title: AAV8(gfp) preferentially targets large diameter dorsal root ganglion neurones after both intra-dorsal root ganglion and intrathecal injection.
abstract: Adeno-associated viral vectors (AAV) are increasingly used to deliver therapeutic genes to the central nervous system (CNS) where they promote transgene expression in post mitotic neurones for long periods with little or no toxicity. In adult rat dorsal root ganglia (DRG), we investigated the cellular tropism of AAV8 containing the green fluorescent protein gene (gfp) after either intra-lumbar DRG or intrathecal injection and showed that transduced DRG neurones (DRGN) expressed GFP irrespective of the delivery route, while non-neuronal cells were GFP(-). After intra-DRG delivery of AAV8(gfp), the mean DRGN transduction rate was 11%, while intrathecal delivery transduced a mean of 1.5% DRGN. After intra-DRG injection, 2% of small DRGN (<30 μm in diameter) were GFP(+) compared with 32% of large DRGN (>60 μm in diameter). Axons of transduced DRGN were also GFP(+); no intra-spinal neurones were transduced. A small number of contralateral DRGN were transduced after intra-DRG injection, suggesting that AAV8 may diffuse from injected DRG into the spinal canal. Microglia and astrocytes were highly ramified with increased GFAP(+) immunoreactivity (i.e. activated) in the neuropil around GFP(+) DRG axon projections within the cord after intra-DRG injection. This study showed that after both intra-DRG and intrathecal delivery, strong preferential AAV8 tropism exists for large DRGN unassociated with cell death, but GFP(+) axons projecting in the spinal cord induced local glial activation. These results open up opportunities for targeted delivery of therapeutics such as neurotrophic factors to the injured spinal cord.
authors.affiliation: Neuropharmacology and Neurobiology Section, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Jacques
authors.forename: Zubair
authors.initials: Z
authors.lastname: Ahmed
authors.forename: Anna
authors.initials: A
authors.lastname: Forbes
authors.forename: Michael R
authors.initials: MR
authors.lastname: Douglas
authors.forename: Vasanthy
authors.initials: V
authors.lastname: Vigenswara
authors.forename: Martin
authors.initials: M
authors.lastname: Berry
authors.forename: Ann
authors.initials: A
authors.lastname: Logan
mesh_terms: D000818:Animals; D000229:Dependovirus / Q000502:physiology*; D005727:Ganglia, Spinal / Q000821:virology; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage*; D049452:Green Fluorescent Proteins / Q000008:administration & dosage; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007278:Injections, Spinal; D009474:Neurons / Q000821:virology*; D051381:Rats; D014161:Transduction, Genetic / Q000379:methods*
chemical_list: D049452:Green Fluorescent Proteins