Cardiovascular diseases (CVDs) represent a major global health problem, due to their continued high incidences and mortality. The last few decades have witnessed new advances in clinical research which led to increased survival and recovery in CVD patients. Nevertheless, elusive and multifactorial pathophysiological mechanisms of CVD development perplexed researchers in identifying efficacious therapeutic interventions. Search for novel and effective strategies for diagnosis, prevention, and intervention for CVD has shifted research focus on extracellular vesicles (EVs) in recent years. By transporting molecular cargo from donor to recipient cells, EVs modulate gene expression and influence the phenotype of recipient cells, thus EVs prove to be an imperative component of intercellular signaling. Elucidation of the role of EVs in intercellular communications under physiological conditions implied the enormous potential of EVs in monitoring and treatment of CVD. The EVs secreted from the myriad of cells in the cardiovascular system such as cardiomyocytes, cardiac fibroblasts, cardiac progenitor cells, endothelial cells, inflammatory cells may facilitate the communication in physiological and pathological conditions. Understanding EVs-mediated cellular communication may delineate the mechanism of origin and progression of cardiovascular diseases. The current review summarizes exosome-mediated paracrine signaling leading to cardiovascular disease. The mechanistic role of exosomes in cardiovascular disease will provide novel avenues in designing diagnosis and therapeutic interventions.

Background: Despite improvements in therapeutics, ischemic heart disease remains a leading cause of death. Cardiac remodeling after myocardial infarction (MI), predominantly due to loss of cardiomyocytes and coronary vasculature, leads to a progressive decline in cardiac function resulting in heart failure. Current therapies for cardiac repair and heart failure are of limited benefit. Cell transplantation therapy upon MI is a very promising therapeutic strategy to replace dead myocardium, reducing scarring and improving cardiac performance. Methods and Results: Our research focuses on endothelial colony-forming cell-derived exosomes (ECFC-exosomes), which are actively secreted endocytic nanovesicles (30-100 nm) that transport functional miRNAs, proteins, mRNAs, and lipids, playing a key role in paracrine intercellular communication. We identified a novel ability of ECFC-exosomes to promote angiogenesis and cardiac tissue repair. Administration of ECFCs to mice following experimental end-organ ischemia resulted in ECFC-exosome-dependent increase in angiogenesis. ECFC-derived exosomes were taken up by endothelial cells leading to their proliferation and migration, tube formation, and formation of new vessels. Administration of ECFC-exosome to a murine model of MI prevented cardiac remodeling and heart failure. The acute MI resulted in severely decreased left ventricle ejection fraction (Sham 71.2% ± 5 .87, MI+Saline 32.9% ± 2.32) and fractional shortening (Sham 29.5% ± 3.20, MI+Saline 13.6% ± 2.87), and the administration of ECFC-exosomes prevented MI-induced cardiac dysfunction (ejection fraction: MI+ECFC-Exo 64.3% ± 8.74; fractional shortening: MI+ECFC-Exo: 26.4% ± 3.13). Next generation sequencing and bioinformatics analyses identified 136 miRNAs present in ECFC-exosome cargo, and factor inhibiting HIF-1α and PTEN as their potential targets in endothelial cells. Increased nuclear HIF-1α levels in response to ECFC-exosome administration, which may aid in the transcriptional function of HIF-1α, corroborated the role of exosomal miRNA in myocardial angiogenesis. We also found decreased levels of PTEN in response to ECFC-exosome treatment, which is a key negative regulator of PI3K/Akt pathways, survival pathways of heart. We also identified the relative angiogenesis expression profile of the peri-infarcted area in response to ECFC-exosome treatment. The ECFC-exosome administration upregulated the levels of VEGF, IGFBP-1 and PDGF, among others proangiogenic factors, and downregulated the levels of angiostatic factors as IP-10 and Thrombospondin-2. Conclusion: Our findings support the view that the ECFC-exosomes represent a novel therapeutic approach to improve cardiac repair after MI.