Implications of AAV Serotypes in Neurological Disorders: Current Clinical Applications and Challenges

Adeno-associated virus (AAV) vectors have emerged as powerful tools for in vivo gene therapy, enabling long-term transgene expression in targeted tissues with minimal pathogenicity. This review examines the AAV serotypes used in clinical gene therapy trials for neurodegenerative (central nervous system, CNS) diseases, highlighting their tropisms, engineering advances, and translational progress. We discuss how capsid modifications, cell-specific promoters, and novel delivery routes are enhancing AAV tropism and reducing immunogenicity to overcome current limitations. Key clinical trials in neurodegenerative disorders (such as Parkinson’s, Alzheimer’s, and Huntington’s disease) are summarized, including delivery methods (intravenous, intracoronary, intrathecal, etc.) and outcomes. We further outline the regulatory landscape with recent approvals of AAV-based therapies and ongoing efforts to address safety challenges like immune responses and vector dose toxicity. A more translational, forward-looking perspective is adopted to consider combination therapies (e.g., AAV with immune modulation or genome editing) and strategic directions to improve the next generation of AAV vectors. Overall, continued innovation in AAV vector design and delivery, alongside careful clinical evaluation, is accelerating the translation of gene therapies for neurodegenerative diseases.