Abstract P374: Functional Impairment Of Cardiac Endothelial Cells In Diabetic Failing Heart Via Dysregulated Exosomal Mirnas

Abstract

Introduction: Cardiac endothelial cells (ECs) and fibroblasts (FBs) together maintain cardiac homeostasis. Their functional impairment aggravates complications in the heart. In diabetes, acute inflammation leads to cardiac FBs activation, which predisposes the diabetic myocardium to severe fibrosis. Further, inflammation-related vascular dysfunction is a major end-organ complication in diabetics. However, it is not known, whether myofibroblast regulates ECs function in a diseased diabetic heart. Therefore, we hypothesized that “myofibroblast in diabetic heart secretes exosomes packed with antiangiogenic/profibrotic factors, which impede EC function and exaggerate pathological remodelling in pressure-overloaded (PO) myocardium. Methods: Exosomes were isolated from diabetic mice plasma and FB condition media by ultracentrifugation and characterized by nanosight & electron microscopy. We cultured mouse primary heart ECs in growth media and treated with exosomes derived from FBs (treated with 25mM glucose or 500nM Angiotensin II (AngII) or both) for 48 hr. Mannitol (25mM) served as control. Results: Ang II and glucose significantly activate FBs as shown by qPCR (fibronectin, collagenase1α1) and western blot (pSmad2, p-p38). Exosomes derived from diabetic Ang II treated FBs significantly impaired ECs function as shown by Matrigel tube formation and Boyden chamber migration assays. Interestingly, ECs markers (eNOS, VEGF, CD31) genes and proteins expression were significantly inhibited in ECs treated with exosomes-derived from glucose and Ang II treated FBs. We, further, checked the effect of diabetic mice plasma exosomes on ECs function and found significantly impaired as shown by tube formation and migration data. Finally, microRNA (miR) array and qPCR analysis revealed that miR-216a-5p, miR-26a-5p and miR7a-5p were highly upregulated in exosomes derived from FBs co-treated with glucose and AngII. Conclusions: Taken together, this study demonstrates that glucose and AngII co-treated FBs-derived exosomes are enriched in pro-fibrotic factors and can lead to EC dysfunction and promotes cardiac fibrosis in PO myocardium. In future studies, we will modulate the target miRs in diabetic FBs to see whether it rescue reparative function of ECs and inhibits fibrosis in failing heart.