What is all that thrombin for?

Altered thrombin generation with prothrombin complex concentrate is not detected by viscoelastic testing: an in vitro study

BACKGROUND

Bleeding guidelines currently recommend use of viscoelastic testing (VET) to direct haemostatic resuscitation in severe haemorrhage. However, VET-derived parameters of clot initiation, such as clotting time (CT) and activated clotting time (ACT), might not adequately reflect a clinically relevant interaction of procoagulant and anticoagulant activity, as revealed by thrombin generation assays. The aim of this study was to evaluate the ability of CT and ACT to indicate thrombin generation activity.

METHODS

Citrated whole blood obtained from 13 healthy volunteers underwent a 50% crystalloid dilution (DL-50%), followed by spiking with four-factor prothrombin complex concentrate (DL-50% + 4F-PCC). Changes in thrombin generation activity were compared with the VET parameters CT and ACT derived from four commercially available viscoelastic devices (ROTEM® Delta, ClotPro®, TEG®6s, and Quantra®) and standard coagulation tests.

RESULTS

Dilution of whole blood resulted in a marked increase in velocity index, peak height, and endogenous thrombin potential (all P<0.01), with a further substantial increase after spiking with 4F-PCC (all P<0.001). In contrast, CT and ACT were significantly prolonged in response to DL-50% on all devices (all P<0.05). Subsequent spiking of diluted blood with 4F-PCC had no impact on CT and ACT derived from VET analysers, but it restored standard coagulation tests without reaching baseline values (all P<0.01).

CONCLUSIONS

Upregulated thrombin generation parameters after PCC spiking were not displayed by CT, ACT, or standard tests. Our results do not support treatment algorithms using prolonged CT or ACT as a trigger for administration of PCC to augment thrombin generation.

Cost-effective, user-friendly detection and preconcentration of thrombin on a sustainable paper-based electrochemical platform

Thrombin overexpression in serum serves as a critical biomarker and is implicated in several diseases associated with significant morbidity and mortality. Existing techniques for thrombin detection are time-consuming and require sophisticated equipment and extensive sample preparation procedures, which further delay the detection and increase the cost of the procedure. Early and accessible diagnosis at the point of care, especially in limited-resource countries, represents the first step of clinical interventions. To overcome these limitations, we have proposed an innovative, sustainable paper-based electrochemical detection platform for thrombin. In this work, a sustainable paper-based aptasensor was rationally designed, characterized, evaluated against conventional gold standard plastic-based substrates, and applied to human serum, yielding a detection limit of ~ 60 pM. The present method provides an efficient and user-friendly way for the detection of thrombin and potentially leading to better management and treatment outcomes for patients.

Comparative assessment of hemostasis in septic patients and healthy controls using standard coagulation tests and whole-blood thromboelastometry

BACKGROUND

Sepsis is associated with dysregulation of procoagulant, anticoagulant, and fibrinolytic pathways.

AIMS

To compare the measurements of coagulation activation, clot formation, stabilization, and lysis between rotational thromboelastometry (ROTEM) and standard coagulation tests (SCTs) on patients with early sepsis (SP) and healthy controls (HC).

METHODS

This observational study included 30 SP and 30 HC. At study inclusion, SCTs and ROTEM analyses were conducted. A modified ROTEM with exogenous tPA was used to investigate fibrinolysis resistance.

RESULTS

SP had longer prothrombin time, higher fibrinogen levels and lower platelet count compared to HC. On ROTEM, clotting initiation was longer in SP than in HC but median clotting time maintained within reference ranges. SP had higher maximum velocity of clot formation, clot firmness, elasticity, and platelet component than HC. Clot lysis indices (CLI) were higher in EXTEM and APTEM (without and with added tPA) in SP compared to HC. The difference in CLI between APTEM and EXTEM was lower for both native and tPA-spiked samples in SP compared with HC.

CONCLUSIONS

While SCTs suggest SP are hypocoagulable, VET revealed normal coagulation initiation in more than 80 % of SP. Compared to HC, SP had increased clot propagation, firmness and elasticity, and decreased platelet-mediated clot retraction and lysis. In sepsis, VET provide more comprehensive information about hemostatic changes than SCTs.

Exosite crosstalk in thrombin

Thrombin is the central mediator of hemostasis, where it converts fibrinogen to fibrin, activates upstream factors to promote coagulation, activates factor XIII and thrombin-activatable fibrinolysis inhibitor to stabilize fibrin, mediates anticoagulation, and modulates cellular activity via cell surface receptors. Thus, regulation of thrombin activity is essential to the hemostatic balance. Thrombin is regulated by positively charged surface domains that surround the active site. These exosites bind substrates, inhibitors, cofactors, and receptors, which coordinate to direct thrombin to the appropriate location and modulate catalytic activity. Thus, the exosites are essential to the activity and regulation of thrombin. In addition to acting as binding sites, the exosites modulate the active site allosterically. Furthermore, the exosites impact each other, whereby the binding of ligands to one exosite impacts the function of the opposing exosite. Given the integral role that exosites play in the regulation of thrombin, they are attractive targets for the regulation of thrombin and for the development of new anticoagulants.

Laboratory and Molecular Diagnosis of Factor XI Deficiency

The prevalence of factor XI (FXI) deficiency is 1 per 10 to 20,000 in the general population, much higher than that reported in most texts. The prevalence is higher in Ashkenazi Jews where it is about 1:20. Clinically, FXI deficiency presents as a mild bleeding disorder mostly associated with posttraumatic or postsurgical hemorrhages or unexplained minor bleeding. It is often discovered due to incidental finding of a prolonged activated partial thromboplastin time (aPTT) on routine laboratory screening. FXI deficiency is an autosomal recessive bleeding disorder with many causative F11 gene defects. Diagnosis is based on FXI activity, antigen levels, and molecular diagnostics. As FXI levels do not correlate with bleeding symptoms, identification of pathogenic genetic variants may be a more accurate predictor of bleeding risk and therefore aid in the clinical management of the patient. Two variants in the F11 gene account for most cases found in the Jewish and Arab populations. Patients with FXI deficiency can develop inhibitors to FXI although spontaneously acquired inhibitors are extremely rare. We will discuss laboratory and molecular assays used to diagnose FXI deficiency as well as interferences that can complicate diagnosis including new anticoagulants and acquired FXI inhibitors.

Haemophilia

Haemophilia A and B are congenital X-linked bleeding disorders resulting from deficiencies in clotting factors VIII (haemophilia A) and IX (haemophilia B). Patients with severe deficiency, defined as having less than 1% of normal plasma factor activivity, often have spontaneous bleeding within the first few years of life. Those with moderate and mild deficiencies typically present with post-traumatic or post-surgical bleeding later in life. A high index of suspicion and measurement of factor activity in plasma facilitates early diagnosis. In the 21st century, therapeutic advances and comprehensive care have substantially improved both mortality and morbidity associated with these conditions. Management strategies for haemophilia include on-demand treatment for bleeding episodes and all surgeries and regular treatment (ie, prophylaxis) aimed at reducing bleeds, morbidity, and mortality, thereby enhancing quality of life. Treatment options include factor replacement therapy, non-replacement therapies that increase thrombin generation, and gene therapies that facilitate in vivo clotting factor synthesis. The therapies differ in their use for prophylaxis and on-demand treatment, the mode and frequency of administration, duration of treatment effect, degree of haemostatic protection, and side-effects. Monitoring the effectiveness of these prophylactic therapies involves assessing annual bleeding rates and joint damage. Personalised management strategies, which align treatment with individual goals (eg, playing competitive sports), initiated at diagnosis and maintained throughout the lifespan, are crucial for optimal outcomes. These strategies are facilitated by a multidisciplinary team and supported by clinician-led education for both clinicians and patients.

Monitoring Hemostatic Function during Cardiac Surgery with Point-of-Care Viscoelastic Assays: A Narrative Review

Bleeding is a well-known and severe complication of cardiac surgery. Cardiopulmonary bypass, along with heparinization and hemodilution, is thought to affect all pathways of the hemostatic process, leading to excessive bleeding and worsened morbidity and mortality. The traditionally used standard laboratory tests (SLTs) were not designed for the surgical setting, have long turnaround times, and are poor predictors of bleeding. This review aims to give an overview of viscoelastic assays (VEAs), compare VEAs to conventional testing methods, and summarize the evidence for VEAs in cardiac surgery. A search of Medline via Pubmed, Scopus, and Embase yielded 2,868 papers, which we reviewed and summarized the key findings. VEAs such as rotational thromboelastometry and thromboelastography provide a quick turnaround, graphical, global impression of hemostasis in whole blood. VEAs allow for the analysis of specific contributors to the coagulation process and may facilitate cause-oriented hemostatic treatment and the development of treatment algorithms. VEAs have been found to have a high specificity and high negative predictive value for coagulopathic bleeding. Patients treated with VEA-based algorithms have been shown to have lower rates of bleeding, transfusion requirements, and exposure to allogeneic blood products. However, VEA-based algorithms have not demonstrated a mortality benefit and evidence for outcomes such as surgical re-exploration and hospital length of stay remains equivocal. In conclusion, VEAs have been shown to be comparable if not superior to SLTs in cardiac surgery. Further large-scale studies are needed to better evaluate the impact of VEAs on clinical outcomes.

