Mouse models of hemostasis

Assessment of anticoagulant safety and coagulation analysis in mice using the VETSCAN® VSpro analyzer

Animal models of thrombosis play a critical role in research, helping us understand the mechanisms of hemostasis and thrombus formation, as well as in the screening of anti-thrombotic drugs. This study aimed to evaluate the safety profile of two anticoagulants in murine research and to assess coagulation parameters, including prothrombin time (PT) and activated partial thromboplastin time (aPTT), using the VETSCAN® VSpro coagulation analyzer in wild-type (C57BL/6) mice following administration of anticoagulants. Two experiments were conducted involving a total of sixty wild-type mice that received two common anticoagulants. Warfarin was administered in the drinking water at varying dosages, while dabigatran was incorporated into a custom-chow diet at two dosages (10 mg/g and 15 mg/g chow). The VSpro was used to establish a reference range for PT and aPTT values in untreated wild-type mice and to monitor coagulation changes in mice undergoing anticoagulant therapy. Dabigatran was well tolerated at both concentrations (10 mg/g and 15 mg/g chow), while warfarin was safe at a concentration of 2.5 mg/L, resulting in a doubling of PT and aPTT compared to baseline levels. Although the VSpro effectively detected coagulation abnormalities in murine models, certain limitations were observed, including out-of-range measurements in cases of coagulopathy. This study provides insights into safe anticoagulant dosages for murine models, supporting the use of dabigatran at 10 mg/g and 15 mg/g chow and warfarin at 2.5 mg/L. The VSpro analyzer was able to monitor coagulation parameters under these conditions, making it a feasible tool for murine research.

"Liver Clots" in Periodontology: A 10-Year Clinical Experience

OBJECTIVES

"Liver clots" are an uncommon complication following periodontal surgery, characterized by their distinctive gelatinous consistency and color resembling 'liver' tissue. Despite anecdotal reports, there is a lack of comprehensive evidence in the literature regarding its incidence, etiopathogenesis and optimal management strategies. This study aimed to address this knowledge gap by retrospectively analyzing cases to provide insights into this unusual post-operative complication.

MATERIALS AND METHODS

In this retrospective descriptive study, data spanning a decade (June 2013-June 2024) were collected from various dental centres. The data included patient demographics, medical history, surgical procedures performed, occurrence of "liver clot" formation, management measures and treatment outcomes.

RESULTS

The 10-year retrospective data revealed a 2.03% incidence of "liver clots" among various periodontal procedures. The highest occurrence was observed following dental extractions, followed by periodontal surgical procedures. The observations also indicated a higher frequency in systemically healthy individuals.

CONCLUSION

"Liver clot" formation is a rare, but specific complication after periodontal surgery. Minimally invasive management approaches are effective, highlighting the importance of vigilance and prompt intervention for optimal patient outcomes. Further research is warranted to elucidate the exact etiopathogenesis and to establish evidence-based management protocols for this unusual complication.

Amitriptyline Decreases Mouse Lung Endothelial Cell Inflammatory Responses to Packed Red Blood Cell Microparticles

INTRODUCTION

Large-volume packed red blood cell (pRBC) transfusion is associated with lung injury and worsened outcomes. Amitriptyline reduces lung injury and inflammation in a murine sepsis model. We hypothesized that red cell microparticles (MP) activate endothelial cells, leading to lung injury and that treatment with amitriptyline would blunt the inflammatory response MPs through inhibition of acid sphingomyelinase (ASM).

METHODS

Murine pRBCs were obtained from C57Bl/6 mice and stored in AS3 for 14 d. The MPs were isolated from pRBCs by serial centrifugation. Mouse lung endothelial cells (MLECs) were pretreated with amitriptyline (0, 2.5, 25, 27 μM, n = 5) for 30 min prior to MP treatment. Chemokine secretion and adhesion molecule shedding was assessed. ASM activity was measured from cell lysates.

RESULTS

MPs increased the secretion of chemokines and shedding of adhesion molecules in MLECs at both four and 24 h. Amitriptyline treatment of MLECs decreased ASM activity in the setting of MPs. Amitriptyline pretreatment decreased the secretion of chemokines and shedding of adhesion molecules in response to MPs at 4 h but did not decrease adhesion molecule shedding at 24 h CONCLUSIONS: Endothelial cell treatment with MPs induces secretion of chemokines responsible for chemotaxis (keratinocyte chemoattractant, regulated upon activation normal T cell expressed and presumably secreted, and G-granulocyte colony-stimulating factor) as well as many downstream proinflammatory effects (interleukin-6). Additionally, MPs induce adhesion molecule shedding (vascular cell adhesion molecule-1, intracellular adhesion molecule-1, P-selectin, and E-selectin), which has been shown to be associated with endothelial cell activation. Amitriptyline pretreatment decreases MLEC inflammatory response and ASM activity is decreased. These data suggest that ASM inhibition in MLECs is a potential strategy to blunt the inflammatory response to the red blood cell storage lesion.

