Investigating the Mechanisms of Small Extracellular Vesicles in Cardiovascular Disease Using the Living Myocardial Slice Platform

Fani Koutentaki¹Laura Nicastro¹Richard J R Kelwick²Paul S Freemont²Cesare M Terracciano^1*

• ¹Imperial College London National Heart and Lung Institute, London, United Kingdom
• ²Imperial College London Department of Infectious Disease, London, United Kingdom

Cardiovascular disease remains the leading cause of death worldwide. Extracellular vesicles (EVs) play a regulatory role in homeostasis, associated with their contribution to cell-cell communication. Recently, it has been confirmed that they also regulate the progression of cardiovascular disease. Specifically, myocardial injury induces an increase in the secretion of small extracellular vesicles (sEVs), both in the cardiac microenvironment and peripheral circulation. Small extracellular vesicles (sEVs) are lipid bilayer particles within the size range of 35-200nm and are secreted by all cell types. Their high content of bioactive cargo – primarily miRNA – is altered in response to external stimuli, leading to behavioral changes of the recipient cells. In the context of cardiovascular disease, this change leads to acute and long term functional, structural, and biochemical effects on the myocardium. However, the mechanism behind the altered sEVs secretion and their changes in content in the context of cardiovascular disease is yet to be determined. That is partially due to the challenges associated with the isolation of cardiac-derived sEVs, which are essential for the investigation of the mechanisms behind cardiovascular disease progression. Living myocardial slices (LMS) provide an ideal platform for the isolation and investigation of sEVs function in the myocardium. Indeed, LMS not only maintain the cellular complexity and architecture of the native adult myocardium but can also be cultured over days/weeks without significant alterations in cardiac function, making them a reliable model for sEVs isolation and characterization at multiple timepoints. This review aims to summarize recent findings on the effect of sEVs on the onset and progression of cardiovascular disease and to discuss different methods for their isolation from LMSs and the investigation of their functional, structural, and biochemical effect on the myocardium.