title: Procoagulant extracellular vesicles in amniotic fluid.
abstract: Embolization of amniotic fluid (AF) into the blood circulation leads to disseminated intravascular coagulation (DIC). Procoagulant phosphatidylserine (PS)- and tissue factor (TF)-exposing extracellular vesicles (EVs) might play an important role in AF embolism-induced DIC. It was the aim of the present study to perform analyses of the procoagulant properties of AF with a panel of functional coagulation assays and flow cytometry. We applied a prothrombinase assay (that quantifies PS exposure on EVs), an EV-associated TF activity assay, a fibrin generation assay, a thrombin generation assay, a whole blood clotting model, and flow cytometry in AF and control plasma. We found that PS exposure on EVs was 21-fold increased in AF compared with plasma. Also, EV-associated TF activity was highly increased in AF compared with plasma. AF-derived EVs activated the blood coagulation cascade via PS and TF in the fibrin and thrombin generation assays. In a whole blood clotting model, AF-derived EVs significantly shortened the clotting time from 734 ± 139 seconds in the presence to 232 ± 139 seconds in the absence of an anti-TF antibody. The contact activation pathway via factor XII (FXII) was not affected. Applying flow cytometry, a subpopulation of PS+and TF+EVs was identified in AF but not in control plasma. In conclusion, we investigated the effect of AF on blood coagulation and found that PS+and TF+EVs determine their procoagulant potential. Taken together, our data further delineate the pathomechanisms underlying AF-induced coagulopathy.
authors.affiliation: Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: Lena
authors.initials: L
authors.lastname: Hell
authors.affiliation: Clinical Division of Neonatology, Paediatric Intensive Care & Neuropaediatrics, Department of Paediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Wisgrill
authors.affiliation: Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: Cihan
authors.initials: C
authors.lastname: Ay
authors.affiliation: Department of Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Spittler
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Schwameis
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Bernd
authors.initials: B
authors.lastname: Jilma
authors.affiliation: Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Pabinger
authors.affiliation: Tumor Immunology Programme, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Altevogt
authors.affiliation: Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria. Electronic address: johannes.thaler@meduniwien.ac.at.
authors.forename: Johannes
authors.initials: J
authors.lastname: Thaler
mesh_terms: D000653:Amniotic Fluid / Q000166:cytology* / Q000378:metabolism*; D004211:Disseminated Intravascular Coagulation / Q000097:blood* / Q000473:pathology; D004619:Embolism, Amniotic Fluid / Q000473:pathology; D000067128:Extracellular Vesicles; D005260:Female; D005337:Fibrin / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D010718:Phosphatidylserines / Q000378:metabolism*; D011247:Pregnancy; D013917:Thrombin / Q000378:metabolism; D013925:Thromboplastin / Q000378:metabolism; D013927:Thrombosis
chemical_list: D010718:Phosphatidylserines; D005337:Fibrin; D013925:Thromboplastin; D013917:Thrombin