Large Extracellular Vesicles Transfer Higher Levels of Prions and Infect Cell Culture Better than Small Extracellular Vesicles

Abstract

Prions are responsible for a number of lethal neurodegenerative and transmissible diseases in humans and animals. Extracellular vesicles, especially small exosomes, have been extensively studied in connection with various diseases. In contrast, larger microvesicles are often overlooked. In this work, we compared the ability of large extracellular vesicles (lEVs) and small extracellular vesicles (sEVs) to spread prions in cell culture. We utilized two cell culture models of prion infection and isolated lEVs by 20,000 × g force and sEVs by 110,000 × g force. The lEV fraction was enriched in β-1 integrin with a vesicle size starting at 150 nm. The fraction of sEVs was depleted of β-1 integrin with a mean size of 79 nm. Both fractions were enriched in prion protein, but the lEVs contained a higher prion-converting activity. In addition, lEV infection led to stronger prion signals in both cell cultures, as detected by cell and western blotting. Our data suggest the importance of lEVs in the trafficking and spread of prions over extensively studied small EVs.