A few upstream bifurcations drive the spatial distribution of red blood cells in model microfluidic networks

Soft Matter ◽  
2022 ◽  
Author(s):  
Adlan Merlo ◽  
Maxime Berg ◽  
Paul Duru ◽  
Frédéric Risso ◽  
Yohan Davit ◽  
...  
Keyword(s):  
Blood Flow ◽  
Spatial Distribution ◽  
Blood Vessel ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Small Vessel ◽  
Microfluidic Networks ◽  
Vessel Walls ◽  
Vessel Networks

The physics of blood flow in small vessel networks is dominated by the interactions between Red Blood Cells (RBCs), plasma and blood vessel walls. The resulting couplings between the microvessel...

scholarly journals Mathematical Models for Some Aspects of Blood Microcirculation

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1020
Author(s):  
Angiolo Farina ◽  
Antonio Fasano ◽  
Fabio Rosso
Keyword(s):  
Blood Flow ◽  
Mathematical Models ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Blood Rheology ◽  
Small Class ◽  
Small Vessels ◽  
Blood Microcirculation ◽  
Peculiar Behavior

Blood rheology is a challenging subject owing to the fact that blood is a mixture of a fluid (plasma) and of cells, among which red blood cells make about 50% of the total volume. It is precisely this circumstance that originates the peculiar behavior of blood flow in small vessels (i.e., roughly speaking, vessel with a diameter less than half a millimeter). In this class we find arteriolas, venules, and capillaries. The phenomena taking place in microcirculation are very important in supporting life. Everybody knows the importance of blood filtration in kidneys, but other phenomena, of not less importance, are known only to a small class of physicians. Overviewing such subjects reveals the fascinating complexity of microcirculation.

Multiscale Modeling of Flow Induced Thrombogenicity Using Dissipative Particle Dynamics and Molecular Dynamics

2013 ◽  
Author(s):  
Danny Bluestein ◽  
João S. Soares ◽  
Peng Zhang ◽  
Chao Gao ◽  
Seetha Pothapragada ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Blood Flow ◽  
Red Blood Cells ◽  
Platelet Activation ◽  
Blood Cells ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
Coagulation Cascade ◽  
Shear Stresses ◽  
Activated Platelets

The coagulation cascade of blood may be initiated by flow induced platelet activation, which prompts clot formation in prosthetic cardiovascular devices and arterial disease processes. While platelet activation may be induced by biochemical agonists, shear stresses arising from pathological flow patterns enhance the propensity of platelets to activate and initiate the intrinsic pathway of coagulation, leading to thrombosis. Upon activation platelets undergo complex biochemical and morphological changes: organelles are centralized, membrane glycoproteins undergo conformational changes, and adhesive pseudopods are extended. Activated platelets polymerize fibrinogen into a fibrin network that enmeshes red blood cells. Activated platelets also cross-talk and aggregate to form thrombi. Current numerical simulations to model this complex process mostly treat blood as a continuum and solve the Navier-Stokes equations governing blood flow, coupled with diffusion-convection-reaction equations. It requires various complex constitutive relations or simplifying assumptions, and is limited to μm level scales. However, molecular mechanisms governing platelet shape change upon activation and their effect on rheological properties can be in the nm level scales. To address this challenge, a multiscale approach which departs from continuum approaches, may offer an effective means to bridge the gap between macroscopic flow and cellular scales. Molecular dynamics (MD) and dissipative particle dynamics (DPD) methods have been employed in recent years to simulate complex processes at the molecular scales, and various viscous fluids at low-to-high Reynolds numbers at mesoscopic scales. Such particle methods possess important properties at the mesoscopic scale: complex fluids with heterogeneous particles can be modeled, allowing the simulation of processes which are otherwise very difficult to solve by continuum approaches. It is becoming a powerful tool for simulating complex blood flow, red blood cells interactions, and platelet-mediated thrombosis involving platelet activation, aggregation, and adhesion.

Hypoxic Vasodilation by Red Blood Cells and Impairment in Vascular Disorders.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1585-1585
Author(s):  
John R. Pawloski ◽  
Timothy J. McMahon ◽  
Greg Ahearne ◽  
Claude A. Piantadosi ◽  
David J. Singel ◽  
...  
Keyword(s):  
Blood Flow ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Vascular Dysfunction ◽  
Aortic Ring ◽  
Efficient Production ◽  
Anion Exchanger 1 ◽  
Rbc Membrane ◽  
Tissue Po2 ◽  
Hypoxic Vasodilation

