Interaction Of Platelets Research Articles

Aspirin Resistance as a Result of Impaired Interaction of Platelets and Neutrophils in Patients with Coronary Heart Disease

Aim. To study the relationship between the levels of synthesis of reactive oxygen species (ROS) by platelets and neutrophils in patients with coronary heart disease (CHD) before and after coronary artery bypass grafting (CABG), depending on sensitivity to acetylsalicylic acid (ASA).Material and methods. The study included 95 patients with coronary artery disease who are indicated for CABG surgery. The control group consisted of 30 healthy donors. The antiplatelet therapy was stopped for at least 5 days before CABG. In the postoperative period, from the first day, all patients were received 100 mg of an enteric form of acetylsalicylic acid (ASA). Resistance to ASA was determined at the level of platelet aggregation with arachidonic acid ≥20% by optical agregometry at least at one observation point: before CABG, on 1-3 day and on 8-10 day after surgery. We evaluated the spontaneous and induced lucigenin-dependent chemiluminescence (CL) of platelets (ADP induction) and neutrophils (zymosan induction) by the exit time to maximum intensity (Tmax), maximum intensity (Imax) and area (S) under the CL curve.Results. 70.5% sensitive (sASA) and 29.5% resistant (rASA) to ASA patients were revealed. Prior to CABG, in sASA patients, the Imax of spontaneous and zymosan-induced neutrophil CL and CL platelet activity was increased relative to control values. Tmax of spontaneous platelet CL, Imax and S under the ADP-induced platelet CL curve were lower in sASA patients, if to compare with rASA patients. On the 1st and 8-10th day after CABG in sASA patients, the CL indicators of neutrophil and platelet activity also remained elevated compared to control values. On the 1st day after CABG decreased levels of S under the spontaneous CL curve of neutrophils in rASA patients was established compared with sASA patients, and increased levels of Imax and S under the curve of induced neutrophil CL were detected in comparison with the control range. In rASA patients, the values of Tmax of spontaneous platelet CL decreased in relation to the values detected in the control group and sASA patients. On the 8–10th day after CABG, most indicators of spontaneous and zymosan-induced CL neutrophils in rASA patients were also increased compared to control values. In rASA patients a positive correlation of Imax-induced CL was found (r=0.83) on the 1st day after CABG and negative correlations of Tmax of spontaneous CL (r=- 0.75) and S under the curve induced CL (r=-0.70) on the 8-10th day were detected between platelets and neutrophils.Conclusion. In sASA patients with coronary heart disease before and after CABG, a high level of synthesis of superoxide radical by neutrophils and platelets was detected. The relationship between the levels of the synthesis of superoxide radical by neutrophils and platelets was found only after CABG in rASA patients. Increased synthesis of superoxide radical due to metabolic and regulatory relationships in neutrophils and platelets stimulates pro-inflammatory processes in coronary artery disease and determines the sensitivity of platelets to ASA.

Mechanobiology of shear-induced platelet aggregation leading to occlusive arterial thrombosis: A multiscale in silico analysis

Occlusive thrombosis in arteries causes heart attacks and strokes. The rapid growth of thrombus at elevated shear rates (~10,000 1/s) relies on shear-induced platelet aggregation (SIPA) thought to come about from the entanglement of von Willebrand factor (VWF) molecules. The mechanism for SIPA is not yet understood in terms of cell- and molecule-level dynamics in fast flowing bloodstreams. Towards this end, we develop a multiscale computational model to recreate SIPA in silico, where the suspension dynamics and interactions of individual platelets and VWF multimers are resolved directly. The platelet-VWF interaction via GP1b-A1 bonds is prescribed with intrinsic binding rates theoretically derived and informed by single-molecule measurements. The model is validated against existing microfluidic SIPA experiments, showing good agreement with the in vitro observations in terms of the morphology, traveling distance and capture time of the platelet aggregates. Particularly, the capture of aggregates can occur in a few milliseconds, comparable to the platelet transit time through pathologic arterial stenotic sections and much shorter than the time for shear-induced platelet activation. The multiscale SIPA simulator provides a cross-scale tool for exploring the biophysical mechanisms of SIPA in silico that are difficult to access with single-molecule measurements or micro-/macro-fluidic assays only.

