Evaluation of Native Extracellular Vesicles in the Myocardial Microenvironment for Therapeutic Potential in the Treatment and Prevention of Aging-Associated Chronic Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death in the United States and worldwide, with myocardial infarction (MI) as the chief cause of death among CVDs. While initial incidence of MI tends to be non-fatal, the tissue response results in thus-far irreversible damage to the myocardium. This damage commonly takes the form of cardiac fibrosis, or excessive scarring and resultant dysfunction of the cardiac tissue, which increases risk and mortality of a future cardiac event. Aging is a major risk factor for cardiovascular disease and numerous other diseases, but the mechanisms of these aging-related effects remain elusive. Extracellular vesicles (EVs) have been recently identified as potential agents of aging-related changes in the microenvironment and key mediators of many chronic changes in the microenvironment. In particular, a new type of EV embedded in the extracellular matrix of human tissue was recently discovered, and can significantly impact both local immune response and local tissue remodeling in wound healing. The main goal of this dissertation was to evaluate the diagnostic and therapeutic potential of EVs native to the cardiac microenvironment in order to diagnose and treat aging-related chronic CVDs. Towards this goal, we have first proven the existence of tissue-embedded EVs (TEVs) in human cardiac tissue and evaluate the cargo and therapeutic potential of these particles. We demonstrated that TEVs from young donor hearts induce reparative, anti-fibrotic wound healing after insult and isolated a key cocktail of miRNAs that could recapitulate this effect. Next, we integrated cardiac fibroblasts into our existing heart-on-a-chip model to develop a biomimetic system for inducing cardiac fibrosis-like effects, and tested the ability of the miRNA cocktail to prevent or reverse fibrosis after fibrosis-inducing damage in a biomimetic environment. Then, to better understand the chronic changes that EV cargo go through and develop diagnostic tools based on these changes, we evaluated the effects of doxorubicin on cardiac tissue for the development of chronic cardiotoxicity. Lastly, we combined both diagnostic and therapeutic knowledge for a full multi-omics profiling of TEVs from young and aged donors compared to age-matched plasma EVs. Using both classical and novel machine-learning based techniques, we developed a unique set of diagnostic biomarkers for aging-related CVDs and identified young-enriched miRNAs which provide therapeutic, anti-fibrotic effects. While this field is still in its infancy, the study of TEVs for the development of both diagnostic and therapeutic tools will be invaluable for the treatment of aging-related CVDs.