We study the biomechanical interactions between the lipid bilayer and the cytoskeleton in a red blood cell (RBC) by developing a general framework for mesoscopic simulations. We treated the lipid ...bilayer and the cytoskeleton as two distinct components and developed a unique whole-cell model of the RBC, using dissipative particle dynamics (DPD). The model is validated by comparing the predicted results with measurements from four different and independent experiments. First, we simulated the micropipette aspiration and quantified the cytoskeletal deformation. Second, we studied the membrane fluctuations of healthy RBCs and RBCs parasitized to different intraerythrocytic stages by the malaria-inducing parasite Plasmodium falciparum . Third, we subjected the RBC to shear flow and investigated the dependence of its tank-treading frequency on shear rate. Finally, we simulated the bilayer–cytoskeletal detachment in channel flow to quantify the strength of such interactions when the corresponding bonds break. Taken together, these experiments and corresponding systematic DPD simulations probe the governing constitutive response of the cytoskeleton, elastic stiffness, viscous friction, and strength of bilayer–cytoskeletal interactions as well as membrane viscosities. Hence, the DPD simulations and comparisons with available independent experiments serve as validation of the unique two-component model and lead to useful insights into the biomechanical interactions between the lipid bilayer and the cytoskeleton of the RBC. Furthermore, they provide a basis for further studies to probe cell mechanistic processes in health and disease in a manner that guides the design and interpretation of experiments and to develop simulations of phenomena that cannot be studied systematically by experiments alone.
Infection of erythrocytes with the human malaria parasite, Plasmodium falciparum, results in dramatic changes to the host cell structure and morphology. The predicted functional localization of the ...STEVOR proteins at the erythrocyte surface suggests that they may be involved in parasite-induced modifications of the erythrocyte membrane during parasite development. To address the biologic function of STEVOR proteins, we subjected a panel of stevor transgenic parasites and wild-type clonal lines exhibiting different expression levels for stevor genes to functional assays exploring parasite-induced modifications of the erythrocyte membrane. Using this approach, we show that stevor expression impacts deformability of the erythrocyte membrane. This process may facilitate parasite sequestration in deep tissue vasculature.
Silver nanoparticles (AgNPs) are increasingly being used as antimicrobial agents and drug carriers in biomedical fields. However, toxicological information on their effects on red blood cells (RBCs) ...and the mechanisms involved remain sparse. In this article, we examined the size dependent nanotoxicity of AgNPs using three different characteristic sizes of 15 nm (AgNPs15), 50 nm (AgNPs50), and 100 nm (AgNPs100) against fish RBCs. Optical microscopy and transmission electron microscopy observations showed that AgNPs exhibited a size effect on their adsorption and uptake by RBCs. The middle sized AgNPs50, compared with the smaller or bigger ones, showed the highest level of adsorption and uptake by the RBCs, suggesting an optimal size of ∼50 nm for passive uptake by RBCs. The toxic effects determined based on the hemolysis, membrane injury, lipid peroxidation, and antioxidant enzyme production were fairly size and dose dependent. In particular, the smallest sized AgNPs15 displayed a greater ability to induce hemolysis and membrane damage than AgNPs50 and AgNPs100. Such cytotoxicity induced by AgNPs should be attributed to the direct interaction of the nanoparticle with the RBCs, resulting in the production of oxidative stress, membrane injury, and subsequently hemolysis. Overall, the results suggest that particle size is a critical factor influencing the interaction between AgNPs and the RBCs.
