Mechanistic Insights into the Cardioprotective Effects of Mesenchymal Stem Cell-Derived Exosomes in Myocardial Ischemic Injury: A Systematic Review

<b>Background:</b> Myocardial ischemic injury, encompassing acute myocardial infarction (MI) and ischemia/reperfusion (I/R) injury, remains a major cause of cardiac morbidity and mortality worldwide, and is driven by interconnected molecular and cellular processes, including cardiomyocyte apoptosis, inflammatory activation, mitochondrial dysfunction, oxidative stress, and impaired angiogenesis. Mesenchymal stem cell (MSC)-derived exosomes have emerged as a promising cell-free nanotherapeutic strategy for cardiac repair due to their ability to transfer bioactive molecules that modulate multiple signaling networks involved in myocardial survival and regeneration. This systematic review aimed to synthesize evidence on the mechanistic basis of MSC-derived exosome mediated cardioprotection in myocardial ischemic injury. <b>Methods:</b> A systematic search of Ovid MEDLINE, Scopus, and Web of Science was conducted to identify studies investigating the effects of MSC-derived exosomes on myocardial ischemic injury. Eligible studies included clinical and preclinical models of MI or I/R injury assessing functional, biochemical, and molecular outcomes. <b>Results</b>: Seven preclinical studies published between 2015 and 2025 met the inclusion criteria. Exosome administration consistently improved cardiac function, reduced infarct size, and preserved myocardial architecture. Biochemical analyses revealed decreased cardiac injury markers, alongside suppressed apoptosis, inflammation, and oxidative stress. Mechanistically, MSC-derived exosomes delivered regulatory miRNAs (e.g., miR-19a, miR-125b, miR-205, miR-294) and lncRNAs (HAND2-AS1) that modulated key signaling pathways including PI3K/Akt, JAK2/STAT3, HAND2-AS1/miR-17-5p/Mfn2, and HIF-1α/VEGF. These molecular effects collectively inhibited apoptotic and inflammatory responses, enhanced mitochondrial integrity, and promoted angiogenesis and myocardial repair. <b>Conclusions:</b> MSC-derived exosomes confer robust cardioprotection against myocardial ischemic injury through integrated anti-apoptotic, anti-inflammatory, antioxidant, and pro-angiogenic mechanisms. Their multifaceted bioactivity, low immunogenicity, and potential for targeted delivery highlight their potential as a next-generation nanomedicine for ischemic heart disease. Future studies should emphasize standardized exosome production, mechanistic profiling, and translational validation in large-animal and clinical models.