Comparing Patency of Pulmonary Stent Implantation and Balloon Angioplasty in Pulmonary Vein Stenosis: A Systematic Review and Meta-Analysis

Pulmonary vein stenosis (PVS) is an insidious diagnosis associated with morbidity and mortality. Pharmacologic therapy may suffice initially, but advanced stages demand mechanical intervention. Pulmonary stent implantation (PSI) and pulmonary balloon angioplasty (PBA) are common strategies, both carrying restenosis risks. This meta-analysis compares PSI and PBA to determine the superior revascularization strategy. We systematically searched databases until November 2023, identifying 11 studies with 780 patients. Studies, including those involving patients undergoing balloon angioplasty (BA) or stent angioplasty (SA) for PVS, were selected. Case reports, editorials, and cross-sectional studies were omitted. Primary outcomes included restenosis requiring reintervention, 5-year freedom from restenosis, and procedure-related complications. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random-effects model. Meta-regression analysis assessed factors like age and stent size. Study quality was evaluated using the Newcastle-Ottawa scale. This Systematic review and meta-analysis incorporated 11 observational studies. PSI exhibited a lower risk of restenosis requiring reintervention (OR 0.34, 95% CI 0.13, 0.87, p = 0.02) and significantly higher 5-year freedom from restenosis (OR 4.42, 95% CI 1.11, 17.62, p = 0.04) compared to PBA, with no significant difference in procedure-related complications. Meta-regression analysis showed age and stent size insignificantly affecting restenosis risk. Our review supports PSI as the preferred revascularization strategy for PVS due to superior patency benefits, emphasizing its role as the initial treatment choice. Further research is warranted for validation, considering individual patient factors in treatment selection.

Effectiveness of low-dose rivaroxaban in preventing recurrent major adverse cardiovascular events in coronary artery disease: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Despite advancements in coronary artery disease (CAD) management, major adverse cardiovascular events persist. Vitamin K antagonists and direct oral anticoagulants present bleeding risks. Low-dose rivaroxaban (2.5 mg) is approved by the European Society of Cardiology and the US Food and Drug Administration for CAD. The survival advantage and risk-benefit profile of combining low-dose rivaroxaban with aspirin for CAD patients remain uncertain. This meta-analysis aims to compare the efficacy of low-dose rivaroxaban plus aspirin versus aspirin monotherapy in CAD patients.

METHODS

We systematically searched databases for randomized controlled trials exploring low-dose rivaroxaban with aspirin in CAD patients. Of the 6220 studies screened, five met the inclusion criteria. Primary outcomes included myocardial infarction, stroke, major bleeding events, and all-cause mortality. The analysis employed a fixed-effects model, calculating hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Five randomized controlled trials involving 41,351 participants were included. Rivaroxaban (2.5 mg) significantly reduced all-cause mortality (HR, 0.88; 95% CI, 0.81-0.95; P = 0.002), myocardial infarction (HR, 0.81; 95% CI, 0.70-0.94; P = 0.006), and stroke (HR, 0.61; 95% CI, 0.49-0.76; P < 0.00001) compared to aspirin alone. However, it increased major bleeding risk (HR, 1.66; 95% CI, 1.40-1.97; P < 0.01). Meta-regression revealed no dose-dependent impact on all-cause mortality.

CONCLUSION

Low-dose rivaroxaban demonstrates survival benefits and reduces myocardial infarction and stroke risks in CAD patients, albeit with an increased risk of major bleeding. Consideration of patient bleeding risk is crucial when adding rivaroxaban to antiplatelet therapy. Further research is warranted to compare its effectiveness and safety with dual antiplatelet therapy or P2Y12 inhibitors.

Modelling the effects of 4-factor prothrombin complex concentrate for the management of factor Xa-associated bleeding

The management of factor Xa (FXa) inhibitor-associated bleeding remains a clinical challenge. Massive bleeding is often associated with complex coagulopathy and, thus, the sole reversal of FXa inhibitors might not be sufficient to restore hemostasis, requiring instead a multimodal approach. Four-factor prothrombin complex concentrate (4F-PCC) is widely recognized as a viable treatment option for FXa inhibitor-associated bleeding. Here, we applied computational models to explore the effect 4F-PCC has on the coagulation cascade and restoration of thrombin generation in a system that simulates a patient that has received a FXa inhibitor. The coagulation model is largely based on a previously developed model with modifications incorporated from various other published sources. The model was calibrated and validated using data from a phase 3 clinical trial of vitamin K antagonist reversal with 4F-PCC. Using the parameters and initial conditions determined during the calibration and validation process, the prothrombin time (PT) test simulations predicted a PT of 11.4 seconds. The model successfully simulated the effects of rivaroxaban and apixaban on total thrombin concentration and showed that 4F-PCC increased thrombin generation in the presence of rivaroxaban or apixaban.

Exploring the Role of Fibrin Gels in Enhancing Cell Migration for Vasculature Formation

A hallmark of angiogenesis is the sprouting of endothelial cells. To replicate this event in vitro, biomaterial approaches can play an essential role in promoting cell migration. To study the capacity of a scaffold of fibrin (fibrinogen:thrombin mix) to support the movement of the endothelial cells, the migration area of spheroids formed with the HULEC cell line was measured. The cells were first allowed to form a spheroid using the hanging drop technique before being encapsulated in the fibrin gel. The cells' migration area was then measured after two days of embedding in the fibrin gel. Various conditions affecting fibrin gel polymerization, such as different concentrations of fibrinogen and thrombin, were evaluated alongside rheology, porosity, and fiber thickness analysis to understand how these factors influenced cell behavior within the composite biomaterial. Data point toward thrombin's role in governing fibrin gel polymerization; higher concentrations result in less rigid gels (loss tangent between 0.07 and 0.034) and increased cell migration (maximum concentration tested: 5 U/mL). The herein presented method allows for a more precise determination of the crosslinking conditions of fibrin gel that can be used to stimulate angiogenic sprouting.

The in vitro effects of acidemia and acidemia reversal on coagulation in dogs

Background

The effect of acidemia on blood coagulation remains inadequately understood in veterinary medicine. Therefore, we assessed the effect of in vitro acidification of canine whole blood on coagulation and investigated whether acidemia-induced coagulopathy could be reversed by reversing acidemia.

Methods

Citrated whole blood samples were taken from six healthy Beagle dogs and categorized, based on pH adjustment, into neutral, weak acidemia (WA), strong acidemia (SA), and reversal from SA. Then, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration, conventional thromboelastography (TEG) parameters, and velocity curve (V-curve) variables of TEG were assessed.

Results

The PT, aPTT, and most TEG parameters showed significant coagulopathy in the SA group compared to the neutral group, with additional significant changes in reaction time (R), clot kinetic (K), maximum amplitude (MA), split point (SP), elasticity (E), thrombodynamic potential index (TPI), and coagulation index (CI) between the SA and WA groups. Among V-curve variables, the maximum rate of thrombus generation (MRTG) and total thrombus generation were significantly inhibited in the SA group compared to the neutral group, with significant differences in the time to maximum rate of thrombus generation (TMRTG) between the WA and SA groups. In the reverse group, aPTT, R, K, α-angle, MRTG, TMRTG, SP, TPI, and CI exhibited significant recovery compared to the SA group.

Conclusion

The in vitro induction of acidemia in canine whole blood leads to impairment of coagulation profiles, and pH correction can reverse most acidemia-induced coagulopathy.

Activated factor X stimulates atrial endothelial cells and tissues to promote remodelling responses through AT1R/NADPH oxidases/SGLT1/2

AIMS

Atrial fibrillation (AF), the most common cardiac arrhythmia favouring ischemic stroke and heart failure involves left atrial remodelling, fibrosis and a complex interplay between cardiovascular risk factors. This study examined whether activated factor X (FXa) induces pro-remodelling and pro-fibrotic responses in atrial endothelial cells (AECs) and human atrial tissues and determined the underlying mechanisms.

