The role of thrombin in haemostasis

Alginate based hemostatic materials for bleeding management: A review

Severe bleeding has caused significant financial losses as well as a major risk to the lives and health of military and civilian populations. Under some situations, the natural coagulation mechanism of the body is unable to achieve fast hemostasis without the use of hemostatic drugs. Thus, the development of hemostatic materials and techniques is essential. Improving the quality of life and survival rate of patients and minimizing bodily damage requires fast, efficient hemostasis and prevention of bleeding. Alginate is regarded as an outstanding hemostatic polymer because of its non-immunogenicity, biodegradability, good biocompatibility, simple gelation, non-toxicity, and easy availability. This review summarizes the basics of hemostasis and emphasizes the recent developments regarding alginate-based hemostatic systems. Structural modifications and mixing with other materials have widely been used for the improvement of hemostatic characteristics of alginate and for making multifunctional medical devices that not only prevent uncontrolled bleeding but also have antibacterial characteristics, drug delivery abilities, and curing effects. This review is hoped to prepare critical insights into alginate modifications for better hemostatic properties.

Sulfated Polysaccharides with Anticoagulant Potential: A Review Focusing on Structure-Activity Relationship and Action Mechanism

Thromboembolism is the culprit of cardiovascular diseases, leading to the highest global mortality rate. Anticoagulation emerges as the primary approach for managing thrombotic conditions. Notably, sulfated polysaccharides exhibit favorable anticoagulant efficacy with reduced side effects. This review focuses on the structure-anticoagulant activity relationship of sulfated polysaccharides and the underlying action mechanisms. It is concluded that chlorosulfonicacid-pyridine method serves as the preferred technique to synthesize sulfated polysaccharides. The anticoagulant activity of sulfated polysaccharides is linked to the substitution site of sulfate groups, degree of substitution, molecular weight, main side chain structure, and glycosidic bond conformation. Moreover, sulfated polysaccharides exert anticoagulant activity via various pathways, including the inhibition of blood coagulation factors, activation of antithrombin III and heparin cofactor II, antiplatelet aggregation, and promotion of the fibrinolytic system.

Topical lyophilized thrombin application improves wound healing for posterior spinal surgery

Background

The erector spinae plane block (ESPB) was proposed as a part of the postoperative multimodal analgesic regimen to improve pain management after posterior spinal surgery. However, ESPB might cause more surgical incisional wound exudate and poor wound healing, which might be improved after topical lyophilized thrombin application.

Materials and methods

We performed a retrospective study on patients who received posterior spinal surgery between January 2018 and December 2021. These patients were assigned into three groups: group A (general anesthesia), group B (general anesthesia with ESPB), and group C (general anesthesia with ESPB and topical 1000-unit thrombin application). Postoperative outcomes, including times of dressing changes, duration of suture removal, and incisional wound healing, were compared among these groups.

Results

Our study included 89 patients, with 48, 20, and 21 patients in groups A, B, and C, respectively. Baseline demographics, height, weight, comorbidities, and operation duration were comparable among the three groups. Group B required statistically significantly more dressing changes and had a prolonged duration of suture removal than group A (9.4 ± 4.7 versus 6.5 ± 2.0 times, 16.2 ± 3.7 versus 14.2 ± 1.4 days, respectively), which could be statistically significantly improved after the thrombin application in group C. Group B also had more frequent poor wound healing (25.0 %), which could also be improved after the thrombin application (0.0 %).

Conclusions

ESPB could cause more dressing changes and poor surgical wound healing after posterior spinal surgery, which could be improved by topical lyophilized thrombin powder application.

Sono-responsive smart nanoliposomes for precise and rapid hemostasis application

Massive hemorrhage caused by injuries and surgical procedures is a major challenge in emergency medical scenarios. Conventional means of hemostasis often fail to rapidly and efficiently control bleeding, especially in inaccessible locations. Herein, a type of smart nanoliposome with ultrasonic responsiveness, loaded with thrombin (thrombin@liposome, named TNL) was developed to serve as an efficient and rapid hemostatic agent. Firstly, the hydrophilic cavities of the liposomes were loaded onto the sono-sensitive agent protoporphyrin. Secondly, a singlet oxygen-sensitive chemical bond was connected with the hydrophobic and hydrophilic ends of liposomes in a chemical bond manner. Finally, based on the host guest effect between ultrasound and the sono-sensitizer, singlet oxygen is continuously generated, which breaks the hydrophobic and hydrophilic ends of liposome fragments, causing spatial collapse of the TNL structure, swiftly releases thrombin loaded in the hydrophilic capsule cavity, thereby achieving accurate and rapid local hemostasis (resulted in a reduction of approximately 67% in bleeding in the rat hemorrhage model). More importantly, after thorough assessments of biocompatibility and biodegradability, it has been confirmed that TNL possesses excellent biosafety, providing a new avenue for efficient and precise hemostasis.