Plant-Based Shape Memory Cryogel for Hemorrhage Control

The escalating global demand for sustainable manufacturing, motivated by concerns over energy conservation and carbon footprints, encounters challenges due to insufficient renewable materials and arduous fabrication procedures to fulfill specific requirements in medical and healthcare systems. Here, biosafe pollen cryogel is engineered as effective hemostats without additional harmful crosslinkers to treat deep noncompressible wounds. A straightforward and low-energy approach is involved in forming stable macroporous cryogel, benefiting from the unique micro-hierarchical structures and chemical components of non-allergenic plant pollen. It is demonstrated that the pollen cryogel exhibits rapid water/blood-triggered shape-memory properties within 2 s. Owing to their inherent nano/micro hierarchical structure and abundant chemical functional groups on the pollen surface, the pollen cryogel shows effective hemostatic performance in a mouse liver penetration model, which is easily removed after usage. Overall, the self-crosslinking pollen cryogel in this work pioneers a framework of potential clinical applications for the first-hand treatment on deep noncompressible wounds.

Whole blood storage duration alters fibrinogen levels and thrombin formation

INTRODUCTION

Whole blood resuscitation for hemorrhagic shock in trauma represents an opportunity to correct coagulopathy in trauma while also supplying red blood cells. The production of microvesicles in stored whole blood and their effect on its hemostatic parameters have not been described in previous literature. We hypothesized that microvesicles in aged stored whole blood are procoagulant and increase thrombin production via phosphatidylserine.

METHODS

Whole blood was obtained from male C57BL/6 male mice and stored in anticoagulant solution for up to 10 days. At intervals, stored whole blood underwent examination with rotational thromboelastography, and platelet-poor plasma was prepared for analysis of thrombin generation. Microvesicles were prepared from 10-day-old whole blood aliquots and added to fresh whole blood or platelet-poor plasma to assess changes in coagulation and thrombin generation. Microvesicles were treated with recombinant mouse lactadherin prior to addition to plasma to inhibit phosphatidylserine's role in thrombin generation.

RESULTS

Aged murine whole blood had decreased fibrin clot formation compared with fresh samples with decreased plasma fibrinogen levels. Thrombin generation in plasma from aged blood increased over time of storage. The addition of microvesicles to fresh plasma resulted in increased thrombin generation compared with controls. When phosphatidylserine on microvesicles was blocked with lactadherin, there was no difference in the endogenous thrombin potential, but the generation of thrombin was blunted with lower peak thrombin levels.

CONCLUSION

Cold storage of murine whole blood results in decreased fibrinogen levels and fibrin clot formation. Aged whole blood demonstrates increased thrombin generation, and this is due in part to microvesicle production in stored whole blood. One mechanism by which microvesicles are procoagulant is by phosphatidylserine expression on their membranes.

4'-O-MethylbavachalconeB Targeted 14-3-3ζ Blocking the Integrin β3 Early Outside-In Signal to Inhibit Platelet Aggregation and Thrombosis

14-3-3ζ protein, the key target in the regulation and control of integrin β3 outside-in signaling, is an attractive new strategy to inhibit thrombosis without affecting hemostasis. In this study, 4'-O-methylbavachalconeB (4-O-MB) in Psoraleae Fructus was identified as a 14-3-3ζ ligand with antithrombosis activity by target fishing combined with ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) analysis. The competitive inhibition analysis showed that 4-O-MB targeted 14-3-3ζ and blocked the 14-3-3ζ/integrin β3 interaction with inhibition constant (Ki) values of 9.98 ± 0.22 μM. Molecular docking and amino acid mutation experiments confirmed that 4-O-MB specifically bound to 14-3-3ζ through LSY9 and SER28 to regulate the 14-3-3ζ/integrin β3 interaction. Besides, 4-O-MB affected the integrin β3 early outside-in signal by inhibiting AKT and c-Src phosphorylation. Meanwhile, 4-O-MB could inhibit ADP-, collagen-, or thrombin-induced platelet aggregation function but had no effect on platelet adhesion to collagen-coated surfaces in vivo. Administration of 4-O-MB could significantly inhibit thrombosis formation without disturbing hemostasis in mice. These findings provide new prospects for the antithrombotic effects of Psoraleae Fructus and the potential application of 4-O-MB as lead compounds in the therapy of thrombosis by targeting 14-3-3ζ.

