Fig. 1

Biogenesis of exosomes and their role in maintaining stemness: exosome formation follows the endocytic-exocytic pathway, which is initiated upon receiving extrinsic or intrinsic signals in a context-dependent manner, i.e., in response to either a disease signal or a reparative signal related to tissue injury. The regions of plasma membrane enriched in lipid-raft microdomains (red bars) are inveginated, resulting in the formation of early endosomes and their maturation into late endosomes (steps 1–3), with a series of changes occurring under the influence of multicomponent sorting machinery [20]. Multivesicular bodies (MVBs) fuse with the plasma membrane and secrete exosomes outwardly; these exosomes may interact with resident cells and may facilitate stemness, i.e., self-renewal, clonal expansion, differentiation, and repair. MSCs, mesenchymal stem cells