Thrombosis and Hemostasis

The research within our LUMC departments is conducted within departmental research programmes. The research programme below is embedded within the department of Internal Medicine / Thrombosis and Hemostasis.

Aim and focus

Research at the section of Thrombosis and Hemostasis focuses on the fundamental mechanistic understanding, diagnosis, treatment, and prevention of blood coagulation disorders, such as bleeding or thrombosis. The diagnosis and discovery of risk factors for these disease states is achieved via clinically oriented patient studies. These studies are complemented by preclinical research on the basic mechanisms of coagulation to elucidate the structure-function relationships of blood coagulation proteins, the pathophysiology of the bleeding disorders von Willebrand disease and hemophilia, the biological mechanism(s) underlying acquired and genetic risk factors for venous thrombosis, and the link between coagulation, tumor progression, and cancer-associated thrombosis. With these basic research themes, we aim to provide the mechanistic framework that will allow for a better interpretation of the clinical findings, with the overall goal of improving the diagnostic tools, tailoring the treatment options, and identifying new leads for therapies. As such, the Thrombosis and Hemostasis research program contributes to the synergy of vascular-related research themes within the department of Internal Medicine and the LUMC research profile ‘Vascular and Regenerative Medicine’. The preclinical research activities are concentrated in the multidisciplinary Einthoven Laboratory for Vascular and Regenerative Medicine.

The clinical and translational research at the Thrombosis and Hemostasis section has as overall goal to optimize and provide the best patient care possible. This is in line with its function as main referral care (‘top referente zorg’, TRF) provider for thrombotic and bleeding disorders. The latter is further supported by the leading role of the section in the Thrombosis Expertise Center Leiden and in the Leiden Expert Center for Hemophilia and Allied Disorders and by participating in the European Reference Network on hematological diseases (EuroBloodNet).

Prevention, diagnosis, and treatment of thrombosis
Our department has a long-standing and strong interest in optimizing diagnostic and therapeutic management of various categories of patients with venous and arterial thrombotic disorders. We are in the continuous process of designing and validating novel non-invasive diagnostic algorithms for suspected venous thromboembolism (VTE) and new imaging methods for detecting thrombosis at unusual anatomical locations and/or challenging clinical circumstances. Additionally, we focus on novel treatment modalities for established VTE. Specifically, optimization of treatment of patients with cancer-associated thrombosis and development of novel Magnetic Resonance Imaging (MRI) modalities that allow for direct thrombus imaging are among our current research priorities. Moreover, we have a leading role in the validation of a novel screening algorithm for chronic thromboembolic pulmonary hypertension (CTEPH) after acute pulmonary embolism and have initiated a trial to evaluate the effect of pulmonary rehabilitation as primary treatment of the post-pulmonary embolism syndrome. A further focus of the clinical studies is the prediction of adverse outcomes after venous thromboembolism, i.e. bleeding from anticoagulant therapy, recurrent thrombo-embolism, and post-thrombotic syndrome, as well as prediction of VTE in high-risk situations (e.g. patients with cancer, patients needing surgery or plaster cast). To this aim we develop, validate, and apply several prediction models to prevent VTE and its complications. We lead several large clinical trials and cohort studies to establish optimal prevention strategies and allow individual, targeted anticoagulant therapy. A final active research program focusses on the use and outcome of oral anticoagulants for the treatment of atrial fibrillation. Research activities involving patient-based studies are conducted within the frame of the Dutch Thrombosis Network (DTN; chair: prof Huisman), which involves a network of thrombosis research-oriented hospitals, as well within large European (Investigation Network on Venous Thromboembolism, INNOVATE), North American (CanVECTOR), and global research consortia (INVENT-VTE). Our department is a multidisciplinary referral center for patients with venous thromboembolic diseases, which connects state-of-the art referral care activities with both educational activities and research.

