Mesenchymal stem cell-derived small extracellular vesicles in the treatment of human diseases: Progress and prospect

Table 1 Classification of different types of extracellular vesicles

Characteristic	Exosomes	Microvesicles	Apoptotic bodies
Size (nm)	20-100	50-1000	500-2000
Morphology	Cup/round shaped	Various shapes	Heterogeneous
Sucrose gradient	1.13–1.19 g/mL	1.04–1.07 g/mL	1.16–1.28 g/mL
Biogenesis	Endosomes	Plasma membrane	Plasma membrane, endoplasmic reticulum
Contents	Nucleic acids, cytoplasmic and membrane protein, major histocompatibility complex, lipid	Nucleic acids, cytoplasmic and membrane protein, receptor proteins, lipid	Nuclear fractions, DNA, cell organelles
Biomarkers	Tetraspanins family, actin, flotillin, Hsc70, Hsp 90, Hsp60 and Hsp20, clathrin, integrins	Integrins, selectins, flotillin-2, CD40, ligand, metalloproteinase	Annexin V positivity, phosphatidyl serine

Hsc: Heat shock cognate; Hsp: Heat shock protein; CD: Cluster of differentiation.