Mudanpioside C Discovered from Paeonia suffruticosa Andr. Acts as a Protein Disulfide Isomerase Inhibitor with Antithrombotic Activities

Paeonia suffruticosa Andr. is a well-known landscape plant worldwide and also holds significant importance in China due to its medicinal and dietary properties. Previous studies have found that Cortex Moutan (CM), the dried root bark of P. suffruticosa, showed antiplatelet and cardioprotective effects, although the underlying mechanism and active compounds remain to be revealed. In this study, protein disulfide isomerase (PDI) inhibitors in CM were identified using a ligand-fishing method combined with the UHPLC-Q-TOF-MS assay. Further, their binding sites and inhibitory activities toward PDI were validated. The antiplatelet aggregation and antithrombotic activity were investigated. The results showed that two structurally similar compounds in CM were identified as the inhibitor for PDI with IC50 at 3.22 μM and 16.73 μM; among them Mudanpioside C (MC) is the most effective PDI inhibitor. Molecular docking, site-directed mutagenesis, and MST assay unequivocally demonstrated the specific binding of MC to the b'-x domain of PDI (Kd = 3.9 μM), acting as a potent PDI inhibitor by interacting with key amino acids K263, D292, and N298 within the b'-x domain. Meanwhile, MC could dose-dependently suppress collagen-induced platelet aggregation and interfere with platelet activation, adhesion, and spreading. Administration of MC can significantly inhibit thrombosis formation without disturbing hemostasis in mice. These findings present a promising perspective on the antithrombotic properties of CM and highlight the potential application of MC as lead compounds for targeting PDI in thrombosis therapy.

Novel 1,3,4-oxadiazole hybrids of 3-n-butylphthalide derivatives as potential anti-ischemic stroke agents

In continuation of our program to search for novel potential anti-ischemic stroke agents, a series of 1,3,4-oxadiazole and sulfoxide hybrids of phthalide derivatives was designed and synthesized in this study to evaluate their anti-ischemic stroke activity. Among them, compounds 5b, 5d, 5 l, and 5 m exhibited excellent inhibitory effects on platelet aggregation induced by adenosine diphosphate (ADP) and arachidonic acid (AA). In particular, compound 5b possessed considerable antithrombotic activity in animal models, as demonstrated by the effective alleviation of carrageenan-induced and FeCl3-induced thrombosis in tail and carotid arteries, respectively. Notably, intraperitoneal administration of compound 5b could better protect the brain from injury caused by ischemia/reperfusion in rats compared with precursor 3-n-butylphthalide. Further pharmacokinetics, liver microsomal stability, and PAMPA-BBB assays also indicated that compound 5b had relatively high bioavailability, metabolic stability, and BBB permeability. Moreover, compound 5b showed a safety profile that was superior to the clinical drugs clopidogrel, aspirin, and 3-n-butylphthalide in the mouse-tail bleeding assay. Finally, molecular docking predicted that the potential target of the antiplatelet aggregation activity of compound 5b was P2Y12 receptor. This research provides a novel candidate compound for the treatment of ischemic stroke.

An architecturally rational hemostat for rapid stopping of massive bleeding on anticoagulation therapy

Hemostatic devices are critical for managing emergent severe bleeding. With the increased use of anticoagulant therapy, there is a need for next-generation hemostats. We rationalized that a hemostat with an architecture designed to increase contact with blood, and engineered from a material that activates a distinct and undrugged coagulation pathway can address the emerging need. Inspired by lung alveolar architecture, here, we describe the engineering of a next-generation single-phase chitosan hemostat with a tortuous spherical microporous design that enables rapid blood absorption and concentrated platelets and fibrin microthrombi in localized regions, a phenomenon less observed with other classical hemostats without structural optimization. The interaction between blood components and the porous hemostat was further amplified based on the charged surface of chitosan. Contrary to the dogma that chitosan does not directly affect physiological clotting mechanism, the hemostat induced coagulation via a direct activation of platelet Toll-like receptor 2. Our engineered porous hemostat effectively stopped the bleeding from murine liver wounds, swine liver and carotid artery injuries, and the human radial artery puncture site within a few minutes with significantly reduced blood loss, even under the anticoagulant treatment. The integration of engineering design principles with an understanding of the molecular mechanisms can lead to hemostats with improved functions to address emerging medical needs.

Discovery and verification of Q-markers for promoting blood circulation and removing stasis of raw and wine-steamed Vaccaria segetalis based on pharmacological evaluation combined with chemometrics

ETHNOPHARMACOLOGICAL RELEVANCE

Dried and mature seeds of Vaccaria segetalis (Neck.) Garcke ex Asch. (VS) are known for their therapeutic effects, as they stimulate blood circulation, promote menstruation and diuresis and eliminate gonorrhoea. However, due to its hard shell, the dissolution of its active ingredients is often improved by steaming and frying in clinical applications. Among the processed products, wine-steamed Vaccaria segetalis (WVS) is one of the commonly used ones. Numerous historical records have shown that wine steaming can enhance the efficacy of drugs to promote blood circulation and remove blood stasis. However, the differences in the efficacy of VS and WVS in promoting blood circulation and removing blood stasis have not been thoroughly studied, and the possible reasons for these differences have not been reported.

