Evolution of Concepts Regarding the Diagnostic and Prognostic Significance of Glial Fibrillary Acidic Protein (GFAP)-Positive Extracellular Vesicles

This review demonstrates that the diagnostic and prognostic significance of glial fibrillary acidic protein (GFAP) is not limited to its use as a marker of astrocytic damage but should also be considered in the context of the diversity of GFAP isoforms, their heterogeneous tissue-specific expression and their pronounced association with extracellular vesicles (EVs). The data presented in this review indicate that GFAP-positive (GFAP+) EVs possess broad clinical relevance in both acute and chronic pathologies of the nervous system, including ischemic stroke, traumatic brain injury, glioblastoma, and potentially diabetic and drug-induced polyneuropathy. Particular attention is given to the critical analysis of methodological approaches for studying GFAP+ EVs, including discussion of their proposed biogenesis, mechanisms of intravesicular incorporation of cytoskeletal fragments, and the hypothetical sorption of GFAP within the vesicular protein corona. A principal conclusion of this work is that, despite the high translational potential of GFAP+ vesicles as a novel liquid biopsy platform, further implementation of this approach in clinical practice will require standardization of EV isolation protocols, harmonization of phenotyping methodologies in accordance with MISEV 2023 recommendations, and large-scale prospective studies aimed at validating the biological nature, origin, and clinical reproducibility of identified GFAP-associated vesicular subpopulations.