Isolation and Functional Characterization of Erythrofibrase: An Alfa-Fibrinogenase Enzyme from Trimeresurus erythrurus Venom of North-East India

Green pit viper bites induce mild toxicity with painful local swelling, blistering, cellulitis, necrosis, ecchymosis and consumptive coagulopathy. Several bite cases of green pit vipers have been reported in several south-east Asian countries including the north-eastern region of India. The present study describes isolation and characterization of a haemostatically active protein from Trimeresurus erythrurus venom responsible for coagulopathy. Using a two-step chromatographic method, a snake venom serine protease erythrofibrase was purified to homogeneity. SDS-PAGE of erythrofibrase showed a single band of ~30 kDa in both reducing and non-reducing conditions. The primary structure of erythrofibrase was determined by ESI LC-MS/MS, and the partial sequence obtained showed 77% sequence similarity with other snake venom thrombin-like enzymes (SVTLEs). The partial sequence obtained had the typical 12 conserved cysteine residues, as well as the active site residues (His57, Asp102 and Ser195). Functionally, erythrofibrase showed direct fibrinogenolytic activity by degrading the Aα chain of bovine fibrinogen at a slow rate, which might be responsible for causing hypofibrinogenemia and incoagulable blood for several days in envenomated patients. Moreover, the inability of Indian polyvalent antivenom (manufactured by Premium Serum Pvt. Ltd., Maharashtra, India) to neutralize the thrombin-like and plasmin-like activity of erythrofibrase can be correlated with the clinical inefficacy of antivenom therapy. This is the first study reporting an α-fibrinogenase enzyme erythrofibrase from T. erythrurus venom, which is crucial for the pathophysiological manifestations observed in envenomated victims.

Haemostatic gene variations in cervical cancer-associated venous thrombosis: considerations for clinical strategies

Venous thromboembolism (VTE) is a life-threatening haemostatic disease frequently diagnosed among the cancer population. The Khorana Score is currently the primal risk assessment model to stratify oncological patients according to their susceptibility to VTE, however, it displays a limited performance. Meanwhile, intensive research on VTE pathophysiology in the general population has uncovered a range of single-nucleotide polymorphisms (SNPs) associated with the condition. Nonetheless, their predictive ability concerning cancer-associated thrombosis (CAT) is controversial. Cervical cancer (CC) patients undergoing chemoradiotherapy often experience VTE, which negatively affects their survival. Thus, aiming for an improvement in thromboprophylaxis, new thrombotic biomarkers, including SNPs, are currently under investigation. In this study, the predictive capability of haemostatic gene SNPs on CC-related VTE and their prognostic value regardless of VTE were explored. Six SNPs in haemostatic genes were evaluated. A total of 401 CC patients undergoing chemoradiotherapy were enrolled in a retrospective cohort study. The implications for the time to VTE occurrence and overall survival (OS) were assessed. CAT considerably impacted the CC patients' OS (log-rank test, P < 0.001). SERPINE1 rs2070682 (T > C) showed a significant association with the risk of CC-related VTE (CC/CT vs. TT, log-rank test, P = 0.002; C allele, Cox model, hazard ratio (HR) = 6.99 and P = 0.009), while F2 rs1799963 (G > A) demonstrated an important prognostic value regardless of VTE (AA/AG vs. GG, log-rank test, P = 0.020; A allele, Cox model, HR = 2.76 and P = 0.026). For the remaining SNPs, no significant associations were detected. The polymorphisms SERPINE1 rs2070682 and F2 rs1799963 could be valuable tools in clinical decision-making, aiding in thromboprophylaxis and CC management, respectively.

Introducing urea into tirapazamine derivatives to enhance anticancer therapy

Tirapazamine (TPZ) has been approved for multiple clinical trials relying on its excellent anticancer potential. However, as a typical hypoxia-activated prodrug (HAP), TPZ did not exhibit survival advantages in Phase III clinical trials when used in combination therapy due to the insufficient hypoxia levels in patients' tumors. In this study, to improve the therapeutic effects of TPZ, we first introduced urea to synthesize a series of urea-containing derivatives of TPZ. All urea-containing TPZ derivatives showed increased hypoxic cytotoxicity (9.51-30.85-fold) compared with TPZ, while maintaining hypoxic selectivity. TPZP, one of these derivatives, showed 20-fold higher cytotoxicity than TPZ while maintaining a similar hypoxic cytotoxicity ratio. To highly efficiently deliver TPZP to the tumors and reduce its side effects on healthy tissues, we further prepared TPZP into a nanodrug with fibrin-targeting ability: FT11-TPZP-NPs. CA4-NPs, a vascular disrupting agent, was used to increase the fibrin level within tumors and exacerbate tumor hypoxia. By being combined with CA4-NPs, FT11-TPZP-NPs can accumulate in the hypoxia-aggravated tumors and activate sufficiently to kill tumor cells. After a single-dose treatment, FT11-TPZP-NPs + CA4-NPs showed a high inhibition rate of 98.1% against CT26 tumor models with an initial volume of ∼480 mm3 and four out of six tumors were completely eliminated; it thereby exerted a significant antitumor effect. This study provides a new strategy for improving the therapeutic effect of TPZ and other HAPs in anticancer therapy.

