Biorheology - Volume 42, issue 5

Authors: Canetta, Elisabetta | Duperray, Alain | Leyrat, Anne | Verdier, Claude

Article Type: Research Article

Abstract: Cell adhesive and rheological properties play a very important role in cell transmigration through the endothelial barrier, in particular in the case of inflammation (leukocytes) or cancer metastasis (cancer cells). In order to characterize cell viscoelastic properties, we have designed a force spectrometer (AFM) which can stretch cells thereby allowing measurement of their rheological properties. This custom-made force spectrometer allows two different visualizations, one lateral and one from below. It allows investigation of the effects of rheology involved during cell stretching. To test the ability of our system to characterize such viscoelastic properties, ICAM-1 transfected CHO cells were analyzed. Two …forms of ICAM-1 were tested; wild type ICAM-1, which can interact with the cytoskeleton, and a mutant form which lacks the cytoplasmic domain, and is unable to associate with the cytoskeleton. Stretching experiments carried out on these cells show the formation of long filaments. Using a previous model of filament elongation, we could determine the viscoelastic properties of a single cell. As expected, different viscoelastic components were found between the wild type and the mutant, which reveal that the presence of interactions between ICAM-1 and the cytoskeleton increases the stiffness of the cell. Show more

Keywords: Cell stretching, AFM, microrheology, adhesion, ICAM-1

Citation: Biorheology, vol. 42, no. 5, pp. 321-333, 2005

Authors: Akers, Walter J. | Cupps, Jay M. | Haidekker, Mark A.

Article Type: Research Article

Abstract: Many disease states have associated blood viscosity changes. Molecular rotors, fluorescent molecules with viscosity sensitive quantum yields, have recently been investigated as a new method for biofluid viscosity measurement. Current viscometer measurements are complicated by proteins adhering to surfaces and forming air-surface layers. It is unknown at this time what effects proteins may have on biofluid viscosity measurements using molecular rotors. To answer this question, binding affinities to blood plasma proteins were investigated by equilibrium dialysis for four hydrophilic molecular rotors. Aqueous solutions of 9-[(2-cyano-2-hydroxy-carbonyl)vinyl]julolidine (CCVJ) and three derivatives were prepared and dialyzed against solutions of bovine source albumin, fibrinogen …and immunoglobulin G approximating normal physiologic concentrations and fresh-frozen human plasma. After equilibration, dye concentration on each side of the dialysis membrane was assessed by spectrophotometry. The relative binding affinity of the four dyes to the proteins and to the plasma was compared. Affinity of all dyes was highest for albumin. The bound dye fraction showed little change in relation to protein concentration in the physiological concentration range. Diol, the most hydrophilic molecular rotor tested showed the lowest affinity for albumin. This study indicates that hydrophilic molecular rotors are well-suited for biofluid viscosity measurement. Show more

Keywords: Viscosity, TICT, CCVJ

Citation: Biorheology, vol. 42, no. 5, pp. 335-344, 2005

Authors: Seong, Jaehoon | Sadasivan, Chander | Onizuka, Masanari | Gounis, Matthew J. | Christian, Fletcher | Miskolczi, Laszlo | Wakhloo, Ajay K. | Lieber, Baruch B.

Article Type: Research Article

Abstract: In this work, we describe a methodology to fabricate transparent elastomeric vascular replicas using rapid prototyping techniques. First, the three-dimensional morphology of an elastase-induced aneurysm model in rabbit is acquired. The morphology is reconstructed from in vivo rotational angiography and it is compared with three-dimensional reconstructions obtained by computerized tomography and magnetic resonance imaging of an intraluminal arterial cast that was obtained from the same animal at sacrifice. Results show that resolution of the imaging modality strongly influences the level of detail, such as small side branches, in the final reconstruction. We developed an average morphology model for elastase-induced aneurysms …in rabbits including the surrounding vasculature and describe a method for rapid prototyping of vascular models from the three-dimensional morphology. Our replicas can be manufactured in a short period of time and the final product is optically clear. In addition, the elasticity of the models can be controlled to represent arterial elasticity, which makes them ideal for optical investigations of detailed flow dynamics using measurement tools such as particle image velocimetry. Show more

Keywords: Image reconstruction, fused deposition modeling, injection cast, representative arterial morphology, compliant vascular models

Citation: Biorheology, vol. 42, no. 5, pp. 345-361, 2005

Authors: Lamkin-Kennard, Kathleen A. | Chuang, Johnson Y.-H. | Kim, Michael B. | Sarelius, Ingrid H. | King, Michael R.

Article Type: Research Article

Abstract: The aim of this study was to characterize the distribution of adherent leukocytes in branched venular convergences in vivo. Intravital microscopy was used to obtain video images of leukocyte adhesion in multiple branched sites in mouse cremaster muscle, during the mild inflammatory response induced by surgical preparation. The average number of cells/vessel length was obtained over several minutes for seven venular convergences with varying geometrical configurations. Results from this study demonstrate a strong tendency of leukocytes to adhere at junctional points between converging vessels. Different vessel configurations were studied and results were shown to be insensitive to precise vessel geometry. …Thus, in post-capillary venules, leukocytes are most likely to adhere at points between converging vessels, regardless of the precise geometrical properties or configuration of the vessels. Hydrodynamic mechanisms due to flow behavior through convergences likely play a significant role in determining locations of cellular adhesion. Future work should concentrate on quantifying the relative contributions of hydrodynamic and biochemical mechanisms to aid in understanding disease processes and development of treatments or therapeutics. Show more

Keywords: Leukocyte, venular branch, intravital microscopy, selectin, hydrodynamics

Citation: Biorheology, vol. 42, no. 5, pp. 363-383, 2005

Authors: Cokelet, Giles R. | Brown, Jennifer R. | Codd, Sarah L. | Seymour, Joseph D.

Article Type: Research Article

Abstract: Magnetic resonance microscopy is used to non-invasively measure the radial velocity distribution in Couette flow of erythrocyte suspensions of varying aggregation behavior at a nominal shear rate of 2.20 s−1 in a 1 mm gap. Suspensions of red blood cells in albumin-saline, plasma and 1.48% Dextran added plasma at average hematocrits near 0.40 are studied, providing a range of aggregation ability. The spatial distribution of the red blood cell volume fraction, hematocrit, is calculated from the velocity distribution. The hematocrit profiles provide direct measure of the thickness of the aggregation and shear rate dependent red blood cell depletion at …the Couette surfaces. At the nominal shear rate studied hematocrit distributions for the red blood cells in plasma show a depletion zone near the inner Couette wall but not the outer wall. The red blood cells in plasma with Dextran show cell depletion regions of approximately 100 μm at both the inner and outer Couette surfaces, with greater depletion at the inner wall, but approach the normal blood hematocrit distribution with a doubling of shear rate due to decreased aggregation. The material response of the blood is spatially dependent with the shear rate and the hematocrit distribution non-uniform across the gap. Show more

Keywords: Shear-diffusivity, cell migration, cell aggregation, shear rate distribution, Rheo-NMR

Citation: Biorheology, vol. 42, no. 5, pp. 385-399, 2005

Article Type: Abstract

Citation: Biorheology, vol. 42, no. 5, pp. 401-419, 2005