Red Blood Cell Aggregation Research Articles

Use of biomedical photonics for in vivo and in vitro assessment of haemostasis and microcirculation in patients on antithrombotic therapy

Abstract Background Antithrombotic therapy in patients with cardiovascular disease requires rapid translation of laboratory assessment of haemorrheological parameters in clinical cardiology practice. Both antiplatelet and anticoagulant agents, especially when used in combination, can potentially increase the risk of severe bleeding. The precise balance between thrombosis and hemorrhage is therefore pivotal to ensure optimal treatment results. Purpose To develop simple and reliable methods to control the haemorheological properties of the blood and to assess the risk of potential bleeding. Methods We assessed platelet aggregation parameters measured in vitro by laser aggregometry and optical trapping techniques in blood samples of 131 patients with coronary artery disease. Additionally, blood rheology and microcirculation parameters were assessed in vivo in the nail-fold area using the digital capillaroscopy system. Results We found a statistically significant correlation between the number of aggregated blood cells in vitro and the presence of aggregates in the blood capillaries in vivo. A significant correlation was also observed between red blood cells (RBC) aggregation time in vitro and capillary flow velocity in vivo. The most severe deterioration of the rheological properties was found in patients with diffuse atherosclerotic disease receiving combined antithrombotic therapy. Interestingly, optical examination of soft tissues surrounding the capillaries of the nail-fold area revealed the presence of micro-hemorrhages in patients with history of hemorrhagic complications on antithrombotic therapy (Fig. 1). Conclusion Novel methods of biomedical photonics applied for in vivo and in vitro assessment of the blood haemorrheological properties can provide important additional information on microcirculation parameters and optimize treatment in patients on antithrombotic therapy. Funding Acknowledgement Type of funding sources: None. In vivo nail-fold digital capillaroscopy

Stroke mechanisms associated with coronavirus disease (COVID-19)

The purpose is to identify the pathophysiological mechanisms of stroke development in patients with COVID-19.MethodsA total of 92 patients (46.72+1.72 years) with impairments of cerebral circulation due to COVID-19 (confirmed by positive PCR test results) had been examined. Among them, 67 patients had an ischemic stroke, 14–a transient ischaemic attack, 11–an intracerebral hemorrhage, 3– a subarachnoid hemorrhage.The parameters of hemostasis were measured by standard methods, electrical and viscoelastic parameters of red blood cells (RBC) by the dielectrophoresis method was carried out.ResultsMost of the surveyed persons (60 patients) showed signs of an intravascular coagulation and thrombosis: accelerated platelet-leukocyte aggregation, increased levels of coagulation products, reduced fibrinolysis activity (p=0.002–0.04). The levels of D-dimer, fibrinogen, ESR, platelet count were significantly higher in this group compared to patients in the second one (p<0.01). A moderate increase in summarized rigidity, viscosity of RBC was noted. The level of RBC hemolysis was associated with platelet count (r=0.727, p<0.05), D-dimer level (r=0.422, p=0.04), and fibrinogen level (r=0.318, p<0.05).In the second group of patients (32 persons with a predominance of men - 25 male subjects), the markers of thrombosis had moderate deviations. A sharply reduced RBC deformability with increased summarized rigidity and viscosity was dominant coupled with the background of high electrical conductivity of cell membranes compared to the indicators in the first group (p<0.01). There was a decrease in membrane capacity, surface charge, electrical dipole moment of the cells and polarizability at all frequencies of the electric field than those in the first group (p=0.0001–0.05). A sharp decrease in RBC deformability creates obstacles to overcoming small-diameter capillaries, leading to violations of microcirculatory blood flow.The RBC deformability was associated with levels of ferritin (r=0.407, p=0.024), HbA1c (r=0.419, p=0.033), uric acid (r=−0.303, p<0.05), and LDL cholesterol (r=0.426, p=0.029).Incubation of blood samples in vitro for 10 min with riboflavin, nicotinamide, inosine, which ensures RBC energy metabolism (anaerobic glycolysis and pentose phosphate pathway) restored the reduced the RBC deformability (p<0.01), and decreased the RBC aggregation (p<0.001). Similar changes were obtained when coenzymes were administered to patients in vivo.ConclusionTwo independent mechanisms of cerebral circulatory disturbances have been identified in COVID-19 stroke patients: both thrombotic and hemorheologic. The thrombotic variant is associated with a procoagulant state and with an activity of inflammation. The hemorheologic variant is caused by a decrease in the activity of the RBC energy metabolism enzymes; it is associated with the presence of metabolic disorders and is to be eliminated by an administration of coenzymes and metabolites.FUNDunding AcknowledgementType of funding sources: Other. Main funding source(s): This research was done within the framework of the topic “Epidemiological monitoring of the population state of health and studies on molecular genetic and molecular biological mechanisms of the development of common internal diseases in Siberia for improvement of the relevant diagnostic, preventive, and therapeutic methods” in State Assignment No. 0324-2018-0001, registration No. AAAA-A17-117112850280-2

