Does extracellular vesicle specificity truly exist?

Extracellular vesicles (EVs) are nano-sized membranous particles secreted by nearly all cell types that facilitate intercellular communication through the transfer of bioactive cargo. Growing evidence suggests that EVs may exhibit targeting specificity toward particular cells, yet the mechanisms remain poorly understood. In this review, we critically examine the concept of EV target specificity by outlining three potential stages where it may arise: (1) EV binding to the recipient cell membrane, (2) internalization and cargo release and (3) the induction of functional responses within recipient cells. We further explore how EV-intrinsic properties, recipient cell characteristics, and the surrounding microenvironment collectively shape these interactions. A key challenge in the field is the frequent assumption that EV uptake equates to functional relevance. In reality, many internalized EVs are recycled or degraded in lysosomes without eliciting any measurable effect. We therefore propose a refined definition of EV specificity, emphasizing that functional outcomes should serve as the central criterion for establishing meaningful EV specificity. Rather than offering definitive answers, this review highlights unresolved questions and calls for deeper investigation into how EVs select their target cells. Understanding these fundamental principles of EV function is critical for advancing the clinical and therapeutic application of EVs.