The costs of health care are increasing rapidly throughout Europe due to ageing of the population. One of the instruments to reduce health care costs is early diagnosis of disease, which improves the efficacy of medical treatment. Making a medical decision requires reliable information. A major part of this information comes from the routine analysis of body fluids such as blood and urine. These fluids contain cells and biomarkers that reflect health and disease. To gain access to this information, clinicians request the collection of blood, urine and other body fluid samples, which are then analysed in hospital laboratories.
Recently, cell-derived microvesicles (MV) have gained a strong clinical interest. We use the term MV in Joint Research Project (JRP) HLT02 as a collective term for all of the different types of vesicles (microparticles, exosomes, etc.) present in human body fluids. MV are released from cells and are present in all body fluids. As MV in patients differ from MV in healthy subjects, MV can be regarded as Novel and non-invasive biomarkers. Moreover, MV affect progression of diseases such as cancer and cardiovascular disease by promoting coagulation, inflammation and angiogensis. The need will be illustrated by three examples. Firstly, ovarian cancer, called the "silent killer", is almost invariably detected when the tumour is at an incurable stage. Blood samples from ovarian cancer patients contain MV originating from tumour cells, and the relevance of these ovarian-derived MV as biomarkers is currently under investigation. Secondly, thrombosis, the second cause of death of all hospitalised cancer patients, is thought to be caused by MV released from tumour cells into the blood. In 2012, a multi-centre trial will start (4,000 patients) to identify high-risk thrombosis cancer patients using a MV-based assay developed in the AMC. Thirdly, preeclampsia is the most frequent disease of pregnant women and threatens the life of both the mother and the unborn child. Preeclampsia is now thought to be caused by the uncontrolled release of vesicles from placental cells into the blood of the mother. Because there are no biomarkers available to detect preeclampsia at an early stage, studies are now ongoing to evaluate the usefulness of placental-derived MV in mother blood as an early and non-invasive biomarker.
Detection of MV is a challenge due to their extremely small size (average diameter less than 100 nm) and heterogeneity. Even state-of-the-art detection techniques for MV detect only 1-2% of all MV present, and thus provide insufficient and incomplete information. Due to detection problems, data from MV research is qualitative rather than quantitative, and cannot be compared between laboratories. Obviously, biomarkers have clinical relevance only when measurements are reliable and comparable.
The aim of this JRP is to develop reliable, comparable and quantitative analysis of MV in biological fluids. The research of this JRP is divided into 4 Work Packages (WP). Methods will be developed for the standardized collection and handling of human body fluids for the isolation of MV, which will be used as input for the other WP’s (WP1). Methods, available in metrological institutes, will be explored to measure the size of single MV, and the size distribution of total MV populations (WP2), chemical composition, morphology and concentration (WP3). Synthetic and biological reference materials will be tested as standards for MV measurements (WP4). Selected reference materials will be analysed by all JRP-Partners and data will be compared between them. The results of this JRP will enable JRP-Partners to perform traceable calibrations of MV measurements.
The impact of the JRP will contribute to standardisation of MV measurements, so that reliable and comparable measurements of MV become possible. We will disseminate the knowledge generated in this JRP by publication of results in scientific journals and in patient platform periodicals, by presentations at international meetings (including the Scientific Standardisation Committee of the International Society on Thrombosis and Haemostasis), by constructing a JRP web site, by developing on-line training materials and a training course, and by distributing and testing selected reference materials in clinical laboratories. In this manner, MV will become available to the European community as Novel and non-invasive biomarkers, and may contribute to early detection of common diseases suchas cancer, diabetes and cardiovascular disease.