Bioinspired Supramolecular Hydrogel from Design to Applications

Nature offers a wealth of opportunities to solve scientific and technological issues based on its unique structures and function. The dynamic non-covalent interaction is considered to be the main base of living functions of creatures including humans, animals, and plants. Supramolecular hydrogels formed by non-covalent bonding interactions has become a unique platform for constructing promising materials for medicine, energy, electronic, and biological substitute. In this review, the self-assemble principle of supramolecular hydrogels is summarized. Next, the stimulation of external environment that triggers the assembly or disassembly of supramolecular hydrogels are recapitulated, including temperature, mechanics, light, pH, ions, etc. The main applications of bioinspired supramolecular hydrogels in terms of bionic objects including humans, animals, and plants are also described. Although so many efforts are done for revealing the synergized mechanism of the function and non-covalent interactions on the supramolecular hydrogel, the complexity and variability between stimulus and non-covalent bonding in the supramolecular system still require impeccable theories. As an outlook, the bioinspired supramolecular hydrogel is just beginning to exhibit its great potential in human life, offering significant opportunities in drug delivery and screening, implantable devices and substitutions, tissue engineering, micro-fluidic devices, and biosensors.

Recent research advances on polysaccharide-, peptide-, and protein-based hemostatic materials: A review

Hemorrhage is a potentially life-threatening emergency that can occur at any time or place. Whether traumatic, congenital, surgical, disease-related, or drug-induced, bleeding can lead to severe complications or death. Therefore, the development of efficient hemostatic materials is critical. However, the results and prognosis demonstrated by clinical means of hemostasis do not reach expectations. With the development of technology, novel hemostatic materials have been developed from polysaccharides (chitosan, hyaluronic acid, alginate, cellulose, cyclodextrins, starch, dextran, and carrageenan), peptides (self-assembling peptides), and proteins (silk fibroin, collagen, gelatin, keratin, and thrombin). These new materials exhibit high hemostatic efficacy due to the enhancement or interaction of various hemostatic mechanisms. The main forms include adhesives, sealants, bandages, hemostatic powders, and hemostatic sponges. This article introduces the clotting process and principles of hemostatic methods and reviews the research on polysaccharide-, peptide-, and protein-based hemostatic materials in the last five years. The design ideas and hemostatic principles of polysaccharide-, peptide-, and protein-based hemostatic materials are mainly introduced. Finally, we summarize material designs, advantages, disadvantages, and challenges regarding hemostatic materials.

Comprehensive Analysis of the Role of Fibrinogen and Thrombin in Clot Formation and Structure for Plasma and Purified Fibrinogen

Altered properties of fibrin clots have been associated with bleeding and thrombotic disorders, including hemophilia or trauma and heart attack or stroke. Clotting factors, such as thrombin and tissue factor, or blood plasma proteins, such as fibrinogen, play critical roles in fibrin network polymerization. The concentrations and combinations of these proteins affect the structure and stability of clots, which can lead to downstream complications. The present work includes clots made from plasma and purified fibrinogen and shows how varying fibrinogen and activation factor concentrations affect the fibrin properties under both conditions. We used a combination of scanning electron microscopy, confocal microscopy, and turbidimetry to analyze clot/fiber structure and polymerization. We quantified the structural and polymerization features and found similar trends with increasing/decreasing fibrinogen and thrombin concentrations for both purified fibrinogen and plasma clots. Using our compiled results, we were able to generate multiple linear regressions that predict structural and polymerization features using various fibrinogen and clotting agent concentrations. This study provides an analysis of structural and polymerization features of clots made with purified fibrinogen or plasma at various fibrinogen and clotting agent concentrations. Our results could be utilized to aid in interpreting results, designing future experiments, or developing relevant mathematical models.

Optimization of Ketobenzothiazole-Based Type II Transmembrane Serine Protease Inhibitors to Block H1N1 Influenza Virus Replication

Human influenza viruses cause acute respiratory symptoms that can lead to death. Due to the emergence of antiviral drug-resistant strains, there is an urgent requirement for novel antiviral agents and innovative therapeutic strategies. Using the peptidomimetic ketobenzothiazole protease inhibitor RQAR-Kbt (IN-1, aka N-0100) as a starting point, we report how substituting P2 and P4 positions with natural and unnatural amino acids can modulate the inhibition potency toward matriptase, a prototypical type II transmembrane serine protease (TTSP) that acts as a priming protease for influenza viruses. We also introduced modifications of the peptidomimetics N-terminal groups, leading to significant improvements (from μM to nM, 60 times more potent than IN-1) in their ability to inhibit the replication of influenza H1N1 virus in the Calu-3 cell line derived from human lungs. The selectivity towards other proteases has been evaluated and explained using molecular modeling with a crystal structure recently obtained by our group. By targeting host cell TTSPs as a therapeutic approach, it may be possible to overcome the high mutational rate of influenza viruses and consequently prevent potential drug resistance.

