Blood clot parameters: Thromboelastography and scanning electron microscopy in research and clinical practice

Exploring the ex vivo effects of Naja mossambica venom on the ultrastructure and viscoelastic properties of human blood

Background

Venomous snake bites have been listed as a neglected tropical disease by the World Health Organization. The Mozambique spitting cobra (Naja mossambica) is found in Sub-Saharan African countries, and its venom has been identified to predominantly result in cytotoxic effects. However, there is limited evidence on the possible hemotoxic effects of this venom on human blood.

Objectives

In this cross-sectional study, we investigated how Mozambique spitting cobra venom affects blood clot formation.

Methods

Cell morphology and clot architecture were studied by using microscopy techniques. We also studied the effects of the venom on platelets by measuring platelet activity with the global thrombosis test, followed by analyzing the viscoelasticity with thromboelastography using a 0.025 ng/μL venom concentration.

Results

The most prominent findings indicated that the viscoelastic profile in the venom-treated blood samples formed an unstable and elastic clot. The clot architecture seen with the scanning electron microscopy analysis showed an altered fibrin network and red blood cells, confirmed by the increased axial ratios, and aggregated platelets with spreading.

Conclusion

These findings may offer insights into the species-specific effects of snake venom on human blood and add value to the clinical workup in confirming envenomation. Further research is needed to correlate the 20 minute whole blood clotting test with measurable values from the thromboelastography within the context of snake envenomation. This may offer a bridge between cost, early diagnosis, and treatment of snake envenomation in resource-constrained countries.

The oxylipin analog CS585 prevents platelet activation and thrombosis through activation of the prostacyclin receptor

Cardiovascular disease remains the primary cause of morbidity and mortality globally. Platelet activation is critical for maintaining hemostasis and preventing the leakage of blood cells from the vessel. There has been a paucity in the development of new drugs to target platelet reactivity. Recently, the oxylipin 12(S)-hydroxy-eicosatrienoic acid (12-HETrE), which is produced in platelets, was shown to limit platelet reactivity by activating the prostacyclin receptor. Here, we demonstrated the synthesis of a novel analog of 12-HETrE, known as CS585. Human blood and mouse models of hemostasis and thrombosis were assessed for the ability of CS585 to attenuate platelet activation and thrombosis without increasing the risk of bleeding. Human platelet activation was assessed using aggregometry, flow cytometry, western blot analysis, total thrombus formation analysis system, microfluidic perfusion chamber, and thromboelastography. Hemostasis, thrombosis, and bleeding assays were performed in mice. CS585 was shown to potently target the prostacyclin receptor on the human platelet, resulting in a highly selective and effective mechanism for the prevention of platelet activation. Furthermore, CS585 was shown to inhibit platelet function in human whole blood ex vivo, prevent thrombosis in both small and large vessels in mouse models, and exhibit long-lasting prevention of clot formation. Finally, CS585 was not observed to perturb coagulation or increase the risk of bleeding in the mouse model. Hence, CS585 represents a new validated target for the treatment of thrombotic diseases without the risk of bleeding or off-target activation observed with other prostaglandin receptor agonists.

Are fibrinaloid microclots a cause of autoimmunity in Long Covid and other post-infection diseases?

It is now well established that the blood-clotting protein fibrinogen can polymerise into an anomalous form of fibrin that is amyloid in character; the resultant clots and microclots entrap many other molecules, stain with fluorogenic amyloid stains, are rather resistant to fibrinolysis, can block up microcapillaries, are implicated in a variety of diseases including Long COVID, and have been referred to as fibrinaloids. A necessary corollary of this anomalous polymerisation is the generation of novel epitopes in proteins that would normally be seen as 'self', and otherwise immunologically silent. The precise conformation of the resulting fibrinaloid clots (that, as with prions and classical amyloid proteins, can adopt multiple, stable conformations) must depend on the existing small molecules and metal ions that the fibrinogen may (and is some cases is known to) have bound before polymerisation. Any such novel epitopes, however, are likely to lead to the generation of autoantibodies. A convergent phenomenology, including distinct conformations and seeding of the anomalous form for initiation and propagation, is emerging to link knowledge in prions, prionoids, amyloids and now fibrinaloids. We here summarise the evidence for the above reasoning, which has substantial implications for our understanding of the genesis of autoimmunity (and the possible prevention thereof) based on the primary process of fibrinaloid formation.

Clot Imaging Using Photostable Nanodiamond

While thrombosis is the leading cause of morbidity and mortality in the United States, an understanding of its triggers, progression, and response to anticoagulant therapy is lacking. Intravital fluorescence microscopy has advanced the study of thrombus formation by providing targeted, multi-color contrast. However, photodegradation of fluorophores limits the application in longitudinal studies (e.g., clot progression and/or dissolution). Fluorescent nanodiamond (FND) is a fluorophore which utilizes intrinsic fluorescence of chromogenic centers within and protected by the diamond crystalline lattice. Recent developments in diamond processing have allowed for the controlled production of nanodiamonds emitting in green or red. Here, the use of FND to label blood clots and/or clot lysis is demonstrated and compared to commonly used organic fluorophores. Model ex vivo clots were formed with incorporated labeled fibrinogen to allow imaging. FND was shown to match the morphology of organic fluorophore labels absent of photobleaching over time. The addition of tissue plasminogen activator (tPa) allowed visualization of the clot lysis stage, which is vital to studies of both DVT and pulmonary embolism resolution.

Unaffected ex vivo clotting cascade by experimental hemostatic nanoparticles when introduced in the presence of recombinant tissue plasminogen activator

CONTEXT

Hemostatic nanoparticles (hNPs) have shown efficacy in decreasing intracerebral hemorrhage (ICH) in animal models and are suggested to be of use to counter tissue plasminogen activator (tPA)-induced acute ICH.