Effect of freezing velocity and platelet size on structural parameters and morphology of freeze-cast porous alumina scaffolds

In this article, we examine the effects of two different platelet sizes (4 and 8 μm respectively) on the architecture of freeze-cast sintered alumina scaffolds as a function of a wide range of freezing velocities, 5–57 μm s−1. The microstructural evolution along the freezing direction has been studied a-priori, explained on the basis of ice physics and the interaction of ceramic platelets with the advancing freezing front. An array of microstructures was produced to delve into the role of platelet sizes and freezing velocities on various structural parameters, viz. wavelength (λ), lamella thickness (δ), and bridge density (ρb). Regarding the pore morphology, transitions from lamellar to dendritic or isotropic structures were identified for the scaffolds containing smaller and bigger platelets, triggered by an increase in freezing velocity as well as platelet size. The different microstructures are quantified with a specific dimensionless parameter m. We identify the microstructure to be lamellar with low bridge density and m > 4. The wavelengths and bridge spacing were comparable for 2 < m < 4 and led to dendritic structure. For the morphologies characterized by m < 2, the spacing among the numerous interlamellar bridges was smaller than the structural wavelength and hence, the scaffolds revealed usually isotropic structure. Finally, the specific processing conditions that yield different morphologies and the parameter m are presented together in the form of a ‘morphology map’ to establish the different microstructural regimes.

Endothelial Shear Stress and Platelet FcγRIIa Expression in Intracranial Atherosclerotic Disease.

Intracranial atherosclerotic disease (ICAD) has been characterized by the degree of arterial stenosis and downstream hypoperfusion, yet microscopic derangements of endothelial shear stress at the luminal wall may be key determinants of plaque growth, vascular remodeling and thrombosis that culminate in recurrent stroke. Platelet interactions have similarly been a principal focus of treatment, however, the mechanistic basis of anti-platelet strategies is largely extrapolated rather than directly investigated in ICAD. Platelet FcγRIIa expression has been identified as a potent risk factor in cardiovascular disease, as elevated expression markedly increases the risk of recurrent events. Differential activation of the platelet FcγRIIa receptor may also explain the variable response of individual patients to anti-platelet medications. We review existing data on endothelial shear stress and potential interactions with the platelet FcγRIIa receptor that may alter the evolving impact of ICAD, based on local pathophysiology at the site of arterial stenosis. Current methods for quantification of endothelial shear stress and platelet activation are described, including tools that may be readily adapted to the clinical realm for further understanding of ICAD.

Biomimetic silk biomaterials: Perlecan-functionalized silk fibroin for use in blood-contacting devices

Blood compatible materials are required for the development of therapeutic and diagnostic blood contacting devices as blood-material interactions are a key factor dictating device functionality. In this work, we explored biofunctionalization of silk biomaterials with a recombinantly expressed domain V of the human basement membrane proteoglycan perlecan (rDV) towards the development of blood compatible surfaces. Perlecan and rDV are of interest in vascular device development as they uniquely support endothelial cell, while inhibiting smooth muscle cell and platelet interactions. rDV was covalently immobilized on silk biomaterials using plasma immersion ion implantation (PIII), a new method of immobilizing proteins on silk biomaterials that does not rely on modification of specific amino acids in the silk protein chain, and compared to physisorbed and carbodiimide immobilized rDV. Untreated and treated silk biomaterials were examined for interactions with blood components with varying degrees of complexity, including isolated platelets, platelet rich plasma, blood plasma, and whole blood, both under agitated and flow conditions. rDV-biofunctionalized silk biomaterials were shown to be blood compatible in terms of platelet and whole blood interactions and the PIII treatment was shown to be an effective and efficient means of covalently immobilizing rDV in its bioactive form. These biomimetic silk biomaterials are a promising platform toward development of silk-based blood-contacting devices for therapeutic, diagnostic, and research applications. Statement of significanceBlood compatible materials are required for the development of therapeutic and diagnostic blood contacting devices as blood-material interactions are a key factor dictating device functionality. In this work, we explored biofunctionalization of silk biomaterials with a recombinantly expressed domain V (rDV) of the human basement membrane proteoglycan perlecan towards the development of blood compatible surfaces. Perlecan and rDV are of interest in vascular device development as they uniquely support endothelial cell, while inhibiting smooth muscle cell and platelet interactions. rDV was covalently immobilized on silk biomaterials using plasma immersion ion implantation (PIII), a new method of immobilizing proteins on silk biomaterials that does not rely on modification of specific amino acids in the silk protein chain. These biomimetic silk biomaterials are a promising platform toward development of silk-based blood-contacting devices for therapeutic, diagnostic, and research applications.