Peripartum Investigation of Red Blood Cell Properties in Women Diagnosed with Early-Onset Preeclampsia.

We investigated peripartum maternal red blood cell (RBC) properties in early-onset preeclampsia (PE). Repeated blood samples were taken prospectively for hemorheological measurements at PE diagnosis (n = 13) or during 26–34 weeks of gestation in healthy pregnancies (n = 24), then at delivery, and 72 h postpartum. RBC aggregation was characterized by M index (infrared light transmission between the aggregated RBCs in stasis) and aggregation index (AI—laser backscattering from the RBC aggregates). We observed significantly elevated RBC aggregation (M index = 9.8 vs. 8.5; AI = 72.9% vs. 67.5%; p < 0.001) and reduced RBC deformability in PE (p < 0.05). A positive linear relationship was observed between AI and gestational age at birth in PE by regression analysis (R2 = 0.554; p = 0.006). ROC analysis of AI showed an AUC of 0.84 (0.68–0.99) (p = 0.001) for PE and indicated a cutoff of 69.4% (sensitivity = 83.3%; specificity = 62.5%), while M values showed an AUC of 0.75 (0.58–0.92) (p = 0.019) and indicated a cutoff of 8.39 (sensitivity = 90.9% and specificity = 50%). The predicted probabilities from the combination of AI and M variables showed increased AUC = 0.90 (0.79–1.00) (p < 0.001). Our results established impaired microcirculation in early-onset PE manifesting as deteriorated maternal RBC properties. The longer the pathologic pregnancy persists, the more pronounced the maternal erythrocyte aggregation. AI and M index could help in the prognostication of early-onset PE, but further investigations are warranted to confirm the prognostic role before the onset of symptoms.

Epinephrine-entrapped chitosan nanoparticles covered by gelatin nanofibers: A bi-layer nano-biomaterial for rapid hemostasis

Uncontrolled hemorrhage accounts for significant death risk both in trauma and surgery. Various bleeding control techniques have been emerged to augment hemostasis, which still has several limitations and drawbacks. In this study, epinephrine-entrapped chitosan nanoparticles were electrosprayed on a base pad and covered by a gelatin nanofiber layer (E-CS-Gl. Physico-chemical characteristics, hemocompatibility, cytotoxicity, and blood coagulation tests were studied in-vitro, and blood coagulation and hemostasis potential tests were performed in-vivo. The in-vitro results showed that the prepared nano-biomaterial is cytocompatible against HuGu cells. Also, hemocompatibility studies showed that PT and aPTT times did not change in comparison with the controls. Further blood coagulation study indicated that E-CS-Gl provides an ultimate interface to induce red blood cell absorption and aggregation, resulting in augmented blood coagulation. E-CS-Gl also caused rapid clotting in rat models of ruptured femoral artery and liver compared to controls. Findings exhibited that E-CS-Gl is a safe and effective hemostatic agent and provides a new approach for fast and safe hemorrhage control.

