Convection-enhanced Delivery of AAV2 in White Matter--a Novel Method for Gene Delivery to Cerebral Cortex

Background: Convection-enhanced delivery (CED) is currently under investigation for delivering therapeutic agents to subcortical targets in the brain. Direct delivery of therapies to the cerebral cortex, however, remains a significant challenge.

New Method: We describe a novel method of targeting adeno-associated viral vector (AAV) mediated gene therapies to specific cerebral cortical regions by performing high volume, high flow rate infusions into underlying white matter in a large animal (porcine) model.

Results: Infusion volumes of up to 700 μl at flow rates as high as 10 μl/min were successfully performed in white matter without adverse neurological sequelae. Co-infusion of AAV2/5-GFP with 0.2% Gadolinium in artificial CSF confirmed transgene expression in the deep layers of cerebral cortex overlying the infused areas of white matter.

Comparison With Existing Methods: AAV-mediated gene therapies have been previously targeted to the cerebral cortex by performing intrathalamic CED and exploiting axonal transport. The novel method described in this study facilitates delivery of gene therapies to specific regions of the cerebral cortex without targeting deep brain structures.

Conclusions: AAV-mediated gene therapies can be targeted to specific cortical regions by performing CED into underlying white matter. This technique could be applied to the treatment of neurological disorders characterised by cerebral cortical degeneration.