The close collaboration of the clinical (prof. dr. MV Huisman, dr. FA Klok, dr. FJM van der Meer) and epidemiological-oriented faculty (Prof. dr. SC Cannegieter) of our section allows for the management of large high-impact clinical trials and well-designed cohort/management studies.

Pathophysiology and etiology of thrombosis
The section is involved in large clinical studies (cohort and case-control) into the etiology of first and recurrent VTE, with a broad array of foci: genetic risk factors, global coagulation assays, clinical risk factors, and the interaction between these factors. Furthermore, novel information on the etiology of VTE forms the basis for translational research that focuses on mechanistic clarification in preclinical studies or validation in clinical studies. To name a few examples, the clinical studies have recently led to better insight into the role of male sex in occurrence of VTE, into obesity, lipids and the association between hepatic triglyceride content and coagulation factor levels, into endogenous hormones and their role in coagulation.
The preclinical research focuses on dissecting the biological mechanism(s) underlying acquired and genetic risk factors for VTE. Using recombinant in vivo models that express disease phenotypes (obesity, spontaneous thrombosis) or that lack genes key to the mechanistic pathways of interest, we have studied several risk conditions in relation to coagulation and thrombosis. Relevant technologies were successfully introduced including analysis of hepatic and vascular coagulation gene expression, experimental and spontaneous thrombosis models, and an in vivo RNA interference (RNAi) strategy that allows simple and fast knockdown of hepatically expressed genes. Currently, we are successfully using this technology to study a number of hepatic genes (potentially) relevant in coagulation and thrombosis. RNAi studies on protein C and antithrombin proved very successful in unravelling the in vivo function of these anticoagulants and also provided novel, controlled models for both venous  and arterial thrombosis research.  Our latest RNAi and recombinant mouse studies focus on SLC44A2, a novel venous thrombosis susceptibility gene, identified by our group in a meta-analysis of genome wide association studies. The research on SLC44A2 is sponsored by the Dutch Thrombosis Foundation and includes collaborations with the University of Michigan, Ann Arbor, USA and Marseille, France. As SLC44A2 also plays a role in transfusion-related disease (TRALI), the link between TRALI and VTE, i.e. two seemingly unrelated diseases, is also investigated in collaboration with the Department of Clinical Immunology and Transfusion Medicine, Giessen University (Germany) under sponsorship of the Landsteiner Foundation for Blood Transfusion Research (LSBR). Another innovative technology that has been introduced are multiplexed targeted proteomics assays to assess the concentration of coagulation and related factors in both mouse and patient plasma. Furthermore, protein-chemistry based research efforts are directed towards the development of therapeutic proteins that reverse the effect of widely used anticoagulant drugs, for which no antidote is available to stop or prevent major bleeding.

Another area of interest is that of coagulation and cancer. These processes are closely intertwined, as coagulation factors promote cancer progression by initiating blood clotting and activating pro-oncogenic receptors on the tumor cell surface. Tumor cells, on the other hand, hyper-activate the blood clotting system resulting in an enhanced risk for developing thrombosis. The main purpose of this research theme is to investigate how coagulation factors promote tumor growth and metastasis, and to investigate how tumor cells induce a hyper-coagulant state through a complementary approach in patient data, preclinical models and genomics. The ultimate goal is to devise strategies to inhibit both tumor progression and occurrence of thrombosis in patients suffering from malignant disease. At present, therapeutic modalities that inhibit blood clotting proteins without interfering with normal hemostasis are being tested in preclinical models.
Over the past 2 years, the department of Thrombosis and Hemostasis has actively participated in three major clinical trials in the field of cancer and thrombosis. Two trials, Hokusai-Cancer and Caravaggio (Prof MV Huisman member of steering committee), focussed on improving the treatment of cancer-associated thrombosis, 1 trial aims at using modern biomarker techniques such as platelet RNA-profiling and proteomics assays (developed by dr. BJM van Vlijmen) to predict occult cancer in patients with unprovoked venous thromboembolism (Dr. F.A. Klok and Prof dr HH Versteeg steering committee). The department has also been extensively involved in a collaboration with the STAC (Scandinavian Thrombosis And Cancer) cohort which has resulted in several papers into the effects of clinical characteristics on risk of thrombosis in cancer patients.