AIM OF THE STUDY

The objective of this study was to identify quality markers (Q-markers) that could differentiate the efficacy of promoting blood circulation and removing blood stasis of VS and WVS, which could serve as a basis for the rational application of VS and WVS in clinical settings.

MATERIALS AND METHODS

A pharmacodynamic comparison between the water extracts of VS and WVS was carried out based on a mouse acute blood stasis model (ABS) and thrombus zebrafish model. The potential bioactive substances of WVS were screened by investigating the correlation between common peaks identified for 10 batches of WVS by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) and their rate of thrombosis inhibition in zebrafish. Furthermore, multivariate statistical analysis of chemical components between VS and WVS was conducted to speculate the Q-markers combined with the results of the bioactive components. Based on the efficacy verification of Q-markers, the content of Q-markers in 10 batches of WVS was evaluated.

RESULTS

The results of efficacy comparison assays demonstrated that the efficacy of WVS was more prominent than VS at the same dose. Five components were screened as effective components of WVS for promoting blood circulation and removing blood stasis by correlation analysis. Furthermore, a total of 24 common ingredients were identified in VS and WVS extracts, and 9 of them showed increased dissolution rate after wine steaming, including 4 active ingredients, Hypaphorine, Vaccarin, Saponarin, and Isovitexin-2″-O-arabinoside, which were screened out by correlation analysis. The monomer test suggested that these 4 components could activate blood circulation and remove blood stasis in a dose-dependent manner. Consequently, Hypaphorine, Vaccarin, Saponarin, and Isovitexin-2″-O-arabinoside were selected as Q-markers to distinguish between VS and WVS. The content determination showed that the total contents of 4 Q-markers of WVS from 10 batches with different origins ranged from 0.478% to 0.716%.

CONCLUSIONS

This study compared the efficacy of VS and WVS in promoting blood circulation and resolving stasis and revealed Q-markers that reflected the difference in efficacy between them for the first time, which laid the foundation for establishing quality standards for WVS.

Investigating clot-flow interactions by integrating intravital imaging with in silico modeling for analysis of flow, transport, and hemodynamic forces

As a blood clot forms, grows, deforms, and embolizes following a vascular injury, local clot-flow interactions lead to a highly dynamic flow environment. The local flow influences transport of biochemical species relevant for clotting, and determines the forces on the clot that in turn lead to clot deformation and embolization. Despite this central role, quantitative characterization of this dynamic clot-flow interaction and flow environment in the clot neighborhood remains a major challenge. Here, we propose an approach that integrates dynamic intravital imaging with computer geometric modeling and computational flow and transport modeling to develop a unified in silico framework to quantify the dynamic clot-flow interactions. We outline the development of the methodology referred to as Intravital Integrated In Silico Modeling or IVISim, and then demonstrate the method on a sample set of simulations comprising clot formation following laser injury in two mouse cremaster arteriole injury model data: one wild-type mouse case, and one diYF knockout mouse case. Simulation predictions are verified against experimental observations of transport of caged fluorescent Albumin (cAlb) in both models. Through these simulations, we illustrate how the IVISim methodology can provide insights into hemostatic processes, the role of flow and clot-flow interactions, and enable further investigations comparing and contrasting different biological model scenarios and parameter variations.

An evolutionary history of F12 gene: Emergence, loss, and vulnerability with the environment as a driver

In the context of macroevolutionary transitions, environmental changes prompted vertebrates already bearing genetic variations to undergo gradual adaptations resulting in profound anatomical, physiological, and behavioral adaptations. The emergence of new genes led to the genetic variation essential in metazoan evolution, just as was gene loss, both sources of genetic variation resulting in adaptive phenotypic diversity. In this context, F12-coding protein with defense and hemostatic roles emerged some 425 Mya, and it might have contributed in aquatic vertebrates to the transition from water-to-land. Conversely, the F12 loss in marine, air-breathing mammals like cetaceans has been associated with phenotypic adaptations in some terrestrial mammals in their transition to aquatic lifestyle. More recently, the advent of technological innovations in western lifestyle with blood-contacting devices and harmful environmental nanoparticles, has unfolded new roles of FXII. Environment operates as either a positive or a relaxed selective pressure on genes, and consequently genes are selected or lost. FXII, an old dog facing environmental novelties can learn new tricks and teach us new therapeutic avenues.

