Role of thrombin to non-physiological shear stress induced platelet activation and function alternation

A Biophysics-Based Mathematical Model of Shear-Induced Platelet Activation and Receptor Shedding: Re-Examining Previous Experimental Data

The power-law model, originally developed for shear-induced hemolysis, has been used to predict shear-induced platelet activation and receptor shedding. However, its empirical nature lacks mechanistic explanations and violates physical reality by not imposing an upper limit, often leading to inaccuracies. Recent studies suggest that the mechanical pulling of platelet GPIb-IX complex triggers the unfolding of its mechanosensitive domain, a crucial process to platelet activation, which can be explained by Bell's model of bond unbinding under force. Motivated by these findings, we propose a novel mathematical model for shear-induced platelet activation (P-selectin) and shear-induced platelet receptor (glycoprotein Ibα [GPIbα], GPVI, and GPIIb/IIIa) shedding based on the principle of bond unbinding. The model was examined using experimental data from previous studies in which blood samples were exposed to different combinations of constant shear stress and exposure time. The new model demonstrated an excellent fit with experimental data with an overall coefficient of determination R2 >0.8, mapping the trends in platelet activation and receptor shedding (except for GPIIb/IIIa) across a range of shear conditions. This new model not only addresses the intrinsic upper bound error in the power-law model but also provides a theoretical foundation into blood damage under shear stress.

Effect of Oxidative Stress on Mitochondrial Damage and Repair in Heart Disease and Ischemic Events

The literature analysis conducted in this review discusses the latest achievements in the identification of cardiovascular damage induced by oxidative stress with secondary platelet mitochondrial dysfunction. Damage to the platelets of mitochondria as a result of their interactions with reactive oxygen species (ROS) and reactive nitrogen species (RNS) can lead to their numerous ischemic events associated with hypoxia or hyperoxia processes in the cell. Disturbances in redox reactions in the platelet mitochondrial membrane lead to the direct oxidation of cellular macromolecules, including nucleic acids (DNA base oxidation), membrane lipids (lipid peroxidation process) and cellular proteins (formation of reducing groups in repair proteins and amino acid peroxides). Oxidative changes in biomolecules inducing tissue damage leads to inflammation, initiating pathogenic processes associated with faster cell aging or their apoptosis. The consequence of damage to platelet mitochondria and their excessive activation is the induction of cardiovascular and neurodegenerative diseases (Parkinson's and Alzheimer's), as well as carbohydrate metabolism disorders (diabetes). The oxidation of mitochondrial DNA can lead to modifications in its bases, inducing the formation of exocyclic adducts of the ethano and propano type. As a consequence, it disrupts DNA repair processes and conduces to premature neoplastic transformation in critical genes such as the p53 suppressor gene, which leads to the development of various types of tumors. The topic of new innovative methods and techniques for the analysis of oxidative stress in platelet mitochondria based on methods such as a nicking assay, oxygen consumption assay, Total Thrombus formation Analysis System (T-Tas), and continuous-flow left ventricular assist devices (CF-LVADs) was also discussed. They were put together into one scientific and research platform. This will enable the facilitation of faster diagnostics and the identification of platelet mitochondrial damage by clinicians and scientists in order to implement adequate therapeutic procedures and minimize the risk of the induction of cardiovascular diseases, including ischemic events correlated with them. A quantitative analysis of the processes of thrombus formation in cardiovascular diseases will provide an opportunity to select specific anticoagulant and thrombolytic drugs under conditions of preserved hemostasis.

In vitro study on device-induced damage to blood cellular components and degradation of von Willebrand factor in a CentriMag pump-assisted circulation

BACKGROUND

High mechanical shear stress (HMSS) generated by blood pumps during mechanical circulatory support induces blood damage (or function alteration) not only of blood cell components but also of plasma proteins.

METHODS

In the present study, fresh, healthy human blood was used to prime a blood circuit assisted by a CentriMag centrifugal pump at a flow rate of 4.5 L/min under three pump pressure heads (75, 150, and 350 mm Hg) for 4 h. Blood samples were collected for analyses of plasma-free hemoglobin (PFH), von Willebrand factor (VWF) degradation and platelet glycoprotein (GP) IIb/IIIa receptor shedding.