All in all, the combined clinical (prof. dr. SC Cannegieter, prof. dr. MV Huisman, dr. FA Klok, dr. FJM van der Meer) and preclinical (prof. dr. HH Versteeg, prof. dr. HCJ Eikenboom, dr. MHA Bos, dr. BJM van Vlijmen) research efforts underscore the high translational setting of this research theme.

Pathophysiology and treatment of bleeding
Research activities focus on the pathophysiology and treatment of inherited and acquired bleeding disorders, with a special focus on von Willebrand disease and hemophilia. The methods range from molecular and cell biological in vitro studies to translational phenotypic and genotypic studies of national as well as international patient cohorts.

Within the Leiden Expert Center for Treatment of Hemophilia and allied disorders, clinical studies involving patients with hemophilia or von Willebrand disease are performed. Several clinically oriented, multicentre, nationwide studies in which we participate are ongoing or are being initiated by us. Current focus is on optimizing the care for pregnant women with bleeding disorders. In previous studies we found that the delivery outcome in women with bleeding disorders is unsatisfactory with an increased risk for postpartum hemorrhage despite specialized care. In prospective studies we aim to optimize this outcome. The treatment with coagulation factor concentrates in patients with hemophilia and von Willebrand disease is optimized in clinical multicenter studies on pharmacokinetic dosing of factor concentrates (Opticlot, ToWin). The pathophysiology, clinical phenotype, and management of von Willebrand disease type 3 is studied in an international multicentre study (3WINTERS-IPS) and of hemophilia in the study ‘Hemophilia in the Netherlands’ (HIN6). We also take part in the national studies on thrombocytopathia (Thrombocytopathia in the Netherlands , TIN study) and rare bleeding disorders (Rare Bleeding in the Netherlands, RBIN study). Furthermore, we are leading in the development of the Dutch Registry of Patients with Hemophilia and associated Disorders. In this registry all patients in the Netherlands will be included and subsequently prospective data will be collected on disease severity and progression using also patient reported outcomes and on the use of clotting factor concentrates and the efficacy and safety thereof.
Regarding bleeding as complication of anticoagulant therapy our research is directed towards improvement of anticoagulant control in patients using vitamin K antagonists (VKA), the safety of VKA and the comparison of therapy with VKA and the new direct oral anticoagulants and on the laboratory control of VKA therapy.  

Preclinical studies investigate structural and functional qualities of circulating endothelial cells from patients with von Willebrand disease and other congenital and acquired bleeding disorders. These, so-called blood outgrowth endothelial cells are a unique cell model to study von Willebrand factor function in its native environment. New, innovative RNA-targeted treatment strategies for correction of von Willebrand disease are being developed in our laboratory. Studies to explain the difference in clinical bleeding phenotype between coagulation factor deficiency and inhibition of coagulation factor function by inhibiting antibodies are being initiated. Furthermore, the basic mechanisms of coagulation are investigated by acquiring a thorough knowledge of the structure-function relationships of blood coagulation proteins, with particular emphasis on blood coagulation factors V and X. For this purpose, a state-of-the-art protein platform specifically designed for the large-scale production and purification of recombinant blood coagulation proteins has been established. In one of the strategies employed, homologous enzymes from distant species such as those found in the venom of specific elapid snakes are examined. These studies aim to uncover novel regulatory processes within enzymes at the molecular level and exploit these findings into innovative therapeutics to fill current voids in treatment options for patients. Moreover, this research line focuses on the development of novel therapeutic blood coagulation proteins that serve as bypassing agents for the prevention and treatment of bleeding. The latter could be bleeds that are typical to hemophilia patients or may be associated with the use of the direct oral anticoagulants.