Thyrotrophin and thyroxine support immune homeostasis in humans.

SummaryThe endocrine and the immune systems interact by sharing receptors for hormones and cytokines, cross‐control and feedback mechanisms. To date, no comprehensive study has assessed the impact of thyroid hormones on immune homeostasis. By studying immune phenotype (cell populations, antibody concentrations, circulating cytokines, adipokines and acute‐phase proteins, monocyte–platelet interactions and cytokine production capacity) in two large independent cohorts of healthy volunteers of Western European descent from the Human Functional Genomics Project (500FG and 300BCG cohorts), we identified a crucial role of the thyroid hormone thyroxin (T4) and thyroid‐stimulating hormone (TSH) on the homeostasis of lymphocyte populations. TSH concentrations were strongly associated with multiple populations of both effector and regulatory T cells, whereas B‐cell populations were significantly associated with free T4 (fT4). In contrast, fT4 and TSH had little impact on myeloid cell populations and cytokine production capacity. Mendelian randomization further supported the role of fT4 for lymphocyte homeostasis. Subsequently, using a genomics approach, we identified genetic variants that influence both fT4 and TSH concentrations and immune responses, and gene set enrichment pathway analysis showed enrichment of fT4‐affected gene expression in B‐cell function pathways, including the CD40 pathway, further supporting the importance of fT4 in the regulation of B‐cell function. In conclusion, we show that thyroid function controls the homeostasis of the lymphoid cell compartment. These findings improve our understanding of the immune responses and open the door for exploring and understanding the role of thyroid hormones in the lymphocyte function during disease.

Significant Differences in Host-Pathogen Interactions Between Murine and Human Whole Blood.

Murine infection models are widely used to study systemic candidiasis caused by C. albicans. Whole-blood models can help to elucidate host-pathogens interactions and have been used for several Candida species in human blood. We adapted the human whole-blood model to murine blood. Unlike human blood, murine blood was unable to reduce fungal burden and more substantial filamentation of C. albicans was observed. This coincided with less fungal association with leukocytes, especially neutrophils. The lower neutrophil number in murine blood only partially explains insufficient infection and filamentation control, as spiking with murine neutrophils had only limited effects on fungal killing. Furthermore, increased fungal survival is not mediated by enhanced filamentation, as a filament-deficient mutant was likewise not eliminated. We also observed host-dependent differences for interaction of platelets with C. albicans, showing enhanced platelet aggregation, adhesion and activation in murine blood. For human blood, opsonization was shown to decrease platelet interaction suggesting that complement factors interfere with fungus-to-platelet binding. Our results reveal substantial differences between murine and human whole-blood models infected with C. albicans and thereby demonstrate limitations in the translatability of this ex vivo model between hosts.

Does Platelet-Rich Fibrin Enhance the Early Angiogenetic Potential of Different Bone Substitute Materials? An In Vitro and In Vivo Analysis.