The aerial parts of Cephalariaanatolica yielded two previously undescribed hederagenin-type triterpene glycosides, namely cephosides B (1) and C (2), in addition to eleven known natural compounds. ...The new compounds were identified as 3-O-β- D -glucopyranosyl-(1 ® 3)- b - D -glucopyranosyl-(1 ® 3)-α- L -rhamnopyranosyl-(1 ® 2)-α- L -arabinopyranosyl hederagenin 28-O-β- D -galactopyranosyl-(1 ® 6)-β- D -glucopyranosyl ester (1) and 3-O-α- L -rhamnopyranosyl-(1 ® 4)- b - D -glucopyranosyl-( 1 ® 3)-α- L -rhamnopyranosyl-(1 ® 2)-α- L -arabinopyranosyl hederagenin 28-O-β- D -galactopyranosyl-(1 ® 6)-β- D -glucopyranosyl ester (2) by 1D and 2D NMR spectroscopic data, HRESIMS analysis and chemical evidence. The two new triterpenoid saponins and the n-butanol extract were evaluated for their hemolytic activity in human erythrocyte cells and immunomodulatory properties in activated whole blood cells by PMA plus ionomycin. While only n-butanol extract increased IL-1β concentration strongly with a value of 760.52 pg/mL, cephoside C and n-butanol extract augmented a slight IFN-γ secretion with values of 4874.11 and 4750.20 pg/mL, respectively. None of the compounds changed IL-2 levels significantly and showed hemolytic activity.
Blood viscosity decreases with shear stress, a property essential for an efficient perfusion of the vascular tree. Shear thinning is intimately related to the dynamics and mutual interactions of ...RBCs, the major component of blood. Because of the lack of knowledge about the behavior of RBCs under physiological conditions, the link between RBC dynamics and blood rheology remains unsettled. We performed experiments and simulations in microcirculatory flow conditions of viscosity, shear rates, and volume fractions, and our study reveals rich RBC dynamics that govern shear thinning. In contrast to the current paradigm, which assumes that RBCs align steadily around the flow direction while their membranes and cytoplasm circulate, we show that RBCs successively tumble, roll, deform into rolling stomatocytes, and, finally, adopt highly deformed polylobed shapes for increasing shear stresses, even for semidilute volume fractions of the microcirculation. Our results suggest that any pathological change in plasma composition, RBC cytosol viscosity, or membrane mechanical properties will affect the onset of these morphological transitions and should play a central role in pathological blood rheology and flow behavior.
ATP-dependent mechanics of red blood cells Betz, Timo; Lenz, Martin; Joanny, Jean-François ...
Proceedings of the National Academy of Sciences - PNAS,
09/2009, Letnik:
106, Številka:
36
Journal Article
Recenzirano
Odprti dostop
Red blood cells are amazingly deformable structures able to recover their initial shape even after large deformations as when passing through tight blood capillaries. The reason for this exceptional ...property is found in the composition of the membrane and the membrane-cytoskeleton interaction. We investigate the mechanics and the dynamics of RBCs by a unique noninvasive technique, using weak optical tweezers to measure membrane fluctuation amplitudes with μs temporal and sub nm spatial resolution. This enhanced edge detection method allows to span over >4 orders of magnitude in frequency. Hence, we can simultaneously measure red blood cell membrane mechanical properties such as bending modulus κ = 2.8 ± 0.3 x 10⁻¹⁹J = 67.6 ± 7.2 kBT, tension σ = 6.5 ± 2.1 x 10⁻⁷N/m, and an effective viscosity ηeff = 81 ± 3.7 x 10⁻³ Pa s that suggests unknown dissipative processes. We furthermore show that cell mechanics highly depends on the membrane-spectrin interaction mediated by the phosphorylation of the interconnection protein 4.1R. Inhibition and activation of this phosphorylation significantly affects tension and effective viscosity. Our results show that on short time scales (slower than 100 ms) the membrane fluctuates as in thermodynamic equilibrium. At time scales longer than 100 ms, the equilibrium description breaks down and fluctuation amplitudes are higher by 40% than predicted by the membrane equilibrium theory. Possible explanations for this discrepancy are influences of the spectrin that is not included in the membrane theory or nonequilibrium fluctuations that can be accounted for by defining a nonthermal effective energy of up to Eeff = 1.4 ± 0.1 kBT, that corresponds to an actively increased effective temperature.
