Fig. 1

Biogenesis of exosoems and the mechanisms of uptake of exosomes involved by the recipient cell. A Early endosomes are produced from the invegination of the cell membrane, which mature into MVBs with ILVs inside. The inward budding of the endosomal membrane leads to ILVs formation. The fusion of the MVBs to the plasma membrane results in the secretion of exosomes extracellularly [71]. B Typical structure of exosomes containing functional DNA, proteins and RNA biomolecules surrounded by a lipid bilayer. C Several mechanisms have been reported for the uptake of exosomes, e.g., include micropinocytosis, phagocytosis, caveolae/raft-dependent endocytosis, receptor-mediated endocytosis, and direct fusion [72]. Adhesion molecules, including integrin, ICAM-1, LFA-1, CD81, and CD9 on the vesicle membranes, also play important roles in the binding and uptake of exosomes. Moreover, several receptor-ligand interactions, such as heparin sulfate proteoglycans-fibronectin, TIM receptors-phosphatidylserine, and epidermal growth factor receptor (EGFR)-epidermal growth factor (EGF), mediate the exosome endocytosis [73]