Theranostics 2017; 7(1):51-66. doi:10.7150/thno.16074

Research Paper

Localized Delivery of shRNA against PHD2 Protects the Heart from Acute Myocardial Infarction through Ultrasound-Targeted Cationic Microbubble Destruction

Li Zhang1*, Zhenxing Sun1*, Pingping Ren1, Manjie You1, Jing Zhang1, Lingyun Fang1, Jing Wang1, Yihan Chen1, Fei Yan2✉, Hairong Zheng2✉, Mingxing Xie1✉

1. Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province Key Laboratory of Molecular Imaging, Wuhan, China;
2. Paul C. Lauterbur Research Center for Biomedical Imaging, Institute of biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
*Both authors contributed equally to this manuscript.

This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY-NC) License. See for full terms and conditions.
Zhang L, Sun Z, Ren P, You M, Zhang J, Fang L, Wang J, Chen Y, Yan F, Zheng H, Xie M. Localized Delivery of shRNA against PHD2 Protects the Heart from Acute Myocardial Infarction through Ultrasound-Targeted Cationic Microbubble Destruction. Theranostics 2017; 7(1):51-66. doi:10.7150/thno.16074. Available from

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Hypoxia-inducible factor 1α (HIF-1α) plays a critical protective role in ischemic heart disease. Under normoxic conditions, HIF-1α was degraded by oxygen-dependent prolyl hydroxylase-2 (PHD2). Gene therapy has become a promising strategy to inhibit the degradation of HIF-1α and to improve cardiac function after ischemic injury. However, conventional gene delivery systems are difficult to achieve a targeted and localized gene delivery into the ischemic myocardia. Here, we report the localized myocardial delivery of shRNA against PHD2 through ultrasound-targeted microbubble destruction (UTMD) for protection the heart from acute myocardial infarction. In this study, a novel cationic microbubble was fabricated by using of the thin-film hydration and sonication method. The resulting microbubbles had a 28.2 ± 2.21 mV surface zeta potential and could greatly improve DNA binding performance, achieving 17.81 ± 1.46 μg of DNA loading capacity per 5 × 108 microbubbles. Combined with these cationic microbubbles, UTMD-mediated gene delivery was evaluated and the gene transfection efficiency was optimized in the H9C2 cardiac cells. Knockdown of PHD2 gene was successfully realized by UTMD-mediated shPHD2 transfection, resulting in HIF-1α-dependent protective effects on H9C2 cells through increasing the expression of HIF-1α, VEGF and bFGF. We further employed UTMD-mediated shPHD2 transfection into the localized ischemic myocardia in a rat ischemia model, demonstrating significantly reduced infarct size and greatly improved the heart function. The silencing of PHD2 and the up-regulation of its downstream genes in the treated myocardia were confirmed. Histological analysis further revealed numbers of HIF-1α- and VEGF-, and CD31-positive cells/mm2 in the shPHD2-treated group were significantly greater than those in the sham or control vector groups (P < 0.05). In conclusion, our study provides a promising strategy to realize ultrasound-mediated localized myocardial shRNA delivery to protect the heart from acute myocardial infarction via cationic microbubbles.

Keywords: Prolyl hydroxylase-2, Ischemic myocardial disease, Gene delivery, Ultrasound, Cationic microbubbles.