Microparticles (MPs) have important physiological and pathological roles in blood coagulation, inflammation and tumor progression. In recent years MPs also have been recognized to participate in... Show moreMicroparticles (MPs) have important physiological and pathological roles in blood coagulation, inflammation and tumor progression. In recent years MPs also have been recognized to participate in important biological processes, such as in signaling and in the horizontal transfer of their specific proteins and mRNAs. However, studies of MPs have been hampered by the lack of methods for the sensitive detection and accurate quantification of MPs. Thus, we have developed a new methodology by using atomic force microscopy (AFM) and cryo-electron microscopy (cryo-EM) to detect, quantify and characterize MPs in plasma. We have shown that AFM detects 1000-fold more platelet derived-MPs than a conventional flow cytometry does. These MPs have diameters ranging from 10-475 nm with a peak at 67.5 nm, which is clearly far below the detection limit of flow cytometry. By using cryo-EM we found that the number of lipoprotein particles exceeds that of MPs or exosomes in plasma. We also demonstrated that by using immuno-magnetic beads selected subset of MPs could directly be captured/depleted from plasma and assessed for MP-associated tissue factor activity. In the future the measurement of MPs will perhaps serve as a diagnostic tool to identify and predict diseases, like cancer. Show less
This thesis elaborates the occurrence of venous thrombosis in cancer patients. Cancer is known to be associated with venous thrombosis with a spectrum of clinical manifestations varying from deep... Show moreThis thesis elaborates the occurrence of venous thrombosis in cancer patients. Cancer is known to be associated with venous thrombosis with a spectrum of clinical manifestations varying from deep vein thrombosis of the leg and pulmonary embolism, recurrent thrombophlebitits saltans et migrans (also called Trousseau__s syndrome) to disseminated intravascular coagulation and arterial embolism. The causes of venous thrombosis can be divided in environmental risk factors such as bed rest, surgery, plaster cast, trauma, long-distance travel, oral contraceptives or pregnancy and puerperium and genetic risk factors such as factor V Leiden and prothrombin 20210A mutation. Various factors may contribute to the development of venous thrombosis in cancer patients, and circulating mucins as well as circulating microparticles which express active TF on their surface may provide a missing link between cancer and thrombosis in (adeno) carcinoma patients. Treatment options include vitamin K antagonists and low-molecular-weight heparins, and the long-term use of these heparins in prevention of venous thrombosis may improve the outcome in comparison with oral anticoagulants. Further research is needed to better understand the morbidity and mortality associated with thrombosis in cancer patients and to optimize strategies of prevention and treatment Show less