METHODS AND RESULTS

AECs collected from porcine hearts and human right atrial appendages (RAA) from patients undergoing heart surgery. Protein expression levels were assessed by Western blot and immunofluorescence staining, mRNA levels by RT-qPCR, formation of reactive oxygen species (ROS) and NO using fluorescent probes, thrombin and angiotensin II generation by specific assays, fibrosis by Sirius red staining and senescence by senescence-associated beta-galactosidase (SA-β-gal) activity. In AECs, FXa increased ROS formation, senescence (SA-β-gal activity, p53, p21), angiotensin II generation and the expression of pro-inflammatory (VCAM-1, MCP-1), pro-thrombotic (tissue factor), pro-fibrotic (TGF-β and collagen-1/3a) and pro-remodelling (MMP-2/9) markers whereas eNOS levels and NO formation were reduced. These effects were prevented by inhibitors of FXa but not thrombin, protease-activated receptors antagonists (PAR-1/2) and inhibitors of NADPH oxidases, ACE, AT1R, SGLT1/SGLT2. FXa also increased expression levels of ACE1, AT1R, SGLT1/2 proteins which were prevented by SGLT1/2 inhibitors. Human RAA showed tissue factor mRNA levels that correlated with markers of endothelial activation, pro-remodelling and pro-fibrotic responses and SGLT1/2 mRNA levels. They also showed protein expression levels of ACE1, AT1R, p22phox, SGLT1/2, and immunofluorescence signals of nitrotyrosine and SGLT1/2 colocalized with those of CD31. FXa increased oxidative stress levels which were prevented by inhibitors of the AT1R/NADPH oxidases/SGLT1/2 pathway.

CONCLUSION

FXa promotes oxidative stress triggering premature endothelial senescence and dysfunction associated with pro-thrombotic, pro-remodelling and pro-fibrotic responses in AECs and human RAA involving the AT1R/NADPH oxidases/SGLT1/2 pro-oxidant pathway. Targeting this pathway may be of interest to prevent atrial remodelling and the progression of atrial fibrillation substrate.

Update on the pathophysiology and management of acute trauma hemorrhage and trauma-induced coagulopathy based upon viscoelastic testing

Uncontrolled hemorrhage and trauma-induced coagulopathy (TIC) are the two predominant causes of preventable death after trauma. Early control of bleeding sources and rapid detection, characterization and management of TIC have been associated with improved outcomes. However, recent surveys confirm vast heterogeneity in the clinical diagnosis and management of hemorrhage and TIC from acute trauma, even in advanced trauma centers. In addition, conventional coagulation assays, although still used frequently during the early assessment of bleeding trauma patients, have their limitations. This narrative review highlights the clinical value of rapid point-of-care viscoelastic testing for the early diagnosis and individualized goal-directed therapy in bleeding trauma patients with TIC.

Is There an Alternative Oral Anticoagulation to Vitamin-K-Antagonists for Patients with Mechanical Aortic Valve Replacement? - A Literature Review

Current guidelines exclusively recommend vitamin-K-antagonists (VKA) as anticoagulation for patients after mechanical aortic valve replacement due to the increased postoperative risk of valve thrombosis and thrombo-embolism. Strict and regular assessments are mandatory during VKA therapy to ensure a potent anticoagulatory effect within the desired range. From the patients' perspective, VKA are associated with relevant interactions and side effects reducing the quality of life and contributing to a high number of patients not achieving the optimal therapeutic target. Direct oral anticoagulants (DOAC) have replaced VKA therapy in the past for several indications, e.g., atrial fibrillation. However, it is still unclear if DOACs could replace VKA therapy in patients after mechanical aortic valve replacement. While the PROACT-Xa study did not show a sufficient anticoagulatory effect of apixaban plus aspirin compared to VKA therapy in patients after mechanical aortic valve replacement, the direct thrombin inhibitor dabigatran and the oral factor Xa inhibitors apixaban and rivaroxaban showed promising results in comparable patient cohorts in smaller studies and case reports. Factor Xa inhibitors were able to prevent thrombosis and thrombo-embolic events in patients after mechanical aortic valve replacement. Therefore, factor Xa inhibitors or factor XI inhibitors could provide a potent alternative to VKA for patients after a mechanical aortic valve replacement.

Global coagulation assays detect an early prothrombotic state in children with acute lymphoblastic leukemia

BACKGROUND

Pediatric patients with acute lymphoblastic leukemia (ALL) are at highest risk of venous thromboembolism during the induction therapy (IT). These events are not predictable by conventional coagulation assays.

OBJECTIVES

To investigate the utility of global coagulation assays (GCAs) for assessing the hemostatic state in children with ALL during IT.

METHODS

We included children with ALL (n = 15) and healthy controls (n = 15). Analyses were performed at different time points during IT of the AIEOP-BFM protocols. In addition to prothrombotic biomarkers, natural anticoagulant proteins, and in vivo thrombin generation (TG) markers, ex vivo TG was measured using the gold standard calibrated automated thrombogram method, automated ST Genesia, and thrombodynamics analyzer (TD). The latter also provided measurement of fibrin clot formation.

RESULTS

Different from conventional coagulation assays and in vivo TG markers, ex vivo GCAs detected increasing prothrombotic changes during IT. Particularly, TG measured with TD as expressed by endogenous thrombin potential was already significantly elevated at days 8 to 12 (P < .01) and continued to increase during IT compared with prior to beginning treatment, indicating a very early shift toward a procoagulant state. A similar pattern was observed for the rate of fibrin clot formation (stationary rate of clot growth: P < .01 at days 8-12). Remarkably, in patients developing thrombotic complications (n = 5), both GCAs, ST Genesia and TD, showed a significantly higher endogenous thrombin potential very early (already at days 8-12, P < .05), well before clinical manifestation.

CONCLUSION

GCAs capture prothrombotic changes early during IT in ALL pediatric patients. If confirmed, this approach will allow tailoring thromboprophylaxis in children with ALL at highest risk for venous thromboembolism.

Protocol for a phase 3, randomised, active-control study of four-factor prothrombin complex concentrate versus frozen plasma in bleeding adult cardiac surgery patients requiring coagulation factor replacement: the LEX-211 (FARES-II) trial

INTRODUCTION

Reduced thrombin generation is an important component of post cardiopulmonary bypass (CPB) coagulopathy. To replenish coagulation factors and enhance thrombin generation in bleeding surgical patients, frozen plasma (FP) and four-factor prothrombin complex concentrate (4F-PCC) are used. However, the efficacy-safety balance of 4F-PCC relative to FP in cardiac surgery is unconfirmed.

METHODS AND ANALYSIS

LEX-211 (FARES-II) is an active-control, randomised, phase 3 study comparing two coagulation factor replacement therapies in bleeding adult cardiac surgical patients at 12 hospitals in Canada and the USA. The primary objective is to determine whether 4F-PCC (Octaplex/Balfaxar, Octapharma) is clinically non-inferior to FP for haemostatic effectiveness. Inclusion criteria are any index (elective or non-elective) cardiac surgery employing CPB and coagulation factor replacement with 4F-PCC or FP ordered in the operating room for bleeding management. Patients will be randomised to receive 1500 or 2000 international units of 4F-PCC or 3 or 4 units of FP, depending on body weight. The primary endpoint of haemostatic treatment response is 'effective' if no additional haemostatic intervention is required from 60 min to 24 hours after the first initiation of 4F-PCC or FP; or 'ineffective' if any other haemostatic intervention (including a second dose of study drug) is required. An estimated 410 evaluable patients will be required to demonstrate non-inferiority (one-sided α of 0.025, power ≥90%, non-inferiority margin 0.10). Secondary outcomes include transfusions, bleeding-related clinical endpoints, coagulation parameters and safety.

ETHICS AND DISSEMINATION

The trial has been approved by the institutional review boards of all participating centres. Trial completion is anticipated at the end of 2024, and results will be disseminated via publications in peer-reviewed journals and conference presentations in 2025. The results will advance our understanding of coagulation management in bleeding surgical patients, potentially reducing the need for allogeneic blood products and improving outcomes in surgical patients.

TRIAL REGISTRATION NUMBER

NCT05523297.

Emerging Trends and Innovations in the Treatment and Diagnosis of Atherosclerosis and Cardiovascular Disease: A Comprehensive Review towards Healthier Aging

Cardiovascular diseases (CVDs) are classed as diseases of aging, which are associated with an increased prevalence of atherosclerotic lesion formation caused by such diseases and is considered as one of the leading causes of death globally, representing a severe health crisis affecting the heart and blood vessels. Atherosclerosis is described as a chronic condition that can lead to myocardial infarction, ischemic cardiomyopathy, stroke, and peripheral arterial disease and to date, most pharmacological therapies mainly aim to control risk factors in patients with cardiovascular disease. Advances in transformative therapies and imaging diagnostics agents could shape the clinical applications of such approaches, including nanomedicine, biomaterials, immunotherapy, cell therapy, and gene therapy, which are emerging and likely to significantly impact CVD management in the coming decade. This review summarizes the current anti-atherosclerotic therapies' major milestones, strengths, and limitations. It provides an overview of the recent discoveries and emerging technologies in nanomedicine, cell therapy, and gene and immune therapeutics that can revolutionize CVD clinical practice by steering it toward precision medicine. CVD-related clinical trials and promising pre-clinical strategies that would significantly impact patients with CVD are discussed. Here, we review these recent advances, highlighting key clinical opportunities in the rapidly emerging field of CVD medicine.

