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Your search keyword '"Dragovic, R."' showing total 3 results
Start Over Author "Dragovic, R." Topic cell-derived microparticles
3 results on '"Dragovic, R."'

1. Review: Does size matter? Placental debris and the pathophysiology of pre-eclampsia.

Author

Redman CW, Tannetta DS, Dragovic RA, Gardiner C, Southcombe JH, Collett GP, and Sargent IL

Subjects
Cell-Derived Microparticles ultrastructure, Cytoplasmic Vesicles metabolism, Cytoplasmic Vesicles ultrastructure, Exosomes metabolism, Exosomes ultrastructure, Female, Humans, Immunomodulation, MicroRNAs blood, MicroRNAs metabolism, Organelle Size, Particle Size, Placenta immunology, Placenta metabolism, Pre-Eclampsia immunology, Pre-Eclampsia physiopathology, Pregnancy, Pregnancy Proteins blood, Pregnancy Proteins genetics, Pregnancy Proteins metabolism, Trophoblasts immunology, Trophoblasts metabolism, Trophoblasts ultrastructure, Cell-Derived Microparticles chemistry, Cell-Derived Microparticles metabolism, Placenta ultrastructure, Pre-Eclampsia blood, Pre-Eclampsia pathology
Abstract

A variety of 'debris' is shed from the syncytial surface of the human placenta ranging from large deported multinuclear fragments to sub-cellular components. It is increasingly clear that at least some of this material has signalling functions. Many categories of circulating debris are increased in pre-eclampsia, and exhibit proteins that are pro-inflammatory and could contribute to the systemic inflammatory response in normal pregnancy, which is exaggerated in pre-eclampsia. It is now evident that there is a large 'hidden' population of microvesicles and nanovesicles (including exosomes) which are hard to investigate because of their size. We have used a new technology, nanoparticle tracking analysis, to measure the size and concentration of syncytiotrophoblast vesicles prepared by placental perfusion. The vesicles range in size from 50 nm to 1 μm with the majority being <500 nm (which includes both exosomes and microvesicles). We speculate whether changes not only in the numbers, but also in the size (beneficial syncytiotrophoblast exosomes and harmful microvesicles) might be important in the maternal syndrome of pre-eclampsia., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Published
2012
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2. Measurement of circulating cell-derived microparticles by flow cytometry: sources of variability within the assay.

Author

Ayers L, Kohler M, Harrison P, Sargent I, Dragovic R, Schaap M, Nieuwland R, Brooks SA, and Ferry B

Subjects
Aged, Annexin A5 analysis, Blood Platelets cytology, Endothelial Cells cytology, Humans, Leukocytes cytology, Middle Aged, Platelet Endothelial Cell Adhesion Molecule-1 analysis, Platelet Membrane Glycoprotein IIb analysis, Reproducibility of Results, Cell-Derived Microparticles metabolism, Flow Cytometry methods
Abstract

Introduction: Circulating cell-derived microparticles (MPs) have been implicated in several disease processes and elevated levels are found in many pathological conditions. The detection and accurate measurement of MPs, although attracting widespread interest, is hampered by a lack of standardisation. The aim of this study was to establish a reliable flow cytometric assay to measure distinct subtypes of MPs in disease and to identify any significant causes of variability in MP quantification., Materials and Methods: Circulating MPs within plasma were identified by their phenotype (platelet, endothelial, leukocyte and annexin-V positivity (AnnV+). The influence of key variables (i.e. time between venepuncture and centrifugation, washing steps, the number of centrifugation steps, freezing/long-term storage and temperature of thawing) on MP measurement were investigated., Results: Increasing time between venepuncture and centrifugation leads to increased MP levels. Washing samples results in decreased AnnV+MPs (P=0.002) and platelet-derived MPs (PMPs) (P=0.002). Double centrifugation of MPs prior to freezing decreases numbers of AnnV+MPs (P=0.0004) and PMPs (P=0.0004). A single freeze thaw cycle of samples led to an increase in AnnV+MPs (P=0.0020) and PMPs (P=0.0039). Long-term storage of MP samples at -80° resulted in decreased MP levels., Conclusions: This study found that minor protocol changes significantly affected MP levels. This is one of the first studies attempting to standardise a method for obtaining and measuring circulating MPs. Standardisation will be essential for successful development of MP technologies, allowing direct comparison of results between studies and leading to a greater understanding of MPs in disease., (Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.)

