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Related Concept Videos

Extrinsic and Intrinsic Pathways of Hemostasis01:20

Extrinsic and Intrinsic Pathways of Hemostasis

Blood clotting or coagulation involves extrinsic and intrinsic pathways, which ultimately merge into the common pathway, forming a fibrin clot.
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which forms a...
Anticoagulant Drugs: Low-Molecular-Weight Heparins01:30

Anticoagulant Drugs: Low-Molecular-Weight Heparins

Hemostasis is a crucial process that prevents excessive blood loss from damaged blood vessels. It involves various mechanisms such as vasoconstriction, platelet adhesion and activation, and fibrin formation. The importance of each mechanism depends on the type of vessel injury. In contrast, thrombosis is the abnormal formation of a blood clot within the blood vessels, leading to potential complications if the clot obstructs blood flow. Thrombosis can be caused by increased coagulability of the...
Formation of the Platelet Plug01:22

Formation of the Platelet Plug

The platelet phase, the second stage of hemostasis, commences around 15-20 seconds after an injury. It follows and overlaps with the vascular phase, during which blood vessels constrict to minimize blood loss.
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
Clot Retraction and Fibrinolysis01:16

Clot Retraction and Fibrinolysis

After a fibrin clot is formed, the next step is clot retraction, a vital process facilitated by platelet contractile proteins, such as actin and myosin. These proteins pull the fibrin strands closer together and condense the clot. This action reduces the size of the clot, creating a smaller, denser structure that effectively seals off the damaged vessel. Clot retraction consolidates the clot and helps with wound healing by bringing the edges of the damaged blood vessel closer together.
Coagulation01:09

Coagulation

The coagulation phase is a critical part of the body's process to prevent blood loss following injury to blood vessels. It involves chemical reactions that form a clot to seal the injured area. The clotting process begins shortly after injury, within 15-20 seconds for severe damage and 1-2 minutes for minor injuries.
During the coagulation phase, clotting factors, or procoagulants, play a vital role in initiating and progressing the coagulation cascade. This cascade is a series of reactions...
Anticoagulant Drugs: Vitamin K Antagonists and Direct Oral Anticoagulants01:18

Anticoagulant Drugs: Vitamin K Antagonists and Direct Oral Anticoagulants

Oral anticoagulants are vital tools in preventing and treating blood clotting disorders. This diverse class of medications can be categorized as vitamin K antagonists, exemplified by warfarin, and direct thrombin inhibitors (DTIs), such as dabigatran, as well as factor Xa inhibitors, including rivaroxaban.
Warfarin, a prominent vitamin K antagonist family member, exerts its effect by inhibiting the enzyme VKORC1 (vitamin K epoxide reductase complex 1). By hindering this enzyme, warfarin...

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Related Experiment Video

Updated: May 24, 2026

Flow Cytometry Analysis of Tissue Factor Expression in Human Platelets
10:08

Flow Cytometry Analysis of Tissue Factor Expression in Human Platelets

Published on: November 22, 2024

Platelet tissue factor pathway inhibitor modulates intravascular coagulation.

Susan A Maroney1, Alan E Mast

  • 1Blood Research Institute, Blood Center of Wisconsin, Milwaukee, WI 53201-2178, USA. susan.maroney@bcw.edu

Thrombosis Research
|March 20, 2012
PubMed
Summary

Platelet tissue factor pathway inhibitor (TFPI) is released upon activation and inhibits clot formation. This finding highlights TFPI

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A Microfluidic Flow Chamber Model for Platelet Transfusion and Hemostasis Measures Platelet Deposition and Fibrin Formation in Real-time

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Ferric Chloride-induced Murine Thrombosis Models
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Ferric Chloride-induced Murine Thrombosis Models

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Flow Cytometry Analysis of Tissue Factor Expression in Human Platelets
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A Microfluidic Flow Chamber Model for Platelet Transfusion and Hemostasis Measures Platelet Deposition and Fibrin Formation in Real-time
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A Microfluidic Flow Chamber Model for Platelet Transfusion and Hemostasis Measures Platelet Deposition and Fibrin Formation in Real-time

Published on: February 14, 2017

Ferric Chloride-induced Murine Thrombosis Models
10:37

Ferric Chloride-induced Murine Thrombosis Models

Published on: September 5, 2016

Area of Science:

  • Hemostasis and Thrombosis
  • Platelet Biology
  • Coagulation Cascade Regulation

Background:

  • Tissue factor pathway inhibitor (TFPI) is a key regulator of the extrinsic coagulation pathway.
  • Platelets store TFPI internally but not in alpha-granules.
  • TFPI release and function on activated platelets are not fully understood.

Purpose of the Study:

  • To investigate the release and functional role of platelet-derived TFPI in hemostasis.
  • To characterize the specific TFPI isoform expressed by activated platelets.
  • To determine the contribution of platelet TFPI to clot formation and regulation.

Main Methods:

  • Platelet activation assays using thrombin and collagen.
  • Soluble and surface-expressed TFPI detection.
  • In vitro inhibition assays of Factor Xa (FXa) generation.
  • Murine vascular injury model to assess clot formation in vivo.

Main Results:

  • Platelet TFPI is released in soluble form and expressed on the surface after dual activation with thrombin and collagen.
  • Platelet TFPI is exclusively the TFPIα isoform.
  • Platelet TFPIα demonstrated physiological activity in inhibiting TF-initiated FXa generation in vitro.
  • Local administration of platelet TFPI dampened clot growth in a murine vascular injury model.

Conclusions:

  • Platelet-derived TFPI, specifically TFPIα, is released upon activation and actively modulates tissue factor activity.
  • Platelet TFPI plays a crucial role in locally regulating clot growth, preventing occlusive thrombus formation.
  • These findings reveal a significant role for platelets in TFPI-mediated anticoagulation within a developing clot.