Factor XI as a therapeutic target in neuroinflammatory disease

PURPOSE OF REVIEW

This review summarizes the pathophysiology and potential therapeutic options for treatment of multiple sclerosis, a common neuronal demyelinating disorder affecting 2.2 million people worldwide. As an autoimmune disorder, multiple sclerosis is associated with neuroinflammation and increased permeability of the blood-brain barrier (BBB), although the cause linking multiple sclerosis with compromised barrier function remains ill-defined. It has been previously shown that coagulation factors, including thrombin and fibrin, exacerbate the inflammatory processes and permeability of the BBB.

RECENT FINDINGS

Increased levels of the coagulation factor (F) XII have been found in patients presenting with relapsing-remitting multiple sclerosis, with a deleterious role for FXII being validated in murine model of multiple sclerosis, experimental autoimmune encephalitis (EAE). Recent work has uncovered a role for the major substrate activated by FXII and thrombin, FXI, in the disorder of EAE. The study found that pharmacological targeting of FXI decreased clinical symptoms, lymphocyte invasion, and white matter destruction in a multiple sclerosis model.

SUMMARY

This review emphasizes the role of FXII and FXI in regulating barrier function and the immune response in neuroinflammation. These new findings broaden the potential for therapeutic utility of FXI inhibitors beyond thrombosis to include neuroinflammatory diseases associated with compromised BBB function, including multiple sclerosis.

[The multidirectional effects of thrombin and the possibility of their control in neurology]

The review presents the main physiological functions of thrombin. The procoagulant and anticoagulant activities of the key serine protease are discussed in both physiological and pathological conditions of hemostasis. The involvement of thrombin in atherogenesis, as well as its role as a mediator of vascular dysfunction and inflammation in both the peripheral and central nervous system, is highlighted. A pronounced imbalance between the pro- and anticoagulant systems leads to an increase in thrombin formation and creates conditions for the development of thrombosis. Tests that allow direct or indirect assessment of thrombin's functional activity are presented. The potential applications of direct thrombin inhibitors and direct blockers of thrombin PAR receptors in vascular neurology are also considered.

Identification of thrombin inhibiting antithrombin-III like protein from Punica granatum using in silico approach and in vitro validation of thrombin inhibition activity in crude protein

Thrombosis is characterized by the formation of clots in the blood vessels. Antithrombin-III deficiency in the blood causes thrombus formation. Supplementing antithrombin-III may serve as anticoagulant therapy. In the present studies, an antithrombin like Protein from Punica granatum has been identified and characterized using in silico approach. Based on sequence homology, an ALPP was selected depending upon its highest binding affinity of -41.28 kcal/mol with thrombin. Thrombin structure complexed with ALPP was docked with TAME using AutoDock Vina. No binding was observed for TAME at Ser195 of thrombin. MD simulation (50 ns) was performed to evaluate the flexibility and stability of docked complexes. In vitro assays with crude protein showed 78% thrombin inhibition at 5 µg and calculated IC50 value was 0.188 µg. The presence of thrombin inhibitors in crude protein was also confirmed by reverse zymography. Thus, it is very likely that the protein identified from P. granatum may act as thrombin inhibitor.

Awareness of individual goals, preferences, and priorities of persons with severe congenital haemophilia A for a tailored shared decision-making approach to liver-directed gene therapy. A practical guideline

In clinical medicine, shared decision making (SDM) is a well-recognized strategy to enhance engagement of both patients and clinicians in medical decisions. The success of liver-directed gene therapy (GT) to transform severe congenital haemophilia A (HA) from an incurable to a curable disease has launched a shift beyond current standards of treatment. However, GT acceptance remains low in the community of HA persons. We argue for both persons with haemophilia (PWH) and specialists in HA care including clinicians, as needing SDM-oriented educational programs devoted to GT. Here, we provide an ad hoc outline to implement education to SDM and tailor clinician information on GT to individual PWHs. Based on routine key components of SDM: patient priorities; recommendations based on individual risk reduction; adverse effects; drug-drug interactions; alternatives to GT; and ongoing re-assessment of the objectives as risk factors (and individual priorities) change, this approach is finalized to exploit efficacious communication.

Discovery, Function, and Engineering of Graspetides

Graspetides are a class of RiPPs (ribosomally synthesized and post-translationally modified peptides) defined by the presence of ester or amide side chain-side chain linkages resulting in peptide macrocycles. The graspetide name comes from the ATP-grasp enzymes that install the side chain-side chain linkages. This review covers the early, activity-based isolation of the first graspetides, marinostatins and microviridins, as well as the key genomics-driven experiments that established graspetide as RiPPs. The mechanism and structure of graspetide-associated ATP-grasp enzymes is discussed. Genome mining methods to discover new graspetides as well as the analytical techniques used to determine the linkages in graspetides are described. Extant knowledge on the bioactivity of graspetides as protease inhibitors is reviewed. Further chemical modifications to graspetides as well graspetide engineering studies are also described. We conclude with several suggestions about future directions of graspetide research.

