Fig. 1

a The structure of exosomes derived from MSCs. MSC-derived exosomes express tetraspanins (CD81, CD63, and CD9), heat shock proteins (HSP60, HSP70, and HSP90), ALG-2 interacting protein X (Alix), TSG101, and adhesion molecules (CD29, CD44, and CD73). Exosomes derived from MSCs carry a complex cargo, including nucleic acids, proteins, lipids, and enzymes. b Biogenesis of MSC-derived exosomes. The biogenesis of exosomes includes the formation of early endosomes through invagination of the plasma membrane, the formation of late endosomes through selection of cargo, and the formation MVB from late endosomes. MVBs contain ILV. The fusion between MVBs and the plasma membrane results in the release of exosomes. The three ways for exosomes to enter recipient cells are receptor-mediated entry, direct membrane fusion, and endocytosis