Diosmina i hesperydyna – obecny stan wiedzy

Diosmin is the 7-rutinoside of 3 ‘, 5,7-trihydroxy-4’-methoxyflavone (7-O-rutinoside of diosmetin), and hespheridine is the 7-rutinoside of 3’, 5,7-trihydroxy-4’-methoxyflavanone (7 -O-rutinoside hesperetin). Diosmin, is a gray-yellow or pale-yellow, hygroscopic powder, whereas hesperidine is in the form of light-yellow spherocrystals. Diosmin was isolated from fruits of the Citrus genus (C. sinensis, C. limonia), now it is obtained semi-synthetically from natural hesperidin. These flavonoids have, among others: antimicrobial, anti-inflammatory, anti-diabetic, anti-cancer, analgesic, antioxidant and possibly anti-virus activity, that cause COVID-19. The metabolism of diosmin takes place initially in the small intestine and involves demethoxylation and hydrolysis. In contrast, oxidation and conjugation take place in the liver. There is no presence of diosmin and diosmetin in the urine, which are mainly eliminated in the form of glucuronic acid conjugates. The dominant metabolite detected in urine samples is m-hydroxy-phenylpropionic acid, excreted in conjugated form. Diosmin may reduce the aggregation of Red Blood Cells, and thus it is able to reduce blood viscosity. The LD50 of the mixture of 90% diosmin and 10% hesperidin for rats is over 3 g/kg. The tests did not reveal any mutagenic effects or effects on reproductive functions. It also does not pose a significant threat during breast feeding, as it poorly passes into breast milk.

Blood compatibility evaluations of CaCO3 particles

CaCO3 particles, due to their unique properties such as biodegradation, pH-sensitivity, and porous surface, have been widely used as carrier materials for delivering drugs, genes, vaccines, and other bioactive molecules. In these applications, CaCO3 particles are often administered intravenously. In this sense, the interaction between CaCO3 particles and blood components plays a key role in their delivery efficacy and biosafety, though the hemocompatibility of CaCO3 particles has not been evaluated until now. Deficiency in the biosafety information has delayed the clinical use of CaCO3 particles in delivery systems. In this work, we investigated the biosafety of CaCO3 particles, focusing on their in vitro and in vivo effects on key blood components (red blood cells, platelets, etc) and coagulation functions. We found in vitro that high concentrations of CaCO3 particles can cause the aggregation and hemolysis of red blood cells, with platelet activation and coagulation prolongation. In vivo, we found that intravenously injected CaCO3 particles at 50 mg kg−1 significantly disturbed the red blood cells, and platelet-related blood routine indexes, but did not induce visible abnormalities in the tissue structures of the key organs. Overall, these effects may be due to the enormous adsorption capability of the porous surface of CaCO3 particles. 0.1 mg ml−1 of the CaCO3 particles exhibit excellent compatibility for their practical applications. These results would be expected to greatly promote the in vivo applications and clinical use of CaCO3 particles in biomedicine.

Indocyanine green angiography imaging findings in artery occlusions

To describe the multimodal imaging features including indocyanine green angiography (ICGA) in cases diagnosed clinically as central retinal artery occlusion (CRAO) at its different disease stages. In this retrospective observational study, patients diagnosed clinically as CRAO or hemi-CRAO were included. All patients underwent multimodal imaging with optical coherence tomography (OCT), fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) were studied. Analysis of ICGA images in different stages of artery occlusions and its correlation with accompanying FFA and OCT images was done. Eight such studies in five patients were available for analysis. The most important observation noted on ICGA was the presence of hypercyanescent spots seen during the acute stages of the disease in four of the five cases. The spots were accompanied by retinal vessel staining on FFA in the corresponding region. As the disease showed signs of resolution, the hypercyanescent spots on ICGA and retinal vessel staining on FFA disappeared. The hypercyanescent spots seen on the ICGA were noted due to the red blood cell aggregation or 'rouleaux' formation. In addition, choroidal perfusion abnormalities were noted on ICGA in all five cases in the acute stage. Choroidal perfusion changes can be identified in acute phase of retinal artery occlusion. Rouleaux formation in the retinal circulation occurs due to the slowing of the blood flow following artery occlusion. These are seen as hypercyanescent spots in the late phase on ICGA.

Rheological Parameters in Patients with Brain Infarct During COVID-19

In the description of the analytical clinical data of the patients with COVID-19 from difference country. In article shows detailed description of the rheological situation in patients with neuropathic during COVID-19. This data was com-pared with results of rheological study in analogical disease group patients with-out COVID-19. The article describes the effect of various anticoagulants on blood rheology, also describing protocols. In vivo, in vitro experiments, that studied a range of rheological parameters different anticoagulants. Measurement of RBC aggregation, RBC deformities, plasma viscosity were study with inno-vative technologies, quantitative methods. The work presents a scientifi c focus, after deep and increase research area is able to transport the newest conclusion to the clinical practice to treatment management of COVID-19.