The impaired angiogenic potential of bone substitute materials (BSMs) may limit regenerative processes. Therefore, changes in the angiogenetic properties of different BSMs in combination with platelet-rich fibrin (PRF) in comparison to PRF alone, as well as to native BSMs, were analyzed in vitro and in vivo to evaluate possible clinical application. In vitro, four BSMs of different origins (allogeneic, alloplastic, and xenogeneic) were biofunctionalized with PRF and compared to PRF in terms of platelet interaction and growth factor release (vascular endothelial growth factor (VEGF), tissue growth factor ß (TGFß) and platelet-derived growth factor (PDGF)) after 15 min. To visualize initial cell–cell interactions, SEM was performed. In vivo, all BSMs (±PRF) were analyzed after 24 h for new-formed vessels using a chorioallantoic membrane (CAM) assay. Especially for alloplastic BSMs, the addition of PRF led to a significant consumption of platelets (p = 0.05). PDGF expression significantly decreased in comparison to PRF alone (all BSMs: p < 0.013). SEM showed the close spatial relation of each BSM and PRF. In vivo, PRF had a significant positive pro-angiogenic influence in combination with alloplastic (p = 0.007) and xenogeneic materials (p = 0.015) in comparison to the native BSMs. For bio-activated xenogeneic BSMs, the branching points were also significantly increased (p = 0.005). Finally, vessel formation was increased for BSMs and PRF in comparison to the native control (allogeneic: p = 0.046; alloplastic: p = 0.046; and xenogeneic: p = 0.050). An early enhancement of angiogenetic properties was demonstrated when combining BSMs with PRF in vitro and led to upregulated vessel formation in vivo. Thus, the use of BSMs in combination with PRF may trigger bony regeneration in clinical approaches.

The prehospital use of younger age whole blood is associated with an improved arrival coagulation profile.

Recent in vitro data have shown that the hemostatic profile of whole blood (WB) degrades significantly after 14 days, yet the optimal storage remains debated. We hypothesized that arrival coagulation studies would be improved in patients receiving younger WB in the prehospital setting. This study was approved by our institutional institutional review board. We evaluated all trauma patients who received prehospital blood products by our helicopter service between July 2017 and July 2019. "Young" WB was defined as 14 days or less. Patients who received at least 1 U of young WB were classified as YOUNG, while the remainder was classified as OLD. Continuous data are presented as medians (25th-75th interquartile range) with comparisons performed using Wilcoxon rank sum. Assessments of clinical hemostatic potential included arrival platelet cell count and rapid thrombelastography. Multivariate regression analysis was also performed (Stata 12.1; College Station, TX). A total of 220 patients received prehospital WB during the study period. Of these, 153 patients received YOUNG WB, while 67 were transfused only OLD WB units. There were no differences in demographics, prehospital or arrival physiology, or Injury Severity Score among the two groups. The measures of clot initiation (activated clotting time) and kinetics (k time) were improved, as were the measures of clot acceleration/fibrinogen function (angle) and platelet function (maximum amplitude). As well, arrival platelet count was higher in the YOUNG cohort. No significant differences in postarrival transfusion were noted (p = 0.220). Multivariate analysis showed the greatest differences in maximum amplitude and α angle but failed to reach significance. Previous in vitro data have suggested deterioration of platelet function in cold-stored WB after 14 days. The current study demonstrated decreased global hemostasis by clinically available laboratory tests, especially related to fibrinogen and platelet interactions on univariate, but not multivariate analysis. This did not translate into increased transfusion requirements. Further studies are needed to determine the optimal storage duration for cold-stored WB for transfusion in the bleeding trauma patient, as well as rule out the presence of confounding variables. Therapeutic, level IV.

Modeling Thrombus Shell: Linking Adhesion Receptor Properties and Macroscopic Dynamics

Damage to arterial vessel walls leads to the formation of platelet aggregate, which acts as a physical obstacle for bleeding. An arterial thrombus is heterogeneous; it has a dense inner part (core) and an unstable outer part (shell). The thrombus shell is very dynamic, being composed of loosely connected discoid platelets. The mechanisms underlying the observed mobility of the shell and its (patho)physiological implications are unclear. To investigate arterial thrombus mechanics, we developed a novel, to our knowledge, two-dimensional particle-based computational model of microvessel thrombosis. The model considers two types of interplatelet interactions: primary reversible (glycoprotein Ib (GPIb)-mediated) and stronger integrin-mediated interaction, which intensifies with platelet activation. At high shear rates, the former interaction leads to adhesion, and the latter is primarily responsible for stable platelet aggregation. Using a stochastic model of GPIb-mediated interaction, we initially reproduced experimental curves that characterize individual platelet interactions with a von Willebrand factor-coated surface. The addition of the second stabilizing interaction results in thrombus formation. The comparison of thrombus dynamics with experimental data allowed us to estimate the magnitude of critical interplatelet forces in the thrombus shell and the characteristic time of platelet activation. The model predicts moderate dependence of maximal thrombus height on the injury size in the absence of thrombin activity. We demonstrate that the developed stochastic model reproduces the observed highly dynamic behavior of the thrombus shell. The presence of primary stochastic interaction between platelets leads to the properties of thrombus consistent with in vivo findings; it does not grow upstream of the injury site and covers the whole injury from the first seconds of the formation. А simplified model, in which GPIb-mediated interaction is deterministic, does not reproduce these features. Thus, the stochasticity of platelet interactions is critical for thrombus plasticity, suggesting that interaction via a small number of bonds drives the dynamics of arterial thrombus shell.

