Fig. 1

Exosome biogenesis, secretion, uptake, and isolation. A Exosome biogenesis occurs within the endosomal system and involves crucial organelles such as mitochondria, the endoplasmic reticulum, and the Golgi apparatus. It commences with plasma membrane invagination, forming early endosomes (ESEs), which subsequently fuse into late endosomes (LSEs). At this juncture, LSEs participate in cargo sorting near the Golgi apparatus, resulting in the generation of multivesicular bodies (MVBs). These MVBs can undergo lysosomal degradation, intracellular recycling, or secretion as exosomes. Once secreted, recipient cells internalize exosomes through mechanisms such as receptor-mediated endocytosis, phagocytosis, or direct fusion with the plasma membrane. B Differential centrifugation is a standard technique for isolating exosomes from conditioned cell culture media. Subsequent purification of the exosomes was achieved via ultracentrifugation at 120,000 × g. The resulting purified exosome suspension was subsequently applied to copper grids for sedimentation, followed by uranyl acetate double staining. The exosomes were subsequently visualized through transmission electron microscopy. The purified exosomes displayed a cup-shaped morphology, ranging in size from 30 to 150 nm, as observed in microscopy images (transmission electron microscopy images derived from exosomes secreted by J774A.1 macrophages extracted by our research group)