Spleen-derived Small Extracellular Vesicles Protect against Myocardial Infarction via Mediating Spleen-heart Crosstalk

Background and AimsAcute myocardial infarction (AMI) triggers systemic responses that influence cardiac injury and repair, but protective mediators within the cardiosplenic axis remain incompletely understood. This study aimed to investigate whether spleen-derived small extracellular vesicles (sEVs) exert cardioprotection after AMI, identify critical cargo, and evaluate their clinical relevance. MethodsThe effects of splenectomy, spleen-derived sEVs and pharmacological inhibition of sEVs biogenesis on cardiac injury were evaluated in mice with AMI. Parabiosis, donor splenectomy, and fluorescent labelling traced the origin and myocardial recruitment of circulating sEVs. 4D-proteomics profiled sEVs cargo with a focus on pyruvate carrier-1 (MPC1). ResultsSplenectomy worsened survival, ventricular function, infarct size, and fibrosis in mice with AMI. AMI upregulated splenic extracellular-vesicle pathways, with sEVs release peaking at day 3 (M3D-sEVs). Labelled splenic sEVs preferentially accumulated in ischemic myocardium, confirmed by parabiosis experiments. M3D-sEVs improved survival and cardiac function and reduced infarct size, fibrosis, apoptosis, inflammation, and hypertrophy. In addition, anti-apoptotic effects were reproduced in vitro. Inhibition of sEVs biogenesis decreased circulating sEVs, aggravated injury, and was rescued by M3D-sEVs. M3D-sEVs were enriched in MPC1, and MPC1 neutralization or pharmacological blockade abrogated sEVs-mediated restoration of respiration, ATP generation, and reduction of reactive oxygen species. Plasma sEVs-associated MPC1 was highest in patients with AMI, intermediate in coronary heart disease, and lowest in controls. ConclusionsThe spleen responds adaptively to AMI by releasing MPC1lenriched sEVs that travel to injured myocardium, preserve mitochondrial energetics, and reduce damage, supporting cargolspecific sEVs augmentation and sEVslMPC1 as a potential therapeutic target and biomarker in ischemic heart disease. Structured graphical abstractAcute myocardial infarction activates a spleen-heart axis in which the spleen releases mitochondrial pyruvate carrier 1 (MPC1) enriched small extracellular vesicles that home to the infarcted myocardium, preserve mitochondrial oxidative phosphorylation, reduce ROS, and limit infarct size, apoptosis, fibrosis, and hypertrophy. Circulating sEVs-associated MPC1 might serve as a potential biomarker for estimating risk of ischemic heart disease. Translational perspectiveO_LIOur findings reveal a novel heart-spleen communication axis mediated by splenic small extracellular vesicles (sEVs) following AMI. These vesicular messengers predominantly deliver mitochondrial pyruvate carrier 1 (MPC1), enhancing cardiac mitochondrial energy metabolism in the injured myocardium, ultimately improving post-AMI functional recovery in experimental models. C_LIO_LIA higher plasma sEVs-associated MPC1 level was observed in AMI patients when compared with non-AMI patients. These findings support the clinical relevance of the spleen-heart axis, introduce sEVs-associated MPC1 as a potential circulating biomarker for early myocardial injury and therapeutic target. C_LI