Increased blood viscosity and red blood cell aggregation in patients with COVID-19

Background: Endothelial injury, hypercoagulability, and decreased blood flow are suspected to play a key role in thrombosis,multiorgan failure, and death of patients with COVID-19. The link between increased blood viscosity and COVID-19- related complications and severity is not formerly established and can only be suspected. Aim(s): The aim of this study was to (1) analyze blood viscosity, red blood cell (RBC) deformability, and aggregation in hospitalized patients with Coronavirus disease 19 (COVID-19);(2) test the associations between impaired blood rheology and blood coagulation;and (3) test the associations between impaired blood rheology and several indicators of clinical severity. Method(s): A total of 172 patients with COVID-19, hospitalized in COVID-unit of the Internal Medicine Department (Lyon, France) participated in this study between January and May 2021. Clinical parameters were collected for each patient. Routine hematological/ biochemical parameters, blood viscosity, RBC deformability and aggregation, and RBC senescence markers were measured on the first day of hospitalization. A control group of 38 healthy individuals was constituted to compare the blood rheological and RBC profile. Rotational thromboelastography was performed in 76 patients to study clot formation dynamics. Result(s): Our study demonstrated that patients with COVID-19 had increased blood viscosity despite lower hematocrit than healthy individuals, as well as increased RBC aggregation. In-vitro experiments demonstrated a strong contribution of plasma fibrinogen in this RBC hyper-aggregation. RBC aggregation correlated positively with clot firmness, negatively with clot formation time, and positively with the length of hospitalization. Patients with oxygen supplementation had higher RBC aggregation and blood viscosity than those without, and patients with pulmonary lesions had higher RBC aggregation and enhanced coagulation than those without. Conclusion(s): This study is the first to demonstrate blood hyper-viscosity and RBC hyper-aggregation in a large cohort of patients with COVID-19 and describe associations with enhanced coagulation and clinical outcomes.

Erythrocyte aggregation in sudden flow arrest is linked to hyperthermia, hypoxemia, and band 3 availability.

BACKGROUND: Erythrocyte aggregation is a phenomenon that is commonly found in several pathological disease states: stroke, myocardial infarction, thermal burn injury, and COVID-19. Erythrocyte aggregation is characterized by rouleaux, closely packed stacks of cells, forming three-dimensional structures. Healthy blood flow monodisperses the red blood cells (RBCs) throughout the vasculature; however, in select pathological conditions, involving hyperthermia and hypoxemia, rouleaux formation remains and results in occlusion of microvessels with decreased perfusion. OBJECTIVES: Our objective is to address the kinetics of rouleaux formation with sudden cessation of flow in variable temperature and oxygen conditions. METHODS: RBCs used in this in vitro system were obtained from healthy human donors. Using a vertical stop-flow system aligned with a microscope, images were acquired and analyzed for increased variation in grayscale to indicate increased aggregation. The onset of aggregation after sudden cessation of flow was determined at proscribed temperatures (37-49°C) and oxygen (0%, 10%), and in the presence and absence of 4, 4'-Diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS). Both autologous and homologous plasma were tested. RESULTS: RBCs in autologous plasma aggregate faster and with a higher magnitude with both hyperthermia and hypoxemia. Preventing deoxyhemoglobin from binding to band 3 with DIDS (dissociates the cytoskeleton from the membrane) fully blocks aggregation. Further, RBC aggregation magnitude is greater in autologous plasma. CONCLUSIONS: We show that the C-terminal domain of band 3 plays a pivotal role in RBC aggregation. Further, aggregation is enhanced by hyperthermia and hypoxemia.

