How to detect and measure microparticles
Birmingham, United Kingdom 
40 slide(s) – 00:28:32 – English – 2010-06-11
Objectives of Presentation by Paul Harrison
1)Definition and Function of Microparticles
2)How to Measure Microparticles
3)New technologies for measuring Microparticles
4)Microparticles as potential biomarkers of different diseases
5)Summary and Future prospects
Circulating microparticles (MPs) are becoming recognised as potentially important biomarkers of disease and their measurement is becoming increasingly popular. There are now a number of different methods available to measure MP within whole blood and/or platelet free plasma (PFP). There is considerable variation in methods of blood sampling, centrifugation (number of steps, time, g values etc) and storage of samples for MP analysis all of which can significantly affect the measurement. MPs are heterogeneous (derived from platelets, leucocytes, erythrocytes and the vascular endothelium), small (between 50 nm and 1.0 microns), express antigens from their cell of origin and are often procoagulant (with expression of anionic phospholipid). Most assays are therefore based upon identifying one or more of these properties by either measurement of their procoagulant potential, capture using a specific ligand (e.g. Annexin–V) or specific antibodies (e.g. tissue factor), by measuring their small size and phenotype (by electron microscopy or flow cytometry). Each of these approaches all have significant limitations. For example the procoagulant and Annexin-V capture assays can only measure procoagulant MP and do not provide information on their size distributions. Although MP size and phenotype can be measured by flow cytometry, many instruments cannot reliably measure particles below ~ 500 nm. A number of alternative technologies are now been investigated for measuring MP (e.g. Atomic Force Microscopy and dynamic light scattering) and are revealing that the number of MP measured has been considerably underestimated by flow cytometry. Standardised and accurate measurement of MP (of all sizes, different phenotypes and concentrations) may provide new diagnostic and prognostic markers of various disease states.
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