Characterization of a recombinant factor IX molecule fused to coagulation factor XIII-B subunit

INTRODUCTION AND AIM

Severe haemophilia B (HB) is characterized by spontaneous bleeding episodes, mostly into joints. Recurrent bleeds lead to progressive joint destruction called haemophilic arthropathy. The current concept of prophylaxis aims at maintaining the FIX level >3-5 IU/dL, which is effective at reducing the incidence of haemophilic arthropathy. Extended half-life FIX molecules make it easier to achieve these target trough levels compared to standard FIX concentrates. We previously reported that the fusion of a recombinant FIX (rFIX) to factor XIII-B (FXIIIB) subunit prolonged the half-life of the rFIX-LXa-FXIIIB fusion molecule in mice and rats 3.9- and 2.2-fold, respectively, compared with rFIX-WT. However, the mechanism behind the extended half-life was not known.

MATERIALS AND METHODS

Mass spectrometry and ITC were used to study interactions of rFIX-LXa-FXIIIB with albumin. Pharmacokinetic analyses in fibrinogen-KO and FcRn-KO mice were performed to evaluate the effect of albumin and fibrinogen on in-vivo half-life of rFIX-LXa-FXIIIB. Finally saphenous vein bleeding model was used to assess in-vivo haemostatic activity of rFIX-LXa-FXIIIB.

RESULTS AND CONCLUSION

We report here the key interactions that rFIX-LXa-FXIIIB may have in plasma are with fibrinogen and albumin which may mediate its prolonged half-life. In addition, using the saphenous vein bleeding model, we demonstrate that rFIX-FXIIIB elicits functional clot formation that is indistinguishable from that of rFIX-WT.

Soluble endoglin reduces thrombus formation and platelet aggregation via interaction with αIIbβ3 integrin

BACKGROUND

The circulating form of human endoglin (sEng) is a cleavage product of membrane-bound endoglin present on endothelial cells. Because sEng encompasses an RGD motif involved in integrin binding, we hypothesized that sEng would be able to bind integrin αIIbβ3, thereby compromising platelet binding to fibrinogen and thrombus stability.

METHODS

In vitro human platelet aggregation, thrombus retraction, and secretion-competition assays were performed in the presence of sEng. Surface plasmon resonance (SPR) binding and computational (docking) analyses were carried out to evaluate protein-protein interactions. A transgenic mouse overexpressing human sEng (hsEng+) was used to measure bleeding/rebleeding, prothrombin time (PT), blood stream, and embolus formation after FeCl3-induced injury of the carotid artery.

RESULTS

Under flow conditions, supplementation of human whole blood with sEng led to a smaller thrombus size. sEng inhibited platelet aggregation and thrombus retraction, interfering with fibrinogen binding, but did not affect platelet activation. SPR binding studies demonstrated that the specific interaction between αIIbβ3 and sEng and molecular modeling showed a good fitting between αIIbβ3 and sEng structures involving the endoglin RGD motif, suggesting the possible formation of a highly stable αIIbβ3/sEng. hsEng+ mice showed increased bleeding time and number of rebleedings compared to wild-type mice. No differences in PT were denoted between genotypes. After FeCl3 injury, the number of released emboli in hsEng+ mice was higher and the occlusion was slower compared to controls.

CONCLUSIONS

Our results demonstrate that sEng interferes with thrombus formation and stabilization, likely via its binding to platelet αIIbβ3, suggesting its involvement in primary hemostasis control.

A site on factor XII required for productive interactions with polyphosphate

BACKGROUND

During plasma contact activation, factor XII (FXII) binds to surfaces through its heavy chain and undergoes conversion to the protease FXIIa. FXIIa activates prekallikrein and factor XI (FXI). Recently, we showed that the FXII first epidermal growth factor-1 (EGF1) domain is required for normal activity when polyphosphate is used as a surface.

OBJECTIVES

The aim of this study was to identify amino acids in the FXII EGF1 domain required for polyphosphate-dependent FXII functions.

METHODS

FXII with alanine substitutions for basic residues in the EGF1 domain were expressed in HEK293 fibroblasts. Wild-type FXII (FXII-WT) and FXII containing the EGF1 domain from the related protein Pro-HGFA (FXII-EGF1) were positive and negative controls. Proteins were tested for their capacity to be activated, and to activate prekallikrein and FXI, with or without polyphosphate, and to replace FXII-WT in plasma clotting assays and a mouse thrombosis model.

RESULTS

FXII and all FXII variants were activated similarly by kallikrein in the absence of polyphosphate. However, FXII with alanine replacing Lys73, Lys74, and Lys76 (FXII-Ala73,74,76) or Lys76, His78, and Lys81 (FXII-Ala76,78,81) were activated poorly in the presence of polyphosphate. Both have <5% of normal FXII activity in silica-triggered plasma clotting assays and have reduced binding affinity for polyphosphate. Activated FXIIa-Ala73,74,76 displayed profound defects in surface-dependent FXI activation in purified and plasma systems. FXIIa-Ala73,74,76 reconstituted FXII-deficient mice poorly in an arterial thrombosis model.

