Small extracellular vesicles are key regulators of non-cell autonomous intercellular communication in senescence via the interferon protein, IFITM3

Senescence is a cellular phenotype present in health and disease, characterized by a stable cell cycle arrest and an inflammatory response, denominated senescence-associated secretory phenotype (SASP). The SASP is important in influencing the behaviour of neighbouring cells and altering the microenvironment; yet, this role has been mainly attributed to soluble factors. Here, we show that both the soluble factors in addition to small extracellular vesicles (sEV) are capable of transmitting paracrine senescence to nearby cells. Analysis of individual cells internalizing sEV, using a Cre-reporter system, show a positive correlation between sEV uptake and senescence activation. Interestingly, we find an increase in the number of multivesicular bodies during senescence in vivo. sEV protein characterization by mass spectrometry (MS) followed by a functional siRNA screen identify the Interferon Induced Transmembrane Protein 3 (IFITM3) as partially responsible for transmitting senescence to normal cells. Altogether, we found that sEV contribute to paracrine senescence. SASP related mRNA transcripts in HFFF2 treated with sEV from iRAS cells in comparison with HFFF2 treated with sEV from iC cells