leukocyte migration and function are coordinated is unknown. Here we show that in immature dendritic cells, which patrol their environment by engulfing extracellular material, cell migration and antigen capture are antagonistic. This antagonism results from transient enrichment of myosin IIA at the cell front, which disrupts the back-to-front gradient of the motor protein, slowing down locomotion but promoting antigen capture. We further highlight that myosin IIA enrichment at the cell front requires the MHC class II-associated invariant chain (Ii). Thus, by controlling myosin IIA localization, Ii imposes on dendritic cells an intermittent antigen capture behaviour that might facilitate environment patrolling. We propose that the requirement for myosin II in both cell migration and specific cell functions may provide a general mechanism for their coordination in time and space.

278 publications.