This research theme benefits from the synergy between the clinical (prof. dr. HCJ Eikenboom, dr. FJM van der Meer) and preclinical (prof. dr. HCJ Eikenboom, dr. MHA Bos) research groups.

Position in international context

The Principal Investigators hold several editorial positions at leading international specialty journals in the field. Prof. dr. HH Versteeg is editor-in-chief of Thrombosis Research and editorial board member of Carcinogenesis. Prof. dr. SC Cannegieter is associate editor of Research and Practice in Thrombosis and Haemostasis and is member of the editorial boards of PLoS Medicine and the Journal of Thrombosis and Haemostasis. Prof. HCJ Eikenboom is associate editor of Hemasphere and member of the editorial board of the British Journal of Haematology and the Journal of Thrombosis and Haemostasis. Prof MV Huisman is associate editor of Thrombosis and Haemostasis. Dr. FA Klok is associate editor of Thrombosis Research, and dr. MHA Bos is member of the editorial boards of Research and Practice in Thrombosis and Haemostasis and Toxins.

Furthermore, the Principal Investigators are actively involved in professional societies and associations. Prof. dr. HCJ Eikenboom is member of the boards of the Dutch Society for Thrombosis and Hemostasis and the Dutch Society of Internists Vascular Medicine, member of the scientific advisory board of the Dutch Thrombosis Foundation and member of the fellowships and Grants Committee of the European Hematology Association (EHA, 2014-2017), member of the scientific program committee of the Dutch Hematology Congress and the congress of the EHA (2014-2017), member of the international advisory board of the GTH (Society of Thrombosis and Haemostasis Research), and was until 2013 chairman of the Scientific Subcommittee on von Willebrand factor of the Scientific and Standardization Committee (SSC) of the International Society on Thrombosis and Haemostasis (ISTH). Prof. dr. SC Cannegieter is member of the Education Committee of the Council of the International Society on Thrombosis and Haemostasis (ISTH) and of the scientific advisory board of the Dutch Thrombosis Foundation, co-chair of the ISTH Scientific Subcommittee on Predictive and Diagnostic Variables, and was a member of the Local Organizing Committee (Education) for the 24th ISTH Congress, held in Amsterdam 2013. Prof dr. MV Huisman is member of the European Society of Cardiology guideline committee on pulmonary embolism 2014 and 2019, of the American College of Clinical Pharmacy guideline committee on VTE 2016, and of the education committee of Dutch Vascular Medicine, and is chair of the Dutch Thrombosis Network and the Dutch guideline on antithrombotic treatment 2016. Dr. MHA Bos is co-chair of the 6th International Conference on Exogenous Factors Affecting Thrombosis and Hemostasis (2019) and member of the ISTH 2013 Scientific Subcommittee on Coagulation & Fibrinolysis and Social Program Committee and board of the Dutch Society for Thrombosis and Hemostasis. Dr. van Vlijmen is member of the scientific program committee of the PhD-training courses of the Dutch Heart Foundation. Dr. Van der Meer is a member of the working group on thrombosis of the European Society of Cardiology and a former member of the board of the Federation of Dutch Anticoagulation Clinics (FNT) and takes part in committees of the FNT on interactions of drugs with VKA, the optimization and standardisation of VKA therapy and research projects initiated by the FNT. He is the chair of the HemoNED foundation for the development of the registry of patients with haemophilia and a member of the Dutch Foundation for Consumer Complaints Boards.
The Principal Investigators have established collaborations with excellent international research groups that focus on:
Deep-vein thrombosis and pulmonary embolism risk stratification, diagnosis, and treatment: Giancarlo Agnelli, Univ. Perugia, Italy; Marion Delcroix, Univ. Leuven, Belgium; Gregoire Le Gal, Marc Rodger, and Philip Wells, Univ. Ottawa, Canada; Stavros Konstantinides, Univ. Mainz, Germany; Guy Meyer, Univ. Paris-Sorbonne, France; Francis Couturaud, Brest, France; Marc Righini, Geneva, Switserland; Walter Ageno, Varese, Italy; Paolo Prandoni, Padova, Italy;  Waleed Ghanima, Univ Oslo, Norway, Pierre-Marie Roy, Angers, France
Pulmonary hypertension and chronic pulmonary embolism: Stavros Konstantinides, Univ. Mainz, Germany; Marion Delcroix, Univ. Leuven, Belgium; Piotr Pruszczyk, Univ. Warshaw, Poland.
The etiology of venous thrombosis: John-Bjarne Hansen, Univ. Tromso, Norway; Henrik Sorensen, Aarhus Univ., Denmark, Suely Rezende, Belo Horizonte, Brazil
Molecular pathways in coagulation: Rodney Camire, Univ. Pennsylvania, US; Michael Holinstat, Univ. Michigan, US; Thomas Renné, Eppendorf Hospital, Hamburg, Germany.
Tissue factor biology: Vladimir Bogdanov, Univ. Cincinnati, US; Janusz Rak, McGill Univ., Canada; Wolfram Ruf, Univ. Mainz/Scripps Research Institute.
von Willebrand disease: Augusto Federici, Univ. Milan, Italy; David Lillicrap and Paula James, Queen's Univ., Kingston, Canada; Anne Goodeve, Univ. Sheffield, UK; Cécile Denis and Peter Lenting, INSERM, Le Kremlin-Bicetre, France.
Developing novel therapies for hemophilia: Federico Mingozzi, INSERM/Genethon, Paris.
Mechanistic follow-up on GWAS findings: Behnaz Bayat, Univ. Giessen, Germany; Thomas Carey, Univ. Michigan, US, Michael Holinstat, Univ. Michigan,US; Grace Thomas, Univ. Marseille, France, Javier Corral, Univ.Murcia, Spain.
Innovative mass spectrometry techniques: Christoph Borchers, Victoria Univ., Canada.
Snake venom evolution and biochemistry: Bryan Fry, Univ. Queensland, Australia; Manjunatha Kini, Univ. Singapore.