Metaphyseal trauma of the lower extremities in major orthopedic surgery as an independent risk factor for deep vein thrombosis

PURPOSE

Major orthopedic surgeries of the lower extremities, which heavily injure the metaphyseal region, are strongly associated with the risk of developing deep vein thrombosis (DVT). This study aims to investigate the role of metaphyseal trauma as an independent risk factor for DVT.

METHODS

Patients undergoing major orthopedic surgery of the hip and knee had their existing DVT risk factors recorded. Metaphyseal trauma was defined by the extent of bone injury during these surgeries. The samples were categorized into three surgery groups: total arthroplasty group (TA), hemiarthroplasty group (HA), and the open reduction internal fixation group (ORIF). Logistic regression test between significant existing risk factors and surgery groups determines the independent association between risk factors and DVT.

RESULT

The study found a 24.8% incidence of asymptomatic DVT in patients undergoing major orthopedic surgeries, with the highest prevalence (37.2%) in TA, which had the largest extent of metaphyseal trauma and the least existing DVT risk factors. TA showed 6.2 OR and 95% CI (p = 0.036) compared to the other existing risk factor in relation to DVT incidence.

CONCLUSION

Metaphyseal bone trauma in the hip and knee major orthopedic surgery is an independent risk factor for deep vein thrombosis.

Intermediate molecular weight-fucosylated chondroitin sulfate from sea cucumber Cucumaria frondosa is a promising anticoagulant targeting intrinsic factor IXa

Thromboembolic diseases pose a serious risk to human health worldwide. Fucosylated chondroitin sulfate (FCS) is reported to have good anticoagulant activity with a low bleeding risk. Molecular weight plays a significant role in the anticoagulant activity of FCS, and FCS smaller than octasaccharide in size has no anticoagulant activity. Therefore, identifying the best candidate for developing novel anticoagulant FCS drugs is crucial. Herein, native FCS was isolated from sea cucumber Cucumaria frondosa (FCScf) and depolymerized into a series of lower molecular weights (FCScfs). A comprehensive assessment of the in vitro anticoagulant activity and in vivo bleeding risk of FCScfs with different molecule weights demonstrated that 10 kDa FCScf (FCScf-10 K) had a greater intrinsic anticoagulant activity than low molecular weight heparin (LMWH) without any bleeding risk. Using molecular modeling combined with experimental validation, we revealed that FCScf-10 K can specifically inhibit the formation of the Xase complex by binding the negatively charged sulfate group of FCScf-10 K to the positively charged side chain of arginine residues on the specific surface of factor IXa. Thus, these data demonstrate that the intermediate molecular weight FCScf-10 K is a promising candidate for the development of novel anticoagulant drugs.

Oligonucleotide based nanogels for cancer therapeutics

Oligonucleotide-based nanogels, as nascent biomaterials, possess several unique functional, structural, and physicochemical features with excellent drug-loading capacity and high potential for cancer gene therapy. Ongoing studies utilizing oligonucleotide-based nanogels hold great promise, as these cutting-edge nanoplatforms can be elegantly developed with predesigned oligonucleotide sequences and complementary strands which are self-assembled or chemically crosslinked leading to the development of nanogels with predictable shape and tunable size with the desired functional properties. Current paper provides a summary of the properties, preparation methods, and applications of oligonucleotide-based nanogels in cancer therapy. The review is focused on both conventional and modified forms of oligonucleotide-based nanogels, including targeted nanogels, smart release nanogels (responsive to stimuli such as pH, temperature, and enzymes), as well as nanogels used for gene delivery. Their application in cancer immunotherapy and vaccination, photodynamic therapy, and diagnostic applications when combined with other nanoparticles is further discussed. Despite emerging designs in the development of oligonucleotide based nanogels, this field of study is still in its infancy, and clinical translation of these versatile nano-vehicles might face challenges. Hence, extensive research must be performed on in vivo behavior of such platforms determining their biodistribution, biological fate, and acute/subacute toxicity.

Investigation of thrombin concentration at the time of clot formation in simultaneous thrombin and fibrin generation assays

Thrombin generation (TG) and fibrin clot formation represent the central process of blood coagulation. Up to 95% of thrombin is considered to be generated after the clot is formed. However, this was not investigated in depth. In this study, we conducted a quantitative analysis of the Thrombin at Clot Time (TCT) parameter in 5758 simultaneously recorded TG and clot formation assays using frozen plasma samples from commercial sources under various conditions of activation. These samples were supplemented with clotting factor concentrates, procoagulant lipid vesicles and a fluorogenic substrate and triggered with tissue factor (TF). We found that TCT is often close to a 10% of thrombin peak height (TPH) yet it can be larger or smaller depending on whether the sample has low or high TPH value. In general, the samples with high TPH are associated with elevated TCT. TCT appeared more sensitive to some procoagulant phenotypes than other commonly used parameters such as clotting time, TPH or Thrombin Production Rate (TPR). In a minority of cases, TCT were not predicted from TG parameters. For example, elevated TCT (above 15% of TPH) was associated with either very low or very high TPR values. We conclude that clotting and TG assays may provide complementary information about the plasma sample, and that the TCT parameter may serve as an additional marker for the procoagulant potential in plasma sample.

Prothrombin Knockdown Protects Podocytes and Reduces Proteinuria in Glomerular Disease

Chronic kidney disease (CKD) is a leading cause of death, and its progression is driven by glomerular podocyte injury and loss, manifesting as proteinuria. Proteinuria includes urinary loss of coagulation zymogens, cofactors, and inhibitors. Importantly, both CKD and proteinuria significantly increase the risk of thromboembolic disease. Prior studies demonstrated that anticoagulants reduced proteinuria in rats and that thrombin injured cultured podocytes. Herein we aimed to directly determine the influence of circulating prothrombin on glomerular pathobiology. We hypothesized that (pro)thrombin drives podocytopathy, podocytopenia, and proteinuria. Glomerular proteinuria was induced with puromycin aminonucleoside (PAN) in Wistar rats. Circulating prothrombin was either knocked down using a rat-specific antisense oligonucleotide or elevated by serial intravenous infusions of prothrombin protein, which are previously established methods to model hypo- (LoPT) and hyper-prothrombinemia (HiPT), respectively. After 10 days (peak proteinuria in this model) plasma prothrombin levels were determined, kidneys were examined for (pro)thrombin co-localization to podocytes, histology, and electron microscopy. Podocytopathy and podocytopenia were determined and proteinuria, and plasma albumin were measured. LoPT significantly reduced prothrombin colocalization to podocytes, podocytopathy, and proteinuria with improved plasma albumin. In contrast, HiPT significantly increased podocytopathy and proteinuria. Podocytopenia was significantly reduced in LoPT vs. HiPT rats. In summary, prothrombin knockdown ameliorated PAN-induced glomerular disease whereas hyper-prothrombinemia exacerbated disease. Thus, (pro)thrombin antagonism may be a viable strategy to simultaneously provide thromboprophylaxis and prevent podocytopathy-mediated CKD progression.

[Update on point-of-care-based coagulation treatment : Systems, reagents, device-specific treatment algorithms]

Viscoelastic test (VET) procedures suitable for point-of-care (POC) testing are in widespread clinical use. Due to the expanded range of available devices and in particular due to the development of new test approaches and methods, the authors believe that an update of the current treatment algorithms is necessary. The aim of this article is to provide an overview of the currently available VET devices and the associated reagents. In addition, two treatment algorithms for the VET devices most commonly used in German-speaking countries are presented.

Thrombin and Thrombin-Incorporated Biomaterials for Disease Treatments

Thrombin, a coagulation-inducing protease, has long been used in the hemostatic field. During the past decades, many other therapeutic uses of thrombin have been developed. For instance, burn treatment, pseudoaneurysm therapy, wound management, and tumor vascular infarction (or tumor vasculature blockade therapy) can all utilize the unique and powerful function of thrombin. Based on their therapeutic effects, many thrombin-associated products have been certificated by the Food and Drug Administration, including bovine thrombin, human thrombin, recombinant thrombin, fibrin glue, etc. Besides, several thrombin-based drugs are currently undergoing clinical trials. In this article, the therapeutic uses of thrombin (from the initial hemostasis to the latest cancer therapy), the commercially available drugs associated with thrombin, and the pros and cons of thrombin-based therapeutics (e.g., adverse immune responses related to bovine thrombin, thromboinflammation, and vasculogenic "rebounds") are summarized. Further, the current challenges and possible future research directions of thrombin-incorporated biomaterials and therapies are discussed. It is hoped that this review may provide a valuable reference for researchers in this field and help them to design safer and more effective thrombin-based drugs for fighting against various intractable diseases.