AIMS

The objective of this study was to test the ability of an hNP preparation to alter the clotting properties of blood exposed to tPA ex vivo.

MATERIALS AND METHODS

Fresh blood samples were obtained from normal male Sprague-Dawley rats (~300 g; n = 6) and prepared for coagulation assays by thromboelastography (TEG) methods. Samples were untreated, exposed to tPA, or exposed to tPA and then to hNP. TEG parameters included reaction time (R, time in minutes elapsed from test initiation to initial fibrin formation), coagulation time (K, time in minutes from R until initial clot formation), angle (α, a measure in degrees of the rate of clot formation), maximum amplitude (MA, the point when the clot reaches its MA in mm), lysis at 30 min after MA (LY30, %), and clot strength (G, dynes/cm2), an index of clot strength.

STATISTICAL ANALYSIS USED

Kruskal-Wallis test was employed to compare TEG parameters measured for untreated control samples versus those exposed to tPA and to compare tPA-exposed samples to samples treated with tPA + hNPs. Significances were inferred at P ≤ 0.05.

RESULTS

Compared to untreated samples, tPA-treated samples showed a trend toward decreased angle and G suggesting potentially clot formation rate and clot strength. The addition of hNP did not affect any of these or other measured indices.

CONCLUSIONS

The data demonstrated no hemostatic effects when the hNP was used in the presence of tPA. The lack of change in any of the TEG parameters measured in the present study may indicate limitations of the hNPs to reverse the thrombolytic cascade initiated by tPA.

Relative Hypercoagulopathy of the SARS-CoV-2 Beta and Delta Variants when Compared to the Less Severe Omicron Variants Is Related to TEG Parameters, the Extent of Fibrin Amyloid Microclots, and the Severity of Clinical Illness

Earlier variants of SARS-CoV-2 have been associated with plasma hypercoagulability (as judged by thromboelastography) and an extensive formation of fibrin amyloid microclots, which are considered to contribute to the pathology of the coronavirus 2019 disease (COVID-19). The newer Omicron variants appear to be far more transmissible, but less virulent, even when taking immunity acquired from previous infections or vaccination into account. We here show that while the clotting parameters associated with Omicron variants are significantly raised over those of healthy, matched controls, they are only raised to levels significantly lower than those seen with more severe variants such as beta and delta. We also observed that individuals infected with omicron variants manifested less extensive microclot formation in platelet-poor plasma compared with those harboring the more virulent variants. The measurement of clotting effects between the different variants acts as a kind of "internal control" that demonstrates the relationship between the extent of coagulopathies and the virulence of the variant of interest. This adds to the evidence that microclots may play an important role in reflecting the severity of symptoms observed in COVID-19.

The protective effect of the spleen in sickle cell patients. A comparative study between patients with asplenia/hyposplenism and hypersplenism

Sickle cell disease (SCD) is caused by a point mutation in the beta-globin gene. SCD is characterized by chronic hemolytic anemia, vaso-occlusive events leading to tissue ischemia, and progressive organ failure. Chronic inflammatory state is part of the pathophysiology of SCD. Patients with SCD have extremely variable phenotypes, from mild disease to severe complications including early age death. The spleen is commonly injured in SCD. Early splenic dysfunction and progressive spleen atrophy are common. Splenomegaly and hypersplenism can also occur with the loss of the crucial splenic function. Acute, life-threatening spleen-related complications in SCD are well studied. The association of laboratory parameters with the spleen status including hyposplenism, asplenia, and splenomegaly/hypersplenism, and their implication in vaso-occlusive crisis and long-term complications in SCD remain to be determined. We evaluated the association between the spleen status with clinical and laboratory parameters in 31 SCD patients: Group a) Patients with asplenia/hyposplenism (N = 22) (including auto-splenectomy and splenectomized patients) vs. Group b) patients with splenomegaly and or hypersplenism (N = 9). Laboratory studies included: Complete Blood Count, reticulocyte count, iron metabolism parameters, C Reactive Protein (CRP), Hb variant distribution, and D-dimer. Metabolic and morphological red blood cell (RBC) studies included: density gradient (by Percoll), glucose consumption, lactate release, and K⁺ leakage, fetal RBC (F-Cells) and F-Reticulocytes, annexinV+, CD71⁺, oxidative stress measured by GSH presence in RBC and finally Howell Jolly Bodies count were all analyzed by Flow Cytometry. Scanning electron microscopy analysis of RBC was also performed. Patients with asplenia/hyposplenism showed significantly higher WBC, platelet, Hematocrit, hemoglobin S, CRP, D-dimer, Gamma Glutamyl Transferase (GGT), cholesterol, transferrin, annexin V+ RBCs, CD71⁺ RBCs, together with a markedly lower F Reticulocyte levels in comparison with splenomegaly/hypersplenism patients. In summary, important differences were also found between the groups in the studied RBCs parameters. Further studies are required to elucidate the effect of the spleen including hyper and hypo-splenia on laboratory parameters and in clinical manifestations, vascular pathology, and long-term complications of SCD. The benefits and risks of splenectomy compared to chronic transfusion need to be evaluated in clinical trials and the standard approach managing hypersplenism in SCD patients should be re-evaluated.

Factor XIII-A Val34Leu and Tyr204Phe variants influence clot kinetics in a cohort of South African type 2 diabetes mellitus patients

Factor XIII, a transglutaminase that plays a crucial role in clot formation, consists of subunits A and B. Single nucleotide polymorphisms in Factor XIII-A have been linked to thrombotic risk. In Type 2 Diabetes mellitus (T2DM), a hypercoagulable state is thought to contribute to the high mortality rate associated with thrombotic diseases. Due to the lack of prevalence data of FXIII-A single nucleotide polymorphisms (SNPs) in T2DM in a South African cohort, this study assessed the prevalence FXIII-A Val34Leu (rs5985) and Tyr204Phe (rs3024477) SNP's and the effect on clot kinetics in T2DM.

