Abstract 444: Dusp4 Overexpressed EC Derived Exosomes Promote Angiogenesis: A Novel Therapeutic Strategy For Ischemic Heart Disease

Abstract

After an ischemia and reperfusion (I/R) injury to the heart, re-establishing blood flow to the infarct region can salvage myocardium, stimulate angiogenesis and recruit progenitor cells for tissue regeneration. Stimulating angiogenesis through the growth of new microcirculation in the peri-infarct area can help preserve and improve cardiac function following myocardial infarction. In this study, we hypothesize that exosomes derived from DUSP4-overexpressed endothelial cells (ECs) stimulate angiogenesis and improve vascular function. DUSP4-derived exosomes (50 μg/ml) promote angiogenesis by increasing tube formation of endothelial cells (2.74 ± 0.14 versus control exosomes 2.17 ± 0.15 in the total length; p < 0.001). Immunoblotting reveals that DUSP4 overexpression in endothelial cells down-regulates p53 (0.59 ± 0.04 versus 1.0 ± 0.01 of control) expression, which modulates the HIF1α pathway and angiogenesis. Moreover, NO is a critical small molecule involved in regulation of vascular tone, vascular growth, platelet aggregation, and modulation of inflammation. The level of NO generation determined using DAF fluorescence microscopy demonstrated that DUSP4 overexpression augments NO generation. The increase in NO generation also correlates to the increase in eNOS protein (1.23 ± 0.20 versus control) and mRNA (5.84 ± 0.37 versus control) expression. The proteomic analysis of control and DUSP4 derived exosomes showed that DUSP4 overexpression up-regulates several key exosomal proteins including HSP70, HSP90, tubulins, Vimentin, and clathrin. More interestingly, several redox proteins were up-regulated in DUSP4 derived exosomes including glutathione S-transferase P, peroxiredoxin-2, peroxiredoxin-4, and protein disulfide-isomerase. Together, these results demonstrate that exosomes derived from DUSP4 reprogrammed ECs are a valuable therapeutic option for the treatment of ischemic heart disease by promoting angiogenesis.