Lift and Down-Gradient Shear-Induced Diffusion in Red Blood Cell Suspensions

Grandchamp, Xavier; Coupier, Gwennou; Srivastav, Aparna; Minetti, Christophe; Podgorski, Thomas

doi:10.1103/physrevlett.110.108101

Cited by 100 publications

(110 citation statements)

References 43 publications

(65 reference statements)

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“…6). In the fluid dynamical regime of bacteria, mechanisms including inertia, buoyancy and deformation that otherwise lead to the accumulation of particles 25 , bubbles 26 or red blood cells 27 , are insignificant or exceedingly slow (Supplementary Information). Instead, shearinduced trapping occurs as a result of self-propulsion, which drives cell accumulations within a timescale governed by the swimming speed and the flow length scale.…”

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confidence: 99%

Bacterial transport suppressed by fluid shear

2014

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Bacteria often live in dynamic fluid environments 1-3 and flow can a ect fundamental microbial processes such as nutrient uptake 1,4 and infection 5 . However, little is known about the consequences of the forces and torques associated with fluid flow on bacteria. Through microfluidic experiments, we show that fluid shear produces strong spatial heterogeneity in suspensions of motile bacteria, characterized by up to 70% cell depletion from low-shear regions due to 'trapping' in high-shear regions. Two mathematical models and a scaling analysis accurately capture these observations, including the maximal depletion at mean shear rates of 2.5-10 s −1 , and reveal that trapping by shear originates from the competition between the cell alignment with the flow and the stochasticity in the swimming orientation. We show that this shear-induced trapping directly impacts widespread bacterial behaviours, by hampering chemotaxis and promoting surface attachment. These results suggest that the hydrodynamic environment may directly a ect bacterial fitness and should be carefully considered in the study of microbial processes.We investigated the effect of flow on motile bacteria by tracking them in precisely controlled laminar flows generated in a microfluidic channel (Fig. 1a). To ensure that the dominant velocity gradients occurred in the horizontal observation plane, at the channel mid-depth, we used a microchannel with aspect ratio H /W > 1 (height H = 750 µm; width W = 425 µm). In that plane, the velocity profile, u(y) = U [1 − 4(y/W ) 2 ], where U is the flow velocity at the channel centreline, is parabolic, and, thus, the shear rate S(y) = du/dy = −8yU /W 2 varies linearly with distance y across the channel and is zero at the centreline (Fig. 1b). In this flow, smooth-swimming Bacillus subtilis bacteria swam unperturbed in straight paths (Fig. 1c) when near the centre of the channel, where the local shear rate was small. Conversely, in high-shear-rate regions, trajectories exhibited frequent loops resulting from rotation of the swimming bacteria by the hydrodynamic torque imparted by the local shear (Fig. 1d). The opposite handedness of the loops on either side of the channel centreline reflects the opposite sign of the shear rate (Fig. 1c,d and Supplementary Movie 1). As shown below, these looping trajectories resulted in bacteria becoming trapped in the high-shear region of the channel.At the population scale, this trapping effect resulted in a marked depletion of cells from the central, low-shear region of the flow, and consequently, in an accumulation in the flanking regions of higher shear. When the flow was impulsively started from rest, the initially uniform distribution of cells over the imaging region across the channel width (Fig. 1e) rapidly (5-10 s) evolved into a distribution characterized by considerably fewer cells in the central part of the channel (Fig. 1f-h). The magnitude of the depletion was severe, with local cell concentrations dropping by 70% (Fig. 1h). The absence of depletion in control experime...

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Bacterial transport suppressed by fluid shear

2014

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“…In the absence of a force, migration away from the wall is expected [9]. When a small force is applied, the cell executes a tumbling motion, as indicated by large variations in the minimum distance from the wall and complete cycles of the orientation angle θ.…”

Section: Resultsmentioning

confidence: 99%

“…Grandchamp et al [9] determined a scaling law for the lift of tumbling red blood cells. However, the cells’ distance from the wall in the Grandchamp et al [9] results are significantly larger than those considered here, and the results presented here consider the effects of a lateral force.…”

Section: Discussionmentioning

confidence: 99%

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Two-dimensional simulation of red blood cell motion near a wall under a lateral force

Hariprasad

Secomb

2014

Phys. Rev. E

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The motion of a red blood cell suspended in a linear shear flow adjacent to a fixed boundary subject to an applied lateral force directed towards the boundary is simulated. A two-dimensional model is used that represents the viscous and elastic properties of normal red blood cells. Shear rates in the range of 100 s−1 to 600 s−1 are considered, and the suspending medium viscosity is 1 cP. In the absence of a lateral force, the cell executes a tumbling motion. With increasing lateral force, a transition from tumbling to tank-treading is predicted. The minimum force required to ensure tank-treading increases non-linearly with the shear rate. Transient swinging motions occur when the force is slightly larger than the transition value. The applied lateral force is balanced by a hydrodynamic lift force resulting from the positive orientation of the long axis of the cell with respect to the wall. In the case of cyclic tumbling motions, the orientation angle takes positive values through most of the cycle, resulting in lift generation. These results are used to predict the motion of a cell close to the outer edge of the cell-rich core region that is generated when blood flows in a narrow tube. In this case, the lateral force is generated by shear-induced dispersion, resulting from cell-cell interactions in a region with a concentration gradient. This force is estimated using previous data on shear-induced dispersion. The cell is predicted to execute tank-treading motions at normal physiological hematocrit levels, with the possibility of tumbling at lower hematocrit levels.

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“…Although this model has been effective in predicting moderate RBC depletion near the wall, it is not capable of predicting near-wall RBCs free layer. Therefore, an improvement would be to introduce the wall effect which is influenced by the particle deformability and the distance from the wall, as described by Pranay et al (2012) [43] Grandchamp et al (2013) [44], and Kumar et al (2012) [45]. Another limitation is the use of 2D approximation of a spheroidal domain.…”

Section: Bulging Saccular Aneurysmmentioning

confidence: 99%

Numerical Simulation of Red Blood Cell-Induced Platelet Transport in Saccular Aneurysms

Aubry

et al. 2017

Applied Sciences

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Abstract:We present a numerical simulation of blood flow in two aneurysmal vessels. Using a multicomponent continuum approach, called mixture theory, the velocity fields and spatial distribution of the red blood cells (RBCs) and the plasma are predicted. Platelet migration is described by a convection-diffusion equation, coupled to the RBC concentration field. The model is applied to study a two-dimensional straight vessel and multiple two-dimensional aneurysm vessels with different neck sizes. The model accurately predicts the enrichment of the platelets near the wall in the straight vessel, agreeing with the experimental measurement quantitatively. The numerical results also show that the near-wall enrichment of the platelets in the parent vessel highly influences the platelet concentration within the aneurysm. The results also indicate that the platelet concentration within the aneurysm increases with Reynolds number and decreases with a smaller neck size. This might have significance on the formation of thrombus (blood clot) within the aneurysm, which in turn may have a protective effect on preventing ruptures. Based on the success with the problems studied, we believe the current model can be a useful tool for analyzing the blood flow and platelets transport within patient specific aneurysms in the future.

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Lift and Down-Gradient Shear-Induced Diffusion in Red Blood Cell Suspensions

Cited by 100 publications

References 43 publications

Bacterial transport suppressed by fluid shear

Bacterial transport suppressed by fluid shear

Two-dimensional simulation of red blood cell motion near a wall under a lateral force

Numerical Simulation of Red Blood Cell-Induced Platelet Transport in Saccular Aneurysms

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