66th Annual ISTH 2020 SSC Virtual Sessions Minutes Subcommittees Biorheology .................................................................................................. 3 Control of Anticoagulation ............................................................................ 6 Disseminated Intravascular Coagulation ...................................................... 10 Factor VIII, Factor IX and Rare Coagulation Disorders ................................ 12 Factor XIII and Fibrinogen ............................................................................ 14 Fibrinolysis ................................................................................................... 18 Genomics in Thrombosis and Hemostasis ................................................... 22 Hemostasis and Malignancy ........................................................................ 25 Lupus Anticoagulant/Phospholipid Dependent Antibodies ........................... 29 Models of Thrombosis and Hemostasis ....................................................... 34 Pediatric and Neonatal Hemostasis and Thrombosis ................................... 39 Perioperative and Critical Care Thrombosis and Hemostasis ...................... 43 Plasma Coagulation Inhibitors ...................................................................... 45 Platelet Immunology ..................................................................................... 53 Platelet Physiology………………………………………………………….…… 56 Predictive and Diagnostic Variables in Thrombotic Disease ........................ 61 Vascular Biology .......................................................................................... 63 Women’s Health Issues in Thrombosis and Hemostasis .............................. 68 SSC Joint Session: Joint Session: Perioperative and Critical Care Thrombosis and Hemostasis, DIC, and Fibrinolysis………………………………………………76 SSC Joint Session: Control of Anticoagulation & Lupus Anticoagulant/Antiphospholipid Antibodies………………..………………………………………………………...78 SSC Joint Session: Pediatric and Neonatal Thrombosis & Hemostasis, Plasma Coagulation Inhibitors, and Women’s Health Issues in Thrombosis and Hemostasis………………………………………………………………………… 89 Biorheology 9 July 2020 12:00 – 14:00 UTC 00:00 – 02:00 UTC Chair: Pierre Mangin Co-Chairs: Elizabeth Gardiner, Wilbur Lam, Mikhail Panteleev, Steve Kerrigan, David Bark and Netanel Korin Talk 1: Vascular Endothelial Cell Dysfunction During Sepsis (Steve Kerrigan, Dublin, IRL) Vascular endothelial cells play a critical role in sepsis and are believed to be a major target of pathogens during the early stages of infection. Accumulating evidence suggests that common sepsis pathogens including bacteria, fungi and viruses, all contain a critical integrin recognition motif, Arg-Gly-Asp (RGD), in their major cell wall exposed proteins that may act as ligands to cross-link to vascular endothelial cells triggering systemic dysregulation resulting in sepsis. Prof. Steve Kerrigan discussed and provided evidence that various sepsis pathogens are capable of binding to the major endothelial cell integrin V3 to cause downstream vascular dysregulation which drives the sustained and excessive sepsis response. Blocking this interaction in vitro and in vivo with a candidate drug prevented this dysregulation and is currently being tested in a preclinical trial as a first in class treatment for sepsis. Talk 2: New Scientific Standardization Committee Project on In Vitro Approach To Study Turbulence Using Small Sample Volumes (David Bark, Colorado State University, USA). Turbulence can occur in human arteries in the presence of a flow disturbance, for example valve or vessel stenosis, in atrial fibrillation, or in regions of blood-contacting medical devices. Turbulent flow is chaotic, with local pressure and velocity fluctuations leading to characteristic mixing. This is in contrast to laminar flow where fluid particles follow smoothly varying paths along laminar layers of fluid, most typical of physiological flow. Turbulence can cause haemolysis, platelet activation, and increased bleeding associated with platelet receptor shedding and acquired von Willebrand syndrome. The presentation of David Bark describes a project in which he aims to standardize terminology and characterization of unstable and turbulent flow for the field of thrombosis and haemostasis. Furthermore, he proposes an experimental tool (vortezer) that can be used to study turbulent flow with small sample sizes. Overall, the project aims to provide consistency in the study of turbulent blood. Q/A: 1) Question from Warwick Nesbitt (Australia) Given the chaotic nature of turbulent flow, how do you reduce this complexity? Answer: We can start simple, e.g. isolated red blood cells to look at haemolysis relative to simplified turbulent parameters like turbulent kinetic energy and exposure time. Also, proteins can be studied in the absence of cells. Methods also exist to simplify turbulence, i.e. create isotropic turbulence. However, these methods are hard to standardize. 