Haemostasis and bleeding
Both coagulation defects and platelet function defects are a major determinant for bleeding complications, which become life threatening if they are combined with severe blood loss after trauma or during surgery. Synapse Research institute is well known as inventor and patent holder of the calibrated thrombin generation test, but Synapse Research Institute is also working on the development of a platelet activation tests to predict the bleeding risk of patients.
Heavy Menstrual Bleeding
Heavy menstrual bleeding (HMB) is a condition that affects 20–30% of women of reproductive age. HMB is commonly found in patients with established haemostatic disorders, like Von Willebrand disease (VWD) and thrombocytopenia. Likewise, impaired VWF levels and function, thrombocytopenia, impaired platelet function and impaired coagulation are more prevalent in women with heavy menstrual bleeding. Synapse Research Institute has shown that 40 % of the women with HMB have either impaired platelet function or an impaired coagulation phenotype.
Eising HP, Roest M, de Groot PG, Huskens D, Konings J, Urbanus RT, de Laat B, Remijn JA. High prevalence of reduced thrombin generation and/or decreased platelet response in women with unexplained heavy menstrual bleeding. Int J Lab Hematol. 2018.
Cardiac surgery with cardiopulmonary bypass (CPB) is associated with blood loss and post-surgery bleeding complications due to haemodilution, coagulation factor consumption and heparin administration. Thrombin generation and platelet activity measurements are the most specific tests to study the impact of disturbed haemostasis during surgery with CPB. Synapse Research Institute has shown that thrombin generation is reduced during surgery with cardiopulmonary bypass because of a balance shift between prothrombin conversion and thrombin inactivation.
Bosch YP, Al Dieri R, ten Cate H, Nelemans PJ, Bloemen S, de Laat B, Hemker C, Weerwind PW, Maessen JG, Mochtar B. Measurement of thrombin generation intra-operatively and its association with bleeding tendency after cardiac surgery. Thromb Res. 2014;133(3):488-494. Kremers RM, Bosch YP, Bloemen S, de Laat B, Weerwind PW, Mochtar B, Maessen JG, Wagenvoord RJ, Al Dieri R, Hemker HC. A reduction of prothrombin conversion by cardiac surgery with cardiopulmonary bypass shifts the haemostatic balance towards bleeding. Thromb Haemost. 2016;116(3):442-451.
Platelet function testing to predict bleeding in thrombocytopenia
Thrombocytopenia, defined as a platelet count below 150 ×109/L, impairs hemostasis and may result in bleeding complications. Thrombocytopenia can develop due to infectious causes (sepsis, chronic liver disease) or immunologic causes (Idiopathic Thrombocytopenic Purpura (ITP), acute respiratory distress syndrome). Furthermore, it is a common complication of open heart surgery, which is associated with bleeding risks and increased mortality. Thrombocytopenia is also a common complication of leukemia and a deleterious side effect of cancer treatment, often resulting in chemotherapy dose reductions, schedule alterations, or the need for platelet transfusions. Chemotherapy induced thrombocytopenia and consequent bleeding is associated with increased morbidity and occasional mortality.
Batman B, van Bladel ER, van Hamersveld M, Pasker-de Jong PCM, Korporaal SJA, Urbanus RT, Roest M, Boven LA, Fijnheer R. Agonist-induced platelet reactivity correlates with bleeding in haemato-oncological patients. Vox Sang. 2017 Nov;112(8):773-779.
Flow cytometry-based platelet function test to explain bleeding complications
Unexplained bleeding complications are still common practice in the medical hospitals. Light transmission aggregometry (LTA) is the golden standard for the identification and diagnosis of platelet function defects (PFD). However, LTA is laborious, relatively insensitive to small changes in platelet function and the outcome is affected by haemolysis and an abnormal platelet count.
Synapse Research Institute has developed a flow cytometry-based whole blood platelet activation test (WB-PACT) that can be used as supportive/complimentary test to LTA1.
The PACT has many advantages:
(1) flow cytometry measures within limited time the specific characteristics of a large number of individual platelets;
(2) platelets are analyzed in their physiological milieu of whole blood;
(3) platelet function can be measured without pretreatment of the blood, allowing measuring both the baseline activation state of circulating platelets and their reactivity in response to various agonists without the influence of artefactual in vitro activation by pre-conditioning of blood;
(4) the technique permits to investigate the aggregation potential as well as the granule release capacity of platelets;
(5) only minimal amounts of blood (5 µl) are needed.
