AAV9 is considered the most efficient AAV serotype targeting blood-brain barriers. To enhance effective gene therapy for CNS illnesses, testing novel vectors with more efficient crossing capabilities is vital

Although gene therapy for CNS diseases shows promise in cell and animal investigations, most human trials have failed to satisfy the requisite requirements. Finding novel techniques to boost the efficacy of gene therapy in treating CNS diseases is still crucial. A growing number of clinical trials have proved the efficacy and safety of using AAV vectors, making AAV vector research a gene therapy hotspot. However, due to the presence of the BBB, many siRNA and DNA with potential therapeutic value are difficult to transport from peripheral circulation to the brain using AAV vectors, limiting the clinical impact of gene therapy drugs in the CNS and posing a major challenge to the field of CNS gene therapy. In early studies, AAV9 was considered the most effective AAV serotype for getting through the blood-brain barrier and transduction to central nervous system cells following intravenous injection. Aavrh10 isolated from rhesus monkeys was equal to, if not superior to, AAV9. AAV-PHP.B, a newly built capsid, exhibits 40-fold greater efficacy than AAV9 in astrocyte and neuron transduction. AAV-PHP.eB, a modified AAV-PHP.B variety, was identified to retain PHP.B's AAV-capacity to transduce astrocytes while enhancing neuronal transduction. While the four serotypes AAV9, AAVrh10, AAV-PHP.B, and AAV-PHP.eB have been validated to penetrate mice's BBB following intravenous injection, the number of AAV vectors that can do so is low. Moreover, the manner in which AAV vectors penetrate the BBB remains unclear. To promote efficient gene therapy for CNS diseases, it is still important to test new vectors with more efficient crossing abilities and understand their crossing processes. In addition to technical challenges, AAV vectors in treating CNS diseases may be limited by cautious attitudes to innovative treatments. Continued advances in AAV vector research, together with early clinical trial outcomes, might help researchers achieve the full potential of AAV-based CNS disease therapies.