RESULTS

The extent of all investigated aspects of blood damage increased with increasing cross-pump pressure and duration. Loss of high-molecular-weight multimers (HMWM)-VWF in Loop 2 and Loop 3 significantly increased after 2 h. PFH, loss of HMWM-VWF, and platelet GPIIb/IIIa receptor shedding showed a good linear correlation with mean shear stress corresponding to the three pump pressure heads.

CONCLUSIONS

HMSS could damage red blood cells, cause pathological VWF degradation, and induce platelet activation and platelet receptor shedding. Different blood components can be damaged to different degrees by HMSS; VWF and VWF-enhanced platelet activation may be more susceptible to HMSS.

Discovery and Characterization of Panaxatriol as a Novel Thrombin Inhibitor from Panax notoginseng Using a Combination of Computational and Experimental Approaches

Thrombin is a crucial enzyme in the coagulation cascade, and inhibitors of thrombin have been extensively studied as potential antithrombotic agents. The objective of this study was to identify natural inhibitors of thrombin from Panax notoginseng and evaluate their biological activity in vitro and binding characteristics. A combined approach involving molecular docking, thrombin inhibition assays, surface plasmon resonance, and molecular dynamics simulation was utilized to identify natural thrombin inhibitors. The results demonstrated that panaxatriol directly inhibits thrombin, with an IC50 of 10.3 µM. Binding studies using surface plasmon resonance revealed that panaxatriol interacts with thrombin, with a KD value of 7.8 µM. Molecular dynamics analysis indicated that the thrombin-panaxatriol system reached equilibrium rapidly with minimal fluctuations, and the calculated binding free energy was - 23.8 kcal/mol. The interaction between panaxatriol and thrombin involves the amino acid residues Glu146, Glu192, Gly216, Gly219, Tyr60A, and Trp60D. This interaction provides a mechanistic basis for further optimizing panaxatriol as a thrombin inhibitor. Our study has shown that panaxatriol serves as a direct thrombin inhibitor, laying the groundwork for further research and development of novel thrombin inhibitors.

Dual-targeting fucoidan-based microvesicle for arterial thrombolysis and re-occlusion inhibition

Arterial thrombosis is a critical thrombotic disease that poses a significant threat to human health. However, the existing clinical treatment of arterial thrombosis lacks effective targeting and precise drug release capability. In this study, we developed a system for targeted delivery and on-demand release in arterial thrombosis treatment. The carrier was constructed using chitosan (CS) and fucoidan (Fu) through layer-by-layer assembly, with subsequent surface modification using cRGD peptide. Upon encapsulation of urokinase-type plasminogen activator (uPA), the resulting therapeutic drug delivery system, uPA-CS/Fu@cRGD, demonstrated dual-targeting abilities towards P-selectin and αIIbβ3, as well as pH and platelet-responsive release properties. Importantly, we have demonstrated that the dual targeting effect exhibits higher targeting efficiency at shear rates simulating thrombosed arterial conditions (1800 s-1) compared to single targeting for the first time. In the mouse common iliac artery model, uPA-CS/Fu@cRGD exhibited great thrombolytic capability while promoting the down-regulation of coagulation factors (FXa and PAI-1) and inflammatory factors (TNF-α and IL-6), thus improving the thrombus microenvironment and exerting potential in preventing re-occlusion. Our dual-target and dual-responsive, fucoidan-based macrovesicle represent a promising platform for advanced drug target delivery applications, with potential to prevent coagulation tendencies as well as improving thrombolytic and reducing the risk of re-occlusion.

Malus baccata (Linn.) Borkh polyphenols-loaded nanoparticles ameliorate intestinal health by modulating intestinal function and gut microbiota

