Therapeutic extracellular vesicles isolated from mesenchymal stem cells: properties, isolation, characterization, and applications in optic neuropathies
Extracellular vesicles (EVs) are promising cell-free therapeutic agents because of their low immunogenicity, excellent biocompatibility, and intrinsic capacity for intercellular communication. Of these, mesenchymal stem cell-derived EVs (MSC-EVs) have attracted considerable interest for their potential in treating optic neuropathies; however, their clinical translation remains limited by standardized manufacturing, quality evaluation, and mechanistic understanding. This review summarizes key advances in therapeutic EV development, including MSC culture, EV production, isolation, and characterization, with a focus on the current strategies and limitations of EV quality assessment. In addition, we propose a pathological-node-based framework to integrate the current evidence for EV therapies with optic neuropathies. Despite differences in EV sources, molecular composition, and proposed mechanisms, the therapeutic effects of diverse EV preparations converge on three shared pathological processes: retinal ganglion cell (RGC) preservation, neuroinflammatory regulation, and metabolic homeostasis maintenance. Finally, we discuss major challenges for clinical translation, including EV heterogeneity, functional EV subpopulations, targeted delivery, engineering strategies, and the establishment of biologically relevant potency assays. This review highlights the need to shift EV studies from empirical preparation toward mechanism-driven design and functional evaluation, thereby facilitating the development of clinically translatable EV-based therapies.