Background: In 2001, we studied the presence and coagulant properties of “microparticles” in the blood of healthy humans. Since then, multiple improvements in detection, isolation and functional characterization of the now called “extracellular vesicles” (EVs) have been made, and shortcomings were identified. Aim: To revisit the presence and function of EVs in blood from healthy humans. Methods: Blood was collected from 20 healthy donors. EV-containing plasma was prepared according to new guidelines, and plasma was diluted to prevent swarm detection. Single EVs were measured by flow cytometry with known sensitivity of fluorescence and light scatter. The haemostatic properties of EVs were measured by thrombin-, fibrin-, and plasmin generation. Plasma concentrations of thrombin-antithrombin complexes and prothrombin fragment 1 + 2 were measured to assess the coagulation status in vivo. Results: Compared to 2001, the total concentrations of detected EVs increased from 190- to 264-fold. In contrast to 2001, however, EVs are non-coagulant which we show can be attributed to improvements in blood collection and plasma preparation. No relation is present between the plasma concentrations of EVs and either TAT or F1 + 2. Finally, we show that EVs support plasmin generation. Discussion: Improvements in blood collection, plasma preparation and detection of EVs reveal that results from earlier studies have to be interpreted with care. Compared to 2001, higher concentrations of EVs are detected in blood of healthy humans which promote fibrinolysis rather than coagulation.

背景：在2001年，我们研究了健康人血液中“微粒”的存在和凝血特性。从那时起，已经对现在称为“细胞外囊泡”（EVs）的检测，分离和功能表征进行了多项改进，并找出了不足之处。目的：研究健康人血液中电动汽车的存在和功能。方法：从20名健康供者那里采集血液。根据新指南制备了含EV的血浆，并稀释血浆以防止群体检测。通过流式细胞术以已知的荧光和光散射灵敏度测量单个电动汽车。通过凝血酶，纤维蛋白和纤溶酶的生成来测量电动汽车的止血性能。测量血浆中凝血酶-抗凝血酶复合物和凝血酶原片段1 + 2的浓度，以评估体内凝血状态。结果：与2001年相比，检测到的电动汽车的总浓度从190倍增加到264倍。然而，与2001年相反，电动汽车是非凝结性的，我们证明其可归因于血液采集和血浆制备方面的改进。EV的血浆浓度与TAT或F1 + 2之间没有关系。最后，我们证明了EV支持纤溶酶的产生。讨论：血液收集，血浆制备和电动汽车检测的改进表明，必须仔细解释早期研究的结果。与2001年相比，在健康人的血液中检测到更高浓度的EV，可促进纤维蛋白溶解而不是凝血。