Clot formation and fibrinolysis assays reveal functional differences among hemostatic agents in hemophilia A plasma

Background

Measuring the activity of hemostatic agents used to treat hemophilia A often requires drug-specific assays. In vitro assays show hemophilic clots have abnormal characteristics, including prolonged clotting time and decreased resistance to fibrinolysis. The ability of certain agents to correct these parameters in vitro is associated with hemostatic efficacy in vivo.

Objectives

To compare effects of established and emerging hemostatic agents on clot formation and fibrinolysis in hemophilia A plasma.

Methods

Pooled and individual hemophilia A platelet-poor plasmas were spiked with replacement (recombinant factor VIII [rFVIII], PEGylated rFVIII, polysialylated rFVIII, and porcine rFVIII) or bypassing (emicizumab, rFVIIa, and activated prothrombin complex concentrate) products. Effects on tissue factor-initiated clot formation and fibrinolysis were measured by turbidity.

Results

Compared to normal pooled plasma, hemophilia-pooled plasma showed reduced clot formation and increased fibrinolysis, and all replacement agents improved these characteristics. rFVIII and PEGylated rFVIII produced similar effects at similar concentrations, whereas polysialylated rFVIII produced slightly higher and porcine rFVIII slightly lower effects at these concentrations. Bypassing agents enhanced clot formation and stability, but patterns differed from replacement agents. The clotting rate showed a concentration-response relationship for all agents. High concentrations of all products produced effects that exceeded the normal range in at least some parameters. Responses of individual donors varied, but all agents improved clot formation and stability in all donors tested.

Conclusion

Clotting and fibrinolysis assays reveal hemostatic effects of replacement and bypassing therapies at clinically relevant concentrations. These assays may help characterize hemostatic agents and optimize dosing.

Thromboelastographic evaluation after cardiac surgery optimizes transfusion requirements in the intensive care unit: a single-center retrospective cohort study using an inverse probability weighting method

OBJECTIVE

There are no reports from Japan showing the effects of using the thromboelastography algorithm on transfusion requirements after Intensive Care Unit (ICU) admission, and post-implementation knowledge regarding the thromboelastography algorithm under the Japanese healthcare system is insufficient. Therefore, this study aimed to clarify the effect of the TEG6s thromboelastography algorithm on transfusion requirements for patients in the ICU after cardiac surgery.

METHODS

We retrospectively compared the requirements for blood transfusion up to 24 h after ICU admission using the thromboelastography algorithm (January 2021 to April 2022) (thromboelastography group; n = 201) and specialist consultation with surgeons and anesthesiologists (January 2018 to December 2020) (non-thromboelastography group; n = 494).

RESULTS

There were no significant between-group differences in terms of age, height, weight, body mass index, operative procedure, duration of surgery or cardiopulmonary bypass, body temperature, or urine volume during surgical intervention. Moreover, there was no significant between-group difference in the amount of drainage at 24 h after ICU admission. However, crystalloid and urine volumes were significantly higher in the thromboelastography group than in the non-thromboelastography group. Additionally, fresh-frozen plasma (FFP) transfusion volumes were significantly lower in the thromboelastography group. However, there were no significant between-group differences in red blood cell count or platelet transfusion volume. After variable adjustment, the amount of FFP used from the operating room to 24 h after ICU admission was significantly reduced in the thromboelastography group.

CONCLUSIONS

The thromboelastography algorithm optimized transfusion requirements at 24 h after admission to the ICU following cardiac surgery.

Point-of-care, goal-directed management of bleeding in trauma patients

PURPOSE OF REVIEW

The purpose of this review is to consider the clinical value of point-of-care (POC) testing in coagulopathic trauma patients with traumatic brain injury (TBI) and trauma-induced coagulopathy (TIC).

RECENT FINDINGS

Patients suffering from severe TBI or TIC are at risk of developing pronounced haemostatic disorders. Standard coagulation tests (SCTs) are insufficient to reflect the complexity of these coagulopathies. Recent evidence has shown that viscoelastic tests (VETs) identify haemostatic disorders more rapidly and in more detail than SCTs. Moreover, VET results can guide coagulation therapy, allowing individualised treatment, which decreases transfusion requirements. However, the impact of VET on mortality remains uncertain. In contrast to VETs, the clinical impact of POC platelet function testing is still unproven.

SUMMARY

POC SCTs are not able to characterise the complexity of trauma-associated coagulopathy. VETs provide a rapid estimation of underlying haemostatic disorders, thereby providing guidance for haemostatic therapy, which impacts allogenic blood transfusion requirements. The value of POC platelet function testing to identify platelet dysfunction and guide platelet transfusion is still uncertain.

Rivaroxaban plus aspirin vs. dual antiplatelet therapy in endovascular treatment in peripheral artery disease and analysis of medication utilization of different lesioned vascular regions

Background

In the management of Peripheral Arterial Disease (PAD), the administration of anticoagulant or antiplatelet agents is imperative. The use of Dual Antiplatelet Therapy (DAPT) in conjunction with rivaroxaban has shown potential in mitigating adverse outcomes. Given the heterogeneity in the pathology of lower limb arteries, there is a compelling case for individualized treatment strategies.

Methods

In a single-center retrospective study on pharmacotherapy for peripheral artery disease, patients were treated with either aspirin combined with rivaroxaban or aspirin coupled with clopidogrel. The primary efficacy outcome encompassed a composite of increases in the Rutherford classification, acute limb ischemia, amputations due to vascular causes, target lesion revascularization, myocardial infarction, ischemic stroke, and cardiovascular death. The primary safety outcome was major bleeding, as defined by the Thrombolysis in Myocardial Infarction (TIMI) criteria; meanwhile, major bleeding as categorized by the International Society on Thrombosis and Haemostasis (ISTH) served as a secondary safety outcome. The study differentiated between two subgroups: patients with only above-the-knee and below-the-knee arterial lesions.

Results

From January 2016 to December 2021, 455 patients received either clopidogrel plus aspirin or rivaroxaban plus aspirin following endovascular treatment (EVT). The rivaroxaban group (n = 220) exhibited a lower incidence of primary efficacy outcomes [49.1% vs. 60.4%, hazard ratio (HR) 0.77, P = 0.006] but had more TIMI major bleeding events (5.9% vs. 2.1%, HR 2.6, P = 0.04). ISTH major bleeding events did not show a significant difference, though a higher percentage of rivaroxaban patients discontinued medication due to bleeding (10% vs. 4.7%, HR 2.2, P = 0.03). In the above-the-knee arterial disease subgroup, the rivaroxaban group demonstrated a lower incidence of primary efficacy outcomes (28.2% vs. 45.2%, HR 0.55, P = 0.02). In the below-the-knee arterial disease subgroup, no significant difference was observed in the occurrence of primary efficacy events between the two groups (58.7% vs. 64.8%, HR 0.76, P = 0.14).

Conclusion

Rivaroxaban plus aspirin improved outcomes compared to DAPT in patients with lower extremity artery disease. Similar findings were observed in the above-the-knee artery lesion-only group. However, in the below-the-knee artery lesion-only group, rivaroxaban plus aspirin did not surpass DAPT in efficacy. Regarding safety, rivaroxaban plus aspirin exhibited higher bleeding risks and more frequent treatment discontinuation than aspirin combined with clopidogrel.

Complement and coagulation crosstalk - Factor H in the spotlight

The immune complement and the coagulation systems are blood-based proteolytic cascades that are activated by pathway-specific triggers, based on protein-protein interactions and enzymatic cleavage reactions. Activation of these systems is finely balanced and controlled through specific regulatory mechanisms. The complement and coagulation systems are generally viewed as distinct, but have common evolutionary origins, and several interactions between these homologous systems have been reported. This complement and coagulation crosstalk can affect activation, amplification and regulatory functions in both systems. In this review, we summarize the literature on coagulation factors contributing to complement alternative pathway activation and regulation and highlight molecular interactions of the complement alternative pathway regulator factor H with several coagulation factors. We propose a mechanism where factor H interactions with coagulation factors may contribute to both complement and coagulation activation and regulation within the haemostatic system and fibrin clot microenvironment and introduce the emerging role of factor H as a modulator of coagulation. Finally, we discuss the potential impact of these protein interactions in diseases associated with factor H dysregulation or deficiency as well as evidence of coagulation dysfunction.

Activated protein C in epilepsy pathophysiology

Epilepsy is one of the most common neurologic disorders that is characterized by recurrent seizures, and depending on the type of seizure, it could lead to a severe outcome. Epilepsy's mechanism of development is not fully understood yet, but some of the common features of the disease are blood-brain barrier disruption, microglia activation, and neuroinflammation. Those are also targets of activated protein C (APC). In fact, by downregulating thrombin, known as a pro-inflammatory, APC acts as an anti-inflammatory. APC is also an anti-apoptotic protein, instance by blocking p53-mediated apoptosis. APC's neuroprotective effect could prevent blood-brain barrier dysfunction by acting on endothelial cells. Furthermore, through the downregulation of proapoptotic, and proinflammatory genes, APC's neuroprotection could reduce the effect or prevent epilepsy pathogenesis. APC's activity acts on blood-brain barrier disruption, inflammation, and apoptosis and causes neurogenesis, all hallmarks that could potentially treat or prevent epilepsy. Here we review both Activated Protein C and epilepsy mechanism, function, and the possible association between them.