Membrane sialic acid (SA) plays an important role in the survival of red blood cells (RBCs), the age‐related reduction in SA content negatively impacts both the structure and function of these cells. ...We have therefore suggested that remodelling the SA in the membrane of aged cells would help recover cellular functions characteristic of young RBCs. We developed an effective method for the re‐sialylation of aged RBCs by which the cells were incubated with SA in the presence of cytidine triphosphate (CTP) and α‐2,3‐sialytransferase. We found that RBCs could be re‐sialylated if they had available SA‐binding groups and after the re‐sialylation, aged RBCs could restore their membrane SA to the level in young RBCs. Once the membrane SA was restored, the aged RBCs showed recovery of their biophysical and biochemical properties to similar levels as in young RBCs. Their life span in circulation was also extended to twofold. Our findings indicate that remodelling membrane SA not only helps restore the youth of aged RBCs, but also helps recover injured RBCs.
Red blood cells (RBCs), also called erythrocytes, are the most abundant type of blood cells. Recently, RBCs have been extensively studied as drug delivery systems because of their remarkable ...properties, including their inherent biocompatibility, low immunogenicity, flexibility, and long systemic circulation. Over the years, a number of different RBC-based drug delivery systems, including genetically engineered RBCs, nongenetically engineered RBCs, and RBC membrane-coated nanoparticles, have been explored, aiming at diverse biomedical applications. These techniques may address many challenging issues faced by traditional drug delivery systems, as demonstrated by the many successful preclinical results. Novel techniques dedicated to producing drug-carrying RBCs are currently undergoing the transition from preclinical research to the clinical realm. In this Topical Review, we will summarize the latest progress in the development of RBC-based smart delivery systems for various biomedical applications.
Although lipid domains have been evidenced in several living cell plasma membranes, their roles remain largely unclear. We here investigated whether they could contribute to function-associated cell ...(re)shaping. To address this question, we used erythrocytes as cellular model since they (i) exhibit a specific biconcave shape, allowing for reversible deformation in blood circulation, which is lost by membrane vesiculation upon aging; and (ii) display at their outer plasma membrane leaflet two types of submicrometric domains differently enriched in cholesterol and sphingomyelin. We here reveal the specific association of cholesterol- and sphingomyelin-enriched domains with distinct curvature areas of the erythrocyte biconcave membrane. Upon erythrocyte deformation, cholesterol-enriched domains gathered in high curvature areas. In contrast, sphingomyelin-enriched domains increased in abundance upon calcium efflux during shape restoration. Upon erythrocyte storage at 4 °C (to mimick aging), lipid domains appeared as specific vesiculation sites. Altogether, our data indicate that lipid domains could contribute to erythrocyte function-associated (re)shaping.
To avoid clearance by the spleen, red blood cells infected with the human malaria parasite Plasmodium falciparum (iRBCs) adhere to the vascular endothelium through adhesive protrusions called “knobs” ...that the parasite induces on the surface of the host cell. However, the detailed relation between the developing knob structure and the resulting movement in shear flow is not known. Using flow chamber experiments on endothelial monolayers and tracking of the parasite inside the infected host cell, we find that trophozoites (intermediate-stage iRBCs) tend to flip due to their biconcave shape, whereas schizonts (late-stage iRBCs) tend to roll due to their almost spherical shape. We then use adhesive dynamics simulations for spherical cells to predict the effects of knob density and receptor multiplicity per knob on rolling adhesion of schizonts. We find that rolling adhesion requires a homogeneous coverage of the cell surface by knobs and that rolling adhesion becomes more stable and slower for higher knob density. Our experimental data suggest that schizonts are at the border between transient and stable rolling adhesion. They also allow us to establish an estimate for the molecular parameters for schizont adhesion to the vascular endothelium and to predict bond dynamics in the contact region.
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