Extracellular vesicle-associated procoagulant activity is highest the first 3 hours after trauma and thereafter declines substantially: A prospective observational pilot study.

BACKGROUND: Trauma patients have high concentrations of circulating extracellular vesicles (EVs) following injury, but the functional role of EVs in this setting is only partly deciphered. We aimed to describe in detail EV-associated procoagulant activity in individual trauma patients during the first 12 hours after injury to explore their putative function and relate findings to relevant trauma characteristics and outcome. METHODS: In a prospective observational study of 33 convenience recruited trauma patients, citrated plasma samples were obtained at trauma center admission and 2, 4, 6, and 8 hours thereafter. We measured thrombin generation from isolated EVs and the procoagulant activity of phosphatidylserine (PS)-exposing EVs. Correlation and multivariable linear regression analyses were used to explore associations between EV-associated procoagulant activity and trauma characteristics as well as outcome measures. RESULTS: EV-associated procoagulant activity was highest in the first 3 hours after injury. EV-associated thrombin generation normalized within 7 to 12 hours of injury, whereas the procoagulant activity of PS-exposing EVs declined to a level right above that of healthy volunteers. Increased EV-associated procoagulant activity at admission was associated with higher New Injury Severity Score, lower admission base excess, higher admission international normalized ratio, prolonged admission activated partial thromboplastin time, higher Sequential Organ Failure Assessment score at day 0, and fewer ventilator-free days. CONCLUSION: Our data suggest that EVs have a transient hypercoagulable function and may play a role in the early phase of hemostasis after injury. The role of EVs in trauma-induced coagulopathy and posttraumatic thrombosis should be studied bearing in mind this novel temporal pattern. LEVEL OF EVIDENCE: Prognostic/epidemiologic, level V.