617 Efficient Gene Delivery to the Enteric Nervous System by IV Delivery of AAV Vectors

Gene therapy may be useful to treat and study the enteric nervous system (ENS). In this study, we characterized transduction efficiency and distribution in the myenteric and submucosal plexuses following intravenous (IV) injection of adeno-associated viral vectors (AAV) expressing GFP in mice. Neonate (P1) mice were injected with AAV9-CB-GFP (3 x 1011 vg) in the temporal vein and juvenile mice (P21) received tail vein injections (2 x 1012 vg). Mice were euthanized at 60-90 days of age, and the myenteric plexus was examined. GFP positive myenteric neurons were found along the entire GI tract in injected mice. Segmental examinations of myenteric neurons in the colon showed no oral-aboral bias. Neuronal transduction ranged from 21-57% depending on the region. GFP co-localized with interneurons, excitatory and sensory myenteric neurons. In contrast, GFP expression in VIP, nNOS and glial cells was absent. However, IV injection of AAV9 with a glial promoter (GFAP) drove GFP expression exclusively in glia. Neonate IV injections with AAV1, 5, and 6 containing the CB-GFP expression cassette produced little to no transgene expression in the myenteric plexus. However, AAV8-CB-GFP showed significantly higher neuronal transduction compared to AAV9 injected mice. AAV8-CB-GFP expressed in all ENS cell types examined including VIP and nNOS neurons and intraganglionic S100 glia. Characterization of AAV-CB-GFP transduction in submucosal neurons is ongoing. These data demonstrate that the ENS is efficiently targeted by AAV8 and AAV9 following IV delivery. Further, transgene expression can be customized with changes in the viral capsid and expression cassette.