MATERIALS AND METHODS

A cohort of T2DM patients (n = 100) and race, age and gender matched healthy controls (n = 101) were recruited following ethical approval. Thromboelastography® (TEG®) was used to assess the viscoelastic properties in platelet poor plasma (PPP) in controls (n = 91) and T2DM patients (n = 91) younger than 50 years old. Genomic DNA was isolated from whole blood using the Quick-DNA™ Miniprep Plus Kit and PCR-RFLP was used to genotype each sample for FXIII-A rs5985 and rs3024477 SNPs.

RESULTS

TEG® analyses indicated a longer R-time (p < 0.0001) and higher TMRTG (p < 0.0001) in PPP of T2DM patients. Control and T2DM genotype distribution conformed to Hardy-Weinberg equilibrium (p > 0.05). There was a higher prevalence of the wildtype genotype of FXIII-A Tyr204Phe (rs3024477) SNP in T2DM (OR = 0.23, 95% CI = 0.12-0.42, p < 0.0001). The 204Phe variant was more frequent in the Caucasians (OR = 0.39, 95% CI = 0.05-0.33, p < 0.0001). The presence of the 204Phe variant in T2DM affected TMRTG (p = 0.0207). The variant affected R time (p = 0.0432) and TMRTG (p = 0.0209 and p = 0.0207) in controls and T2DM, respectively.

CONCLUSION

An inverse association with T2DM and FXIII-A Tyr204Phe was found. A hypo coagulable PPP clot profile was observed in T2DM. A shorter reaction time was observed and but faster rate at which the clot reached maximum strength in both controls and T2DM in the presence of the 204Phe variant.

The Occurrence of Hyperactivated Platelets and Fibrinaloid Microclots in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

We have previously demonstrated that platelet-poor plasma (PPP) obtained from patients with Long COVID/Post-Acute Sequelae of COVID-19 (PASC) is characterized by a hypercoagulable state and contains hyperactivated platelets and considerable numbers of already-formed amyloid fibrin(ogen) or fibrinaloid microclots. Due to the substantial overlap in symptoms and etiology between Long COVID/PASC and ME/CFS, we investigated whether coagulopathies reflected in Long COVID/PASC—hypercoagulability, platelet hyperactivation, and fibrinaloid microclot formation—were present in individuals with ME/CFS and gender- and age-matched healthy controls. ME/CFS samples showed significant hypercoagulability as judged by thromboelastography of both whole blood and platelet-poor plasma. The area of plasma images containing fibrinaloid microclots was commonly more than 10-fold greater in untreated PPP from individuals with ME/CFS than in that of healthy controls. A similar difference was found when the plasma samples were treated with thrombin. Using fluorescently labelled PAC-1, which recognizes glycoprotein IIb/IIIa, and CD62P, which binds P-selectin, we observed hyperactivation of platelets in ME/CFS hematocrit samples. Using a quantitative scoring system, the ME/CFS platelets were found to have a mean spreading score of 2.72 ± 1.24 vs. 1.00 (activation with pseudopodia formation) for healthy controls. We conclude that ME/CFS is accompanied by substantial and measurable changes in coagulability, platelet hyperactivation, and fibrinaloid microclot formation. However, the fibrinaloid microclot load was not as great as was previously noted in Long COVID/PASC. Fibrinaloid microclots, in particular, may contribute to many ME/CFS symptoms, such as fatigue, seen in patients with ME/CFS, via the (temporary) blockage of microcapillaries and hence ischemia. Furthermore, fibrinaloid microclots might damage the endothelium. The discovery of these biomarkers represents an important development in ME/CFS research. It also points to possible uses for treatment strategies using known drugs and/or nutraceuticals that target systemic vascular pathology and endothelial inflammation.

The risk of thromboembolic events with early intravenous 2- and 4-g bolus dosing of tranexamic acid compared to placebo in patients with severe traumatic bleeding: A secondary analysis of a randomized, double-blind, placebo-controlled, single-center trial

BACKGROUND

Screening for the risk of thromboembolism (TE) due to tranexamic acid (TXA) in patients with severe traumatic injury has not been performed in randomized clinical trials. Our objective was to determine if TXA dose was independently-associated with thromboembolism.

STUDY DESIGN AND METHODS

This is a secondary analysis of a single-center, double-blinded, randomized controlled trial comparing placebo to a 2-g or 4-g intravenous TXA bolus dose in trauma patients with severe injury. We used multivariable discrete-time Cox regression models to identify associations with risk for thromboembolic events within 30 days post-enrollment. Event curves were created using discrete-time Cox regression.

RESULTS

There were 50 patients in the placebo group, 49 in the 2-g, and 50 in the 4-g TXA group. In adjusted analyses for thromboembolism, a 2-g dose of TXA had an hazard ratio (HR, 95% confidence interval [CI]) of 3.20 (1.12-9.11) (p = .029), and a 4-g dose of TXA had an HR (95% CI) of 5.33 (1.94-14.63) (p = .001). Event curves demonstrated a higher probability of thromboembolism for both doses of TXA compared to placebo. Other parameters independently associated with thromboembolism include time from injury to TXA administration, body mass index, and total blood products transfused.

DISCUSSION

In patients with severe traumatic injury, there was a dose-dependent increase in the risk of at least one thromboembolic event with TXA. TXA should not be withheld, but thromboembolism screening should be considered for patients receiving a dose of at least 2-g TXA intravenously for traumatic hemorrhage.