Cell Surface Platelet Tissue Factor Expression: Regulation by P2Y12 and Link to Residual Platelet Reactivity

BACKGROUND

ADP-induced platelet activation leads to cell surface expression of several proteins, including TF (tissue factor). The role of ADP receptors in platelet TF modulation is still unknown. We aimed to assess the (1) involvement of P2Y1 and P2Y12 receptors in ADP-induced TF exposure; (2) modulation of TFpos-platelets in anti-P2Y12-treated patients with coronary artery disease. Based on the obtained results, we revisited the intracellular localization of TF in platelets.

METHODS

The effects of P2Y1 or P2Y12 antagonists on ADP-induced TF expression and activity were analyzed in vitro by flow cytometry and thrombin generation assay in blood from healthy subjects, P2Y12-/-, and patients with gray platelet syndrome. Ex vivo, P2Y12 inhibition of TF expression by clopidogrel/prasugrel/ticagrelor, assessed by VASP (vasodilator-stimulated phosphoprotein) platelet reactivity index, was investigated in coronary artery disease (n=238). Inhibition of open canalicular system externalization and electron microscopy (TEM) were used for TF localization.

RESULTS

In blood from healthy subjects, stimulated in vitro by ADP, the percentage of TFpos-platelets (17.3±5.5%) was significantly reduced in a concentration-dependent manner by P2Y12 inhibition only (-81.7±9.5% with 100 nM AR-C69931MX). In coronary artery disease, inhibition of P2Y12 is paralleled by reduction of ADP-induced platelet TF expression (VASP platelet reactivity index: 17.9±11%, 20.9±11.3%, 40.3±13%; TFpos-platelets: 10.5±4.8%, 9.8±5.9%, 13.6±6.3%, in prasugrel/ticagrelor/clopidogrel-treated patients, respectively). Despite this, 15% of clopidogrel good responders had a level of TFpos-platelets similar to the poor-responder group. Indeed, a stronger P2Y12 inhibition (130-fold) is required to inhibit TF than VASP. Thus, a VASP platelet reactivity index <20% (as in prasugrel/ticagrelor-treated patients) identifies patients with TFpos-platelets <20% (92% sensitivity). Finally, colchicine impaired in vitro ADP-induced TF expression but not α-granule release, suggesting that TF is open canalicular system stored as confirmed by TEM and platelet analysis of patients with gray platelet syndrome.

CONCLUSIONS

Data show that TF expression is regulated by P2Y12 and not P2Y1; P2Y12 antagonists downregulate the percentage of TFpos-platelets. In clopidogrel good-responder patients, assessment of TFpos-platelets highlights those with residual platelet reactivity. TF is stored in open canalicular system, and its membrane exposure upon activation is prevented by colchicine.

Antithrombin Deficiency Is Associated with Prothrombotic Plasma Fibrin Clot Phenotype

BACKGROUND

 Deficiency of antithrombin increases risk of venous thromboembolism. We hypothesized that antithrombin deficiency affects fibrin clot structure and function.

METHODS

 We evaluated 148 patients (age: 38 [32-50] years; 70% women) with genetically confirmed antithrombin deficiency and 50 healthy controls. Fibrin clot permeability (Ks) and clot lysis time (CLT) along with thrombin generation capacity were assessed before and after antithrombin activity normalization in vitro.

RESULTS

 Antithrombin-deficient patients had lower antithrombin activity (-39%) and antigen levels (-23%) compared with controls (both p < 0.01). Prothrombin fragment 1 + 2 levels were 26.5% higher in patients with antithrombin deficiency than in controls along with 94% increased endogenous thrombin potential (ETP) and 108% higher peak thrombin (all p < 0.01). Antithrombin deficiency was associated with 18% reduced Ks and 35% prolonged CLT (both p < 0.001). Patients with type I (n = 65; 43.9%) compared with type II antithrombin deficiency (n = 83; 56.1%) had 22.5% lower antithrombin activity (p < 0.001) and despite similar fibrinogen levels, 8.4% reduced Ks, 18% prolonged CLT, and 30% higher ETP (all p < 0.01). Reduced Ks was associated with lower antithrombin antigen level (β = - 6.1, 95% confidence interval [CI]: -1.7 to -10.5), while prolonged CLT was associated with lower antithrombin antigen (β = - 69.6, 95% CI: -9.6 to -129.7), activity (β = - 2.4, 95% CI: -0.3 to -4.5), higher PAI-1 (β = 12.1, 95% CI: 7.7-16.5), and thrombin-activatable fibrinolysis inhibitor levels (β = 3.8, 95% CI: 1.9-5.7). Addition of exogenous antithrombin reduced ETP (-42%) and peak thrombin (-21%), and improved Ks (+8%) and CLT (-12%; all p < 0.01).

CONCLUSION

 Our study suggests that enhanced thrombin generation and prothrombotic plasma fibrin clot phenotype can contribute to increased risk of thrombosis in patients with antithrombin deficiency.

Development and validation of a stability-indicating RP-HPLC method for the determination of fifteen impurities in rivaroxaban

A simple and stability-indicating reverse phase high-performance liquid chromatographic (RP-HPLC) method for the determination of rivaroxaban (RIX) and its related substances was developed. Fifteen impurities of RIX, including three unreported isomers, were identified, synthesized, purified, and confirmed using MS, 1H NMR, 13C NMR, and HSQC spectral methods. This new method offered baseline separation for all monitored impurities, and was fast and reliable when compared to the European Pharmacopoeia method. Optimum separation for RIX and its related impurities was achieved on an octyldecyl silica column (YMC Core C18, 4.6 ×100 mm, 2.7 µm) by using a gradient HPLC method in 38 min. The final method was validated with respect to precision, LOD and LOQ, linearity, accuracy, and robustness. This developed method was suitable for routine quality control and drug analysis of RIX active substance.

Label-free multiplex sensing from buffer and immunoglobulin G sensing from whole blood with photonic crystal slabs using angle-tuning of an optical interference filter

Direct detection of biomarkers from unpurified whole blood has been a challenge for label-free detection platforms, such as photonic crystal slabs (PCS). A wide range of measurement concepts for PCS exist, but exhibit technical limitations, which render them unsuitable for label-free biosensing with unfiltered whole blood. In this work, we single out the requirements for a label-free point-of-care setup based on PCS and present a wavelength selecting concept by angle tuning of an optical interference filter, which fulfills these requirements. We investigate the limit of detection (LOD) for bulk refractive index changes and obtain a value of 3.4 E-4 refractive index units (RIU). We demonstrate label-free multiplex detection for different types of immobilization entities, including aptamers, antigens, and simple proteins. For this multiplex setup we detect thrombin at a concentration of 6.3 µg/ml, antibodies of glutathione S-transferase (GST) diluted by a factor of 250, and streptavidin at a concentration of 33 µg/ml. In a first proof of principle experiment, we demonstrate the ability to detect immunoglobulins G (IgG) from unfiltered whole blood. These experiments are conducted directly in the hospital without temperature control of the photonic crystal transducer surface or the blood sample. We set the detected concentration levels into a medical frame of reference and point out possible applications.

The use of prothrombin complex concentrate in chronic liver disease: A review of the literature

Patients with chronic liver disease (CLD) and cirrhosis present a rebalanced hemostatic system in the three phases of haemostasis. This balance is however unstable and can easily tip towards bleeding or thrombosis. Management of both spontaneous bleeding and bleeding during invasive procedures remains a challenge in this patient population. Transfusion of blood products can result in circulatory overload and thereby worsen portal hypertension. As an alternative to fresh frozen plasma (FFP), prothrombin complex concentrates (PCC) may have merit in patients with liver disease because of their low volume. The impact of PCC in in-vitro spiking experiments of cirrhotic plasma is promising, but also warrants cautious use in light of thromboembolic risk. The majority of existing studies carried-out in CLD patients are retrospective or do not have an adequate control arm. A prospective study (the PROTON trial) was set up in 2013 to investigate the utility of PCC in patients undergoing liver transplantation. However, the study has never recruited the planned number of patients. Robust data on PCC safety in CLD is also required. The limited existing evidence does not seem to indicate an excessive thromboembolic risk. Currently, the utilisation of PCC in CLD cannot be routinely recommended but can provide an option for carefully selected cases in which other measures were not sufficient to control bleeding and after delicately weighing risks and benefits.

