Shuaihua Qiao,1,2,* Baochuan Wu,3,* Lin Chen,3 Lingyu Ma,1 Yi Wang,3 Biao Xu,1 Rong Gu3 

1Department of Cardiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu Province, People’s Republic of China; 2School of Cardiovascular and Metabolic Medicine & Sciences, Faculty of Life Sciences & Medicine, King’s College London, London, UK; 3Department of Cardiology, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, Nanjing, Jiangsu Province, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Rong Gu; Biao Xu, Department of Cardiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, No. 321 Zhongshan Road, Nanjing, Jiangsu Province, 210008, People’s Republic of China, Tel/Fax +86-25-68182812, Email gurong.nju@163.com; xubiao62@nju.edu.cn

Background: Ischemia/reperfusion (I/R) injury following acute myocardial infarction (AMI) induces myocardial apoptosis. Exosomes from KLF2-overexpressing endothelial cells (KLF2-EXO) dampened the effects of I/R injury. The intra-lymph node drainage pathway provides an alternative method to study the therapeutic effects of exosomes. In this study, we explored the role of intra-lymph node injection of KLF2-EXO in myocardial I/R injury.
Method and Result: Exosomes were isolated from KLF2-overexpressing mouse coronary endothelial cell supernatant via gradient centrifugation. The mice were subjected to ischemia and reperfusion, and an appropriate dosage of KLF2-EXO was administrated via intra-inguinal lymph node injection. KLF2-EXO attenuated I/R injury and alleviated myocardiocyte apoptosis in heart tissue, and immunofluorescence staining indicated KLF2-EXO could be transferred into the heart. MiRNA-sequencing of KLF2-EXO implicated that miRNA-486-5p (miR-486-5p) was a potent candidate mediator that inhibited myocardiocyte apoptosis, and the miR-486-5p antagomir reversed the effect. Further bioinformatics analysis and confirmation experiments revealed that PTEN functions as a downstream target and that the PTEN- PI3K/Akt pathway participates in the regulation of cardiomyocyte apoptosis.
Conclusion: Our data demonstrated that intra-lymph node injection of KLF2-EXO attenuated myocardial I/R injury in mice by delivering miR-486-5p to target PTEN- PI3K/Akt pathway, which restrained myocardiocyte apoptosis. KLF2-EXO may serve as an alternative therapy for myocardial I/R injury.

Keywords: intra lymph node injection, Krüppel-like factor 2-overexpressing mouse coronary endothelial cells, exosomes, myocardial ischemia/reperfusion injury, myocardiocyte apoptosis, miRNA-486-5p