Ex vivo Vitamin D supplementation improves viscoelastic profiles in prostate cancer patients

BACKGROUND: Increased risk of thromboembolic events is associated with prostate cancer, specifically linked to activation of tissue factor. Vitamin D has potential anticoagulant effects by the downregulation of tissue factor expression. OBJECTIVES: To evaluate the effects on clot formation, the morphological and viscoelastic profiles of prostate cancer patients, before and after ex vivo supplementation of Vitamin D was studied. METHODS: Participants were recruited into a metastatic, non-metastatic and reference group. Whole blood samples were treated ex vivo with a dose of 0.5μg/kg Calcitriol. Clot kinetics were assessed using Thromboelastography ®. Morphology of the blood components were studied using scanning electron microscopy (SEM). RESULTS: Results from the Thromboelastography ® and SEM indicated no major differences between the non-metastatic group before and after treatment compared to the reference group. The Thromboelastography ® showed that the metastatic group had an increased viscoelastic profile relating to a hypercoagulable state. Visible changes with regards to platelet activation and fibrin morphology were demonstrated with SEM analysis of the metastatic group. The viscoelastic and morphological properties for the non-metastatic group after treatment improved to be comparable to the reference group. CONCLUSION: Vitamin D supplementation may lead to a more favorable viscoelastic profile, with less dangerous clots forming.

Application of magnetically actuated self-clearing catheter for rapid in situ blood clot clearance in hemorrhagic stroke treatment

Maintaining the patency of indwelling drainage devices is critical in preventing further complications following an intraventricular hemorrhage (IVH) and other chronic disease management. Surgeons often use drainage devices to remove blood and cerebrospinal fluid but these catheters frequently become occluded with hematoma. Using an implantable magnetic microactuator, we created a self-clearing catheter that can generate large enough forces to break down obstructive blood clots by applying time-varying magnetic fields. In a blood-circulating model, our self-clearing catheters demonstrated a > 7x longer functionality than traditional catheters (211 vs. 27 min) and maintained a low pressure for longer periods (239 vs. 79 min). Using a porcine IVH model, the self-clearing catheters showed a greater survival rate than control catheters (86% vs. 0%) over the course of 6 weeks. The treated animals also had significantly smaller ventricle sizes 1 week after implantation compared to the control animals with traditional catheters. Our results suggest that these magnetic microactuator-embedded smart catheters can expedite the removal of blood from the ventricles and potentially improve the outcomes of critical patients suffering from often deadly IVH.

In-vitro thromboelastographic characterization of reconstituted whole blood utilizing cryopreserved platelets

Conducting in-vitro thrombosis research presents numerous challenges, the primary of which is working with blood products, whether whole blood or fractionated whole blood, that have limited functional shelf-lives. As a result, being able to significantly prolong the clotting functionality of whole blood via fractionation and recombination promises greater accessibility via resource minimization in the realm of thrombosis research. Whole blood with CPDA1 from healthy volunteers was fractionated and stored as frozen platelet-free plasma (PFP, -20°C), refrigerated packed red blood cells (pRBCs, 4°C) and cryopreserved platelets (-80°C). Subsequent recombination of the above components into their native ratios were tested via thromboelastography (TEG) to capture clotting dynamics over a storage period of 13 weeks in comparison to refrigerated unfractionated WB+CPDA1. Reconstituted whole blood utilizing PFP, pRCBs and cryopreserved platelets were able to maintain clot strength (maximum amplitude) akin to day-0 whole blood even after 13 weeks of storage. Clots formed by reconstituted whole blood exhibited quicker clotting dynamics with nearly two-fold shorter R-times and nearly 1.3-fold increase in fibrin deposition rate as measured by TEG. Storage of fractionated whole blood components, in their respective ideal conditions, provides a means of prolonging the usable life of whole blood for in-vitro thrombosis research. Cryopreserved platelets, when recombined with frozen PFP and refrigerated pRBCs, are able to form clots that nearly mirror the overall clotting profile expected of freshly drawn WB.

TEG®, Microclot and Platelet Mapping for Guiding Early Management of Severe COVID-19 Coagulopathy

An important component of severe COVID-19 disease is virus-induced endothelilitis. This leads to disruption of normal endothelial function, initiating a state of failing normal clotting physiology. Massively increased levels of von Willebrand Factor (VWF) lead to overwhelming platelet activation, as well as activation of the enzymatic (intrinsic) clotting pathway. In addition, there is an impaired fibrinolysis, caused by, amongst others, increased levels of alpha-(2) antiplasmin. The end result is hypercoagulation (proven by thromboelastography^® (TEG^®)) and reduced fibrinolysis, inevitably leading to a difficult-to-overcome hypercoagulated physiological state. Platelets in circulation also plays a significant role in clot formation, but they themselves may also drive hypercoagulation when they are overactivated due to the interactions of their receptors with the endothelium, immune cells or circulating inflammatory molecules. From the literature it is clear that the role of platelets in severely ill COVID-19 patients has been markedly underestimated or even ignored. We here highlight the value of early management of severe COVID-19 coagulopathy as guided by TEG^®, microclot and platelet mapping. We also argue that the failure of clinical trials, where the efficacy of prophylactic versus therapeutic clexane (low molecular weight heparin (LMWH)) were not always successful, which may be because the significant role of platelet activation was not taken into account during the planning of the trial. We conclude that, because of the overwhelming alteration of clotting, the outcome of any trial evaluating an any single anticoagulant, including thrombolytic, would be negative. Here we suggest the use of the degree of platelet dysfunction and presence of microclots in circulation, together with TEG^®, might be used as a guideline for disease severity. A multi-pronged approach, guided by TEG^® and platelet mapping, would be required to maintain normal clotting physiology in severe COVID-19 disease.