Critical Role of Hemopexin Mediated Cytoprotection in the Pathophysiology of Sickle Cell Disease.

Circulating hemopexin is the primary protein responsible for the clearance of heme; therefore, it is a systemic combatant against deleterious inflammation and oxidative stress induced by the presence of free heme. This role of hemopexin is critical in hemolytic pathophysiology. In this review, we outline the current research regarding how the dynamic activity of hemopexin is implicated in sickle cell disease, which is characterized by a pathological aggregation of red blood cells and excessive hemolysis. This pathophysiology leads to symptoms such as acute kidney injury, vaso-occlusion, ischemic stroke, pain crises, and pulmonary hypertension exacerbated by the presence of free heme and hemoglobin. This review includes in vivo studies in mouse, rat, and guinea pig models of sickle cell disease, as well as studies in human samples. In summary, the current research indicates that hemopexin is likely protective against these symptoms and that rectifying depleted hemopexin in patients with sickle cell disease could improve or prevent the symptoms. The data compiled in this review suggest that further preclinical and clinical research should be conducted to uncover pathways of hemopexin in pathological states to evaluate its potential clinical function as both a biomarker and therapy for sickle cell disease and related hemoglobinopathies.

Numerical simulation of spatiotemporal red blood cell aggregation under sinusoidal pulsatile flow

Previous studies on red blood cell (RBC) aggregation have elucidated the inverse relationship between shear rate and RBC aggregation under Poiseuille flow. However, the local parabolic rouleaux pattern in the arterial flow observed in ultrasonic imaging cannot be explained by shear rate alone. A quantitative approach is required to analyze the spatiotemporal variation in arterial pulsatile flow and the resulting RBC aggregation. In this work, a 2D RBC model was used to simulate RBC motion driven by interactional and hydrodynamic forces based on the depletion theory of the RBC mechanism. We focused on the interaction between the spatial distribution of shear rate and the dynamic motion of RBC aggregation under sinusoidal pulsatile flow. We introduced two components of shear rate, namely, the radial and axial shear rates, to understand the effect of sinusoidal pulsatile flow on RBC aggregation. The simulation results demonstrated that specific ranges of the axial shear rate and its ratio with radial shear rate strongly affected local RBC aggregation and parabolic rouleaux formation. These findings are important, as they indicate that the spatiotemporal variation in shear rate has a crucial role in the aggregate formation and local parabolic rouleaux under pulsatile flow.

Prevention of Renal Medullary Vascular Congestion is Associated with Reduced Mortality and Preservation of Capillary Density Following Renal Ischemia

The aggregation of red blood cells in the microvascular of the renal medulla is a hallmark of ischemic acute kidney injury (AKI). Our lab has recently shown that pretreatment with low dose lipopolysaccharide (LPS) prior to ischemia-reperfusion (IR) prevents this vascular congestion. It remains unknown, however, whether prevention of medullary vascular congestion improves recovery from IR. The goal of the current study was to test the hypothesis that ‘prevention of vascular congestion with low dose LPS improves functional recovery of the kidney and attenuates rarefaction of the renal medulla following IR’. Male WKY rats (8 weeks) were implanted with radiotelemetry devices (DSI, St. Paul, MN) and allowed to recover for two weeks prior to beginning blood pressure measurement. Rats were then randomized to receive injections (i.p.) of either low dose LPS (1000µg/kg) (n=4) to prevent vascular congestion or saline control (n=4) once daily for 3 days. 1 day following the 3rd injection, all rats underwent a 45 minute, warm bilateral IR and were allowed to recover for 7 days. Blood pressure was measured for the duration of the study. Plasma was collected by tail vein pre-IR and at sacrifice for measurement of creatinine (Cr) and blood urea nitrogen (BUN). Vascular rarefaction was assessed at sacrifice in histological kidney sections via %Threshold Area of CD34+ vascular endothelium (Metamorph). Following recovery of IR, there was a 100% and 50% survival rate in LPS treated and saline control rats, respectively. Saline control rats (with vascular congestion following IR) had a decrease in CD34+ vascular density in the inner stripe of the outer medulla (OM) (Unpaired t-test, p=0.05) and the inner medulla (Unpaired t-test, p=0.009), but there were no differences in CD34+ staining in the cortex (Unpaired t-test, p=0.159) or outer stripe of the OM (Unpaired t-test, p=0.095) (Table 1). There were no differences in 24 hour mean arterial pressure between groups over the course of the study (two-way RM ANOVA, pINTERACTION=0.689). At sacrifice, plasma Cr (pINTERACTION=0.249) and BUN (pINTERACTION=0.345) were not different between groups and had recovered to near pre-IR values. Prevention of vascular congestion in LPS treated rats increased the 7 day survival to 100% following a 45 minute bilateral IR in contrast to control rats which, as expected, had a 50% survival rate. Importantly, this prevention of congestion was associated with preserved capillary density (CD43+) in the renal medulla. These data indicate an important role of vascular congestion to independently drive increased mortality and capillary rarefaction following IR. As renal vascular rarefaction has been implicated as an important factor in the progression to chronic kidney disease following AKI, prevention of vascular congestion may be an important target to prevent this deleterious sequelae.

