MSC-Derived Extracellular Vesicles Mitigate Ischemia-Induced Energetic Dysfunction During Ex Situ Perfusion of Rat Livers.

Despite advances in liver machine perfusion (MP), ischemia-reperfusion injury (IRI) remains a major challenge in liver transplantation, with energetic stress and mitochondrial dysfunction recognized as key drivers of damage exacerbation. We investigated whether fractions enriched with extracellular vesicles (EVs) derived from mesenchymal stromal cells can preserve energetic homeostasis in rat livers undergoing normothermic MP (NMP). An established NMP rat model was used (n = 5 per group). After procurement, livers underwent NMP for 4 h, preceded or not by 30 min cold ischemia (CI). EVs (NMP + EVs and CI + NMP + EVs) or saline (NMP and CI + NMP) were randomly administered to the perfusion fluid. Perfusate samples were collected throughout the procedure, and biopsies were taken at the end of NMP. Ischemic livers exhibited succinate accumulation, flavin mononucleotide (FMN) release, activation of reverse electron transport, and adenosine triphosphate (ATP) depletion. EV treatment effectively counteracted these effects, restoring a metabolic profile comparable to that of non-ischemic livers. Moreover, EVs improved adenosine monophosphate/ATP ratios and prevented AMP-activated protein kinase activation, a key energy-stress sensor. Furthermore, EVs reduced oxidative stress markers, cell death mediators, and pro-inflammatory cytokines, indicating a broad cytoprotective and anti-inflammatory effect. These findings support the potential of EVs to preserve mitochondrial function, restore energy balance, and reduce inflammation, thereby improving liver cell viability during NMP.