Fibrin clot properties in cardiovascular disease: from basic mechanisms to clinical practice

Fibrinogen conversion into insoluble fibrin and the formation of a stable clot is the final step of the coagulation cascade. Fibrin clot porosity and its susceptibility to plasmin-mediated lysis are the key fibrin measures, describing the properties of clots prepared ex vivo from citrated plasma. Cardiovascular disease (CVD), referring to coronary heart disease, heart failure, stroke, and hypertension, has been shown to be associated with the formation of dense fibrin networks that are relatively resistant to lysis. Denser fibrin mesh characterized acute patients at the onset of myocardial infarction or ischaemic stroke, while hypofibrinolysis has been identified as a persistent fibrin feature in patients following thrombotic events or in those with stable coronary artery disease. Traditional cardiovascular risk factors, such as smoking, diabetes mellitus, hyperlipidaemia, obesity, and hypertension, have also been linked with unfavourably altered fibrin clot properties, while some lifestyle modifications and pharmacological treatment, in particular statins and anticoagulants, may improve fibrin structure and function. Prospective studies have suggested that prothrombotic fibrin clot phenotype can predict cardiovascular events in short- and long-term follow-ups. Mutations and splice variants of the fibrinogen molecule that have been proved to be associated with thrombophilia or increased cardiovascular risk, along with fibrinogen post-translational modifications, prothrombotic state, inflammation, platelet activation, and neutrophil extracellular traps formation, contribute also to prothrombotic fibrin clot phenotype. Moreover, about 500 clot-bound proteins have been identified within plasma fibrin clots, including fibronectin, α2-antiplasmin, factor XIII, complement component C3, and histidine-rich glycoprotein. This review summarizes the current knowledge on the mechanisms underlying unfavourable fibrin clot properties and their implications in CVD and its thrombo-embolic manifestations.

Interface Engineering of "Clickable" Organic Electrochemical Transistors toward Biosensing Devices

"Clickable" organic electrochemical transistors (OECTs) allow the reliable and straightforward functionalization of electronic devices through the well-known click chemistry toolbox. In this work, we study various aspects of the click chemistry-based interface engineering of "clickable" OECTs. First, different channel architectures are investigated, showing that PEDOT-N₃ films can properly work as a channel of the transistors. Furthermore, the Cu(I)-catalyzed click reaction of ethynyl-ferrocene is studied under different reaction conditions, endowing the spatial control of the functionalization. The strain-promoted and catalyst-free cycloaddition of a dibenzocyclooctyne-derivatized poly-l-lysine (PLL-DBCO) is also performed on the OECTs and validated by a fiber optic (FO)-SPR setup. The further immobilization of an azido-modified HD22 aptamer yields OECT-based biosensors that are employed for the recognition of thrombin. Finally, their performance is evaluated against previously reported architectures, showing higher density of the immobilized HD22 aptamer, and originating similar K_D values and higher maximum signal change upon analyte recognition.

The Tissue Factor Pathway in Cancer: Overview and Role of Heparan Sulfate Proteoglycans

Historically, the only focus on tissue factor (TF) in clinical pathophysiology has been on its function as the initiation of the extrinsic coagulation cascade. This obsolete vessel-wall TF dogma is now being challenged by the findings that TF circulates throughout the body as a soluble form, a cell-associated protein, and a binding microparticle. Furthermore, it has been observed that TF is expressed by various cell types, including T-lymphocytes and platelets, and that certain pathological situations, such as chronic and acute inflammatory states, and cancer, may increase its expression and activity. Transmembrane G protein-coupled protease-activated receptors can be proteolytically cleaved by the TF:FVIIa complex that develops when TF binds to Factor VII (PARs). The TF:FVIIa complex can activate integrins, receptor tyrosine kinases (RTKs), and PARs in addition to PARs. Cancer cells use these signaling pathways to promote cell division, angiogenesis, metastasis, and the maintenance of cancer stem-like cells. Proteoglycans play a crucial role in the biochemical and mechanical properties of the cellular extracellular matrix, where they control cellular behavior via interacting with transmembrane receptors. For TFPI.fXa complexes, heparan sulfate proteoglycans (HSPGs) may serve as the primary receptor for uptake and degradation. The regulation of TF expression, TF signaling mechanisms, their pathogenic effects, and their therapeutic targeting in cancer are all covered in detail here.

Investigating thrombin-loaded fibrin in whole blood clot microfluidic assay via fluorogenic peptide

During clotting under flow, thrombin rapidly generates fibrin, whereas fibrin potently sequesters thrombin. This co-regulation was studied using microfluidic whole blood clotting on collagen/tissue factor, followed by buffer wash, and a start/stop cycling flow assay using the thrombin fluorogenic substrate, Boc-Val-Pro-Arg-AMC. After 3 min of clotting (100 s-1) and 5 min of buffer wash, non-elutable thrombin activity was easily detected during cycles of flow cessation. Non-elutable thrombin was similarly detected in plasma clots or arterial whole blood clots (1000 s-1). This thrombin activity was ablated by Phe-Pro-Arg-chloromethylketone (PPACK), apixaban, or Gly-Pro-Arg-Pro to inhibit fibrin. Reaction-diffusion simulations predicted 108 nM thrombin within the clot. Heparin addition to the start/stop assay had little effect on fibrin-bound thrombin, whereas addition of heparin-antithrombin (AT) required over 6 min to inhibit the thrombin, indicating a substantial diffusion limitation. In contrast, heparin-AT rapidly inhibited thrombin within microfluidic plasma clots, indicating marked differences in fibrin structure and functionality between plasma clots and whole blood clots. Addition of GPVI-Fab to blood before venous or arterial clotting (200 or 1000 s-1) markedly reduced fibrin-bound thrombin, whereas GPVI-Fab addition after 90 s of clotting had no effect. Perfusion of AF647-fibrinogen over washed fluorescein isothiocyanate (FITC)-fibrin clots resulted in an intense red layer around, but not within, the original FITC-fibrin. Similarly, introduction of plasma/AF647-fibrinogen generated substantial red fibrin masses that did not penetrate the original green clots, demonstrating that fibrin cannot be re-clotted with fibrinogen. Overall, thrombin within fibrin is non-elutable, easily accessed by peptides, slowly accessed by average-sized proteins (heparin/AT), and not accessible to fresh fibrinogen.

The endogenous thrombin potential in patients with left ventricular assist device or heart transplant

Background

The Heartmate 3 (HM 3) is a left ventricular assist device featuring less shear stress, milder acquired von Willebrand syndrome, and fewer bleeding incidences than its predecessor the Heartmate II (HM II). The novel surface coating of the HM 3 suggests less contact activation of plasmatic coagulation. We hypothesized that patients with HM 3 exhibit fewer aberrations in their thrombin potential than patients with HM II. We compared these results with the thrombin potential of patients with heart transplantation (HTX).

Methods

Thrombin generation in plasma samples of patients with HM II (n = 16), HM 3 (n = 20), and HTX (n = 13) was analyzed 3 days after implantation/transplantation and after long-term support (3-24 months) with HM II (n = 16) or HM 3 (n = 12) using calibrated automated thrombography. Heparin in postoperative samples was antagonized with polybrene.

Results

Three days postoperatively HM II patients exhibited a lower endogenous thrombin potential (ETP) than HM 3 and HTX patients (HM II: 947 ± 291 nM*min; HM 3: 1231 ± 176 nM*min; HTX: 1376 ± 162 nM*min, p < 0.001) and a lower velocity index of thrombin generation (HM II: 18.74 ± 10.90 nM/min; HM 3: 32.41 ± 9.51 nM/min; HTX: 37.65 ± 9.41 nM/min, p < 0.01). Subtle differences in the thrombin generation profiles remained in HM II and HM 3 patients under long-term support (Velocity Index: HM II: 38.70 ± 28.46 nM/min; HM 3: 73.32 ± 32.83 nM/min, p < 0.05). Prothrombin fragments 1 + 2 were higher in HM II than in HM 3 patients (HM II: 377.7 ± 208.4 pM; HM 3: 202.1 ± 87.7 pM, p < 0.05) and correlated inversely with the ETP (r = -0.584, p < 0.05).

Conclusion

We observed a more aberrant thrombin generation in HM II than in HM 3 despite comparable anticoagulation and routine parameters. A trend toward lower values was still observable in HM 3 compared to HTX patients. Calibrated automated thrombography may be a good tool to monitor the coagulation state of these patients and guide anticoagulation in the future.