Integrin α4β1/VCAM-1 Interaction Evokes Dynamic Cell Aggregation Between Immune Cells and Human Lung Microvascular Endothelial Cells at Infectious Hemolysis

Bacterial and viral infection is a common cause of pneumonia, respiratory failure, and even acute respiratory distress syndrome. Increasing evidence indicates that red blood cells (RBCs) may contribute to immune response and inflammation. However, the precise molecular mechanisms that link RBC and hemolysis to the development and progression of inflammatory pathologies are not entirely understood. In this study, we used bacterial endotoxin, lipopolysaccharide (LPS), to mimic an infectious hemolysis and found that RBCs dynamically regulated cell aggregation between immune cells and human lung microvascular endothelial cells (HLMVEC). When RBCs were treated with LPS, integrin α4β1 was increased and was accompanied by cytokines and chemokines release (TNF-α, IL-1β, IL-6, IL-8, IFN-γ, CXCL12, CCL5, CCL7 and CCL4). Upon α4β1 elevation, RBCs not only facilitated mature monocyte derived dendritic cell (mo-DCs) adhesion but also promoted HLMVEC aggregation. Furthermore, co-culture of the supernatant of LPS pre-treated RBCs with mo-DCs could promote naïve CD4 T cell proliferation. Notably, the filtered culture from LPS-lysed RBCs further promoted mo-DCs migration in a concentration dependent manner. From a therapeutic perspective, cyclic peptide inhibitor of integrin α4β1 combined with methylprednisolone (α4β1/Methrol) remarkably blocked RBCs aggregation to mo-DCs, HLMVEC, or mo-DCs and HLMVEC mixture. Moreover, α4β1/Methrol dramatically reduced mo-DCs migration up-regulated glucocorticoid-induced leucine zipper in mo-DCs, and ultimately reversed immune cell dysfunction induced by hemolysis. Taken together, these results indicate that integrin α4β1 on RBCs could mediate cell-cell interaction for adaptive immunity through influencing cell adhesion, migration, and T cell proliferation.

Changes of Hematological and Hemorheological Parameters in Rabbits with Hypercholesterolemia.

Hypercholesterolemia plays an important role in the development of atherosclerosis, leading to endothelial dysfunction, ischemic events, and increased mortality. Numerous studies suggest the pivotal role of rheological factors in the pathology of atherosclerosis. To get a more detailed hematological and hemorheological profile in hypercholesterolemia, we carried out an experiment on rabbits. Animals were divided into two groups: the control group (Control) was kept on normal rabbit chow, the high-cholesterol diet group (HC) was fed with special increased cholesterol-containing food. Hematological parameters (Sysmex K-4500 automate), whole blood and plasma viscosity (Hevimet-40 capillary viscometer), red blood cell (RBC) aggregation (Myrenne MA-1 aggregometer), deformability and mechanical stability (LoRRca MaxSis Osmoscan ektacytometer) were tested. The white blood cell and platelet count, mean corpuscular volume, and mean corpuscular hemoglobin were significantly higher in the HC group, while the RBC count, hemoglobin, and hematocrit values were lower than the Control data. Viscosity values corrected to 40% hematocrit were higher in the HC group. The RBC aggregation significantly increased in the HC vs. the Control. The HC group showed significantly worse results both in RBCs’ deformability and membrane stability. In conclusion, the atherogenic diet worsens the hematological and macro- and micro-rheological parameters, affecting blood flow properties and microcirculation.