National collaborations:
The Principal Investigators collaborate closely with all of the University Medical Centers and Universities, as well as with many regional hospitals across the Netherlands, among which HagaZiekenhuis, Alrijne, Haaglanden Medisch Centrum, Diakonessenhuis Utrecht, etc.

Cohesion within LUMC

The Thrombosis and Hemostasis research program partakes in the LUMC research profile ‘Vascular and Regenerative Medicine’. As founder and active member of the Einthoven Laboratory for Vascular and Regenerative Medicine, the section closely collaborates with the research sections of the department of Internal Medicine.

In addition, we have active collaborations with the departments of:
Center for Proteomics and Metabolomics: dr. NM Palmblad, dr. Y Mohammed (multiplexed targeted proteomics assay using mass spectrometry analysis)
Clinical Epidemiology: prof. dr. FR Rosendaal (epidemiological methods); prof. dr. S le Cessie (medical statistics and epidemiological methods)
Surgery: Dr P.J. Kuppen. (Investigations on the relationship between coagulation and cancer in clinical settings); prof. Dr. I. Schipper (thrombosis related to trauma surgery)
Molecular Cell Biology: prof. dr. AJ Koster (electron microscopic imaging)
Neurosurgery: dr. CLA Vleggeert-Lankamp (thromboprophylaxis of patients undergoing neurosurgery); prof. dr. WN Peul (coagulopathy in neurotrauma)
Orthopedics: prof. dr. RGHH Nelissen  and prof. Dr. T. Vliet Vlieland (thrombosis related to orthopedic procedures)
Radiology: prof. dr. A de Roos, dr. LJM Kroft (diagnostic studies in VTE).
Pediatrics, dr. GT Wagenaar; Anatomy and Embryology, dr. DCF Salvatori  (mouse pulmonoray pathology)