Reduction in Red Blood Cell Lysis by Polymer Intervention During Rodent Liver Normothermic Machine Perfusion.

Abstract

Background: Normothermic machine perfusion (NMP) has emerged as a promising strategy to improve the preservation and utilization of donor livers, particularly from extended criteria donors and those donated after circulatory death. Despite its advantages, hemolysis remains a major challenge, leading to free hemoglobin release, oxidative stress, and endothelial injury, ultimately affecting graft viability. This study evaluated the use of poloxamer 188 (P188) and Ficoll PM70 as membrane-stabilizing agents to mitigate hemolysis in rodent liver NMP models. We assessed their effects on red blood cell (RBC) stability and grafts during machine perfusion in both a model of donation after brain death and a model of warm ischemia injury.

Methods: Rat livers were subjected to NMP with RBC-based perfusates containing P188 and/or Ficoll PM70, or an untreated control. Hemolysis was measured using a NanoDrop spectrophotometer to quantify the free hemoglobin concentration. Hemodynamic stability, liver injury markers, and histological analysis were analyzed to determine the overall graft viability.

Results: Treatment with P188 or Ficoll PM70 significantly reduced circulating free hemoglobin in donation after brain death livers, minimizing hemolysis. Similarly, the combination of P188 and Ficoll PM70 significantly reduced hemolysis in warm ischemia livers and showed preserved liver sinusoidal endothelial cells. However, the reduction in hemolysis did not result in improved parameters measured during ex vivo machine perfusion.

Conclusions: The use of Poloxamer 188 and Ficoll PM70 in NMP shows promise in reducing RBC hemolysis without compromising perfusion hemodynamics. Additionally, both polymers demonstrated improved preservation of liver sinusoidal endothelial cells, as evidenced by histological analysis. However, some findings suggest that P188 may induce the release of proinflammatory cytokines in the perfusate. Overall, these findings highlight the potential of P188 and PM70 in enhancing NMP protocols for liver transplantation, though further studies are necessary to confirm their efficacy and safety before clinical translation.