Abstract Physiological O2 gradients are principal regulators of blood flow in the microcirculation: position-to-position changes in hemoglobin (Hb) O2 saturation are coupled to regulated vasodilation (“hypoxic vasodilation”). The mechanism by which graded changes in O2 content of blood evoke this response has been a great challenge to understand. A new role for red blood cells (RBCs) in hypoxic dilation of blood vessels and inhibition of platelet activation involving release of nitric oxide (NO) bioactivity is described. We show that NO groups can be transferred within hemoglobin (Hb) from hemes to highly-conserved cysteine thiols (β-Cys93) to form bioactive S-nitrosohemoglobin (SNO-Hb), and that efficient production of SNO-Hb requires selective processing of NO within the β-subunits. Bioactive SNO-Hb is localized primarily to the RBC membrane through interaction with Band 3, the transmembrane anion-exchanger 1 protein (AE1). Upon deoxygenation, transfer of the NO group from β-Cys93 of Hb to a cysteine thiol within AE1 serves the RBC vasodilator activity. In this way, O2 binding in Hb modulates the release of NO bioactivity. We further show that RBC NO bioactivity is inversely proportional to pO2 and impaired in disease. In an aortic ring bioassay sparged with variable concentrations of O2, addition of normal human RBCs elicited graded responses from relaxation at tissue pO2 (~3–7 mm Hg, hypoxic vasodilation), to loss of relaxation and progressively greater contractions at pO2’s of 10–63 mm Hg (hyperoxic vasoconstriction). Notably, RBC SNO-Hb levels and hypoxic vasodilation are impaired in several diseases characterized by vascular dysfunction. For example, in RBCs from patients with pulmonary arterial hypertension (PAH), we found decreased (13% of control) SNO-Hb content (assessed by photolysis-chemiluminescence) and impaired O2-dependent vasodilation (bioassay). RBCs from patients with other ischemic disorders have also been examined: RBCs demonstrate a pathogenesis-based impairment in their ability to mediate hypoxic vasodilation by NO. These results confirm the (patho)physiologic importance of RBC NO, and suggest that RBC dysfunction may contribute to impaired blood flow in diseases of the heart, lung and blood.

Effects of Pan-Selectin Antagonist GMI-1070 on the Treatment of Vaso-Occlusion in Sickle Cell Mice

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 535-535 ◽  
Author(s):  
Jungshan Chang ◽  
John T Patton ◽  
Paul S. Frenette ◽  
John L. Magnani
Keyword(s):  
Blood Flow ◽  
Red Blood Cells ◽  
Sickle Cell ◽  
Small Molecule ◽  
Vascular Endothelium ◽  
Intravital Microscopy ◽  
Blood Cells ◽  
Tnf Α ◽  
Sickle Red Blood Cells ◽  
Adherent Leukocytes

Abstract Acute vaso-occlusion (VOC) in patients with sickle cell disease (SCD) induces intense pain arising from organ damage and is the major cause of morbidity and mortality. Hypoxia and abnormal sickle red blood cells (RBC) induce inflammatory mediators and activation of the vascular endothelium leading to the recruitment of adherent leukocytes and sickle RBC followed by aggregates that eventually occlude blood flow. Previous studies have implicated the critical roles of cell adhesion molecules E- and P-selectins by using intravital microscopy in SCD mice (Berkeley strain) with altered genetic backgrounds (SCD transplanted in recipients lacking E-and P-selectins), or antibodies against endothelial selectins, or small molecules directed against the selectins. Here, we designed a treatment protocol for this SCD mouse model, in which a small molecule pan-selectin antagonist (GMI-1070) is administered to sickle cell mice late in the process of established vaso-occlusion in order to test the effects of GMI-1070 in a more clinically relevant model. GMI-1070 is a small molecule pan-selectin antagonist designed on the bioactive conformation of the carbohydrate ligand and inhibits leukocyte adhesion to activated endothelium in vitro with particularly strong activity against E-selectin (IC50 = 3.4 μM). Berkeley SCD mice were generated by bone marrow transplantation into lethally irradiated C57BL/6 male mice and the fully engrafted (100% donor RBC chimerism) mice were used for intravital microscopy experiments. VOC events were induced by injection with TNF-α at time 0 and the formation of occlusions were allowed to proceed as long as possible just prior to the death of the control mice. GMI-1070 (20 mg/kg) or vehicle (PBS pH 7.4) were administered at t = 110 min. Post-capillary and collecting venules in the cremaster muscle were analyzed for effects on an established VOC event. Under these conditions, GMI-1070 significantly increased the microcirculatory blood flow to levels observed in non-sickle cell mice (vehicle: 237 ± 15 nL/sec; GMI-1070: 533 ± 58 nL/sec; p<0.0001). The recruitment of adherent leukocytes to the vascular endothelium was also significantly reduced (vehicle: 2235 ± 156; GMI-1070: 1270 ± 203 cells/mm2; p=0.0013), and there were significant and dramatic reductions in the capture of sickle red blood cells to adherent leukocytes (vehicle: 0.68 ± 0.27; GMI-1070: 0.03 ± 0.01 interactions/WBC, min, 100ml; p=0.0003). Mice began to succumb to VOC within 2.5 hours after injection of TNF-α and surgical trauma which continued until all of the control SCD mice died. Administration of GMI-1070 prevented the death of half of the treated mice within the timeframe of the experiment and extended the median survival of mice from 5 hours (control, vehicle-treated) to greater than 9 hours for the GMI-1070- treated SCD mice (p = 0.0067). These studies show that GMI-1070 can significantly and dramatically improve the condition and survival of the animals with a severe VOC even when dosed well after the initiating challenge. Thus these data strongly support the use of GMI-1070 for the treatment of patients in acute vaso-occlusive crisis. GMI-1070 is currently in a Phase I clinical trial.

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