The aim of this study was to construct the nanoparticles based on Hohenbuehelia serotina polysaccharides and mucin for encapsulation of the polyphenols from Malus baccata (Linn.) Borkh (MBP-MC-HSP NPs), and investigate their effects on intestinal function and gut microbiota in mice. The results showed that MBP-MC-HSP NPs did not have any toxic and side effect by determining organ indexes and hematological parameters. The colonic index, colonic length as well as colonic histology were significantly improved by treatment of MBP-MC-HSP NPs. Moreover, MBP-MC-HSP NPs could increase the fecal moisture (84.71 %) and accelerate the intestinal peristalsis (77.87 %), thus reducing the defecation time (1.68 h) of mice at certain extent. Through production of acetic acid, propionic acid and n-butyric acid, MBP-MC-HSP NPs remarkably decreased the pH of colonic feces to maintain intestinal health. 16S rRNA sequencing analysis showed that MBP-MC-HSP NPs could improve the abundances of Lactobacillus, Butyicicoccus and Ruminococcus and suppress the richness of Prevotella, Bifidobacterium and Desulfovibrio, thereby optimizing the structure and composition of gut microbiota. Furthermore, the metabolic profiles of gut microbiota were influenced by MBP-MC-HSP NPs based on prediction of KEGG and COG databases. Overall, this study suggests that MBP-MC-HSP NPs can be developed and utilized as probiotics in the nutritional food field.

Deep Vein Thrombosis Is Facilitated by Endothelial-Derived Extracellular Vesicles via the PDI-GRP94-GPIIb/IIIa Pathway in Mice

AIMS

Deep vein thrombosis (DVT) is a prevalent cardiovascular condition. Endothelial-derived extracellular vesicles (EVs) may play a crucial role in platelet-dependent DVT development via platelet activation, but the mechanism is not clear yet. This research aims to understand how platelets and endothelial-derived EVs work in DVT.

METHODS

The interaction between protein disulfide isomerase (PDI) and glucose-regulated protein 94 (GRP94) was founded by molecular docking. Inferior vena cava stasis-induced mice received PDI and GRP94 inhibitor treatments. Platelet activation, endothelial-derived EVs, and PDI were measured using flow cytometry. The expression of PDI and dimetric GRP94 in platelets co-cultured with hypoxic endothelial cells was confirmed by Western blot or native PAGE. The fluorescence resonance energy transfer assay shows conformational changes in GPIIb/IIIa on platelet surfaces. A tracking experiment was performed using PKH26, which labelled endothelial-derived EVs, and the endocytosis of EVs by platelets was tracked by confocal microscope.

RESULTS

In a DVT mouse model, platelets enhance venous thrombus formation in a coagulation-independent manner, instead, platelet activation and the length of the thrombus are related to PDI and GRP94 activity. Next, we found that the expression level of endothelial-derived EVs carrying PDI is significantly increased in plasma. Endothelial-derived EVs carrying PDI are endocytosed by platelets, in which the content of GRP94 dimer is elevated, and consequently increases the expression of surface GPIIb/IIIa. In addition, PDI allosterically interacts with GPIIb/IIIa, which is re-configurated into an activated form.

CONCLUSION

Endothelial-derived EVs carrying PDI induce DVT via interplay with GRP94 and GPIIb/IIIa in platelets. These findings emphasize the significance of platelets in DVT formation, and PDI may be a suitable target in DVT prevention.

The role of biomechanical stress in extracellular vesicle formation, composition and activity

Extracellular vesicles (EVs) are cornerstones of intercellular communication with exciting fundamental, clinical, and more broadly biotechnological applications. However, variability in EV composition, which results from the culture conditions used to generate the EVs, poses significant fundamental and applied challenges and a hurdle for scalable bioprocessing. Thus, an understanding of the relationship between EV production (and for clinical applications, manufacturing) and EV composition is increasingly recognized as important and necessary. While chemical stimulation and culture conditions such as cell density are known to influence EV biology, the impact of biomechanical forces on the generation, properties, and biological activity of EVs remains poorly understood. Given the omnipresence of these forces in EV preparation and in biomanufacturing, expanding the understanding of their impact on EV composition-and thus, activity-is vital. Although several publications have examined EV preparation and bioprocessing and briefly discussed biomechanical stresses as variables of interest, this review represents the first comprehensive evaluation of the impact of such stresses on EV production, composition and biological activity. We review how EV biogenesis, cargo, efficacy, and uptake are uniquely affected by various types, magnitudes, and durations of biomechanical forces, identifying trends that emerge both generically and for individual cell types. We also describe implications for scalable bioprocessing, evaluating processes inherent in common EV production and isolation methods, and propose a path forward for rigorous EV quality control.