FEATURES OF THE PARAMETERS OF RED BLOOD CELLS AND HEMOSTASIS IN PATIENTS WITH STROKES ASSOCIATED WITH CORONAVIRUS INFECTION

Objective: The purpose is to identify the peculiarities of the parameters of red blood cells (RBC) and hemostasis in patients with strokes associated with coronavirus infection. Design and method: A total of 124 patients (48.5 + 1.9 years) with impairments of cerebral circulation due to COVID-19 (confirmed by positive PCR test) had been examined. Among them, 74 patients had ischemic stroke, 25- transient ischaemic attack, 17- intracerebral hemorrhage, 8- subarachnoid hemorrhage. The parameters of hemostasis were measured by standard methods, electrical, viscoelastic parameters of RBC - by dielectrophoresis. Results: 71 patients (the 1st group) showed signs of intravascular coagulation and thrombosis: accelerated platelet-leukocyte aggregation, increased levels of coagulation products, reduced fibrinolysis activity (p = 0.001-0.04). The levels of D-dimer, fibrinogen, ESR, platelet count were higher in this group compared to the second one (p < 0.01). A moderate increase of RBC summarized rigidity, viscosity was noted. The level of RBC hemolysis was associated with platelet count (r = 0.735,p = 0.03), D-dimer (r = 0.482, p < 0.05), fibrinogen level (r = 0.374, p = 0.04). In 2nd group (53 persons), the markers of thrombosis had moderate deviations. Sharply reduced RBC deformability with increased summarized rigidity, viscosity was dominant coupled with the background of high electrical conductivity of cell membranes compared to the indicators in the 1st group (p < 0.01). There was a decrease of membrane capacity, surface charge, cell dipole moment, polarizability than those in the 1st group (p = 0.0001-0.05). A sharp decrease of RBC deformability creates obstacles to overcoming small-diameter capillaries, leading to violations of microcirculatory blood flow. RBC deformability was associated with levels of ferritin (r = 0.451, p = 0.02), HbA1c (r = 0.480, p = 0.03), uric acid (r = -0.371, p < 0.05), LDL cholesterol (r = 0.461, p = 0.02). Incubation of blood samples in vitro for 10 min with riboflavin, nicotinamide, inosine, which ensures RBC energy metabolism, restored the reduced RBC deformability (p < 0.01), altered cell morphology (p = 0.04), decreased RBC aggregation (p < 0.001). Conclusions: The revealed features of parameters of RBC hemostasis in stroke patients with coronavirus infection are associated with two independent pathogenetic mechanisms: thrombotic and hemorheologic. The thrombotic variant is due to procoagulant state and an activity of inflammation. The hemorheologic variant is caused by decrease of RBC energy metabolism, activity of enzymes.

Rheological status (erythrocyte aggregation index, erythrocyte deformation index, plasma viscosity) in the Covid-19 patients with “Covid toes” and in patients with Raynaud’s phenomenon

One of complications of Covid-19 infection is the so-called “Covid toes”. This is disease with nonstudied pathophysiological mechanisms, which in some ways is like Raynaud’s phenomenon. Our goal was to research the rheological differences and similarities between these diagnoses. We studied rheological status in a group of patients with the so-called “Covid toes” and a group with Reynaud’s phenomenon as well as in a control group healthy individual. We measured simultaneously the erythrocyte aggregation index, the erythrocyte deformation index and the blood plasma viscosity. The methods for indices measurement were composed by our research group (Rheology and Diagnostic Analytical Services Laboratory in Ivane Beritashvili Center of Experimental Biomedicine). Based on our data, we can evaluate rheological changes observed in both groups examined. In the patients with Reynaud’s phenomenon, rheological changes were not associated with an increase in the erythrocyte aggregation index. Significantly elevated levels of the erythrocyte aggregation index have been obtained only in the group of COVID-19 patients with Covid toes. Our studies presented new scientific focus and research area, able to “transport” our experimental and analytical conclusions to the field of routine clinical practice-for successful management and treatment of “Covid toes” as one of complications of COVID-19. © 2022, Bulgarska Akademiya na Naukite. All rights reserved.