Published
2011
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3. Standardization of extracellular vesicle measurements by flow cytometry through vesicle diameter approximation

Author

van der Pol, E., Sturk, A., van Leeuwen, T., Nieuwland, R., Coumans, F., Mobarrez, F., Arkesteijn, G., Wauben, M., Siljander, P. R.M., Sánchez-López, V., Otero-Candelera, R., Ramón, L. A., Dolz, S., Vila, V., Mackman, N., Geddings, J., Mullier, F., Bailly, N., Han, J. Y., Kwaan, H. C., Weiss, I. M., Buzás, E. I., Pállinger, E., Harrison, P., Kraan, J., Hedley, B. D., LazoLangner, A., Enjeti, A., Norris, P. J., Paris, C., Susen, S., Bonnefoy, A., Delorme, I., Chandler, W. L., Hau, C., Aass, H. C.D., Connor, D., Wu, X., Dragovic, R., Uotila, L. M., Lacroix, R., Robert, S., Dep Infectieziekten Immunologie, LS Celbiologie-Algemeen, Sub General Pharmaceutics, Sub Algebra,Geometry&Mathem. Logic begr., LS Pharma, dB&C I&I, Hematology, Erasmus School of Economics, Medical Oncology, General Practice, Business Economics, ACS - Atherosclerosis & ischemic syndromes, CCA - Imaging and biomarkers, Biomedical Engineering and Physics, ACS - Microcirculation, Laboratory for General Clinical Chemistry, Laboratory Specialized Diagnostics & Research, Dep Infectieziekten Immunologie, LS Celbiologie-Algemeen, Sub General Pharmaceutics, Sub Algebra,Geometry&Mathem. Logic begr., LS Pharma, and dB&C I&I

Subjects
0301 basic medicine, Materials science, Light, Platelet Function Tests, cell-derived microparticles, blood platelets, exosomes, 030204 cardiovascular system & hematology, Bead, Light scattering, Flow cytometry, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, medicine, Calibration, Humans, Scattering, Radiation, Particle Size, Cell Size, Observer Variation, standardization, medicine.diagnostic_test, Vesicle, flow cytometry, Integrin beta3, Reproducibility of Results, Phycoerythrin, Hematology, Extracellular vesicle, Volumetric flow rate, 030104 developmental biology, chemistry, visual_art, visual_art.visual_art_medium, Polystyrene, extracellular vesicles, Biomarkers, Biomedical engineering
Abstract

Essentials Platelet extracellular vesicles (EVs) concentrations measured by flow cytometers are incomparable. A model is applied to convert ambiguous scatter units to EV diameter in nanometer. Most included flow cytometers lack the sensitivity to detect EVs of 600 nm and smaller. The model outperforms polystyrene beads for comparability of platelet EV concentrations. Summary: Background Detection of extracellular vesicles (EVs) by flow cytometry has poor interlaboratory comparability, owing to differences in flow cytometer (FCM) sensitivity. Previous workshops distributed polystyrene beads to set a scatter-based diameter gate in order to improve the comparability of EV concentration measurements. However, polystyrene beads provide limited insights into the diameter of detected EVs. Objectives To evaluate gates based on the estimated diameter of EVs instead of beads. Methods A calibration bead mixture and platelet EV samples were distributed to 33 participants. Beads and a light scattering model were used to set EV diameter gates in order to measure the concentration of CD61–phycoerythrin-positive platelet EVs. Results Of the 46 evaluated FCMs, 21 FCMs detected the 600–1200-nm EV diameter gate. The 1200–3000-nm EV diameter gate was detected by 31 FCMs, with a measured EV concentration interlaboratory variability of 81% as compared with 139% with the bead diameter gate. Part of the variation in both approaches is caused by precipitation in some of the provided platelet EV samples. Flow rate calibration proved essential because systems configured to 60 μL min−1 differed six-fold in measured flow rates between instruments. Conclusions EV diameter gates improve the interlaboratory variability as compared with previous approaches. Of the evaluated FCMs, 24% could not detect 400-nm polystyrene beads, and such instruments have limited utility for EV research. Finally, considerable differences were observed in sensitivity between optically similar instruments, indicating that maintenance and training affect the sensitivity.

Published
2018

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