(1) Background: Extracellular vesicles (EVs) have been recognized as a cellular communication tool with cardioprotective properties; however, it is unknown whether cardioprotection by remote ischemic conditioning (RIC) involves EVs. (2) Methods: We randomized patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) to additionally receive a protocol of RIC or a sham-intervention. Blood was taken before and immediately, 24 h, four days and one month after PCI. Additionally, we investigated EVs from healthy volunteers undergoing RIC. EVs were characterized by a high-sensitive flow cytometer (Beckman Coulter Cytoflex S, Krefeld, Germany). (3) Results: We analyzed 32 patients (16 RIC, 16 control) and five healthy volunteers. We investigated platelet-, endothelial-, leukocyte-, monocyte- and granulocyte-derived EVs and their pro-thrombotic sub-populations expressing superficial phosphatidylserine (PS+). We did not observe a significant effect of RIC on the numbers of circulating EVs, although granulocyte-derived EVs were significantly higher in the RIC group. In line, RIC had not impact on EVs in healthy volunteers. Additionally, we observed changes of PS+/PEV, EEVs and PS+/CD15+ EVs irrespective of RIC with time following STEMI. 4) Conclusion: We provide further insights into the course of different circulating EVs during the acute and sub-acute phases of STEMI. With respect to the investigated EV populations, RIC seems to have no effect, with only minor differences found for granulocyte EVs.

(1) Background: Cell salvage is highly recommended in orthopedic surgery to avoid allogeneic transfusions. Preparational steps during cell salvage may induce extracellular vesicle (EV) formation with potential thrombogenic activity. The purpose of our study was to assess the appearance of EVs at retransfusion. (2) Methods: After ethics committee approval and informed consent, blood was withdrawn from the autotransfusion system (Xtra, Sorin, Germany) of 23 patients undergoing joint arthroplasty. EVs were assessed by flow cytometry in two times centrifugated samples. EVs were stained with specific antibodies against cellular origins from platelets (CD41), myeloid cells (CD15), monocytes (CD14), and erythrocytes (CD235a). The measured events/µL in the flow cytometer were corrected to the number of EVs in the retransfusate. (3) Results: We measured low event rates of EVs from platelets and myeloid origin (<1 event/µL) and from monocytic origin (<2 events/µL). Mean event rates of 17,042 events/µL (range 12–81,164 events/µL) were found for EVs from red blood cells. (4) Conclusion: Retransfusate contains negligible amounts of potentially thrombogenic EVs from platelet and monocytic origin. Frequent EVs from erythrocytes may indicate red blood cell destruction and/or activation during autologous cell salvage. Further research is needed to investigate the clinical relevance of EVs from salvaged red blood cells.

Background Due to their role in transportation of different molecules, such as microRNAs and mRNAs, extracellular vesicles (EVs) enable inter-cellular communication. Therefore, they are potential biomarkers in several kinds of disease. Information on their kinetics during acute and subacute ST-elevation myocardial infraction (STEMI) is limited and potential influence of remote ischemic conditioning (RIC) has not been investigated in humans so far. Methods We conducted a randomized, controlled trial in patients with first-ever STEMI; all patients received primary percutaneous coronary intervention (PCI). Additionally, the interventional group received a protocol of RIC (5 min inflation of a blood pressure cuff on the left upper arm to 200mmHg, 5 min deflation, 4 repetitions in total), whereas controls received sham-intervention (cuff placement). Citrate-plasma for EV analysis was taken prior to (baseline) and immediately after PCI, as well as after 24 hours, 4 days and 1 months. EVs were characterized by a high-sensitive flow cytometer using fluorescence-triggering. EVs were defined as being positive for the intra-vesicular marker CalceinAM or superficial expression of phosphatidylserine (PS; target of Lactadherin) in addition to another superficial epitope. Mixed-models were used to investigate changes over time; time and RIC were treated as fixed effects, patients were treated as random effects to account for the multiple testing design. Results We included 32 patients (16 RIC, 16 control). There was a significant impact of RIC on the changes in platelet (CD41) EVs from baseline (P=0.03, Figure). Furthermore, pro-coagulatory platelet EV (PS+/CD41+) were influenced by time after STEMI (after PCI P=0.017; 24h P=0.005) with significant interaction with RIC immediately and 24h after PCI (P for interaction of time with RIC; after PCI P=0.024, after 24h P=0.008). Likewise, monocyte (CD14) EVs increased significantly with time (4 days P=0.005, 1 Month P<0.001) with significant reduced levels of monocyte EVs by RIC at these time points (P for interaction at 4 days = 0.0493; and 1 month <0.001). There was also a significant change from baseline without any effect of RIC observed in inflammatory/leucocyte EVs (CD66b+; P for change from baseline for all time points <0.001). Pro-coagulatory and inflammatory (PS+/CD15+) EVs were significantly reduced over time (at 24h P=0.007; at 4 days P=0.049, at 1 month P=0.002). Finally, endothelial (CD31+/CD41-) EVs were significantly increased at 1 month after STEMI (P=0.032). Conclusion Several circulating EV sub-population are influenced by the acute phase of STEMI. RIC significantly impacts on the changes in platelet EVs during the initial phase after STEMI. Future studies are needed to clarify the functional importance of theses changes and whether this influence is part of a cardioprotective effect of RIC. Acknowledgement/Funding LBC for Cardiovascular Research Vienna; ATVB Vienna, a grant of the “Medical Scientific Fund of the Mayor of the City of Vienna”