Comparative Hemolytic Effects of Ex Vivo Lung Perfusion Perfusates: An In Vitro Blood Loop Approach

BACKGROUND: Ex vivo lung perfusion (EVLP) enables transplant physicians to assess and optimize donor lung quality, thereby expanding the donor pool and improving clinical outcomes. However, elevated hemolysis and lactate accumulation within the EVLP perfusate may compromise graft viability. METHODS: The primary goal of this study was to evaluate the hemocompatibility of two cellular perfusates-whole blood (WB) and leukocyte-depleted blood (LD)-using identical mock EVLP loops. Saline-washed red blood cells (RBC) were included as an additional background reference perfusate. All perfusates were filtered and diluted to a hematocrit of 19.1% ± 1.3% and circulated for 10 h at 37°C with a flow rate of 2.7 ± 0.2 L/min. RESULTS: Over the course of in vitro blood circulation, the rates of increase in hemolysis and lactate levels were significantly higher in the WB group than in the LD and RBC groups (p < 0.05), with no significant differences observed between LD and RBC. The normalized index of hemolysis at 10 h was significantly greater in the WB group compared with LD (p < 0.01) and RBC (p < 0.05). CONCLUSIONS: These findings suggest that, in blood-based ex vivo perfusion, leukocyte depletion is associated with reduced hemolysis and lactate accumulation. In addition, a simple yet promising in vitro blood loop approach can be used to evaluate perfusate quality and improve EVLP outcomes.