FIGURE 1.

Mesenchymal stromal cell extracellular vesicle (MSC-EV) biogenesis and contents. MSC-EV subtypes (exosomes, microvesicles, and apoptotic bodies) present three distinct molecular biogenesis pathways. Exosomes are nano-sized (50–150 nm) bioparticles released upon fusion of multivesicular bodies (MVB) with the plasma membrane, carrying a conserved set of proteins (heat shock protein [HSP70/90], CD9/63/87). Microvesicles are 100–1000 nm in size shed from cell membrane through direct outward budding. Apoptotic bodies (ApoBDs) are defined as 1000–5000 nm in diameter formed during plasma membrane blebbing in late stage of apoptosis