In vitro Validation of a Novel Disposable Remover to Remove Activated Leukocytes Generated During Cardiopulmonary Bypass: A Pilot Study.

Background: Cardiopulmonary bypass (CPB) is associated with activation of pro-inflammatory cells, which infiltrate tissues and cause injury. Here we explored a novel disposable remover to remove inflammatory leukocytes in order to reduce risk of complications after CPB. This is a substudy within a previously registered clinical trial (NCT05400356) that aims to validate a novel disposable remover to remove activated leukocytes generated during CPB. Methods: The device contains an enhanced biocompatible leukocyte membrane (Chinese patent CN202310822538.X) coated with RGD peptide (Arg-Gly-Asp), which binds to specific polypeptide groups on activated leukocytes, leading to their affinity-based adsorption. The device was integrated into a closed extracorporeal circuit containing a blood reservoir, roller pump, and tubes. Blood from seven patients (150 mL per patient) was driven through the circuit for 10 min at 300 mL/min. Counts of leukocytes and their surface molecules were examined before circulation and after 2.5, 5, 7.5, and 10 min of circulation. The types and morphology of blood cells captured on the filter membrane were also examined. Results: Counts of neutrophils and neutrophils expressing the activation markers CD11b, CD54, CD64 or CD181 decreased rapidly by 36-39% during the first 2.5 min of circulation, after which their counts decreased more slowly. In contrast, counts of monocytes or lymphocytes did not change significantly during circulation. After use, the membrane was still smooth and intact, and it contained substantial numbers of intact activated leukocytes, based on immunostaining against activated cells and scanning electron microscopy. Smears of blood samples before and after circulation showed no significant differences in each leukocyte morphology. Conclusion: This novel disposable remover can preferentially remove activated neutrophils from blood ex vivo, with minimal apparent impact on other leukocytes and blood components. Trial Registration: This substudy is part of a prospective cohort study registered at the Clinical Trials Registry (NCT05400356) on 27 May 2022.