Posted by: Kasra
Application of exosomes for therapeutic, especially as drug delivery agents has been always an interest. However, there is limited knowledge on how these vesicles interact with the variety of the cells inside the body and how does the body react to their presence.
Takahashi et al. have used exosomes released by a melanoma cell line that also produces Gaussia luciferase (gLuc) to shed some light on this question. They intravenously injected the chemiluminescent exosomes into mice and watched how they go around in the body. Benefiting from the strong chemiluminescence of gLuc, they used in vivo imaging systems to visualize the localization of exosomes in the mouse during time. Surprisingly, they observed that exosomes were cleared from the serum very rapidly, with less than 5% remaining 5 minutes after administration. Also, the organs taking most shares of the exosomes were the liver and later the lungs. In the discussion, the authors mention that the reason for rapid clearance of exosomes from the serum could be unspecific interactions of the vesicles with blood cells. Exosomes express a multitude of adhesion proteins on their surface, allowing them to potentially bind various kinds of cells. We are far from fully understanding the dynamics of cell adhesion. But maybe careful engineering of proteins expressed on exosome surface could help in that direction, besides making progress in development of better targeted exosome therapeutics.
Takahashi Y, Nishikawa M, Shinotsuka H, Matsui Y, Ohara S, Imai T, & Takakura Y (2013). Visualization and in vivo tracking of the exosomes of murine melanoma B16-BL6 cells in mice after intravenous injection. Journal of biotechnology PMID: 23562828