Decoding metastasis initiation through spatiotemporal extracellular vesicle-mediated intercellular signaling

Metastatic colonization is governed by the earliest interactions between disseminated tumor cells (DTCs) and the tissue microenvironment. Extracellular vesicles (EVs) have emerged as critical mediators of this early communication, conditioning distant organs before and after DTC arrival. Despite extensive characterization of cancer EV cargoes and functions, a fundamental question remains unresolved: when, where, and to which cell types cancer EVs are delivered during the initial stages of metastatic colonization. This knowledge gap stems from limitations of conventional in vitro and in vivo assays, which lack physiological architecture or sufficient spatiotemporal resolution. Recent advances in physiological metastatic models, including organotypic ex vivo models, together with innovative EV labeling and tracking technologies, now enable direct visualization of EV transfer within native-like tissue contexts. Here, we propose a conceptual framework in which metastatic colonization is "decoded" as a spatiotemporally orchestrated EV-mediated intercellular signaling, where EV distribution, tropism, and recipient-cell responses collectively define DTC fate. We discuss how integrating these emerging platforms can decode EV-mediated communication during metastatic colonization that leads to therapeutic development.