Vascular Endothelial Damage: The Role of Syndecan-1 and Hyaluronan as Severity Indicators in COVID-19

SARS-CoV-2 was firstly found in bronchoalveloar lavage (BAL) of three suspected COVID-19 patients at Jinyintan Hospital, Wuhan, Hubei Province, China. The cases are still raisingwith2,12% global mortality rate. Hypoxic respiratory failure due to acute respiratory distress syndrome (ARDS) is the main cause of COVID-19 death. Endothelial cell damage has an important role in the pathogenesis of ARDS and multi-organ dysfuntion of COVID-19 patients. The endothelium is protected by mural cells, which keep vascular integrity. Inflammation is prevented by these cells by inhibiting the interaction of immune cells and platelets with endothelial cells. These cells also prevent coagulation by producing glycocalyx, coagulation inhibitors, and blood-clotting enzyme. Vascular glycocalyx has an important role to maintain endothelial function and is disrupted systemically in elderly and patients with various comorbidities, which can be a probable mechanism for the serious complications of COVID-19. Glycocalyx disruption in severe and critical COVID-19 patients causes increased levels of its components such assyndecan-1 and hyaluronan in the serum. Previous studies showed the significant increase ofsyndecan-1 and hyaluronan levels in septic, and severe Kawasaki and dengue patients. These biomarkers are also markers of organ damage. Therefore, hyaluronan and syndecan-1can be significant prognostic factors for morbidity and survival in patients with COVID-19.

Взаимодействие тромбоцитов, фактора фон Виллебранда и лейкоцитов в цельной крови при высоких скоростях сдвига опосредовано GPIIb/IIIa тромбоцитов

Взаимодействие тромбоцитов, фактора фон Виллебранда и лейкоцитов в цельной крови при высоких скоростях сдвига опосредовано GPIIb/IIIa тромбоцитов

Importance of Platelet - Endothelial Cell Interaction during Postoperative Liver Regeneration

Introduction: Interleukin-6 (IL-6) is a well-known regulator of liver regeneration, specifically during the early period. Within this project, we wanted to identify the time course of IL-6 production within the human liver during the early phase of liver regeneration as a result of the potential interaction of platelets and liver sinusoidal endothelial cells (LSECs).

Endothelial Activation and Immune Thrombocytopenia: An Engagement Waiting for Consolidation.

Immune thrombocytopenia (ITP) appears to be a heterogeneous disease. In some patients, autoimmunity may be associated with an inflammatory process, and in other patients, low platelets may interfere with other aspects of the coagulation system. Either may predispose to thrombosis or bleeding. Further investigation of the interactions of platelets, with inflammatory cytokines and endothelial biomarkers, may help us to better understand the disease, and to recognize those patients at risk of bleeding, or conversely thrombosis. The aim of this work is to estimate von Willebrand factor (vWF) and vascular cellular adhesion molecule (V-CAM) serum levels in adult immune thrombocytopenic patients (ITP) and to decipher their possible clinical correlates. Eighty adults (≥ 18 years) were enrolled in the study; naive newly diagnosed 40 patients with primary ITP (according to the ASH 2019) and 40 sex and age-matched healthy controls, all groups are subjected for complete blood count (CBC), liver, and renal function tests, ESR, CRP, V-CAM, and VWF-Ag by enzyme-linked immunosorbent assay (ELISA). There was a highly statistically significant difference between case and control as regards to the mean level of VWF-Ag and V-CAM. vWF and V-CAM could serve as biomarkers for endothelial alterations and should be investigated as a predictor of thrombocytopenic bleeding and tailor patient management accordingly.

