Abstract
Heart transplantation is severely limited by the shortage of suitable donor grafts, partly due to myocardial vulnerability to ischemia-reperfusion injury and the lack of standardized preservation strategies. Current solutions only partially maintain myocardial viability, compromising post-transplant function. To address this issue, we made further improvements to our preservation solution, LYPS (Lyon Preservation Solution), based on mitochondrial metabolic activation and the limitation of membrane depolarization. We first evaluated commonly used extracellular solutions (Celsior and St. Thomas (ST)) on cardiac cell lines (H9C2) exposed to 20 h of cold (4 °C) simulated ischemia followed by 2 h of simulated reperfusion. In parallel, the same three solutions were compared in isolated pig hearts subjected to 20 h of cold static storage followed by reperfusion, with a group directly reperfused with blood at 37 °C serving as the control. Heart function was assessed using a non-working heart preparation, while mitochondrial functions and electrophysiological analysis were evaluated via biopsies and isolated cardiomyocytes. LYPS provided superior protection against cell death and mitochondrial membrane potential loss in vitro, outperformed ST in preserving mitochondrial function, and limited troponin I release by the heart. During reperfusion, LYPS-treated hearts showed improved functional recovery and contractility and better rhythmicity with almost no defibrillation requirements. These effects may involve the modulation of the repolarizing IK(1) current. Overall, LYPS effectively preserves myocardial viability and function, representing a promising strategy to enhance graft quality during long-term cold preservation, even through using cold static storage.