Hemolysis During Ex Vivo Lung Perfusion Is Associated with Endothelial Injury, Cytokine Release, and Primary Graft Dysfunction

Primary graft dysfunction (PGD) is a major cause of early morbidity and mortality after lung transplantation. During blood-based ex vivo lung perfusion (EVLP), hemolysis releases plasma-free hemoglobin (pfHb) and other erythrocyte-derived products that may promote endothelial injury and inflammation. We investigated whether EVLP-associated hemolysis is associated with cytokine release, endothelial dysfunction, and grade 3 PGD (PGD3). In this prospective, single-center observational study, end-EVLP perfusate from 57 double-lung transplant recipients supported with the Organ Care System Lung was analyzed for pfHb, 26 cytokines, blood counts, and associations with PGD3 within 72 h after transplantation. A mock EVLP blood-loop model was used to evaluate the effects of red blood cell storage duration and circuit run time on hemolysis. Generated hemolytic perfusates were applied to human lung microvascular endothelial cells to assess barrier injury and inflammatory activation. Among the 57 recipients, 32 (56.1%) developed PGD3 at any time point within 72 h after transplantation. Higher end-EVLP pfHb, interleukin-6, and interleukin-8 levels were associated with PGD3, and pfHb correlated positively with interleukin-6 and interleukin-8. Hemolysis increased with longer blood storage and EVLP duration, with storage duration emerging as the dominant contributor in the blood-loop model. Hemolytic perfusate disrupted endothelial junctions, increased permeability, and induced interleukin-6 and interleukin-8 release. EVLP-associated hemolysis is linked to endothelial barrier injury, inflammatory activation, and PGD3 after lung transplantation. Reducing hemolysis through improved blood-product selection and EVLP circuit management may represent a modifiable strategy to improve posttransplant outcomes.