Integrin beta 1 and fibronectin mediate extracellular vesicle uptake and functional RNA delivery.

Extracellular vesicles (EVs) are cell-derived vesicles secreted by all cell types into the extracellular spaces. EVs comprise a heterogenous population of vesicles that carry bioactive molecules, such as proteins, lipids, and RNAs, which they can deliver to recipient cells. Over the past few years, EVs have been recognized for their vital role in intercellular communication, and thereby in various physiological and pathological processes. In addition, EVs are increasingly being studied as potential drug delivery vehicles. It is therefore crucial to understand the mechanisms and molecular players underlying EV uptake and functional cargo delivery. Several studies have investigated various EV uptake pathways; nonetheless, molecular mechanisms governing uptake and cargo transfer remain largely lacking. Here, we show, using a CRISPR/Cas9-mediated reporter system, that integrin β1 on recipient cells plays an important role in EV uptake and EV-mediated RNA delivery. Additionally, using both RNA interference and blocking antibodies, we show that association of integrin β1 with integrin α4 is essential for this process. We demonstrate that α4β1 on recipient cells interacts with EVs through surface localized fibronectin via binding to its leucine-aspartic acid-valine motif, and that blocking of this interaction reduces both EV uptake and RNA delivery. Thus, we identify a key mechanism in EV uptake and cargo delivery which could potentially facilitate research into EV biology and pave the way for the development of novel therapeutic approaches by targeting pathways that lead to functional cargo delivery.