Mitochondrial dysfunction is a critical pathological trait of numerous neurodegenerative and inflammatory central nervous system (CNS) disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Cellular stressors can directly modulate mitochondrial metabolism and increase the production of reactive oxygen species (ROS), thereby triggering mitochondrial retrograde signaling that alters nuclear gene expression and promotes the release of deleterious signal components into the cytoplasm. These processes contribute to neuronal injury and the progression of disease pathology. Emerging evidence underlines the therapeutic potential of extracellular vesicles (EVs) derived from stem cells such as mesenchymal stem cells (MSCs), neuronal stem cells (NSCs), and induced pluripotent stem cells (iPSCs) in reversing mitochondrial dysfunction. These nanoscale vesicles, which encapsulate transcription factors, nucleic acids, proteins, lipids, and even mitochondria, facilitate intercellular communication and influence the biological behaviour of recipient cells. Notably, stem cell-derived EVs have been shown to enhance mitochondrial function by improving the maximal oxygen consumption rate and spare respiratory capacity in injured neuronal cells. The molecular cargo within EVs, including miR-21, miR-29, and antioxidant enzymes, has been implicated in regulating mitochondrial biogenesis, reducing oxidative stress, and modulating pathways associated with apoptosis, mitophagy, and energy metabolism. Importantly, EVs can cross the blood-brain barrier (BBB), offering a minimally invasive strategy for targeted CNS delivery. In conclusion, stem cell-derived EVs represent a promising, cell-free therapeutic approach to restoring mitochondrial homeostasis and preventing neuronal disorders.
