Bulletin of the American Physical Society
69th Annual Meeting of the APS Division of Fluid Dynamics
Volume 61, Number 20
Sunday–Tuesday, November 20–22, 2016; Portland, Oregon
Session E20: Bio: Red Blood Cells |
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Chair: Zhangli Peng, University of Notre Dame Room: D137-138 |
Sunday, November 20, 2016 5:37PM - 5:50PM |
E20.00001: Particle-based modeling effect of shape transform of single sickle red blood cells Jun Yang, George Karniadakis, Ming Dao Sickle red blood cells often exhibit various sickled shapes as well as higher shear and bending stiffness. To study the membrane biomechanical properties related to cell morphology, we employed multiscale coarse grain models based on dissipative particle dynamics (DPD). Through the proper orthogonal decomposition (POD) we analyst the membrane fluctuation of a single cell which probe the membrane mechanical properties. In this work, the membrane mechanics alteration caused by cell volume and surface area variation are tested. We verified that with same ratio of surface area and volume, volume differences will not affect the membrane fluctuation. We also found that by expanding the whole cell the membrane fluctuation performance does not change. To further quantify the pure shape effects, we generate cells with different aspect ratio of major axis and minor axis at which membrane exhibit different fluctuation indicating the mechanical properties divergence. Through the spatial-temporal autocorrelation of membrane fluctuations characteristics, the membrane bending stiffness and shear modulus are carefully calibrated against QPI experimental data. [Preview Abstract] |
Sunday, November 20, 2016 5:50PM - 6:03PM |
E20.00002: Human spleen and red blood cells Igor Pivkin, Zhangli Peng, George Karniadakis, Pierre Buffet, Ming Dao Spleen plays multiple roles in the human body. Among them is removal of old and altered red blood cells (RBCs), which is done by filtering cells through the endothelial slits, small micron-sized openings. There is currently no experimental technique available that allows us to observe RBC passage through the slits. It was previously noticed that people without a spleen have less deformable red blood cells, indicating that the spleen may play a role in defining the size and shape of red blood cells. We used detailed RBC model implemented within the Dissipative Particle Dynamics (DPD) simulation framework to study the filter function of the spleen. Our results demonstrate that spleen indeed plays major role in defining the size and shape of the healthy human red blood cells. [Preview Abstract] |
Sunday, November 20, 2016 6:03PM - 6:16PM |
E20.00003: Dynamics of Red Cells in Spleen: How Does Vesiculation Happen? Qiang Zhu, Sara Salehyar, Pedro Cabrales, Robert Asaro Vesiculation of red blood cells as a result of local separation between lipid bilayer and cytoskeleton is known to happen in vivo, most likely inside spleen where they sustain large mechanical loads during the passage through venus slits. There is, however, little knowledge about the detailed scenario and condition. We address this question via a fluid-cell interaction model by coupling a multiscale model of the cell membrane (including molecular details) with a fluid dynamics model based on boundary-integral equations. A numerical flow channel is created where the cell is driven through a narrow slit by pressure (imitating the transit through venus slits in spleen). The concentration is the occurrence of large dissociation (negative) pressure between the skeleton/membrane connection that promotes separation, a precursor of vesicle formation. Critical levels for the negative pressure are estimated using published data. By following the maximum range of pressure, we conclude that for vesiculation to happen there must be biochemical influences (e.g. binding of degraded haemoglobin) that significantly reduce effective attachment density. This is consistent with reported trends in vesiculation that are believed to occur in cases of various hereditary anemias and during blood storage. Our findings also suggest the criticality of understanding the biochemical phenomena involved with cytoskeleton/membrane attachment. [Preview Abstract] |
Sunday, November 20, 2016 6:16PM - 6:29PM |
E20.00004: Dynamics of Red Blood Cells through submicronic splenic slits Emmanuele Helfer, Priya Gambhire, Scott Atwell, Frederic Bedu, Igor Ozerov, Annie Viallat, Anne Charrier, Catherine Badens Red Blood Cells (RBCs) are periodically monitored for changes in their deformability by the spleen, and are entrapped and destroyed if unable to pass through the splenic interendothelial slits (IESs). In particular, in sickle cell disease (SCD), where hemoglobin form fibers inside the RBCs, and in hereditary spherocytosis (HS), where RBCs are more spherical and membrane-cytoskekeleton bonds are weakened, the loss of RBC deformability leads to spleen dysfunction. By combining photolithography and anisotropic wet etching techniques, we developed a new on-chip PDMS device with channels replicating the submicronic physiological dimensions of IESs to study the mechanisms of deformation of the RBCs during their passage through these biomimetic slits. For the first time, with HS RBCs, we show the disruption of the links between the RBC membrane and the underlying spectrin network. In the case of SCD RBCs we show the appearance of a tip at the front of the RBC with a longer time relaxation due to the increased cytoplasmic viscosity. [Preview Abstract] |
Sunday, November 20, 2016 6:29PM - 6:42PM |
E20.00005: Multiscale Modeling of Red Blood Cells Squeezing through Submicron Slits Zhangli Peng, Huijie Lu A multiscale model is applied to study the dynamics of healthy red blood cells (RBCs), RBCs in hereditary spherocytosis, and sickle cell disease squeezing through submicron slits. This study is motivated by the mechanical filtration of RBCs by inter-endothelial slits in the spleen. First, the model is validated by comparing the simulation results with experiments. Secondly, the deformation of the cytoskeleton in healthy RBCs is investigated. Thirdly, the mechanisms of damage in hereditary spherocytosis are investigated. Finally, the effects of cytoplasm and membrane viscosities, especially in sickle cell disease, are examined. The simulations results provided guidance for future experiments to explore the dynamics of RBCs under extreme deformation. [Preview Abstract] |
Sunday, November 20, 2016 6:42PM - 6:55PM |
E20.00006: Stretching Behavior of Red Blood Cells at High Strain Rates Jordan Mancuso, William Ristenpart Most work on the mechanical behavior of red blood cells (RBCs) has focused on simple shear flows. Relatively little work has examined RBC deformations in the physiologically important extensional flow that occurs at the entrance to a constriction. In particular, previous work suggests that RBCs rapidly stretch out and then retract upon entering the constriction, but to date no model predicts this behavior for the extremely high strain rates typically experienced there. In this work, we use high speed video to perform systematic measurements of the dynamic stretching behavior of RBCs as they enter a microfluidic constriction. We demonstrate that a simple viscoelastic model captures the observed stretching dynamics, up to strain rates as high as 1000 s$^{-1}$. The results indicate that the effective elastic modulus of the RBC membrane at these strain rates is an order of magnitude larger than moduli measured by micropipette aspiration or other low strain rate techniques. [Preview Abstract] |
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