Exosomes on surface of HeLa cell

This image shows a scanning electron micrograph of the surface of a HeLa cell that has been treated with a drug to induce exosome (here seen as small particles) release. Exosomes are a type of vesicle, or fluid-filled space surrounded by a membrane, that are released from cells. Our understanding of how they behave is in its infancy, but exosomes have already been implicated in numerous disease states, including neurodegenerative diseases and cancer. Here, it is shown for the first time that exosomes remain associated to the surface of cells following their expulsion from the cell. The image helps to demonstrate that exosomes are retained in small clusters, and further work has shown that these clusters are held together by the protein 'tetherin' which plays a similar role in holding viruses to the surface of cells as a means of limiting viral spread.