Hemostasis – compendium for students

Hemostasis is one of many well-known systems that ensure a constant conditions of the organism's internal environment. This process is usually divided into two main stages: coagulation and fibrinolysis. Both of them occur simultaneously and under physiological conditions they are in dynamic equilibrium. There are primary and secondary hemostasis. The primary hemostasis leads to the formation a platelet clot that forms almost directly after a blood vessel has been ruptured. In the other hand, the secondary hemostasis is the activation of coagulation, which leads to the strengthening of the platelet plug through the fibrin network formation as a result of the polymerization of the soluble plasma protein fibrinogen. The key role in hemostasis plays the interaction of platelets – which are the smallest non nucleated blood cells that are formed from the cytoplasm of megakaryocytes, and plasma coagulation factors with vascular endothelial cells and subendothelial tissues. In this report it is decribed the process of physiological hemostasis, especially the newer concept of blood coagulation.

Towards the Therapeutic Use of Thrombospondin 1/CD47 Targeting TAX2 Peptide as an Antithrombotic Agent.

TSP-1 (thrombospondin 1) is one of the most expressed proteins in platelet α-granules and plays an important role in the regulation of hemostasis and thrombosis. Interaction of released TSP-1 with CD47 membrane receptor has been shown to regulate major events leading to thrombus formation, such as, platelet adhesion to vascular endothelium, nitric oxide/cGMP (cyclic guanosine monophosphate) signaling, platelet activation as well as aggregation. Therefore, targeting TSP-1:CD47 axis may represent a promising antithrombotic strategy. Approach and Results: A CD47-derived cyclic peptide was engineered, namely TAX2, that targets TSP-1 and selectively prevents TSP-1:CD47 interaction. Here, we demonstrate for the first time that TAX2 peptide strongly decreases platelet aggregation and interaction with collagen under arterial shear conditions. TAX2 also delays time for complete thrombotic occlusion in 2 mouse models of arterial thrombosis following chemical injury, while Thbs1-/- mice recapitulate TAX2 effects. Importantly, TAX2 administration is not associated with increased bleeding risk or modification of hematologic parameters. Overall, this study sheds light on the major contribution of TSP-1:CD47 interaction in platelet activation and thrombus formation while putting forward TAX2 as an innovative antithrombotic agent with high added-value.

Features of pathogenetic mechanisms of the interaction of viruses and platelets in patients with immune thrombocytopenia (review of literature)

Annotation. One of the urgent interdisciplinar problems of modern medicine is to study the mechanisms of development of virus-induced thrombocytopenia in patients. The aim is to sum up current knowledge of viruses and platelets interaction, how viruses affect platelet and modulate adaptive immune response. A systematic review of the articles in the Pub Med database was conducted between 2007 and 2020, using search terms: platelets, thrombocytopenia, viral infection. Current data on the study of the mechanisms of platelet interaction with different types of viruses in immune thrombocytopenia in children were analyzed. We studied activation of platelets by a viral infection and how the immune response works. We know that the immune response is a cyclic multistage process involving T-lymphocytes, B-lymphocytes, macrophages, cytokines, Nk-cells. Antiplatelet antibodies are increase platelet clearance from the blood. The combination of antibodies with platelets leads to phagocytosis. In patients with immune thrombocytopenia ІgG antibodies are produced against GP/ІІ b/ІІІ or GP/І b/ІХ glycoproteins located on the platelet surface. In this situation it is possible to produce antibodies of other subclasses of ІgG, also a complement of fixing Іg G, rarelyІg А to other glycoprotein, or to other complexes Іb ІХ, Іа/ІІа. Since megakaryocytes express glycoprotein ІІb/ІІІа, Ів as well as other platelet antigens, they become a target for autoantibodies. Viruses can interact directly with platelets and megakaryocytes. In addition, platelets can be activated by viral antigen-antibody complexes and B- lymphocytes can produce antiplatelet antibodies. All of these processes are activate platelets and lead to increased consumption and remove of platelets, this causes hemorrhagic manifestation in patients.

