Exosome Biology at the Interface of Neurodegeneration and Therapeutic Innovation.

Neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, are defined by progressive neuronal loss, protein misfolding, and chronic neuroinflammation, yet effective disease-modifying therapies remain absent. Exosomes have emerged as key mediators of central nervous system communication and are increasingly central to the biology of neurodegeneration. These nanoscale vesicles transport proteins, lipids, and nucleic acids across cellular and anatomical barriers, influencing synaptic function, immune signaling, and metabolic homeostasis. Under pathological conditions, exosomes facilitate the spread of misfolded proteins such as amyloid-β, p-tau, α-synuclein, and TDP-43, thereby accelerating network-level degeneration. At the same time, their cargo exhibits disease-specific molecular signatures detectable in peripheral biofluids, supporting their development as minimally invasive biomarkers for early diagnosis and longitudinal monitoring. Advances in exosome engineering further underscore their potential as therapeutic delivery vehicles capable of crossing the blood-brain barrier and targeting pathogenic pathways with RNA-based therapeutics, proteins, or gene-editing systems. Together, these findings position exosomes as pivotal contributors to both the mechanistic progression and translational targeting of neurodegenerative diseases.