Stabilization of red blood cell aggregation evaluation using short-axis view of vein of ultrasound

Red blood cell (RBC) aggregation is the reversible adhesion of RBCs among themselves. We previously reported a positive correlation between blood glucose level and the degree of RBC aggregation (the brightness of the B-mode image). In the present study, we investigated the contribution to the brightness according to the deviation from the central axis in measurements along with the long-axis view of the vein. The results show that the brightness changed significantly for a slight change in the lateral position in the short-axis image. We found that the stability of the measurements was not guaranteed in the long-axis view and estimated the correct analysis window range for the short-axis view.

Numerical investigations of anisotropic structures of red blood cell aggregates on ultrasonic backscattering

Although quantitative ultrasound techniques based on the parameterization of the backscatter coefficient (BSC) have been successfully applied to blood characterization, theoretical scattering models assume blood as an isotropic scattering medium. However, the red blood cell (RBC) aggregates form anisotropic structures such as rouleaux. The present study proposes an anisotropic formulation of the effective medium theory combined with the local monodisperse approximation (EMTLMA) that considers perfectly aligned prolate-shaped aggregates. Theoretical BSC predictions were first compared with computer simulations of BSCs in a forward problem framework. Computer simulations were conducted for perfectly aligned prolate-shaped aggregates and more complex configurations with partially aligned prolate-shaped aggregates for which the size and orientation of RBC aggregates were obtained from blood optical observations. The isotropic and anisotropic EMTLMA models were then compared in an inverse problem framework to estimate blindly the structural parameters of RBC aggregates from the simulated BSCs. When considering the isotropic EMTLMA, the use of averaged BSCs over different insonification directions significantly improves the estimation of aggregate structural parameters. Overall, the anisotropic EMTLMA was found to be superior to the isotropic EMTLMA in estimating the scatterer volume distribution. These results contribute to a better interpretation of scatterer size estimates for blood characterization.

In vivo photoacoustic assessment of the oxygen saturation changes in the human radial artery: a preliminary study associated with age.

.Significance: We demonstrate the potential of probing the change under blood flow in vivo using photoacoustic (PA) imaging and sheds light on the complex relationship between RBC aggregation and oxygen delivery.Aim: To conduct in vivo assessments of the in the radial artery of healthy volunteers and simultaneously probe the relation between the and hemodynamic behavior such as red blood cell (RBC) aggregation.Approach: The effects of PA-based measurements of blood hemodynamics were studied as a function of the subjects’ age (20s, 30s, and 40s). The pulsatile blood flow in the human radial artery of 12 healthy subjects was imaged in the 700 to 900 nm optical wavelength range using a linear array-based PA system.Results: The PA power when blood velocity is minimum () was larger than the one attained at maximum blood velocity (), consistent with predictions based on the cyclical variation of RBC aggregation during pulsatile flow. The difference between and at 800 nm () increased with age (1.7, 2.2, and 2.6 dB for age group of 20s, 30s, and 40s, respectively). The computed from was larger than the one from .Conclusions: The increased with participant age. The metric could be a surrogate of noninvasively monitoring the age-induced changes in RBC aggregation. The change during a cycle of pulsatile blood flow also increased with age, demonstrating that RBC aggregation can affect the change.

Relationship between capillary blood flow parameters measured in vivo and microrheologic parameters of blood measured in vitro in arterial hypertension and coronary heart disease

