Name: Video: Isolation of Extracellular Vesicle (EV)-Rich Plasma from Human Blood and Detection of Activated Clotting Time
Uploaded: 2023-08-04T13:40:00
Description: 85 Views. Isolation of Extracellular Vesicle (EV)-Rich Plasma from Human Blood and Detection of Activated Clotting Time

isolation of extracellular vesicle (ev)-rich plasma from human blood and detection of activated clotting time

Assessing Blood Hypercoagulation of EV-Rich Plasma

Thrombosis, which is caused by hypercoagulability, plays a significant role in various diseases, including brain trauma1, pre-eclampsia2, tumors3, and fracture patients4. The mechanism underlying hypercoagulability is complex, and recent emphasis has been placed on the role of extracellular vesicles (EV) in coagulation disorders. EVs are vesicle-like bodies with a bilayer structure that detach from the cell membrane, ranging in diameter from 10 nm to 1000 nm. They are associated with a variety of disease processes, particularly coagulation disorders5. Several studies have identified EVs as a promising predictor of thrombosis risk6,7. The procoagulant activity of EVs depends on the expression of coagulation factors, primarily tissue factor (TF) and phosphatidylserine (PS). EVs with robust procoagulant activity significantly enhance the catalytic efficiency of tenase and prothrombin complex, thereby promoting thrombin-mediated fibrinogen and local thrombosis8. Elevated levels of EVs and their causal relationship with hypercoagulability have been observed in numerous diseases9. Consequently, standardizing the detection of EVs and reporting their procoagulant activity is an important area of investigation10.
To date, only a few commercial kits are available for detecting the procoagulant activity of EVs. The MP-Activity assay and the MP-TF assay, produced by a commercial company, are functional assays used to measure EV&#39;s procoagulant activity in plasma11. These assays employ a principle similar to that of enzyme-linked immunosorbent assays to detect PS and TF on EVs. However, these kits are expensive and limited to a few high-level research institutions. The process is complex and time-consuming, making it challenging to implement them in clinical settings. Additionally, a commercially developed procoagulant phospholipid (PPL) assay mixes PS-free plasma with test plasma, measuring clotting time to quantitatively detect levels of PS-positive EVs12. However, these assays primarily focus on PS and TF on EVs, overlooking other clotting pathways that circulating EVs may be involved in12.
The plasma coagulation system is intricate and comprises both &#34;invisible&#34; and &#34;visible&#34; components, including coagulants, anticoagulants, fibrinolytic systems, and EVs suspended in the plasma. Physiologically, these components maintain a dynamic balance. In pathological conditions, significantly increased EVs in circulation contribute to hypercoagulability, particularly in patients with brain trauma, preeclampsia, fractures, and various types of cancer13. Currently, the evaluation of coagulation status in clinical laboratories primarily involves assessing the coagulation system, anticoagulation system, and fibrinolysis14,15,16,17. Prothrombin time, activated partial thromboplastin time, thrombin time, and international normalized ratio are commonly used to evaluate coagulation factor levels in the coagulation system18. However, recent studies have revealed that these tests do not fully reflect the hypercoagulability of certain diseases19. Other assay methods, such as thromboelastometry (TEG), rotational TEG, and Sonoclot analysis, measure whole-blood viscoelastic changes20,21. Since whole blood samples contain numerous blood cells and platelets, these tests are more likely to indicate the clotting status of the sample as a whole. Some researchers have reported on the role of blood cells and platelets in procoagulant activity22,23. A recent study also discovered that previous coagulation function tests face difficulties in detecting changes in microparticles&#39; procoagulant activity24. Therefore, a hypothesis has been proposed that the procoagulant function of EVs can be evaluated by viscoelastic measurements of the activated clotting time (ACT) in EV-rich plasma.

Author Spotlight: Deciphering Coagulation Disorders in Traumatic Brain Injury Patients 

Determination of the Procoagulant Activity of Extracellular Vesicle (EV) Using EV-Activated Clotting Time (EV-ACT)

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Isolation of Extracellular Vesicle (EV)-Rich Plasma from Human Blood and Detection of Activated Clotting Time   

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85 Views. Isolation of Extracellular Vesicle (EV)-Rich Plasma from Human Blood and Detection of Activated Clotting Time

Video: Isolation of Extracellular Vesicle (EV)-Rich Plasma from Human Blood and Detection of Activated Clotting Time   

The role of extracellular vesicles (EV) in various diseases is gaining increased attention, particularly due to their potent procoagulant activity. However, there is an urgent need for a bedside test to assess the procoagulant activity of EV in clinical settings. This study proposes the use of thrombin activation time of EV-rich plasma as a measure of EV's procoagulant activity. Standardized procedures were employed to obtain sodium-citrated whole blood, followed by differential centrifugation to obtain EV-rich plasma. The EV-rich plasma and calcium chloride were added to the test cup, and the changes in viscoelasticity were monitored in real-time using an analyzer. The natural coagulation time of EV-rich plasma, referred to as EV-ACT, was determined. The results revealed a significant increase in EV-ACT when EV was removed from plasma obtained from healthy volunteers, while it significantly decreased when EV was enriched. Furthermore, EV-ACT was considerably shortened in human samples from preeclampsia, hip fracture, and lung cancer, indicating elevated levels of plasma EV and promotion of blood hypercoagulation. With its simple and rapid procedure, EV-ACT shows promise as a bedside test for evaluating coagulation function in patients with high plasma EV levels.

This protocol investigates the use of extracellular vesicle (EV)-rich plasma as an indicator of the coagulative ability of EV. EV-rich plasma is obtained through a process of differential centrifugation and subsequent recalcification.

The role of extracellular vesicles (EV) in various diseases is gaining increased attention, particularly due to their potent procoagulant activity. ...