Platelet adhesion, aggregation, thrombi formation

THROMBOSIS

There are different types of blood clots.  A blood clot in the vein (usually leg or pelvis) is known as Deep Vein Thrombosis (DVT) and a clot that travels to the lungs is known as a Pulmonary Embolism (PE).  Together, these are known as Venous ThromboEmbolisms (VTE).  

The body uses platelets (thrombocytes) and fibrin to form a blood clot.  This usually occurs when there is an injury to a blood vessel and the formation of a blood clot is the body's way of preventing blood loss.  However, even when there is no injury to a blood vessel, blood clots may form and this is the basis of a huge area of research - understanding why and how it may be controlled.  

Platelet adhesion, aggregation and thrombi formation is an area of research which must be conducted under shear flow conditions.  

The importance of shear stress when studying thrombosis

It is important to study platelet adhesion, aggregation and thrombi formation under shear flow conditions because increased shear conditions have been shown to activate platelets, alter the cellular localization of proteins such as tissue factor (TF) and TF pathway inhibitor, and regulate gene production, [1]:

"Thrombosis occurs in a dynamic rheological field where flow conditions regulate the transport of coagulation factors, inhibitors, and cells. Hemodynamic forces regulate not only the predilection of specific anatomic sites to thrombosis but strongly influence the biochemical makeup of thrombi and the reaction pathways involved in thrombus formation."

HOW DOES IT WORK?

Platelets are small blood cells of 2–3 µm in diameter, also called thrombocytes.  Platelets perform a very important function - they help your body to form clots to stop bleeding at a blood vessel site of injury (i.e. at the damaged endothelium).  Blood clot formation is a multi-step process contributing to hemostasis:

  • Adhesion:  platelets adhere around the site of injury.  Exposed collagen and VWF anchor platelets to the subendothelium via GPIa/IIa and GPIb/IX/V receptors, respectively.  

  • Activation:  platelets change shape, cell-membrane receptors are activated resulting in cell signalling cascade

  • Aggregation:  platelets and cells aggregate through receptors.

As this platelet plug forms, the coagulation cascade kicks in and the blood changes from a liquid to a gel, forming a blood clot.

 

Key players in thrombosis:  

  • Von Willebrand Factor (VWF)

  • Collagen

  • Fibrinogen

Platelet Adhesion & Activation

 

WHAT DO I NEED TO GET STARTED?

We have solutions to suit every budget.  Our VenaFlux Solutions can customise around what you already have or we can provide a complete automated solution depending on your needs.   Click here to explore the options or for more information, see our VenaFlux Solutions page.

In general, as a minimum, you will need the following to execute thrombosis experiments:

  • Microfluidic pump: The Mirus pump delivers cell samples or whole blood at a constant or variable shear stress / shear flow rate into the microcapillaries of the biochips.  This mimics in vivo physiological shear stress.  

  • Biochips: while some researchers have their own home-made flow chambers, there ware some distinct advantages to using Cellix's biochips for thrombosis studies.  Low sample volume is often a problem as researchers work with tiny volumes drawn from mice or precious human donor samples.  This is easily overcome with Cellix's biochips which have small microcapillaries easily enabling high shear flow rates / shear stresses even with a small sample volume.

    • Vena8 Fluoro+ Biochips: coat the microcapillaries with VWF, collagen, fibrinogen or other receptor of interest.  Using the Mirus pump, you can then flow platelets or whole blood over the surface and investigate the interaction.

    • VenaDelta Y2 Biochips:  Mimic the distorted and branched path of the vascular system that cause more disturbed flow patterns, particularly around valves. Using channels with changing geometry under lower shear conditions, researchers have shown, for example, that VWF captures platelets appreciably more efficiently in areas of disturbed flow.

Platelet adhesion & aggregation in VWF-coated Vena8 Fluoro+ biochips*

Platelet and leukocyte adhesion in areas of low turbulent flow in Vena8 DeltaY2 biochips*

*Ref:  Activated αIIbβ3 on platelets mediates flow-dependent NETosis via SLC44A2

  • Temperature Control: working at the right temperature for your cells is crucial and our microenvironmental chamber for our biochips provides an excellent solution to ensure your cells are happy throughout your experiments. 

  • Microscope:  for cell imaging.  If you already have a microscope, we recommend the VenaFlux Starter.

  • Digital camera:  for image capture.  If you already have a digital camera compatible with your microscope, we recommend the VenaFlux Starter.

  • Cell analysis software:  for analysis of images or video captured.  A typical measurement for thrombosis studies includes the area coverage of the thrombi in the microcapillaries, i.e. the number of individual thrombi and aggregates are established. 

 

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RECOMMENDED PRODUCTS

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  • Mirus Evo Pump

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  • Mirus Evo Pump

  • Microenvironmental Chamber

  • Image Pro Cell Analysis Software

  • Microscope:  Zeiss AxioVert A1

  • Digital Camera:  Retiga R6

  • Dell PC with VenaFluxAssay software.

Automated microscope

The ultimate solution...

  • Mirus Evo Pump

  • Microenvironmental Chamber

  • Image Pro Cell Analysis Software

  • Microscope:  Zeiss AxioObserver 7

  • Digital Camera:  Prime BSI

  • Dell PC with VenaFluxAssay software.

 
 

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