Introduction. Blood microcirculation and its microrheologic properties are impaired in cardiovascular diseases. Microrheologic properties are characterized by the red blood cells (RBC) ability to aggregate and disaggregate. Therefore, the correlation studies between RBC aggregation and microcirculation disorders in pathologies are of interest for the development of theoretical concepts related to blood flow and for clinical practice.Aim. To analyze the correlation between capillary blood flow parameters measured in vivo and microrheologic blood parameters measured in vitro in patients suffering arterial hypertension (AH) and coronary heart disease (CHD).Materials and methods. We studied 3 groups of people: patients suffering AH, patients suffering AH+CHD and healthy donors. The characteristic aggregation time and aggregation index were measured in vitro by laser aggregometry. Analysis of capillary blood velocity (CBV) and assessment of the presence and absence of RBC aggregates in the nail bed capillaries were performed in vivo using vital digital capillaroscopy (VDC).Results. RBC aggregation for groups of patients suffering AH and AH+CHD was increased compared to the control group. Thus, in these patients groups, the characteristic aggregation time significantly decreases by an average of (38±13) %. Comparison of the results obtained using in vitro and in vivo methods showed the aggregation index for individuals with high CBV was significantly lower than for individuals with low CBV. The tendency is that the number of aggregates in the capillaries increases with a decrease in CBV.Conclusion. RBC aggregation is increased in groups of patients suffering AH and AH+CHD compared to the control group. The correlation between parameters measured in vitro and in vivo is evident for patients divided into subgroups according to parameters measured using the VDC. The obtained results allow us to conclude that the used methods are applicable in clinical practice.

Влияние доноров газотрансмиттеров (оксида азота, сульфида водорода и монооксида углерода) на микрореологические свойства эритроцитов

Введение. Микрореологические свойства эритроцитов — их деформируемость и агрегация в значительной степени определяют текучесть цельной крови и ее кислородотранспортный потенциал. При этом эритроциты — это клетки-мишени, на которые действуют сигнальные молекулы. Последние могут регуляторно изменять микромеханические свойства эритроцитов и реологию крови в целом. К сигнальным молекулам относятся и газотрансмиттеры (ГТ) — такие соединения, как оксид азота (NO), сульфид водорода (H2S) и монооксид углерода (CO). Доноры ГТ могут быть основой для разработки лекарственных препаратов для коррекции реологических свойств крови. Цель работы: изучение изменений микрореологических характеристик эритроцитов под влиянием доноров трех газотрансмиттеров — NO, H2S и CO. Материалы и методы. Эритроциты и их восстановленные тени инкубировали с нитропруссидом натрия (НПН, 100 мкмоль) — донором NO, гидросульфидом натрия (NaHS, 100 мкмоль) — донором H2S и трикарбонилхлор (глицинат) рутением (II) (CORM-3, 50 мкмоль) — донором СО. После этого регистрировали деформируемость эритроцитов (ИУЭ), их агрегацию (ПАЭ) и вязкость суспензий (ВС). Результаты. Установлено, что под влиянием всех трех доноров ГТ происходят заметные изменения микрореологических характеристик эритроцитов и их теней (в среднем на 13–16%; p &lt; 0,05). Важно заметить, что сдвиги ИУЭ, ПАЭ и ВС под влиянием доноров газотрансмиттеров были сходными по величине, и суммарная разница их микрореологических эффектов на три разных донора ГТ не превышала 3%. Заключение. На основании полученных данных и их анализа можно заключить, что эритроциты качественно и количественно примерно одинаково отвечают на действие трех разных доноров ГТ положительными изменениями их микрореологических характеристик и особенно агрегации, которая снижалась более чем на 30%. Background. Erythrocytes microrheological properties (deformability and aggregation) largely determine the fluidity of whole blood and its oxygen transport potential. At the same time erythrocytes are target cells for signaling molecules acting. The latter can regulate erythrocytes micromechanical properties and blood rheology in general. Signaling molecules also include gasotransmitters (GT) — compounds such as nitrogen oxide (NO), hydrogen sulfide (H2S) and carbon monoxide (CO). GT donors can form the basis of drugs for blood rheology correction. Objectives: to study the changes of erythrocytes microrheological characteristics under the influence of donors of three gasotransmitters — NO, H2S and CO. Materials/Methods. Erythrocytes and their restored shadows were incubated with sodium nitroprusside (SNP, 100 μmol) — NO donor, sodium hydrosulfide (NaHS, 100 μmol) — H2S donor, and with tricarbonylchlor (glycinate) ruthenium (II) (CORM-3, 50 μmol) — CO donor. Thereafter we registered erythrocytes deformability (ED), their aggregation (EA) and suspensions viscosity (SV). Results. All three GT donors noticeably changed microrheological characteristics of erythrocytes and their shadows (on average by 13–16%; p &lt; 0.05). It’s important that the shifts of ED, EA, and SV under the influence of gasotransmitter donors were similar in magnitude, and the total difference in their microrheological effects on three different GT donors did not exceed 3%. Conclusions. Erythrocytes qualitatively and quantitatively approximately equally responded to the action of three different GT donors by positive changes in their microrheological characteristics and especially by aggregation that decreased by more than 30%.