Hemocompatibility poly (lactic acid) nanostructures: A bird’s eye view

The usage of clinical devices in the cardiovascular treatment, hemodialyze system and other biomedical applications has improved recently. Direct contacts of biomaterials like poly(lactic acid) biopolymer with blood result in the activating of platelets, white blood cells , coagulation structure and complement cascades. Poly(lactic acid) is a sustainable, renewable, compostable, biobased, biodegradable, bioabsorbable , biocompatible polymer. This polymer has many applications in the synthesis of blood contacting mats like nanofibrous vascular scaffolds and hemodialyze nanosheets.Mechanical interruption of the blood vessel wall throughout grafting of cardiovascular devices starts local hemostatic replies. Improving the safety of the blood contacting nanostructure grafts is a main necessity. The controlling of the interactions of proteins and platelets to the surface of a blood contacting biomaterial is a significant factor. So, the assessments of these material’s influences on blood are necessary.This article references more than 80 articles published in the last decade and reviews the latest hemocompatibility assays of poly(lactic acid) nanostructures used in the blood contacting field.

Emicizumab Augments Thrombus Formation in Whole Blood from Patients with Hemophilia A under High Shear Flow Conditions.

Emicizumab is a bispecific antibody to factor (F) IXa and FX that mimics the FVIIIa cofactor function. Emicizumab prophylaxis markedly decreases bleeding episodes in patients with hemophilia A (PwHAs), irrespective of the presence of FVIII inhibitors. However, thrombotic microangiopathy (TMA) was reported when repeated high doses of activated prothrombin complex concentrates (aPCC) were concomitantly used with emicizumab. Although bypassing agents (BPAs) are vital in the hemostatic treatment for PwHAs with inhibitors, the mechanism of emicizumab-related TMA remains unclear. To assess the risk of excessive thrombus formation associated with BPAs and emicizumab under high shear conditions. Perfusion flow-chamber experiments under high shear conditions were performed using whole blood from PwHAs in the presence of emicizumab without or together with FVIII or BPAs ex vivo. Emicizumab (100 μg/mL) added ex vivo to whole blood from PwHAs improved defective thrombus formation in a similar manner to that observed with the addition of recombinant FVIII at the early phase, while FVIII continued to be important at the later stages. aPCC (1.2 U/mL equivalent to 100 U/kg) or recombinant FVIIa (1.1 µg/mL; equivalent to 90 µg/kg) together with emicizumab further promoted platelet interactions and fibrin formation ex vivo but did not induce excessive thrombus formation. Emicizumab enhanced thrombin generation at local sites and improved defective hemostasis in whole blood from PwHAs under high shear conditions. Simple concomitant use of BPAs with emicizumab did not mediate excessive thrombus formation and remains an option for hemostatic management of emicizumab-treated PwHAs with inhibitors.

Characterization of Integrin αIIbβ3-Mediated Outside-in Signaling by Protein Kinase Cδ in Platelets.

Engagement of integrin αIIbβ3 promotes platelet–platelet interaction and stimulates outside-in signaling that amplifies activation. Protein kinase Cδ (PKCδ) is known to play an important role in platelet activation, but its role in outside-in signaling has not been established. In the present study, we determined the role of PKCδ and its signaling pathways in integrin αIIbβ3-mediated outside-in signaling in platelets using PKCδ-deficient platelets. Platelet spreading to immobilized fibrinogen resulted in PKCδ phosphorylation, suggesting that αIIbβ3 activation caused PKCδ activation. αIIbβ3-mediated phosphorylation of Akt was significantly inhibited in PKCδ -/- platelets, indicating a role of PKCδ in outside-in signaling. αIIbβ3-mediated PKCδ phosphorylation was inhibited by proline-rich tyrosine kinase 2 (Pyk2) selective inhibitor, suggesting that Pyk2 contributes to the regulation of PKCδ phosphorylation in outside-in signaling. Additionally, Src-family kinase inhibitor PP2 inhibited integrin-mediated Pyk2 and PKCδ phosphorylation. Lastly, platelet spreading was inhibited in PKCδ -/- platelets compared to the wild-type (WT) platelets, and clot retraction from PKCδ -/- platelets was markedly delayed, indicating that PKCδ is involved in the regulation of αIIbβ3-dependent interactivities with cytoskeleton elements. Together, these results provide evidence that PKCδ plays an important role in outside-in signaling, which is regulated by Pyk2 in platelets.