A Multichannel Portable Platform With Embedded Thermal Management for Miniaturized Dielectric Blood Coagulometry

This article presents a standalone, multichannel, miniaturized impedance analyzer (MIA) system for dielectric blood coagulometry measurements with a microfluidic sensor termed ClotChip. The system incorporates a front-end interface board for 4-channel impedance measurements at an excitation frequency of 1 MHz, an integrated resistive heater formed by a pair of printed-circuit board (PCB) traces to keep the blood sample near a physiologic temperature of 37 °C, a software-defined instrument module for signal generation and data acquisition, and a Raspberry Pi-based embedded computer with 7-inch touchscreen display for signal processing and user interface. When measuring fixed test impedances across all four channels, the MIA system exhibits an excellent agreement with a benchtop impedance analyzer, with rms errors of ≤0.30% over a capacitance range of 47-330 pF and ≤0.35% over a conductance range of 2.13-10 mS. Using in vitro-modified human whole blood samples, the two ClotChip output parameters, namely, the time to reach a permittivity peak (Tpeak) and maximum change in permittivity after the peak (Δϵr,max) are assessed by the MIA system and benchmarked against the corresponding parameters of a rotational thromboelastometry (ROTEM) assay. Tpeak exhibits a very strong positive correlation (r = 0.98, p < 10-6, n = 20) with the ROTEM clotting time (CT) parameter, while Δϵr,max exhibits a very strong positive correlation (r = 0.92, p < 10-6, n = 20) with the ROTEM maximum clot firmness (MCF) parameter. This work shows the potential of the MIA system as a standalone, multichannel, portable platform for comprehensive assessment of hemostasis at the point-of-care/point-of-injury (POC/POI).

Long Non-Coding RNAs in Venous Thromboembolism: Where Do We Stand?

Venous thromboembolism (VTE), a common condition in Western countries, is a cardiovascular disorder that arises due to haemostatic irregularities, which lead to thrombus generation inside veins. Even with successful treatment, the resulting disease spectrum of complications considerably affects the patient's quality of life, potentially leading to death. Cumulative data indicate that long non-coding RNAs (lncRNAs) may have a role in VTE pathogenesis. However, the clinical usefulness of these RNAs as biomarkers and potential therapeutic targets for VTE management is yet unclear. Thus, this article reviewed the emerging evidence on lncRNAs associated with VTE and with the activity of the coagulation system, which has a central role in disease pathogenesis. Until now, ten lncRNAs have been implicated in VTE pathogenesis, among which MALAT1 is the one with more evidence. Meanwhile, five lncRNAs have been reported to affect the expression of TFPI2, an important anticoagulant protein, but none with a described role in VTE development. More investigation in this field is needed as lncRNAs may help dissect VTE pathways, aiding in disease prediction, prevention and treatment.

Polydopamine-Coated Polycaprolactone Electrospun Nanofiber Membrane Loaded with Thrombin for Wound Hemostasis

Hemorrhagic shock is the primary cause of death in patients with severe trauma, and the development of rapid and efficient hemostatic methods is of great significance in saving the lives of trauma patients. In this study, a polycaprolactone (PCL) nanofiber membrane was prepared by electrospinning. A PCL-PDA loading system was developed by modifying the surface of polydopamine (PDA), using inspiration from mussel adhesion protein, and the efficient and stable loading of thrombin (TB) was realized to ensure the bioactivity of TB. The new thrombin loading system overcomes the disadvantages of harsh storage conditions, poor strength, and ease of falling off, and it can use thrombin to start a rapid coagulation cascade reaction, which has the characteristics of fast hemostasis, good biocompatibility, high safety, and a wide range of hemostasis. The physicochemical properties and biocompatibility of the PCL-PDA-TB membrane were verified by scanning electron microscopy, the cell proliferation test, the cell adhesion test, and the extract cytotoxicity test. Red blood cell adhesion, platelet adhesion, dynamic coagulation time, and animal models all verified the coagulation effect of the PCL-PDA-TB membrane. Therefore, the PCL-PDA-TB membrane has great potential in wound hemostasis applications, and should be widely used in various traumatic hemostatic scenarios.

Nucleic acid aptamer-based biosensors and their application in thrombin analysis

Thrombin is a multifunctional serine protease that plays an important role in coagulation and anticoagulation processes. Aptamers have been widely applied in biosensors due to their high specificity, low cost and good biocompatibility. This review summarizes recent advances in thrombin quantification using aptamer-based biosensors. The primary focus is optical sensors and electrochemical sensors, along with their applications in thrombin analysis and disease diagnosis.

