Effects of flow and diffusion on chemotaxis studies in a microfabricated gradient generator

Walker, Gregg B.; Sai, Jiqing; Richmond, Ann; Stremler, Mark A.; Chung, Chang Y.; Wikswo, John P.

doi:10.1039/b417245k

Cited by 247 publications

(263 citation statements)

References 23 publications

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“…For the slow flow rate used in our experiments the neutrophil trajectory deviations were about 10%, in concordance with previously reported observations. 27 Other potential sources of errors, like the distortion of the gradient due to the alterations of the laminar flow by the cells themselves, were avoided by the use of channels an order of magnitude larger than the cells.…”

Section: Discussionmentioning

confidence: 99%

Microfluidic system for measuring neutrophil migratory responses to fast switches of chemical gradients

et al. 2006

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Experimental systems that provide temporal and spatial control of chemical gradients are required for probing into the complex mechanisms of eukaryotic cell chemotaxis. However, no current technique can simultaneously generate stable chemical gradients and allow fast gradient changes. We developed a microfluidic system with microstructured membranes for exposing neutrophils to fast and precise changes between stable, linear gradients of the known chemoattractant Interleukin-8 (IL-8). We observed that rapidly lowering the average concentration of IL-8 within a gradient, while preserving the direction of the gradient, resulted in temporary neutrophil depolarization. Fast reversal of the gradient direction while increasing or decreasing the average concentration also resulted in temporary depolarization. Neutrophils adapted and maintained their directional motility, only when the average gradient concentration was increased and the direction of the gradient preserved. Based on these observations we propose a two-component temporal sensing mechanism that uses variations of chemokine concentration averaged over the entire cell surface and localized at the leading edge, respectively, and directs neutrophil responses to changes in their chemical microenvironment.

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Section: Discussionmentioning

confidence: 99%

Microfluidic system for measuring neutrophil migratory responses to fast switches of chemical gradients

et al. 2006

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“…However, this term also introduces a cellular inertia: in the absence of a chemoattractant gradient and at low densities of surrounding cells, cells continue moving at constant speed. Studies in other organisms and cell types show that cells, while they do exhibit persistence, do not accelerate in response to chemoattractant gradients, primarily because their maximum velocity is limited [43,57].…”

Section: Chemotaxis-based Modelsmentioning

confidence: 99%

Modeling Morphogenesisin silicoandin vitro: Towards Quantitative, Predictive, Cell-based Modeling

Merks

Koolwijk

2009

Math. Model. Nat. Phenom.

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Abstract. Cell-based, mathematical models help make sense of morphogenesis-i.e. cells organizing into shape and pattern-by capturing cell behavior in simple, purely descriptive models. Cell-based models then predict the tissue-level patterns the cells produce collectively. The first step in a cell-based modeling approach is to isolate sub-processes, e.g. the patterning capabilities of one or a few cell types in cell cultures. Cell-based models can then identify the mechanisms responsible for patterning in vitro. This review discusses two cell culture models of morphogenesis that have been studied using this combined experimental-mathematical approach: chondrogenesis (cartilage patterning) and vasculogenesis (de novo blood vessel growth). In both these systems, radically different models can equally plausibly explain the in vitro patterns. Quantitative descriptions of cell behavior would help choose between alternative models. We will briefly review the experimental methodology (microfluidics technology and traction force microscopy) used to measure responses of individual cells to their micro-environment, including chemical gradients, physical forces and neighboring cells. We conclude by discussing how to include quantitative cell descriptions into a cell-based model: the Cellular Potts model.

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“…The equations (1)- (4) include two supposes: (1) suppose that velocity (u) of plate is very slow and F viscous = µdu dy ≈ 0 according to Newton's law of viscosity 35 when top plate is moving, and ignore the viscous friction since it is an inner force. (2) suppose that friction between droplets and top plate exists (if it is nonsexist, F 1 and F 2 are 0 calculated by these equations) and physic model of solid-liquid is similar to solid-solid contact since droplets support heavy top plate.…”

Section: Theoretical Analysismentioning

confidence: 99%

Optimization and limit of a tilt manipulation stage based on the electrowetting-on-dielectric principle

et al. 2017

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This work designed a new tilt manipulation stage based on the electrowetting-on-dielectric (EWOD) principle as the actuating mechanism and investigated the performance of that stage. The stage was fabricated using a universal MEMS (Micro-Electro-Mechanical System) fabrication method. In the previously demonstrated form of this device, the tilt stage consisted of a top plate that functions as a mirror, a bottom plate that was designed for changing the shape of water droplets, and supporters that were fixed between the top and bottom plate. That device was actuated by a voltage applied to the bottom plate, resulting in a static electric force actuating the shape change in the droplets by moving the top plate in the vertical direction. Previous experimental results indicated that that device can tilt at up to ±1.8°, with a resolution of 7 μm in displacement and 0.05° in angle. By selecting the best combination of the dielectric layer, the tilt angle was maximized. The new device, fabricated using a common and straightforward fabrication method, avoids deflection of the top plate and grounding in the bottom plate. Because of the limit of Teflon and other MEMS materials, this device has a tilt angle in the range of 3.2-3.5° according to the experimental data for friction and the EWOD device limit, which is close to 1.8°. This paper also describe the investigation of the effects of various parameters, e.g., various dielectric materials, thicknesses, and droplet type and volume, on the performance of the stage. The results indicate that the apparent frictions coefficient of the solid-liquid interface may remain constant, i.e., the friction force is proportional to the normal support force and the apparent frictions coefficient.

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Effects of flow and diffusion on chemotaxis studies in a microfabricated gradient generator

Cited by 247 publications

References 23 publications

Microfluidic system for measuring neutrophil migratory responses to fast switches of chemical gradients

Microfluidic system for measuring neutrophil migratory responses to fast switches of chemical gradients

Modeling Morphogenesisin silicoandin vitro: Towards Quantitative, Predictive, Cell-based Modeling

Optimization and limit of a tilt manipulation stage based on the electrowetting-on-dielectric principle

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