In collaboration with the University Hospital Ghent, Belgium, Synapse Research Institute found a moderate correlation between LTA and WB-PACT (Spearman R of 0.63 and a κ agreement of 0.43)2. More importantly, our findings indicate that platelet function analysis by WB-PACT are of additional value to LTA for the diagnosis of PFD. This was confirmed in a collaborative study with the University Medical Center Utrecht, The Netherlands 3.
1. Huskens D, Sang Y, Konings J, van der Vorm L, de Laat B, Kelchtermans H, Roest M. Standardization and reference ranges for whole blood platelet function measurements using a flow cytometric platelet activation test. PloS One. 2018; 13(2):e0192079.
2. Dana Huskens, Mark Roest, Lisa Florin, Bas de Laat, Katrien M. Devreese. Flow cytometric analysis of platelet function in patients on antiplatelet therapy and suspected thrombocytopathy, Abstract ISLH 2018.
2. van Asten I, Schutgens REG, Baaij M, Zandstra J, Roest M, Pasterkamp G, Huisman A, Korporaal SJA, Urbanus RT. Validation of flow cytometric analysis of platelet function in patients with a suspected platelet function defect. J Thromb Haemost. 2018.
Quality of platelet transfusions
Platelet transfusions are expensive and have a certain risk of side effects. Therefore, according to current guidelines, prophylactic platelet transfusions are only given to patients with severe thrombocytopenia (platelet counts below 10 ×109/L) and not to patients with moderate thrombocytopenia. However, there is a general consensus that platelet count measurements are not sufficient for adequate selection of eligible patients for prophylactic transfusion. In fact, large clinical studies have shown that many severe thrombocytopenic patients do not develop bleeding complications, whereas high rates of patients with moderate thrombocytopenia (10 - 50 ×109/L platelets) do develop bleeding complications.
Synapse Research Institute has developed a platelet activation tests to measure platelet function in platelet concentrates and a test that may predict the effectivity of platelet concentrate treatment on bleeding risk of thrombocytopenic patients. This test may be used as quality control for platelet transfusion therapy and it may improve the selection of patients who should receive platelets transfusion reducing the incidence of bleeding complications.
1.Kicken CH, Roest M, Henskens YM, de Laat B, Huskens D. Application of an optimized flow cytometry-based quantification of Platelet Activation PACT): Monitoring platelet activation in platelet concentrates. PLoS One. 2017 Feb 16;12(2):e0172265.
2. Bikker A, Bouman E, Sebastian S, Korporaal SJ, Urbanus RT, Fijnheer R, Boven LA, Roest M. Functional recovery of stored platelets after transfusion. Transfusion. 2016 May;56(5):1030-7
3. Batman B, van Bladel ER, van Hamersveld M, Pasker-de Jong PCM, Korporaal SJA, Urbanus RT, Roest M. Boven LA, Fijnheer R. Agonist-induced platelet reactivity correlates with bleeding in haemato-oncological patients. Vox Sang. 2017 Nov;112(8):773-779.
Bleeding and Liver disease
Patients with liver disease have a challenging haemostatic profile.
Synapse Research Institute started a collaboration with the University Medical Center Groningen and The Liver Intensive Care Department of Kings College in London to develop a laboratory tool to define a haemostatic phenotype in individual patients with liver disease. In these studies, we specifically focus on:
(1) Adult patients with compensated and decompensated cirrhosis, acute-on-chronic liver failure (ACLF), and acute liver failure (ALF). Although bleeding complications are relatively uncommon in these patients, they often are treated prophylactically with preventive platelet concentrates, fresh frozen plasma, or prothrombin complex concentrates transfusions because of reduced platelet counts and/or impaired coagulation tests.(2) Adult patients pre and post Hepato-Pancreato-Biliary (HPB) surgery (notably liver transplant, major hepatectomy, and pancreatic resection). Although patients with hepatic and pancreatic cancers have increased risks for development of venous thromboembolism, 29% of patients undergoing HPB will receive perioperative transfusions.