Thrombin generation and implications for hemophilia therapies: A narrative review

Thrombin plays an essential role in achieving and maintaining effective hemostasis and stable clot formation. In people with hemophilia, deficiency of procoagulant factor (F)VIII or FIX results in insufficient thrombin generation, leading to reduced clot stability and various bleeding manifestations. A correlation has been found between the bleeding phenotype of people with hemophilia and the extent of thrombin generation, with individuals with increased thrombin generation being protected from bleeding and those with lower thrombin generation having increased bleeding tendency. The amount, location, and timing of thrombin generation have been found to affect the formation and stability of the resulting clot. The goal of all therapies for hemophilia is to enhance the generation of thrombin with the aim of restoring effective hemostasis and preventing or controlling bleeding; current treatment approaches rely on either replacing or mimicking the missing procoagulant (ie, FVIII or FIX) or rebalancing hemostasis through lowering natural anticoagulants, such as antithrombin. Global coagulation assays, such as the thrombin generation assay, may help guide the overall management of hemostasis by measuring and monitoring the hemostatic potential of patients and, thus, assessing the efficacy of treatment in people with hemophilia. Nevertheless, standardization of the thrombin generation assay is needed before it can be adopted in routine clinical practice.

The Choice between Plasma-Based Common Coagulation Tests and Cell-Based Viscoelastic Tests in Monitoring Hemostatic Competence: Not an either-or Proposition

There has been a significant interest in the last decade in the use of viscoelastic tests (VETs) to determine the hemostatic competence of bleeding patients. Previously, common coagulation tests (CCTs) such as the prothrombin time (PT) and partial thromboplastin time (PTT) were used to assist in the guidance of blood component and hemostatic adjunctive therapy for these patients. However, the experience of decades of VET use in liver failure with transplantation, cardiac surgery, and trauma has now spread to obstetrical hemorrhage and congenital and acquired coagulopathies. Since CCTs measure only 5 to 10% of the lifespan of a clot, these assays have been found to be of limited use for acute surgical and medical conditions, whereby rapid results are required. However, there are medical indications for the PT/PTT that cannot be supplanted by VETs. Therefore, the choice of whether to use a CCT or a VET to guide blood component therapy or hemostatic adjunctive therapy may often require consideration of both methodologies. In this review, we provide examples of the relative indications for CCTs and VETs in monitoring hemostatic competence of bleeding patients.

The Effect on Hemostasis of Gelatin-Graphene Oxide Aerogels Loaded with Grape Skin Proanthocyanidins: In Vitro and In Vivo Evaluation

Using in vitro and in vivo models, this study investigated the hemostatic potential to control bleeding of both unloaded gelatin-graphene oxide aerogels and the same loaded with proanthocyanidins (PAs) from Vitis vinifera grape skin extract. Our results showed that the physicochemical and mechanical properties of the aerogels were not affected by PA inclusion. In vitro studies showed that PA-loaded aerogels increased the surface charge, blood absorption capacity and cell viability compared to unloaded ones. These results are relevant for hemostasis, since a greater accumulation of blood cells on the aerogel surface favors aerogel–blood cell interactions. Although PAs alone were not able to promote hemostasis through extrinsic and intrinsic pathways, their incorporation into aerogels did not affect the in vitro hemostatic activity of these composites. In vivo studies demonstrated that both aerogels had significantly increased hemostatic performance compared to SpongostanTM and gauze sponge, and no noticeable effects of PA alone on the in vivo hemostatic performance of aerogels were observed; this may have been related to its poor diffusion from the aerogel matrix. Thus, PAs have a positive effect on hemostasis when incorporated into aerogels, although further studies should be conducted to elucidate the role of this extract in the different stages of hemostasis.

Preparation and blood compatibility of polyethersulfone dialysis membrane modified by apixaban as coagulation factor Xa inhibitor

Blood purification therapy is widely used in the treatment of critically ill patients. However, most dialysis membranes are prone to thrombosis. Activated coagulation factor X (FXa) functions at the intersection of intrinsic, extrinsic, and common coagulation pathways and plays a central role in thrombogenesis. To date, few dialysis membranes that directly inhibit FXa have been reported. We modified a polyethersulfone(PES) membrane using apixaban as an FXa inhibitor and investigated the performance of this membrane (AMPES). The contact angle of the modified membrane was reduced. PWF and retention rates of BSA were increased, demonstrating good hydrophilicity and dialysis performance. Albumin adsorption was reduced from 141.8 ± 15.5 to 114.1 ± 6.9 μg cm^-2. Reduced protein adsorption, especially targeted anti-FXa effect, inhibited the activation of intrinsic, extrinsic, and common coagulation pathways, as evidenced by significant prolongations of activated partial thromboplastin time, prothrombin time, and thrombin time by 145.04, 46.84 and 11.46 s, respectively. Furthermore, we determined the FXa concentration of each group, and found that the modified membrane had better anticoagulant performance through the inhibition of FXa. Favorable antiplatelet activity was also demonstrated. Thromboelastogram was used to comprehensively evaluate the anticoagulant and antithrombotic activities of the modified membrane. The R value was increased by 43.1 min, while the reduction in α angle was 42.5°. The coagulation comprehensive index reduction was 34.3. In addition, C3a and C5a were decreased by 15.3 % and 30.4 %, respectively. Furthermore, in vitro cytotoxicity and erythrocyte stability testing as well as in vivo murine experiments demonstrated the biosafety of the modified membrane. These results indicate that the AMPES dialysis membrane has an excellent potential for clinical applications.

Fibrin Sealants: Challenges and Solutions

Intraoperative bleeding and postoperative bleeding are major surgical complications. Tissue sealants, hemostats, and adhesives provide the armamentarium for establishing hemostatic balance, including the tissue sealant fibrin. Fibrin sealants combine advantages including instantaneous effect, biocompatibility, and biodegradability. However, several challenges remain. This review summarizes current fibrin product generations and highlights new trends and potential strategies for future improvement.

[Coagulation diagnostics in the clinical routine-Part 1 : Evaluation of the risk of bleeding before surgery, interventions and diagnostics in bleeding diathesis]

This article on coagulation diagnostics is published in two parts covering five common clinical scenarios for coagulation diagnostics. Part 1 deals with the diagnostics prior to invasive interventions and coagulation diagnostics to clarify a tendency to bleeding. The global parameters Quick and activated partial thromboplastin time are established for monitoring certain anticoagulants; however, they are not predictive with respect to the risk of bleeding prior to elective invasive interventions. In this context, disorders of primary hemostasis are frequent, which are insufficiently detected by the global parameters. Most clinical bleeding tendencies are due to acquired causes. These include anticoagulants and diseases which can be accompanied by tendency to bleeding. For coagulation tests preanalytical issues are essential in order to avoid false results. The interpretation should always be made in the context of the current physiological state.

Revised model of the tissue factor pathway of thrombin generation: Role of the feedback activation of FXI

BACKGROUND

Biochemical reaction networks are self-regulated in part due to feedback activation mechanisms. The tissue factor (TF) pathway of blood coagulation is a complex reaction network controlled by multiple feedback loops that coalesce around the serine protease thrombin.

OBJECTIVES

Our goal was to evaluate the relative contribution of the feedback activation of coagulation factor XI (FXI) in TF-mediated thrombin generation using a comprehensive systems-based analysis.

MATERIALS AND METHODS

We developed a systems biology model that improves the existing Hockin-Mann (HM) model through an integrative approach of mathematical modeling and in vitro experiments. Thrombin generation measured using in vitro assays revealed that the feedback activation of FXI contributes to the propagation of thrombin generation based on the initial concentrations of TF or activated coagulation factor X (FXa). We utilized experimental data to improve the robustness of the HM model to capture thrombin generation kinetics without a role for FXI before including the feedback activation of FXI by thrombin to construct the extended (ext.) HM model.

RESULTS AND CONCLUSIONS

Using the ext.HM model, we predicted that the contribution of positive feedback of FXI activation by thrombin can be abolished by selectively eliminating the inhibitory function of tissue factor pathway inhibitor (TFPI), a serine protease inhibitor of FXa and TF-activated factor VII (FVIIa) complex. This prediction from the ext.HM model was experimentally validated using thrombin generation assays with function blocking antibodies against TFPI and plasmas depleted of FXI. Together, our results demonstrate the applications of combining experimental and modeling techniques in predicting complex biochemical reaction systems.

Advancing in the understanding of coagulopathy during hemorrhagic shock: From the triad to the deadly pentad

The deadly triad concept represented a dogma in the definition of poor outcomes and death associated with major bleeding in trauma. This model of end-stage disease was then rapidly transferred to other major bleeding scenarios. However, and notwithstanding the fact that it represented a severe scenario, the original triad fails to establish a sequence, which would be relevant when defining the objectives during the initial treatment of severe bleeding.  It has been recently suggested that hypoxia and hyperglycemia should be included as isolated, determining factors in this model. Likewise, the model admits only one scenario where all the conditions shall co-exist, knowing that each one of them contributes with a different risk burden. Based on a structured review, we submit a pentad model that includes a natural pattern of events occurring with hypoxemia as the main trigger for the development of hypocalcemia, hyperglycemia, acidosis and hypothermia, as hallmarks of multiple system impairment. This severity model of major bleeding ends with coagulopathy as a result of the failure to resolve the rest of the previous components.