Trapped! Flow studies reveal Thrombosis target
At Cellix, we take our hats off to our academic colleagues who are creating experimental methodologies that drive learning and new discoveries. Thrombosis has always been a key application of our VenaFlux Solutions and this year has been no exception. With COVID-19 at the centre of our lives, the link between COVID-19 and thrombosis has also been at the centre of our customers' research.
But thrombosis has been affecting lives long before COVID-19. So today, as part of World Thrombosis Day, we asked the Cellix team to select one recent paper that encompasses clever design, innovative use of microfluidics and which, in their opinion, was particularly significant for thrombosis research and potential new treatments.
The paper selected is from Prof. Jim Crawley's group at Imperial College London in collaboration with the University of Cambridge, published in eLife, April 2020:
Activated αIIbβ3 on platelets mediates flow-dependent NETosis via SLC44A2
The researchers of this study focused on how recruited platelets interact with neutrophils and whether this promotes the onset of Deep Vein Thrombosis (DVT). Results of this study suggest that blocking the interaction between ‘primed’ platelets and neutrophils could reduce the risk of DVT. Drugs targeting a receptor on the surface of neutrophils called SLC44A2, could inhibit inappropriate clotting without causing excess bleeding, essentially preventing these so-called neutrophil extracellular traps.
It's an extensive piece of work (a 32-pager!) but well worth the read and if you're thinking about doing similar studies, we encourage you to take a closer look at this paper as it overcomes some of the challenges with whole blood studies which are often overlooked - see below.
The researchers used Cellix's VenaFlux Solution (Mirus pump, Vena8 Fluoro+ biochips and VenaDeltaY2 biochips) to mimic the flow of blood to study how human platelets change when they are exposed to Von Willebrand Factor (VWF). This revealed that VWF 'primes' the platelets to interact with neutrophils via a protein called integrin αIIbβ3.
Vena8 Fluoro+ microchannels were coated with full-length VWF (FL-VWF; i-iii). Whole blood labeled with DiOC6 was perfused at 1000 s−1. Representative images of platelets (green) after 30, 90 and 180 s are shown. Scale; 50 μm.
Further experiments show that this integrin binds to a protein on the surface of neutrophils called SLC44A2. Once the neutrophils interacted with the 'primed' platelets, they started making traps which increased the size of the blood clot by capturing other blood cells and proteins. It was also shown that under flow, this interaction transduces a signal into neutrophils capable of driving NETosis (neutrophil cell death characterised by extracellular expulsion of DNA). Giving rise to their findings, the researchers studied a genetic variant of the SLC44A2 protein which is found in 22% of people and is associated with a lower risk of developing DVT. This genetic mutation caused SLC44A2 to interact with ‘primed’ platelets more weakly, which may explain why people with this genetic variant are protected from getting DVT.
(a) Relative neutrophil binding after 15min of leukocyte perfusion at 50 s-1 to activated αIIbβ3 captured and activated by LIBS2/anti-Beta3, activating antibody in the presence and absence of increasing concentrations of anti-SLC44A2 #1 or #2 antibodies.
(b) Neutrophils bound to activated αIIbβ3: i) in the absence of antibody, ii) in the presence of control IgG and iii) in the presence of anti-SLC44A2 #1
VenaFlux Solutions overcomes challenges of Whole Blood Thrombosis Studies:
1. Low Sample Volume: a vacutainer of blood is not a lot to work with particularly if the study is focused on high blood flow / high shear stress studies. This is particularly true if you're using mouse blood for your studies. In these cases, sample volume becomes critical.
The small microchannels of the Vena8 Fluoro+ biochips enable researchers to maximise even the smallest blood samples available to them
- even at high shear stresses / high flow rates!
2. Multiplexed Assays: VenaFlux Solutions include simple plug-and-play tubing to run 8 assays in parallel, while motorised microscope stages scan the
Vena8 Fluoro+ biochips capturing images automatically.
If you're not sure which VenaFlux Solution is right for you and would like some advice,