Extracellular Vesicles for Space Biomedical Research.

Extracellular vesicles (EVs) are regulated, information-rich nanovesicles that reflect aspects of parent-cell state, making them promising readouts on biological adaptation. Microgravity perturbs mechanotransduction, mitochondrial stress and quality control, and autophagy-endolysosomal trafficking, processes that can reshape EV biogenesis and cargo selection. However, spaceflight EV studies remain sparse and methodologically inconsistent, complicating mechanistic interpretation and cross-mission comparison. In this review, we define an EV-centred framework that links microgravity-sensitive changes in cytoskeletal tension, membrane trafficking, mitochondrial quality control, and autophagy-endolysosomal routing to four measurable EV outputs: concentration, subtype balance, surface phenotype, and molecular cargo. We use this framework to organize current evidence from spaceflight and simulated microgravity studies, while considering the limitations introduced by heterogeneous isolation and characterization methods. We then examine microgravity-relevant EV culture systems, including high-density three-dimensional tissues, organoids, spheroids, and perfused tissue chips that support serial collection of conditioned media or effluent, together with compact capture and concentration approaches and core characterization strategies. Finally, we discuss the potential use of EVs as longitudinal liquid-biopsy readouts of stress and aging-like trajectories, as regenerative products relevant to musculoskeletal, vascular, and immune risks, and as engineered delivery vehicles. We identify EV uptake and biodistribution under altered gravity as a major translational gap and emphasize the need for standardized workflows that improve experimental rigor and biological interpretation in spaceflight research.