The Value of Detecting Pathological Changes During Clot Formation in Early Disease Treatment-Naïve Breast Cancer Patients

Breast cancer (BC) is one of the most prevalent forms of cancer in women worldwide. Clinical research indicates that BC patients are at an increased risk for thrombotic events, drastically decreasing their quality-of-life and treatment outcomes. There is ample evidence of this in the literature, but it is mainly focused on metastatic BC. Therefore, coagulopathies of nonmetastatic BC are understudied and require in-depth investigation. In this study, clot kinetics and ultrastructure were used to investigate treatment-naïve, nonmetastatic BC patients using scanning electron microscopy, Thromboelastography®, and confocal laser scanning microscopy. It was demonstrated that nonmetastatic BC patients exhibit minimal ultrastructural alterations of the clot components and no changes in the clot kinetics. However, BC patients presented changes to fibrinogen protein structure, compared to matched controls, using an amyloid-selective stain. Together, these findings suggest that coagulation dysfunction(s) in BC patients with early disease manifest at the microlevel, rather than the macrolevel. This study presents novel insights to a method that are more sensitive to coagulation changes in this specific patient group, emphasizing that the coagulation system may react in different forms to the disease, depending on the progression of the disease itself.

High-resolution scanning electron microscopy for the analysis of three-dimensional ultrastructure of clots in acute ischemic stroke

BACKGROUND

Characterization of acute ischemic stroke (AIS) clots has typically focused on two-dimensional histological analysis of the thrombus. The three-dimensional (3D) architecture and distribution of components within emboli have not been fully investigated. The aim of this study was to examine the composition and microstructure of AIS clots using histology and serial block-face scanning electron microscopy (SBFSEM).

METHODS

As part of the multi-institutional STRIP registry, 10 consecutive AIS emboli were collected from 10 patients treated by mechanical thrombectomy. Histological and immunohistochemical analysis was performed to determine clot composition. SBFSEM was used to assess the ultrastructural organization of the clots and specific features of individual components.

RESULTS

Quantification of Martius Scarlett Blue stain identified fibrin (44.4%) and red blood cells (RBCs, 32.6%) as the main components. Immunohistochemistry showed a mean platelet and von Willebrand factor content of 23.9% and 11.8%, respectively. The 3D organization of emboli varied greatly depending on the region analyzed. RBC-rich areas were composed mainly of tightly packed RBCs deformed into polyhedrocytes with scant fibrin fibers interwoven between cells. The regions with mixed composition showed thick fibrin fibers along with platelets, white blood cells and RBC clusters. Fibrin-rich areas contained dense fibrin masses with sparse RBC. In three cases, the fibrin formed a grid-like or a sponge-like pattern, likely due to thrombolytic treatment. Segmentation showed that fibrin fibers were thinner and less densely packed in these cases.

CONCLUSIONS

3D-SEM provides novel and potentially clinically relevant information on clot components and ultrastructure which may help to inform thrombolytic treatment and medical device design.

Detection of Citrullinated Fibrin in Plasma Clots of Rheumatoid Arthritis Patients and Its Relation to Altered Structural Clot Properties, Disease-Related Inflammation and Prothrombotic Tendency

Aims

The risk of cardiovascular events in patients with Rheumatoid Arthritis (RA) is disproportionately heightened as a result of systemic inflammation. The relative effect of autoimmune-associated citrullination on the structure and thrombotic potential of fibrin(ogen) remains unknown. We therefore compared indices of vascular function, inflammation, coagulation and fibrin clot composition in RA patients with healthy controls and evaluated parameter association with disease presence.

Methods

Blood samples were collected from 30 RA patients and 30 age- and gender-matched healthy volunteers. Levels of serum amyloid A (SAA), c-reactive protein (CRP), soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular cell adhesion molecule 1 (sVCAM-1) was measured using a sandwich immunoassay. Whole blood coagulation was assessed using Thromboelastography (TEG^®). Fibrin clot networks and fiber structure was investigated using Scanning Electron Microscopy. The detection and quantification of citrullination in formed fibrin clots was performed using a fluorescently labeled Citrulline monoclonal antibody with Fluorescence Wide Field Microscopy.

Results

Concentrations of SAA, CRP and ICAM-1 were significantly elevated in RA patients compared to controls. TEG parameters relating to coagulation initiation, rate of fibrin cross-linking, and time to reach maximum thrombus generation were attenuated in RA patients. Microscopic analysis revealed denser networks of thicker fibrin fibers in RA patients compared to controls and multiple citrullinated regions within fibrin clot structures in RA patients were present.

Conclusion

Our findings provide novel evidence for the citrullination of fibrin within vasculature is more prominent in RA plasma compared to control plasma and plasma is more accessible than synovial fluid. Citrullinated fibrinogen could play a role as a determinant of thrombotic risk in RA patients.

The Immunologic Effect of Early Intravenous Two and Four Gram Bolus Dosing of Tranexamic Acid Compared to Placebo in Patients With Severe Traumatic Bleeding (TAMPITI): A Randomized, Double-Blind, Placebo-Controlled, Single-Center Trial

Background

The hemostatic properties of tranexamic acid (TXA) are well described, but the immunological effects of TXA administration after traumatic injury have not been thoroughly examined. We hypothesized TXA would reduce monocyte activation in bleeding trauma patients with severe injury.

Methods

This was a single center, double-blinded, randomized controlled trial (RCT) comparing placebo to a 2 g or 4 g intravenous TXA bolus dose in trauma patients with severe injury. Fifty patients were randomized into each study group. The primary outcome was a reduction in monocyte activation as measured by human leukocyte antigen-DR isotype (HLA-DR) expression on monocytes 72 h after TXA administration. Secondary outcomes included kinetic assessment of immune and hemostatic phenotypes within the 72 h window post-TXA administration.

Results

The trial occurred between March 2016 and September 2017, when data collection ended. 149 patients were analyzed (placebo, n = 50; 2 g TXA, n = 49; 4 g TXA, n = 50). The fold change in HLA-DR expression on monocytes [reported as median (Q1–Q3)] from pre-TXA to 72 h post-TXA was similar between placebo [0.61 (0.51–0.82)], 2 g TXA [0.57 (0.47–0.75)], and 4 g TXA [0.57 (0.44–0.89)] study groups (p = 0.82). Neutrophil CD62L expression was reduced in the 4 g TXA group [fold change: 0.73 (0.63–0.97)] compared to the placebo group [0.97 (0.78–1.10)] at 24 h post-TXA (p = 0.034). The fold decrease in plasma IL-6 was significantly less in the 4 g TXA group [1.36 (0.87–2.42)] compared to the placebo group [0.46 (0.19–1.69)] at 72 h post-TXA (p = 0.028). There were no differences in frequencies of myeloid or lymphoid populations or in classical complement activation at any of the study time points.