Acute Myocardial Infarction in Patients with Hereditary Thrombophilia-A Focus on Factor V Leiden and Prothrombin G20210A

Factor V (FV) Leiden and prothrombin G20210A are the most common hereditary thrombophilias. While their role in venous thromboembolism is well known, there are still uncertainties regarding their relationship with arterial thrombotic events, especially coronary ones. Our research, based on an in-depth analysis of the available literature, provides up-to-date information on the relationship between FV Leiden and prothrombin G20210A and acute myocardial infarction. FV Leiden and prothrombin G20210A screening should be implemented only in select cases, such as acute coronary syndrome in young individuals and/or in the absence of traditional cardiovascular risk factors and/or in the absence of significant coronary artery stenosis at angiography. Their identification should be followed by the implementation of optimal control of modifiable traditional cardiovascular risk factors to reduce the risk of recurrent events and genotyping and genetic counseling of all family members of affected cases for proper prophylaxis. An extended dual antiplatelet therapy (DAPT) may be considered, given the lower risk of bleeding under DAPT conferred by FV Leiden.

Effects of Rheum rhaponticum and Rheum rhabarbarum extracts on haemostatic activity of blood plasma components and endothelial cells in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional medicine recommends the use of Rheum rhaponticum L. and R. rhabarbarum L. to treat over thirty complaints, including disorders related to the cardiovascular system such as heartache, pains in the pericardium, epistaxis and other types of haemorrhage, blood purification as well as disorders of venous circulation.

AIM OF THE STUDY

This work was dedicated to examining for the first time the effects of extracts from petioles and roots of R. rhaponticum and R. rhabarbarum, as well as two stilbene compounds (rhapontigenin and rhaponticin) on the haemostatic activity of endothelial cells and functionality of blood plasma components of the haemostatic system.

MATERIALS AND METHODS

The study was based on three main experimental modules, including the activity of proteins of the human blood plasma coagulation cascade and the fibrinolytic system as well as analyses of the haemostatic activity of human vascular endothelial cells. Additionally, interactions of the main components of the rhubarb extracts with crucial serine proteases of the coagulation cascade and fibrinolysis (i.e. thrombin, the coagulation factor Xa and plasmin) were analyzed in silico.

RESULTS

The examined extracts displayed anticoagulant properties and significantly reduced the tissue factor-induced clotting of human blood plasma (by about 40%). Inhibitory effects of the tested extracts on thrombin and the coagulation factor Xa (FXa) were found as well. For the extracts, the IC₅₀ was ranging from 20.26 to 48.11 μg/ml. Modulatory effects on the haemostatic response of endothelial cells, including the release of von Willebrand factor, tissue-type plasminogen activator and the plasminogen activator inhibitor-1, have been also found.

CONCLUSIONS

Our results indicated for the first time that the examined Rheum extracts influenced the haemostatic properties of blood plasma proteins and endothelial cells, with the prevalence of the anticoagulant action. The anticoagulant effect of the investigated extracts may be partly attributed to the inhibition of the FXa and thrombin activities, the key serine proteases of the blood coagulation cascade.

Pathophysiological Role of Microglial Activation Induced by Blood-Borne Proteins in Alzheimer's Disease

The blood-brain barrier (BBB) restricts entry of neurotoxic plasma components, blood cells, and pathogens into the brain, leading to proper neuronal functioning. BBB impairment leads to blood-borne protein infiltration such as prothrombin, thrombin, prothrombin kringle-2, fibrinogen, fibrin, and other harmful substances. Thus, microglial activation and release of pro-inflammatory mediators commence, resulting in neuronal damage and leading to impaired cognition via neuroinflammatory responses, which are important features observed in the brain of Alzheimer's disease (AD) patients. Moreover, these blood-borne proteins cluster with the amyloid beta plaque in the brain, exacerbating microglial activation, neuroinflammation, tau phosphorylation, and oxidative stress. These mechanisms work in concert and reinforce each other, contributing to the typical pathological changes in AD in the brain. Therefore, the identification of blood-borne proteins and the mechanisms involved in microglial activation and neuroinflammatory damage can be a promising therapeutic strategy for AD prevention. In this article, we review the current knowledge regarding the mechanisms of microglial activation-mediated neuroinflammation caused by the influx of blood-borne proteins into the brain via BBB disruption. Subsequently, the mechanisms of drugs that inhibit blood-borne proteins, as a potential therapeutic approach for AD, along with the limitations and potential challenges of these approaches, are also summarized.

