Exosomes are nano-sized vesicles derived from the fusion of multivesicular bodies with the surrounding plasma membrane. Exosomes have several diagnostic and therapeutic potentials in cancer and other diseases, so tracking exosomes is an important issue.
Here, Weill Cornell Medicine researchers report a simple exosome tagging strategy that uses a natural metabolic incorporation of an azido-sugar into glucan and a strain-promoted azide-alkyne click reaction. In culture, tetra-acetylated N-azidoacetyl-D-mannosamine (Ac4ManNAz) was spontaneously incorporated into glycans within cells and then redistributed into their exosomes. These azido-containing exosomes were then labeled with azadibenzylcyclooctin (ADIBO) fluorescent dyes by a bioortogonal click reaction.
Cell uptake and in vivo tracking of fluorescence-labeled exosomes were evaluated in various tumor-bearing cells and mice. Highly metastatic cancer-derived exosomes showed increased self-esteem in vitro and selective organ distribution in vivo.