Preservation of Circulatory Death Donor Rat Hearts Using Hemoglobin-Based Oxygen Carriers for Normothermic Machine Perfusion: Enhancing Viability and Functionality

Abstract

Ischemia-reperfusion injury (IRI) remians a critical barrier to successful transplantation of donation after circulatory death (DCD) hearts, compromising myocardial viability through oxidative stress, inflammation, and apoptotic pathways. Hemoglobin-based oxygen carriers (HBOCs) are being investigated as substitutes for blood and red blood cells (RBCs) in ex vivo heart perfusion (EVHP), with potential to ameliorate myocardial IRI for DCD hearts. This study aimed to compare the efficacy of HBOC versus conventional blood/RBC perfusion in mitigating IRI using a rat DCD heart EVHP and transplantation model. Donor hearts were perfused ex vivo for four hours with blood, RBCs, or HBOC. Myocardial function was evaluated using hemodynamic parameters, blood gas analysis, and markers of oxidative stress, apoptosis, and inflammation. Following transplantation, histological and molecular assessments were conducted. HBOC perfusion resulted in significantly reduced IRI and inflammation, with lower 4-HNE and cytokine levels than blood perfusion. Hemodynamic performance, including developed pressure and dp/dt values, was superior in the HBOC group. In contrast, blood-perfused hearts exhibited higher potassium and lactate levels, indicating ongoing injury. Post-transplant analysis showed that HBOC-treated hearts had less structural damage and inflammation. Our findings establish HBOC's dual cytoprotective action: preventing IRI initiation during ischemia through optimized oxygen delivery and interrupting reperfusion-induced injury cascades via antioxidant/anti-inflammatory mechanisms. These results demonstrate that EVHP with HBOC could be a promising DCD hearts preservation strategy, which can attenuate myocardial IRI and improve post-transplant cardiac function in marginal donor hearts.