CONCLUSION

FXII Lys73, Lys74, Lys76, and Lys81 form a binding site for polyanionic substances such as polyphosphate that is required for surface-dependent FXII function.

A review of hemostatic chemical components and their mechanisms in traditional Chinese medicine and ethnic medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine and ethnic medicine together play an important value in the modern medicine system that is different from that of chemical drugs. Chinese medicine and ethnic medicine with hemostatic effect have unique advantages and development potential in the prevention and treatment of clinical hemorrhagic diseases, reflecting multi-component, multi-target and multi-pathway effects.

AIM OF THE STUDY

In this paper, the active ingredients related to the hemostatic effect of traditional Chinese medicine and ethnic medicine are taken as the starting point, and the traditional Chinese medicine and ethnic medicine with traditional hemostatic purposes are reviewed, and the existing research progress on the active ingredients and their mechanism of action of these drugs is systematically expounded, aiming to provide theoretical reference for the development of traditional hemostatic drugs, the discovery of hemostatic active ingredients and the research of new hemostatic methods.

MATERIALS AND METHODS

Hemostatic chinese medicine and ethnic medicine were collected and summarized from the classic books of Materia Medica, public literature database and doctoral or master's thesis repositories. At the same time, we discussed the classification of various types of hemostatic active ingredients of traditional Chinese medicine and ethnic medicine according to the different mechanisms of hemostasis.

RESULTS

A total of 436 traditional Chinese medicine and ethnic medicine with hemostatic effects have been collected, and their hemostatic active ingredients include alkaloids, quinones, flavonoids, phenylpropanoids, organic acids, amino acids, terpenoids, steroids, phenols, tannins, esters, polysaccharides and herbal extracts, etc. These active ingredients accelerate the formation of hemostasis by improving endogenous and exogenous hemostatic pathways mainly through enhancing vascular wall contraction, increasing platelet aggregation, promoting coagulation system activation and inhibiting fibrinolysis.

CONCLUSIONS

This article reviews the previous data on various aspects of the hemostatic effect of traditional Chinese medicine and ethnomedicine. Many traditional hemostatic drugs have been discovered and many active ingredients and mechanisms have been reported. However, although there are a large number of drugs with traditional hemostatic effects, there are still few developed and applied. At the same time, the hemostatic components of many drugs still remain in the study of the activity of their total extracts, and the potential link between some drug components achieving hemostatic effects through different mechanisms remains to be elucidated.

Increased reactive oxygen species lead to overactivation of platelets in essential thrombocythemia

INTRODUCTION

Platelet function, rather than platelet count, plays a crucial role in thrombosis in essential thrombocythemia (ET). However, little is known about the abnormal function of platelets in ET. Here, we investigated the functional characteristics of platelets in ET hemostasis to explore the causes of ET platelet dysfunction and new therapeutic strategies for ET.

MATERIALS AND METHODS

We analyzed platelet aggregation, activation, apoptosis, and reactive oxygen species (ROS) in ET patients and JAK2V617F-positive ET-like mice. The effects of ROS on platelet function and the underlying mechanism were investigated by inhibiting ROS using N-acetylcysteine (NAC).

RESULTS

Platelet aggregation, activation, apoptosis, ROS, and clot retraction were elevated in ET. No significant differences were observed between ET patients with JAK2V617F or CALR mutations. Increased ROS activated the JAK-STAT pathway, which may further influence platelet function. Inhibition of platelet ROS by NAC reduced platelet aggregation, activation, and apoptosis, and prolonged bleeding time. Furthermore, NAC treatment reduced platelet count in ET-like mice by inhibiting platelet production from megakaryocytes.

CONCLUSIONS

Elevated ROS in ET platelets resulted in enhanced platelet activation, function and increased risk of thrombosis. NAC offers a potential therapeutic strategy for reducing platelet count.

Multifunctional Dual Cross-Linked Bioadhesive Patch with Low Immunogenic Response and Wet Tissues Adhesion

The development of bioadhesives is an important, yet challenging task as seemingly mutually exclusive properties need to be combined in one material, that is, strong adhesion, water resistance, and high biocompatibility. Here, a biocompatible and biodegradable protein-based bioadhesive patch (PBP) with high adhesion strength and low immunogenic response is reported. PBP exists as a strong adhesion for biological surfaces, which is higher than some conventional bioadhesives (i.e., polyethylene glycol and fibrin). Robust adhesion and strength are realized through the removal of interfacial water and fast formation of multiple supramolecular interactions induced by metal ions. The PBP's high biocompatibility is evaluated and immunogenic response in vitro and in vivo is neglected. The strong adhesion on soft biological tissues qualifies the PBP as biomedical glue outperforming some commercial products for applications in hemostasis performance, accelerated wound healing, and sealing of defected organs, anticipating to be useful as a tissue adhesive and sealant.