A Non-competitive Serpin-Like Thrombin Inhibitor Isolated from Moringa oleifera Exhibit a High Affinity for Thrombin

The majority of the clotting factors involved in blood coagulation pathways are serine proteases and thrombin is one of the key serine proteases involved in blood clotting. Many synthetic and chemical drugs targeting these proteases as therapeutics are known. However, they are associated with serious side effects such as bleeding, haemorrhage, edema etc. Serine protease inhibitors from plants have been suggested as one of the potential anticoagulant molecules against thrombosis. In the present work, a direct thrombin inhibitor from Moringa oleifera was isolated, purified and characterized. The homogeneity of the inhibitor is confirmed on native- PAGE. The purified inhibitor (5 µg) showed 63% thrombin inhibition at pH 7.2 at 37 °C. The IC₅₀ value of the isolated inhibitor was determined as 4.23 µg. The inhibitor on SDS-PAGE appeared as a single protein-stained band corresponding to 50 kDa thereby indicating its molecular weight as 50 kDa. Purified thrombin inhibitor (5 µg) showed 12% inhibition of trypsin, and 17% inhibition of chymotrypsin. This suggests more specificity of purified inhibitor towards thrombin. The isolated inhibitor showed a non-competitive mode of inhibition against thrombin as determined by the Dixon plot. The inhibition constant (Ki) was calculated as 4.35 × 10^-7 M. The present work reports for the first time a direct thrombin inhibitor from M. oleifera which may be further explored as an antithrombotic drug.

The Novel Role of Noncoding RNAs in Modulating Platelet Function: Implications in Activation and Aggregation

It is currently believed that plaque complication, with the consequent superimposed thrombosis, is a key factor in the clinical occurrence of acute coronary syndromes (ACSs). Platelets are major players in this process. Despite the considerable progress made by the new antithrombotic strategies (P2Y12 receptor inhibitors, new oral anticoagulants, thrombin direct inhibitors, etc.) in terms of a reduction in major cardiovascular events, a significant number of patients with previous ACSs treated with these drugs continue to experience events, indicating that the mechanisms of platelet remain largely unknown. In the last decade, our knowledge of platelet pathophysiology has improved. It has been reported that, in response to physiological and pathological stimuli, platelet activation is accompanied by de novo protein synthesis, through a rapid and particularly well-regulated translation of resident mRNAs of megakaryocytic derivation. Although the platelets are anucleate, they indeed contain an important fraction of mRNAs that can be quickly used for protein synthesis following their activation. A better understanding of the pathophysiology of platelet activation and the interaction with the main cellular components of the vascular wall will open up new perspectives in the treatment of the majority of thrombotic disorders, such as ACSs, stroke, and peripheral artery diseases before and after the acute event. In the present review, we will discuss the novel role of noncoding RNAs in modulating platelet function, highlighting the possible implications in activation and aggregation.

Designing Smaller, Synthetic, Functional Mimetics of Sulfated Glycosaminoglycans as Allosteric Modulators of Coagulation Factors

Natural glycosaminoglycans (GAGs) are arguably the most diverse collection of natural products. Unfortunately, this bounty of structures remains untapped. Decades of research has realized only one GAG-like synthetic, small-molecule drug, fondaparinux. This represents an abysmal output because GAGs present a frontier that few medicinal chemists, and even fewer pharmaceutical companies, dare to undertake. GAGs are heterogeneous, polymeric, polydisperse, highly water soluble, synthetically challenging, too rapidly cleared, and difficult to analyze. Additionally, GAG binding to proteins is not very selective and GAG-binding sites are shallow. This Perspective attempts to transform this negative view into a much more promising one by highlighting recent advances in GAG mimetics. The Perspective focuses on the principles used in the design/discovery of drug-like, synthetic, sulfated small molecules as allosteric modulators of coagulation factors, such as antithrombin, thrombin, and factor XIa. These principles will also aid the design/discovery of sulfated agents against cancer, inflammation, and microbial infection.

Chitosan-based hemostatic sponges as new generation hemostatic materials for uncontrolled bleeding emergency: Modification, composition, and applications

The choice of hemostatic technique is a curial concern for surgery and as first-aid treatment in combat. To treat uncontrolled bleeding in complex wound environments, chitosan-based hemostatic sponges have attracted significant attention in recent years because of the excellent biocompatibility, degradability, hemostasis and antibacterial properties of chitosan and their unique sponge-like morphology for high fluid absorption rate and priority aggregation of blood cells/platelets to achieve rapid hemostasis. In this review, we provide a historical perspective on the use of chitosan hemostatic sponges as the new generation of hemostatic materials for uncontrolled bleeding emergencies in complex wounds. We summarize the modification of chitosan, review the current status of preparation protocols of chitosan sponges based on various composite systems, and highlight the recent achievements on the detailed breakdown of the existing chitosan sponges to present the relationship between their composition, physical properties, and hemostatic capacity. Finally, the future opportunities and challenges of chitosan hemostatic sponges are also proposed.

