Exosomes and Cardiovascular Protection

Abstract

Most, if not all, cells of the cardiovascular system secrete small, lipid bilayer vesicles called exosomes. Despite technical challenges in their purification and analysis, exosomes from various sources have been shown to be powerfully cardioprotective. Indeed, it is possible that much of the so-called "paracrine" benefit in cardiovascular function obtained by stem cell therapy can be replicated by the injection of exosomes produced by stem cells. However, exosomes purified from plasma appear to be just as capable of activating cardioprotective pathways. We discuss the potential roles of endogenous exosomes in the cardiovascular system, how this is perturbed in cardiovascular disease, and evaluate their potential as therapeutic agents to protect the heart.

Keywords: Cardioprotection; Exosomes; Microparticles; Microvesicles; Stem cells.

Fig. 1

a Fusion of multivesicular endosomes with the plasma membrane of sheep reticulocytes and their release by exocytosis as exosomes. The gold-labelled antibodies against transferrin receptors bind to 50-nm vesicles which are inside openings of 300–800 nm in diameter. Reprinted with permission from Pan et al. [3]. b, c Cryo-electron microscopy of EVs from pure plasma. Spherical EVs embedded in a thin film of frozen platelet-free plasma. EV diameters are 185 nm in (b) and 45 nm and 60 nm in (c). The lipid bilayer at the periphery of EVs is resolved in two dark lines 4 nm apart (arrow in b). The granular aspect of the background is due to the high protein content of plasma. Scale bars: 100 nm. Reprinted with permission from [14]. d Transmission electron microscopy of exosome enriched from rat plasma by differential ultracentrifugation. Scale bar: 100 nm. e Size distribution exosome produced by primary adult rat cardiomyocytes as determined by nanoparticle tracking analysis