Alterations to Sphingomyelin Metabolism Affect Hemostasis and Thrombosis

BACKGROUND

Our recent studies suggest that sphingomyelin levels in the plasma membrane influence TF (tissue factor) procoagulant activity. The current study was performed to investigate how alterations to sphingomyelin metabolic pathway would affect TF procoagulant activity and thereby affect hemostatic and thrombotic processes.

METHODS

Macrophages and endothelial cells were transfected with specific siRNAs or infected with adenoviral vectors to alter sphingomyelin levels in the membrane. TF activity was measured in factor X activation assay. Saphenous vein incision-induced bleeding and the inferior vena cava ligation-induced flow restriction mouse models were used to evaluate hemostasis and thrombosis, respectively.

RESULTS

Overexpression of SMS (sphingomyelin synthase) 1 or SMS2 in human monocyte-derived macrophages suppresses ATP-stimulated TF procoagulant activity, whereas silencing SMS1 or SMS2 increases the basal cell surface TF activity to the same level as of ATP-decrypted TF activity. Consistent with the concept that sphingomyelin metabolism influences TF procoagulant activity, silencing of acid sphingomyelinase or neutral sphingomyelinase 2 or 3 attenuates ATP-induced enhanced TF procoagulant activity in macrophages and endothelial cells. Niemann-Pick disease fibroblasts with a higher concentration of sphingomyelin exhibited lower TF activity compared with wild-type fibroblasts. In vivo studies revealed that LPS+ATP-induced TF activity and thrombin generation were attenuated in ASMase^-/- mice, while their levels were increased in SMS2^-/- mice. Further studies revealed that acid sphingomyelinase deficiency leads to impaired hemostasis, whereas SMS2 deficiency increases thrombotic risk.

CONCLUSIONS

Overall, our data indicate that alterations in sphingomyelin metabolism would influence TF procoagulant activity and affect hemostatic and thrombotic processes.

A Common Missense Variant Causing Factor XI Deficiency and Increased Bleeding Tendency in Maine Coon Cats

Hereditary factor XI (FXI) deficiency is characterized as an autosomal mild to moderate coagulopathy in humans and domestic animals. Coagulation testing revealed FXI deficiency in a core family of Maine Coon cats (MCCs) in the United States. Factor XI-deficient MCCs were homozygous for a guanine to adenine transition resulting in a methionine substitution for the highly conserved valine-516 in the FXI catalytic domain. Immunoblots detected FXI of normal size and quantity in plasmas of MCCs homozygous for V516M. Some FXI-deficient MCCs experienced excessive post-operative/traumatic bleeding. Screening of 263 MCCs in Europe revealed a mutant allele frequency of 0.232 (23.2%). However, V516M was not found among 100 cats of other breeds. Recombinant feline FXI-M516 (fFXI-M516) expressed ~4% of the activity of wild-type fFXI-V516 in plasma clotting assays. Furthermore, fFXIa-M516 cleaved the chromogenic substrate S-2366 with ~4.3-fold lower catalytic efficacy (kcat/Km) than fFXIa-V516, supporting a conformational alteration of the protease active site. The rate of FIX activation by fFXIa-M516 was reduced >3-fold compared with fFXIa-V516. The common missense variant FXI-V516M causes a cross-reactive material positive FXI deficiency in MCCs that is associated with mild-moderate bleeding tendencies. Given the prevalence of the variant in MCCs, genotyping is recommended prior to invasive procedures or breeding.

Murine Models in the Evaluation of Heparan Sulfate-Based Anticoagulants

Evaluating prospective anticoagulant therapies in animal thrombosis and bleeding models are standard pre-clinical approaches. Mice are frequently used for initial evaluations because a variety of models have been developed in this well-characterized species, and mice are relatively inexpensive to maintain. Because mice seem to be resistant to forming "spontaneous" thrombosis, vessel injury is used to induce intravascular clot formation. For the purpose of testing heparin-based drugs, we adapted a well-established model in which thrombus formation in the carotid artery is induced by exposing the vessel to ferric chloride. For studying anticoagulant effects on venous thrombosis, we use a model in which the inferior vena cava is ligated and the size of the resulting clots are measured. The most common adverse effect of anticoagulation therapy is bleeding. We describe a simple tail bleeding time that has been used for many years to study the effects of anticoagulants on hemostasis. We also describe a more reproducible, but more technically challenging, saphenous vein bleeding model that is also used for this purpose.

Research-Relevant Clinical Pathology Resources: Emphasis on Mice, Rats, Rabbits, Dogs, Minipigs, and Non-Human Primates

Clinical pathology testing for investigative or biomedical research and for preclinical toxicity and safety assessment in laboratory animals is a distinct specialty requiring an understanding of species specific and other influential variables on results and interpretation. This review of clinical pathology principles and testing recommendations in laboratory animal species aims to provide a useful resource for researchers, veterinary specialists, toxicologists, and clinical or anatomic pathologists.