Thrombosis Models: An Overview of Common In Vivo and In Vitro Models of Thrombosis

Occlusions in the blood vessels caused by blood clots, referred to as thrombosis, and the subsequent outcomes are leading causes of morbidity and mortality worldwide. In vitro and in vivo models of thrombosis have advanced our understanding of the complex pathways involved in its development and allowed the evaluation of different therapeutic approaches for its management. This review summarizes different commonly used approaches to induce thrombosis in vivo and in vitro, without detailing the protocols for each technique or the mechanism of thrombus development. For ease of flow, a schematic illustration of the models mentioned in the review is shown below. Considering the number of available approaches, we emphasize the importance of standardizing thrombosis models in research per study aim and application, as different pathophysiological mechanisms are involved in each model, and they exert varying responses to the same carried tests. For the time being, the selection of the appropriate model depends on several factors, including the available settings and research facilities, the aim of the research and its application, and the researchers' experience and ability to perform surgical interventions if needed.

Dual signal amplification coupling with DNA-templated silver nanoclusters for sensitive and label-free detection of thrombin

Sensitive and reliable determination of thrombin is relevant in the realms of medical and biological research as it serves as an essential biomarker of a number of blood-related illnesses. Herein, we integrate allosteric probe-based specific identification of thrombin and dual signal amplification to present an unique fluorescent technique for label-free and sensitive thrombin detection. Based on DNA polymerase and endonuclease-assisted signal amplification, the method exhibits a high sensitivity with a low limit of detection of 2.3 pM, while maintaining an excellent selectivity and stability. More importantly, the approach is successfully applied in analyzing the effect of nalbuphine on coagulation function of mice. Overall, this approach possesses the advantages of high specificity and sensitivity in label-free detection of thrombin, which is promising in the diagnosis of blood-related diseases.

Ultrasensitive thrombin sensing platform based on three-way junction initiated dual signal amplification

The sensitive and precise quantitative determination of thrombin is important for both fundamental research and clinical diagnostics of hypoxic ischemic encephalopathy because it is a key biological molecule in hemostasis and hemolysis. Herein, we depict a sensitive and label-free thrombin detection approach by taking the advantages of aptamer’s superior capability to bind with thrombin and the high efficiency of three-way junction initiated dual signal recycle. In this method, a capture probe which is inserted with an aptamer sequence is designed to specifically identify thrombin molecule and facilitate the signal amplification. Based on the DNA polymerase and endonuclease Nb.BbvCI-assisted chain extension, a large amount of single-strand DNA sequences that can fold into G-quadruplex are produced to specifically recognize commercial fluorescent dye thioflavin T for signal generation. Consequently, the approach exhibits a high detection sensitivity with the limit of detection as low as 768 fM, holding a great promise for detection of thrombin and disease diagnosis in the clinic.

Coagulation and complement: Key innate defense participants in a seamless web

In 1969, Dr. Oscar Ratnoff, a pioneer in delineating the mechanisms by which coagulation is activated and complement is regulated, wrote, “In the study of biological processes, the accumulation of information is often accelerated by a narrow point of view. The fastest way to investigate the body’s defenses against injury is to look individually at such isolated questions as how the blood clots or how complement works. We must constantly remind ourselves that such distinctions are man-made. In life, as in the legal cliché, the devices through which the body protects itself form a seamless web, unwrinkled by our artificialities.” Our aim in this review, is to highlight the critical molecular and cellular interactions between coagulation and complement, and how these two major component proteolytic pathways contribute to the seamless web of innate mechanisms that the body uses to protect itself from injury, invading pathogens and foreign surfaces.

The Vascular Endothelium and Coagulation: Homeostasis, Disease, and Treatment, with a Focus on the Von Willebrand Factor and Factors VIII and V

The vascular endothelium has several important functions, including hemostasis. The homeostasis of hemostasis is based on a fine balance between procoagulant and anticoagulant proteins and between fibrinolytic and antifibrinolytic ones. Coagulopathies are characterized by a mutation-induced alteration of the function of certain coagulation factors or by a disturbed balance between the mechanisms responsible for regulating coagulation. Homeostatic therapies consist in replacement and nonreplacement treatments or in the administration of antifibrinolytic agents. Rebalancing products reestablish hemostasis by inhibiting natural anticoagulant pathways. These agents include monoclonal antibodies, such as concizumab and marstacimab, which target the tissue factor pathway inhibitor; interfering RNA therapies, such as fitusiran, which targets antithrombin III; and protease inhibitors, such as serpinPC, which targets active protein C. In cases of thrombophilia (deficiency of protein C, protein S, or factor V Leiden), treatment may consist in direct oral anticoagulants, replacement therapy (plasma or recombinant ADAMTS13) in cases of a congenital deficiency of ADAMTS13, or immunomodulators (prednisone) if the thrombophilia is autoimmune. Monoclonal-antibody-based anti-vWF immunotherapy (caplacizumab) is used in the context of severe thrombophilia, regardless of the cause of the disorder. In cases of disseminated intravascular coagulation, the treatment of choice consists in administration of antifibrinolytics, all-trans-retinoic acid, and recombinant soluble human thrombomodulin.