(78c) Fluorescent Chiral Quantum Dots to Explore Origin-Dependent Exosome Uptake and Cargo Release

Exosomes have come into the spotlight as promising nanocarriers for drug delivery. However, the clinical application of exosomes remains a challenge due to the limited understanding of their physiological properties. While exosomes typically undergo cellular uptake through two potential routes, 1) endocytosis and 2) membrane fusion, the intricate mechanisms involved in their origin-dependent uptake and subsequent cargo release are not fully explored. Herein, we unravel the mechanisms governing exosome entry into recipient cells and subsequent intracellular release of their cargo. In this study, we utilized chiral graphene quantum dots as representative exosomal cargo, taking advantage of their effective lipid membrane permeability, as well as their unique optical properties for tracking. To investigate the cell-of-origin specific cellular entry mechanism and the following intracellular cargo fate of exosomes, we used confocal laser scanning microscopy imaging analysis, mass spectrometry-based proteomics, western blot, and fluorometry. We observed that the preferential cellular uptake of exosomes derived from the same cell-of-origin (intraspecies exosomes) is 1.4 to 3.2 times higher than that of exosomes derived from different cell-of-origin (cross-species exosomes). This uptake enhancement was attributed to the receptor-ligand interaction-mediated endocytosis, as we confirmed a 1.6 to 2.1 times higher lysosomal uptake of intraspecies exosomes and identified the expression of specific ligands (TGF-β1, GalNAc, and NRG1) on exosomes that favorably interact with receptors (TβR, ASGPR, and ErbB4) on their parental cells. On the other hand, we found that the uptake of cross-species exosomes primarily occurred through membrane fusion (colocalization correlation value of PCC > 0.7), followed by direct cargo release, whereas intraspecies exosomes exhibited a lower correlation value (PCC = 0.3~0.5). Overall, our study opens up new avenues for understanding cell-exosome communication profiles, which are essential for fully utilizing exosomes as drug delivery carriers for future clinical applications.