Efficacy and safety of next-generation tick transcriptome-derived direct thrombin inhibitors

Despite their limitations, unfractionated heparin (UFH) and bivalirudin remain standard-of-care parenteral anticoagulants for percutaneous coronary intervention (PCI). We discovered novel direct thrombin inhibitors (DTIs) from tick salivary transcriptomes and optimised their pharmacologic activity. The most potent, ultravariegin, inhibits thrombin with a K_i of 4.0 pM, 445-fold better than bivalirudin. Unexpectedly, despite their greater antithrombotic effect, variegin/ultravariegin demonstrated less bleeding, achieving a 3-to-7-fold wider therapeutic index in rodent thrombosis and bleeding models. When used in combination with aspirin and ticagrelor in a porcine model, variegin/ultravariegin reduced stent thrombosis compared with antiplatelet therapy alone but achieved a 5-to-7-fold lower bleeding time than UFH/bivalirudin. Moreover, two antibodies screened from a naïve human antibody library effectively reversed the anticoagulant activity of ultravariegin, demonstrating proof-of-principle for antidote reversal. Variegin and ultravariegin are promising translational candidates for next-generation DTIs that may reduce peri-PCI bleeding in the presence of antiplatelet therapy.

Snake extract-laden hemostatic bioadhesive gel cross-linked by visible light

Bioadhesives reduce operation time and surgical complications. However, in the presence of blood, adhesion strength is often compromised. Inspired by the blood clotting activity of snake venom, we report a visible light-induced blood-resistant hemostatic adhesive (HAD) containing gelatin methacryloyl and reptilase, which is a hemocoagulase (HC) extracted from Bothrops atrox HAD leads to the activation and aggregation of platelets and efficiently transforms fibrinogen into fibrin to achieve rapid hemostasis and seal the tissue. Blood clotting time with HAD was about 45 s compared with 5 to 6 min without HAD. HAD instantaneously achieved hemostasis on liver incision (~45 s) and cut rat tail (~34 s) and reduced blood loss by 79 and 78%, respectively. HAD is also efficient in sealing severely injured liver and abdominal aorta. HAD has great potential to bridge injured tissues by combing hemostasis with adhesives.

Methods to Investigate miRNA Function: Focus on Platelet Reactivity

MicroRNAs (miRNAs) are small noncoding RNAs modulating protein production. They are key players in regulation of cell function and are considered as biomarkers in several diseases. The identification of the proteins they regulate, and their impact on cell physiology, may delineate their role as diagnostic or prognostic markers and identify new therapeutic strategies. During the last 3 decades, development of a large panel of techniques has given rise to multiple models dedicated to the study of miRNAs. Since plasma samples are easily accessible, circulating miRNAs can be studied in clinical trials. To quantify miRNAs in numerous plasma samples, the choice of extraction and purification techniques, as well as normalization procedures, are important for comparisons of miRNA levels in populations and over time. Recent advances in bioinformatics provide tools to identify putative miRNAs targets that can then be validated with dedicated assays. In vitro and in vivo approaches aim to functionally validate candidate miRNAs from correlations and to understand their impact on cellular processes. This review describes the advantages and pitfalls of the available techniques for translational research to study miRNAs with a focus on their role in regulating platelet reactivity.

Murine cadherin-6 mediates thrombosis in vivo in a platelet-independent manner

BACKGROUND

Platelet adhesion is the critical process mediating stable thrombus formation. Previous reports of cadherin-6 on human platelets have demonstrated its role in platelet aggregation and thrombus formation.

OBJECTIVES

We aimed to further characterize the importance of cadherin-6 in thrombosis in vivo.

METHODS

Cadherin-6 platelet expression was evaluated by western blotting, flow cytometry, and immunoprecipitation. Thrombosis was evaluated using the FeCl3 and Rose Bengal carotid artery models in C57Bl6 mice treated with anti-cadherin-6 or IgG and wild-type or Cdh6-/- mice. Platelet function was compared in wild-type and Cdh6-/- mice using tail-clip assays, aggregometry, and flow cytometry.

RESULTS

Human platelet expression of cadherin-6 was confirmed at ~3000 copies per platelet. Cdh6-/- mice or those treated with anti-cadherin-6 antibody showed an increased time to occlusion in both thrombosis models. Cadherin-6 was not expressed on mouse platelets, and there were no differences in tail bleeding times, platelet aggregation, or platelet activation in wild-type versus Cdh6-/- mice.

CONCLUSIONS

Cadherin-6 plays an essential role in thrombosis in vivo. However, cadherin-6 is not expressed on murine platelets. These data are in contrast to human platelets, which express a functional cadherin-6/catenin complex. The essential, platelet-independent role for cadherin-6 in hemostasis may allow it to be an effective and safe therapeutic target.