gms | German Medical Science

Objectives: Hemorrhagic shock (HS) is responsible for approximately 2 million deaths per year worldwide and is caused in 80% by polytrauma. These patients need a precise and quick diagnostic, which should be based on a combination of laboratory markers and radiological diagnostics. Extracellular vesicles (EVs) were described as potential new markers and mediators in trauma. The aim of the present study was to analyse, whether the surface epitopes of plasma-EVs reflect HS in polytraumatized patients and whether cell-specific EV subpopulations are useful diagnostic tools.

Methods: Plasma samples from polytraumatized patients (ISS 16) with (n=10, Mean ISS 26.6) and without HS (n=15, Mean ISS 53.8), were collected at the emergency room (ER) and 24 h after trauma. Plasma-EVs were isolated via size exclusion chromatography and EV-concentrations were detected by Coomassie Plus (Bradford) Assay. The EVs subpopulations were investigated by a bead-based multiplex flow cytometry measurement (FACS Diva) of surface epitopes and were compared with healthy controls (n=10). To investigate the diagnostic and prognostic potential of EVs subpopulations, results were correlated with clinical outcome parameters documented in the electronical patients’ record.

Results: The isolated EVs showed the typical size of exosomes (200 nm) and expressed exosome-specific tetraspanins CD9, CD8 and CD63. In the ER samples, the total amount of plasma EVs was significantly reduced only in the group of polytrauma patients with HS. Furthermore, we found significant reduction of CD42a+ and CD41b+ (platelet-derived) EVs and leukocyte-derived CD29+ EVs in all polytrauma patients, as compared to healthy volunteers (*p<0.05). CD44+ and CD31+ EVs were lowered only in the group of patients with HS (*p<0.05). Both these EV populations showed a moderate correlation (r²=0.42) with the transfusion of erythrocyte concentrate, the ventilation time, were associated with non-survival and the need for catecholamines (*p<0.05).

Conclusion: Our data reveal that polytrauma patients with hemorrhagic shock are characterized by a reduction of CD44+ and CD31+ plasma-EVs. Both EV populations showed a moderate correlation with the need of erythrocyte transfusion, were associated with non-survival and the need for catecholamines. Therefore, CD44+ and CD31+ EVs should be considered in future studies to understand the sequelae of HS in trauma patients.