Delivery of therapeutic genes to large regions of the central nervous system (CNS) with minimal damage from local surgery is a long sought goal of the neurodegenerative disease field. The discovery that Adeno-associated virus (AAV) serotype 9 can cross the blood-brain barrier (BBB) when administered systemically delivering genes into the brain and spinal cord has been an important leap forward in this direction. While initial characterizations of AAV9 transduction largely focused on cells of the brain and spinal cord, studies have also shown that AAV9 can reach the retina when administered through this route. Altogether these findings establish systemic gene delivery using AAV9 as an important tool for the development of gene therapies or creation of animal models of neurodegenerative disease. To harvest the full potential of this system, efforts have been invested in finding alternative and possibly more potent AAV vectors for systemic gene delivery across the BBB. Multiple variants have been systematically evaluated after intravascular infusion in neonatal mice. Several AAVs have shown CNS transduction with AAVrh.10 showing comparable transduction to AAV9 in many brain regions. Furthermore, directed evolution and rational capsid mutagenesis have been implemented to strengthen this powerful transgenesis approach at the vector level. Collectively data indicate that hemodynamics, as well as viral receptors play a role in the transduction patterns of AAV after intravascular administration. The AAVs that achieve stable widespread gene transfer in the CNS are likely to become remarkably useful platforms for the development of therapeutic approaches for neurodegenerative disorders while remaining precious biological tools for neuroscience research.
Delivery of therapeutic genes to large regions of the central nervous system (CNS) with minimal damage from local surgery is a long sought goal of the neurodegenerative disease field. The discovery that Adeno-associated virus (AAV) serotype 9 can cross the blood-brain barrier (BBB) when administered systemically delivering genes into the brain and spinal cord has been an important leap forward in this direction. While initial characterizations of AAV9 transduction largely focused on cells of the brain and spinal cord, studies have also shown that AAV9 can reach the retina when administered through this route. Altogether these findings establish systemic gene delivery using AAV9 as an important tool for the development of gene therapies or creation of animal models of neurodegenerative disease. To harvest the full potential of this system, efforts have been invested in finding alternative and possibly more potent AAV vectors for systemic gene delivery across the BBB. Multiple variants have been systematically evaluated after intravascular infusion in neonatal mice. Several AAVs have shown CNS transduction with AAVrh.10 showing comparable transduction to AAV9 in many brain regions. Furthermore, directed evolution and rational capsid mutagenesis have been implemented to strengthen this powerful transgenesis approach at the vector level. Collectively data indicate that hemodynamics, as well as viral receptors play a role in the transduction patterns of AAV after intravascular administration. The AAVs that achieve stable widespread gene transfer in the CNS are likely to become remarkably useful platforms for the development of therapeutic approaches for neurodegenerative disorders while remaining precious biological tools for neuroscience research.