Conclusion

In trauma patients with severe injury, 4 g intravenous bolus dosing of TXA has minimal immunomodulatory effects with respect to leukocyte phenotypes and circulating cytokine levels.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT02535949.

Gingipain R1 and Lipopolysaccharide From Porphyromonas gingivalis Have Major Effects on Blood Clot Morphology and Mechanics

Background:Porphyromonas gingivalis and its inflammagens are associated with a number of systemic diseases, such as cardiovascular disease and type 2 diabetes (T2DM). The proteases, gingipains, have also recently been identified in the brains of Alzheimer's disease patients and in the blood of Parkinson's disease patients. Bacterial inflammagens, including lipopolysaccharides (LPSs) and various proteases in circulation, may drive systemic inflammation.

Methods: Here, we investigate the effects of the bacterial products LPS from Escherichia coli and Porphyromonas gingivalis, and also the P. gingivalis gingipain [recombinant P. gingivalis gingipain R1 (RgpA)], on clot architecture and clot formation in whole blood and plasma from healthy individuals, as well as in purified fibrinogen models. Structural analysis of clots was performed using confocal microscopy, scanning electron microscopy, and AFM-Raman imaging. We use thromboelastography® (TEG®) and rheometry to compare the static and dynamic mechanical properties of clots.

Results: We found that these inflammagens may interact with fibrin(ogen) and this interaction causes anomalous blood clotting.

Conclusions: These techniques, in combination, provide insight into the effects of these bacterial products on cardiovascular health, and particularly clot structure and mechanics.

Comparison of pathological clotting using haematological, functional and morphological investigations in HIV-positive and HIV-negative patients with deep vein thrombosis

BACKGROUND

Patients infected with the human immunodeficiency virus (HIV) are more prone to systemic inflammation and pathological clotting, and many may develop deep vein thrombosis (DVT) as a result of this dysregulated inflammatory profile. Coagulation tests are not routinely performed unless there is a specific reason.

METHODS

We recruited ten healthy control subjects, 35 HIV negative patients with deep vein thrombosis (HIV negative-DVT), and 13 HIV patients with DVT (HIV positive-DVT) on the primary antiretroviral therapy (ARV) regimen-emtricitabine, tenofovir and efavirenz. Serum inflammatory markers, haematological results, viscoelastic properties using thromboelastography (TEG) and scanning electron microscopy (SEM) of whole blood (WB) were used to compare the groups.

RESULTS

The DVT patients (HIV positive and HIV negative) had raised inflammatory markers. The HIV positive-DVT group had anaemia in keeping with anaemia of chronic disorders. DVT patients had a hypercoagulable profile on the TEG but no significant difference between HIV negative-DVT and HIV positive-DVT groups. The TEG analysis compared well and supported our ultrastructural results. Scanning electron microscopy of DVT patient's red blood cells (RBCs) and platelets demonstrated inflammatory changes including abnormal cell shapes, irregular membranes and microparticle formation. All the ultrastructural changes were more prominent in the HIV positive-DVT patients.

CONCLUSIONS

Although there were trends that HIV-positive patients were more hypercoagulable on functional tests (viscoelastic profile) compared to HIV-negative patients, there were no significant differences between the 2 groups. The sample size was, however, small in number. Morphologically there were inflammatory changes in patients with DVT. These ultrastructural changes, specifically with regard to platelets, appear more pronounced in HIV-positive patients which may contribute to increased risk for hypercoagulability and deep vein thrombosis.

Colorectal cancer is associated with increased circulating lipopolysaccharide, inflammation and hypercoagulability

Gut dysbiosis contributes to the development of a dysfunctional gut barrier, facilitating the translocation of bacteria and inflammagens, and is implicated in colorectal cancer (CRC) pathogenesis. Such 'leaky gut' conditions result in systemic inflammation, of which a hallmark is increased hypercoagulability. Fluorescence antibody confocal microscopy was used to determine circulating levels of lipopolysaccharide (LPS) in control and CRC populations. Here we showed that circulating levels of LPS are significantly elevated in the CRC population. We also showed that markers of inflammation and hypercoagulability are increased in this population. Furthermore, anomalous blood clotting and structural changes in blood components are presented. Importantly, the association between LPS levels, inflammation, and hematological dysfunction was analysed. Statistical regression models were applied to identify markers with strong association with CRC, and to investigate the correlation between markers. A core aim is enhanced biomarker discovery for CRC. We conclude that circulating LPS can promote systemic inflammation and contribute to the development of a pathological coagulation system, with resulting chronic inflammation and an activated coagulation system implicated in tumorigenesis. Blood-based screening tools are an emerging research area of interest for CRC screening. We propose the use of additional (novel) biomarkers to effectively screen for CRC.

Both lipopolysaccharide and lipoteichoic acids potently induce anomalous fibrin amyloid formation: assessment with novel Amytracker™ stains

In recent work, we discovered that the presence of highly substoichiometric amounts (10⁻⁸ molar ratio) of lipopolysaccharide (LPS) from Gram-negative bacteria caused fibrinogen clotting to lead to the formation of an amyloid form of fibrin. We here show that the broadly equivalent lipoteichoic acids (LTAs) from two species of Gram-positive bacteria have similarly (if not more) potent effects. Using thioflavin T fluorescence to detect amyloid as before, the addition of low concentrations of free ferric ion is found to have similar effects. Luminescent conjugated oligothiophene dyes (LCOs), marketed under the trade name Amytracker™, also stain classical amyloid structures. We here show that they too give very large fluorescence enhancements when clotting is initiated in the presence of the four amyloidogens (LPS, ferric ions and two LTA types). The staining patterns differ significantly as a function of both the amyloidogens and the dyes used to assess them, indicating clearly that the nature of the clots formed is different. This is also the case when clotting is measured viscometrically using thromboelastography. Overall, the data provide further evidence for an important role of bacterial cell wall products in the various coagulopathies that are observable in chronic, inflammatory diseases. The assays may have potential in both diagnostics and therapeutics.

