Extracellular vesicles (EV) are secreted by nearly every mammalian cell type and contain a wealth of bioactive cargo capable of modulating target cell physiology and function though a variety of paracrine signaling mechanisms (Leavitt et al., 2019). Human embryonic stem cell (hESC)-derived extracellular vesicles (hESC-derived EV), were extracted from the hESC line H9 (WA09 Wicell Research Institute, Inc., Madison, WI). We analyzed the bioactive protein cargo to identify components that help to resolve radiation-induced injury to the lung in mice when injected in vivo.