2) Question from Laura Haynes (USA): Can we look at coagulation in turbulent flow systems? Answer Internet stopped working properly. Clarification from Liz Gardiner (Australia): Can geometry be controlled to generate turbulence? Answer: Temporally or spatially decelerating flow can trigger/induce turbulence. Creation of a shear layer through techniques like a cross flow can also create turbulent flow. However, for standardizing, the vortexer may be best. 3) Question from Warwick Nesbitt (Australia) Do you have experimental evidence that there is a change in soluble agonists in turbulence? Can you comment on diffusion and margination. Answer: I don’t have a definite answer from my own experiments. However, with turbulent flow, more convection occurs at the wall, which would clear agonists, reducing coagulation potential. We also think about damage caused to platelets from turbulent flow, which could lead to increased release of soluble agonists. Talk 3: Regulation of Coagulation by Flow: A Primer (Laura Haynes, Michigan, USA). Laura Haynes focused on the role of flow in the regulation of coagulation. As is well-described by Virchow’s Triad, circulatory stasis is a risk factor for thrombosis, by reducing representation of the circulatory system to a series of tubes in which coagulation reactions occur on perturbed endothelium on the walls of the tubes where substrates and products of the reaction are constantly delivered to and taken away from sites of injury under laminar flow conditions. Under these conditions, at low shear rates typical of the venous system, there can be depletion of some substrates at low plasma concentrations (e.g. factor X) that may become depleted in the vicinity of the catalytically active wall region, while other substrates at higher plasma concentrations (e.g. prothrombin) will not become significantly depleted in this region. This results in a refined mechanism for regulating thrombus formation and growth at the level of localized substrate concentrations. When developing these simplified models of coagulation dynamics under flow it is important that we fully describe the systems that we are using take into account how dimensions of the flow chamber will impact the interpretation of these studies. Talk 4: Using static mixers for coagulation in microfluidic flow-based assays (Rolf Urbanus, Utrecht, the Netherlands) Rolf Urbanus focused his talk on static mixers which allow the recalcification of sodium citrate anticoagulated whole blood during flow experiments, limiting unwanted activation of the coagulation system prior to start of the experiment. TF-dependent coagulation was studied by coupling a custom made static mixer to a microfluidic device containing a collagen and TF coated surface. Data indicated TF-dependent fibrin formation during a typical 30 minute perfusion run. Modulation of surface TF concentration allowed analysis of the contribution of intrinsic pathway components FVIII and FXI to both fibrin formation and platelet adhesion at venous or arterial shear rates. Talk 5: Platelet-fibrin formation under flow: obstacles and opportunities (Paola van der Meijden, Maastricht, the Netherlands) Current routine tests for the evaluation of haemostasis separately measure the different pathways of haemostasis and do not take into account the interdependency of the pathways and blood flow. The use of flow chamber devices, with its many different designs, allows the simultaneous assessment of platelet and coagulation activation under flow. In the Maastricht flow chamber 2-3 microspots of platelet- and coagulation-activating substrates can be assessed. Paloa van der Meiden showed that the collagen/TF content in the microspots and the shear rate affect the platelet-fibrin distribution throughout the thrombus and thereby the microelasticity of the thrombi, as determined by nanoindentation. The microspot-based assay on thrombus formation with coagulation was further developed by including platelet substrates with varying activity and anticoagulant proteins (APC and thrombomodulin), providing information on platelet, thrombus and fibrin parameters. Examples with blood from patients with haemostatic abnormalities were shown to illustrate the sensitivity of the assay for the different haemostatic processes. Furthermore, she showed the development of a vessel-on-a- chip model with non-confluent endothelial cells to study the local inhibitory role of these endothelial cell patches on thrombus formation.