Prediction of bleeding by thromboelastography in ICU patients with haematological malignancy and severe sepsis

: ICU patients with haematological malignancy have an increased risk of bleeding. Recently, global haemostatic methods such as thromboelastography (TEG) have gained impact in evaluating coagulation. The aim of this study was to observe whether TEG could predict bleeding in haematological ICU patients with severe sepsis. Post-hoc single-centre analysis of patients with haematological malignancy included in the Scandinavian Starch for Severe Sepsis/Septic Shock (6S) trial. Clinical characteristics, TEG measurements and details regarding bleeding complications were retrieved from the 6S database. The association between TEG and bleeding were analysed by Cox regression and receiver operating characteristic curves. A total of 202 patients with severe sepsis were admitted to the ICU of Rigshospitalet, Copenhagen and included in the 6S trial. Forty-one had haematological malignancy and were analysed in the current study. During ICU stay, 20 patients (49%) had bleeding complications and 13 (32%) patients bled within the first 5 ICU days. We observed no associations between TEG and subsequent bleeding in Cox regression models. TEG variables at baseline had low predictive value for bleeding. Baseline TEG variables did not add value in identifying patients with high risk of bleeding in ICU patients with haematological malignancy and severe sepsis.

Serum amyloid A binds to fibrin(ogen), promoting fibrin amyloid formation

Complex associations exist between inflammation and thrombosis, with the inflammatory state tending to promote coagulation. Fibrinogen, an acute phase protein, has been shown to interact with the amyloidogenic ß-amyloid protein of Alzheimer’s disease. However, little is known about the association between fibrinogen and serum amyloid A (SAA), a highly fibrillogenic protein that is one of the most dramatically changing acute phase reactants in the circulation. To study the role of SAA in coagulation and thrombosis, in vitro experiments were performed where purified human SAA, in concentrations resembling a modest acute phase response, was added to platelet-poor plasma (PPP) and whole blood (WB), as well as purified and fluorescently labelled fibrinogen. Results from thromboelastography (TEG) suggest that SAA causes atypical coagulation with a fibrin(ogen)-mediated increase in coagulation, but a decreased platelet/fibrin(ogen) interaction. In WB scanning electron microscopy analysis, SAA mediated red blood cell (RBC) agglutination, platelet activation and clumping, but not platelet spreading. Following clot formation in PPP, the presence of SAA increased amyloid formation of fibrin(ogen) as determined both with auto-fluorescence and with fluorogenic amyloid markers, under confocal microcopy. SAA also binds to fibrinogen, as determined with a fluorescent-labelled SAA antibody and correlative light electron microscopy (CLEM). The data presented here indicate that SAA can affect coagulation by inducing amyloid formation in fibrin(ogen), as well as by propelling platelets to a more prothrombotic state. The discovery of these multiple and complex effects of SAA on coagulation invite further mechanistic analyses.

The Potential of LPS-Binding Protein to Reverse Amyloid Formation in Plasma Fibrin of Individuals With Alzheimer-Type Dementia

Many studies indicate that there is a (mainly dormant) microbial component in the progressive development of Alzheimer-type dementias (ADs); and that in the case of Gram-negative organisms, a chief culprit might be the shedding of the highly inflammagenic lipopolysaccharide (LPS) from their cell walls. We have recently shown that a highly sensitive assay for the presence of free LPS [added to platelet poor plasma (PPP)] lies in its ability (in healthy individuals) to induce blood to clot into an amyloid form. This may be observed in a SEM or in a confocal microscope when suitable amyloid stains (such as thioflavin T) are added. This process could be inhibited by human lipopolysaccharide-binding protein (LBP). In the current paper, we show using scanning electron microscopy and confocal microscopy with amyloid markers, that PPP taken from individuals with AD exhibits considerable amyloid structure when clotting is initiated with thrombin but without added LPS. Furthermore, we could show that this amyloid structure may be reversed by the addition of very small amounts of LBP. This provides further evidence for a role of microbes and their inflammagenic cell wall products and that these products may be involved in pathological clotting in individuals with AD.

No effects without causes: the Iron Dysregulation and Dormant Microbes hypothesis for chronic, inflammatory diseases

Since the successful conquest of many acute, communicable (infectious) diseases through the use of vaccines and antibiotics, the currently most prevalent diseases are chronic and progressive in nature, and are all accompanied by inflammation. These diseases include neurodegenerative (e.g. Alzheimer's, Parkinson's), vascular (e.g. atherosclerosis, pre-eclampsia, type 2 diabetes) and autoimmune (e.g. rheumatoid arthritis and multiple sclerosis) diseases that may appear to have little in common. In fact they all share significant features, in particular chronic inflammation and its attendant inflammatory cytokines. Such effects do not happen without underlying and initially 'external' causes, and it is of interest to seek these causes. Taking a systems approach, we argue that these causes include (i) stress-induced iron dysregulation, and (ii) its ability to awaken dormant, non-replicating microbes with which the host has become infected. Other external causes may be dietary. Such microbes are capable of shedding small, but functionally significant amounts of highly inflammagenic molecules such as lipopolysaccharide and lipoteichoic acid. Sequelae include significant coagulopathies, not least the recently discovered amyloidogenic clotting of blood, leading to cell death and the release of further inflammagens. The extensive evidence discussed here implies, as was found with ulcers, that almost all chronic, infectious diseases do in fact harbour a microbial component. What differs is simply the microbes and the anatomical location from and at which they exert damage. This analysis offers novel avenues for diagnosis and treatment.