Circulating cellular clusters: A proposed mechanism and novel biomarker for immunothrombosis and clinical outcomes in patients with covid-19

Introduction: Circulating Cellular Clusters (CCCs) have been studied in the context of cancer;however, CCCs in other inflammatory conditions, such as COVID-19, have not been explored. Hypothesis: CCC phenotypes play a role in immunothrombosis and in the development of adverse events. Methods: Blood samples were collected from patients with a positive SARS-CoV2 PCR treated at the Massachusetts General Hospital. Imaging flow cytometry was used to characterize CCCs, including: platelet-leukocyte aggregates (PLAs), leukocyte clusters (LCs) and platelet-erythrocyte aggregates (PEAs) (Fig1A). CCC phenotypes were compared with controls and were correlated with clinical outcomes. CCCs identified to be significant were used to guide a computational model investigating the mechanism of CCC formation and their behavior in circulation (Fig1C). Results: Forty-six COVID-19 and 12 control samples were analyzed. Statistically significant positive correlations were identified between CCCs and clinical outcomes in patients with COVID19 (Fig1B). Using these data as inputs, computational simulations illustrated that CCCs may form in the circulation and be recruited by existing thrombi and sites of inflammation, or may detach from thrombogenic sites (Fig1D). Conclusions: CCCs are correlated with the development of significant clinical outcomes and cluster phenotypes appear to be associated with specific outcomes. CCCs may form de novo in the circulation or via the detachment from a thrombus. These CCCs may subsequently attach to a second thrombus downstream or serve as their own nidus for thrombus development, resulting in vessel lumen occlusion. Computational modeling serves as a powerful tool for the exploration of the pathophysiological mechanism by which CCCs contribute to thrombus formation. These findings may serve as novel biomarkers and aid in the identification of new drug targets for immunothrombotic complications in severe inflammatory conditions.

Myocardial involvement in COVID-19: data from 102 unselected autopsies during the first wave of pandemic

Background: Myocardial involvement in COVID-19 has been described as either coronary artery related ischemic lesions, lymphocyte myocarditis or microangiopathy. Assessment of the link between COVID-19 and the cause of death has been hampered by the limited number of autopsies performed during the pandemics and risk factors associated with the type and extent of myocardial damage remain poorly described. In Russia, the mandatory autopsy approach has been advocated for the cases of suspected COVID- 19 related deaths. Purpose: To describe the prevalence, extent and risk factors associated with myocardial damage in an unselected cohort of patients deceased with COVID-19. Methods: Consecutive patients with PCR-confirmed or suspected COVID- 19 who died either in-hospital (clinical autopsy) or out-of-hospital (forensic autopsy) during COVID-19 pandemic underwent post-mortem PCR on pulmonary parenchymal tissue. Tissue PCR-positive cases were referred for histology study of pulmonary and extrapulmonary organ specimens through a central laboratory. Based on the extent of diffuse alveolar damage (DAD), COVID-19 was categorized as either being related to death or a concomitant condition not associated with death. Myocardial involvement was categorized as either (1) coronary artery related myocardial infarction, (2) microangiopathy with interstitial edema and erythrocyte aggregates occluding the capillaries with or without lymphomononuclear infiltration and (3) lymphocyte myocarditis. The presence of myocardial involvement was assessed with regard to age, gender and autopsy-verified significant coronary artery disease (CAD) and diabetes (information available only for the clinical autopsy cohort). Results: 102 autopsies were included, of whom 42 were clinical and 60 forensic (age 73±15 years, 50% men;58% had CAD). Ten patients from the clinical autopsy cohort had diabetes (24%). Deaths were COVID-19 related in 80 patients (78%). Myocardial infarction was noted in 3 (2.9%) patients. Microangiopathy was seen in 45 (44%) and lymphocyte myocarditis in 2 (1.9%) patients, of whom it was the primary cause of death in one. The prevalence of microangiopathy did not differ between patients with and without significant DAD (46% vs 45%, p=0.848). Patients with diabetes were more likely to have microangiopathy with lymphomononuclear infiltration in the myocardium than patients without diabetes (40% vs 3.1%, p=0.008;OR=22, 95% CI 1.63-305, p=0.020 after adjustment for age, gender and CAD) Conclusion: Systematically performed autopsies revealed causative association between SARS-CoV2 and death in the vast majority. Myocardial involvement was observed in nearly half of the patients and was not related to the extent of DAD. Myocarditis appears to be a rare finding, though it can be the primary cause of death. Microangiopathy with capillary occlusion and lymphomononuclear infiltration in the myocardium was associated with the history of diabetes.