AdliestISEV2019 ABSTRACT BOOKgynaecological malignancy with 5-year survival rate below 30 . HGSC is often accompanied by ascites, a pathological accumulation of fluid inside the peritoneum, which may be exploited as a liquid biopsy containing not just cancer cells, but in addition the tumour microenvironment like extracellular vesicles (EVs). Tumour cells make substantially a lot more EVs than wholesome cells, therefore malignant ascites will be the source of enriched pool of EVs of HGSC origin. Methods: Ascitic fluids depleted of cells were fractioned making use of size-exclusion chromatography and two fractions containing and not containing EVs had been further analysed. In parallel, small EVs had been also isolated from ascitic fluids utilizing differential ultracentrifugation followed by purification step in sucrose/D2O cushion. In total, 24 malignant ascites and 5 non-malignant ascites were utilised for EV isolation and further analysed working with high-resolution hybrid mass spectrometer Orbitrap Fusion Lumos Tribrid. The subsequent information visualization and statistical analyses had been performed utilizing in-house-developed pipelines in KNIME atmosphere. Outcomes: We identified 2441 proteins, in total, in the EVs from the ascites amongst which 21 had been present in all 29 EV samples and not in non-vesicular fractions. Numerous of these proteins were particularly enriched in smaller EVs in malignant ascites in comparison with non-malignant ascites. These proteins are now being evaluated as biomarkers. Summary/P2X1 Receptor Compound Conclusion: Employing sophisticated mass spectrometry, we identified candidate proteins that are specifically enriched in tiny EVs of HGSC. These proteins warrant additional investigation as they may act as essential players in HGSC progression as well as serve as possible prognostic/diagnostic/screening biomarkers of HGSC. MMP Formulation Funding: Czech Science Foundation, Grant No. GJ1711776Y.OWP3.09=PT09.Identification of single tumour-derived extracellular vesicles by implies of optical tweezers and Raman spectroscopy Agustin Enciso-Martineza, Edwin van der Polb, Aufried Lenferinkc, Leon Terstappena and Cees Ottoa Health-related Cell Biophysics, University of Twente, Enschede, Netherlands; Amsterdam UMC, University of Amsterdam, Division of Biomedical Engineering and Physics, Amsterdam, Netherlands, Amsterdam, Netherlands; cUniversity of Twente, Enschede, Netherlandsb aIntroduction: EVs derived from cancer cells play a part in tumour cell proliferation, migration, invasion and metastasis. Their presence in physique fluids, which include blood, makes them possible biomarkers for cancer disease. Having said that, the identification of single tdEVs is usually challenging on account of their heterogeneity, their ultra-small size, their size overlap with many other typical EVs and contaminants in body fluids along with the lack of expertise on their chemical composition. Methods: Synchronized optical tweezers and Raman spectroscopy have enabled a study of individual EVs. The new method detects person trapping events from Rayleigh scattering. The synchronous recording of Raman scattering enabled the acquisition of Raman spectra of each person and a number of EVs, disclosing their chemical composition. In addition, Mie light scattering theory has been employed to relate the Rayleigh scattering intensity to the size of trapped EVs. Outcomes: The light scattered of trapped EVs gave rise to step-wise time traces that may be employed to distinguish individual trapping events from accumulative cluster events on account of the discrete nature on the measures which correspond to.