A Molecular Communication Detection Method for the Deformability of Erythrocyte Membrane in Blood Vessels.

Molecular communication (MC) inspired drug delivery holds considerable promise as a new design for targeted therapy with high efficiency and minimal toxicity. The process of drug delivery can be modelled in a blood flow-based MC system, where nanoparticles (NPs) carry therapeutic agents through the blood vessel channels to the targeted diseased tissue. Most previous studies in the flow-based MC consider a Newtonian fluid with a laminar flow, which ignores the influence of red blood cells (RBCs). However, the nature of blood flow is a complex and non-Newtonian fluid composed of proteins, platelets, plasma and deformable cells, especially RBCs. The ability to change their shapes is essential to the proper functioning of RBCs in the microvasculature. Different shapes of RBCs have a great impact on the performance of blood flow. Changes in the properties and shapes of RBCs are often associated with different diseases, such as sickle cell anemia, diabetes, and malaria. Thus, it is highly important to establish a more realistic blood flow MC model considering the deformable cells. According to our previous study, the motion and adhesion of individual NPs are modelled through the Brownian adhesion dynamics. Subsequently, this paper establishes a particle-cell hybrid model in the flow-based MC, which focuses on the RBC deformation, aggregation, and dispersion in the blood suspension. Based on the state of the RBC deformation and aggregation in the vessels with different flow rates, this paper proposes a novel methodology for detecting the deformability of the cells. The blood state in terms of RBC deformability is determined by the difference in NPs' concentration at the receiving end., this paper sheds some light on the influence of RBCs on the motion of NPs, which provides new insights on the design of targeted drug delivery and the detection of vascular diseases.

Microfluidics in Sickle Cell Disease Research: State of the Art and a Perspective Beyond the Flow Problem

Sickle cell disease (SCD) is the monogenic hemoglobinopathy where mutated sickle hemoglobin molecules polymerize to form long fibers under deoxygenated state and deform red blood cells (RBCs) into predominantly sickle form. Sickled RBCs stick to the vascular bed and obstruct blood flow in extreme conditions, leading to acute painful vaso-occlusion crises (VOCs) – the leading cause of mortality in SCD. Being a blood disorder of deformed RBCs, SCD manifests a wide-range of organ-specific clinical complications of life (in addition to chronic pain) such as stroke, acute chest syndrome (ACS) and pulmonary hypertension in the lung, nephropathy, auto-splenectomy, and splenomegaly, hand-foot syndrome, leg ulcer, stress erythropoiesis, osteonecrosis and osteoporosis. The physiological inception for VOC was initially thought to be only a fluid flow problem in microvascular space originated from increased viscosity due to aggregates of sickled RBCs; however, over the last three decades, multiple molecular and cellular mechanisms have been identified that aid the VOC in vivo. Activation of adhesion molecules in vascular endothelium and on RBC membranes, activated neutrophils and platelets, increased viscosity of the blood, and fluid physics driving sickled and deformed RBCs to the vascular wall (known as margination of flow) – all of these come together to orchestrate VOC. Microfluidic technology in sickle research was primarily adopted to benefit from mimicking the microvascular network to observe RBC flow under low oxygen conditions as models of VOC. However, over the last decade, microfluidics has evolved as a valuable tool to extract biophysical characteristics of sickle red cells, measure deformability of sickle red cells under simulated oxygen gradient and shear, drug testing, in vitro models of intercellular interaction on endothelialized or adhesion molecule-functionalized channels to understand adhesion in sickle microenvironment, characterizing biomechanics and microrheology, biomarker identification, and last but not least, for developing point-of-care diagnostic technologies for low resource setting. Several of these platforms have already demonstrated true potential to be translated from bench to bedside. Emerging microfluidics-based technologies for studying heterotypic cell–cell interactions, organ-on-chip application and drug dosage screening can be employed to sickle research field due to their wide-ranging advantages.