Differential in vivo biodistribution of 131I-labeled exosomes from diverse cellular origins and its implication in the theranostic application.

Exosomes are critical mediators of intercellular crosstalk and regulator of cellular/tumor microenvironment. Exosomes have great prospects for clinical application as theranostic and prognostic probe. Nevertheless, the advancement of the exosomes research has been thwarted by limited knowledge elucidating the most efficient isolation method and their in vivo trafficking. Here we have showed that combination of two size-based methods using 0.20 {micro}m syringe filter and 100k centrifuge membrane filter followed by ultracentrifugation method yields a greater number of uniform exosomes. We also demonstrated the visual representation and quantification of differential in vivo distribution of radioisotope 131I-labelled exosomes from diverse cellular origins, e.g., tumor cells with or without treatments (HET0016 and GW2580), myeloid-derived suppressor cells and endothelial progenitor cells. We also determined that the distribution was dependent on the protein/cytokine contents of the exosomes. The applied in vivo imaging modalities can be utilized to monitor disease progression, metastasis, and exosome-based targeted therapy. Abbreviations