Blood clot parameters: Prejudgment of fibrinolysis in thromboelastography

BACKGROUND

Thromboelastography (TEG) is a physical method to simulate the whole process of coagulation and fibrinolysis in the human body environment, and then it also can quickly determine whether patients with hypercoagulable, low coagulation, fibrinolysis or other symptoms. The first step in the diagnosis is based on two parameters: Estimated percentage of lysis (EPL) or the Lysis at 30 min (LY30). These two parameters are used to determine whether the sample has fibrinolysis. However, the determination of LY30 takes a long time, although EPL can reflect real-time fibrinolysis, sometimes the secondary fibrinolysis is not obvious.

MATERIALS AND METHODS

We have an extensive database of results from TEG of fibrinolysis and healthy whole blood (WB). These results were generated using citrated WB, followed by the addition of CaCl₂, to initiate clot formation.

RESULTS

According to the characteristics of fibrinolysis, a new parameter clot retention time (CRT) was proposed to predict the status of fibrinolysis, and the normal range of the parameters was obtained in this paper.

CONCLUSION

It is essential for the clinician to determine the fibrinolytic and ultimately contribute to the treatment of patients. We believe this parameter will add to the standardization of TEG parameters. The new parameter will also shorten the measurement time of non-fibrinolytic samples, which has definite physiological and pathological significance.

Simultaneous presence of hypercoagulation and increased clot lysis time due to IL-1β, IL-6 and IL-8

Circulating cytokines, and particularly the interleukin (IL)-family are known to play an important role in inflammation. These molecules circulate in the blood and therefore have a direct effect on the plasma molecules and the formed elements like the erythrocytes and platelets. Aberrant coagulation (hypercoagulation or blood clots that form too easily) and clot lyses (hypofibrinolysis, where clots do not dissolve properly, with an abnormally low rate of clot lysis time), are usually the hallmarks of many inflammatory conditions. However, the mechanism by which cross-linking augments clot stiffness remains undetermined. IL-1β; IL-6 and IL-8 has been found to be involved in most chronic and acute inflammatory diseases. In the present study, we investigate clot structure of healthy blood, with the addition of these 3 interleukins, to determine the individual effects at concentrations that mimic low-grade, chronic inflammation. Previous studies showed that clot rheological behavior is regulated by at least the following three factors, fibrinogen concentration, fibrin network architecture and FXIIIa-induced ligation. We investigated clot formation and lysis using thromboelastography (TEG), before and after exposure, and created clots by adding thrombin to whole blood. This allowed us to look at extensive fibrin fiber formation and their interactions with particularly the erythrocytes, using scanning electron microscopy (SEM). Our results showed that IL-1β; IL-6 and IL-8 causes hypercoagulation and results in a disheveled fibrin clot, with trapped RBCs. IL-8 showed eryptosis (a type of apoptosis in erythrocytes). Our lysis results showed that both clot lysis time and maximum rate of lysis are decreased, with the addition of the interleukins. This is a novel finding and the observations reported in this paper, therefore points to the importance of looking at the effects of individual circulating inflammagens, to better understand the role that each play in the expression of disease. These methods can be used for an individualized patient-orientated approach in healthcare to track blood viscosity in conditions with acute and chronic inflammation.

The inflammatory effects of TNF-α and complement component 3 on coagulation

Tissue necrosis factor-α (TNF-α) and complement component 3 (C3) are two well-known pro-inflammatory molecules. When TNF-α is upregulated, it contributes to changes in coagulation and causes C3 induction. They both interact with receptors on platelets and erythrocytes (RBCs). Here, we look at the individual effects of C3 and TNF-α, by adding low levels of the molecules to whole blood and platelet poor plasma. We used thromboelastography, wide-field microscopy and scanning electron microscopy to study blood clot formation, as well as structural changes to RBCs and platelets. Clot formation was significantly different from the naïve sample for both the molecules. Furthermore, TNF-α exposure to whole blood resulted in platelet clumping and activation and we noted spontaneous plasma protein dense matted deposits. C3 exposure did not cause platelet aggregation, and only slight pseudopodia formation was noted. Therefore, although C3 presence has an important function to cause TNF-α release, it does not necessarily by itself cause platelet activation or RBC damage at these low concentrations. We conclude by suggesting that our laboratory results can be translated into clinical practice by incorporating C3 and TNF-α measurements into broad spectrum analysis assays, like multiplex technology, as a step closer to a patient-orientated, precision medicine approach.

Interleukin-12 and its procoagulant effect on erythrocytes, platelets and fibrin(ogen): the lesser known side of inflammation

Inflammation, with its associated inflammatory molecules, is integral to most chronic diseases, including the various cardiovascular diseases. Interleukin 12 (IL12) is one of the inflammatory cytokines that is upregulated during inflammation; however, we know very little about its exact effect on red blood cells (RBCs), platelets and fibrin(ogen). IL12 is an important pleiotropic cytokine in early inflammatory responses and has potent immunomodulatory, antitumour and anti-infection activity. Here we investigate how low levels of circulating IL12, comparable to levels found during chronic inflammation, affect coagulation parameters, platelets and RBCs. We used thromboelastography, scanning electron microscopy, refractometery and wide-field microscopy. Our results show that IL12 caused hypercoagulation, platelet activation and spreading, as well as RBC agglutination. This phenomenon has far-reaching implications for treatment of the plethora of conditions where IL12 is upregulated, since it suggests aberrant haemorheology as agglutination affects blood flow. This information might be used in future to target the lowering of IL12 in inflammatory conditions, as well as address RBC agglutination.