Exosomal miR-455-3p from BMMSCs prevents cardiac ischemia-reperfusion injury

Objective Bone marrow mesenchymal stem cells (BMMSCs) exert protective effects against myocardial infarction (MI). Here, we focused on the function and mechanism of miR-455-3p from BMMSCs-derived exosomes (BMMSCs-Exo) in myocardial infarction. Materials and methods BMMSCs were isolated from rat bone marrow, and the exosomes from the culture medium of BMMSCs were separated, and administered to H9C2 cells under hypoxia-reperfusion (H/R) stimulation. MTT and TUNEL staining analyzed cell viability and apoptosis, respectively. RT-qPCR determined miR-455-3p expression. Apoptosis-related proteins, autophagy-associated proteins, and the MEKK1-MKK4-JNK signaling pathway were detected. The interaction between miR-455-3p and MEKK1 was confirmed through dual luciferase activity and RIP assay. An in vivo ischemia reperfusion (I/R) model was established in rats. 2, 3, 5 triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (H&E) staining, Masson staining, and TUNEL staining evaluated the infarct volume and histopathological changes. Results miR-455-3p′s expression was down-regulated in BMMSCs-derived exosomes, I/R myocardial tissues, and H/R myocardial cells. miR-455-3p enriched by BMMSC exosomes reduced H/R-mediated cardiomyocyte damage and death-related autophagy. miR-455-3p upregulation suppressed MEKK1-MKK4-JNK. MEKK1 overexpression notably mitigated cell apoptosis, cramped cell viability, suppressed autophagy expansion, and attenuated Exo-miR-455-3p′s protection on H/R myocardial cells. In-vivo trials reflected that BMMSC exosomes enriched with miR-455-3p repressed ischemia reperfusion-induced myocardial damage and myocardial cell function. Conclusion miR-455-3p, shuttled by exosomes from MSCs, targets the MEKK1-MKK4-JNK signaling pathway to guard against myocardial ischemia-reperfusion damage.