Advancing MSC-EV Therapies: Harnessing Preconditioning and Mito-EVs to Tackle Neuroinflammation and Neurodegeneration

Neuroinflammation plays a central role in the onset and progression of neurodegenerative disorders. Several disease-modifying therapies have been developed to target neuroinflammatory pathways in specific disorders. However, their ability to stop disease progression or restore neuronal and mitochondrial homeostasis remains limited. This is still a major unmet clinical need. In this context, mesenchymal stromal cell (MSC)-derived Extracellular Vesicles (EVs) have emerged as a promising cell-free therapeutic strategy due to their ability to modulate immune responses and promote neuroprotection through the delivery of bioactive cargo. Recent evidence has identified a distinct subset of EVs, known as mitochondrial EVs (mito-EVs), which carry mitochondrial DNA, proteins, and functional components. These vesicles may uniquely influence cellular bioenergetics, redox balance, and neuroinflammatory signaling, offering additional therapeutic potential compared to conventional MSC-EVs. This review summarizes the role of MSC-derived EVs in neuroinflammatory disorders, with a particular focus on mito-EVs. It also discusses preconditioning strategies to enhance EV efficacy, including hypoxic, inflammatory, pharmacological priming and genetic engineering approaches. Finally, we critically evaluate current preclinical evidence regarding the treatment of major neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, Multiple Sclerosis, and Amyotrophic Lateral Sclerosis, as well as Traumatic Injury, highlighting the key challenges for clinical translation.