Influence of hemoadsorption during cardiopulmonary bypass on blood vesicle count and function.

Background: Extracorporeal circulation during major cardiac surgery triggers a systemic inflammatory response affecting the clinical course and outcome. Recently, extracellular vesicle (EV) research has shed light onto a novel cellular communication network during inflammation. Hemoadsorption (HA) systems have shown divergent results in modulating the systemic inflammatory response during cardiopulmonary bypass (CPB) surgery. To date, the effect of HA on circulating microvesicles (MVs) in patients undergoing CPB surgery is unknown.

Methods: Count and function of MVs, as part of the extracellular vesicle fraction, were assessed in a subcohort of a single-center, blinded, controlled study investigating the effect of the CytoSorb device during CPB. A total of 18 patients undergoing elective CPB surgery with (n = 9) and without (n = 9) HA device were included in the study. MV phenotyping and counting was conducted via flow cytometry and procoagulatory potential was measured by tissue factor-dependent MV assays.

Results: Both study groups exhibited comparable counts and post-operative kinetics in MV subsets. Tissue factor-dependent procoagulatory potential was not detectable in plasma at any timepoint. Post-operative course and laboratory parameters showed no correlation with MV counts in patients undergoing CPB surgery.

Conclusion: Additional artificial surfaces to the CPB-circuit introduced by the use of the HA device showed no effect on circulating MV count and function in these patients. Larger studies are needed to assess and clarify the effect of HA on circulating vesicle counts and function. Trial registration ClinicalTrials.Gov Identifier: NCT01879176; registration date: June 17, 2013; https://clinicaltrials.gov/ct2/show/NCT01879176.