Intracisternal vs intraventricular injection of AAV1 result in comparable, widespread transduction of the dog brain.

Widespread distribution of transduced brain cells following delivery of AAV vectors into the cerebrospinal fluid (CSF) of the cisterna magna (CM) has been demonstrated in large animal brains. In humans, intraventricular injection is preferred to intracisternal injection for CSF delivery due to the risk of brain stem injury. One study in the dog reported adverse reactions to AAV vectors expressing GFP injected into the lateral ventricle but not when injected into the CM.

Widespread correction of brain pathology in feline alpha-mannosidosis by dose escalation of intracisternal AAV vector injection.

Alpha-mannosidosis is caused by a genetic deficiency of lysosomal alpha-mannosidase, leading to the widespread presence of storage lesions in the brain and other tissues. Enzyme replacement therapy is available but is not approved for treating the CNS, since the enzyme does not penetrate the blood-brain barrier. However, intellectual disability is a major manifestation of the disease; thus, a complimentary treatment is needed.

Transduction characteristics of alternative adeno-associated virus serotypes in the cat brain by intracisternal delivery.

Multiple studies have examined the transduction characteristics of different AAV serotypes in the mouse brain, where they can exhibit significantly different patterns of transduction. The pattern of transduction also varies with the route of administration. Much less information exists for the transduction characteristics in large-brained animals.

Global CNS correction in a large brain model of human alpha-mannosidosis by intravascular gene therapy.

Intravascular injection of certain adeno-associated virus vector serotypes can cross the blood-brain barrier to deliver a gene into the CNS. However, gene distribution has been much more limited within the brains of large animals compared to rodents, rendering this approach suboptimal for treatment of the global brain lesions present in most human neurogenetic diseases. The most commonly used serotype in animal and human studies is 9, which also has the property of being transported via axonal pathways to distal neurons.

In Situ Hybridization for Detection of AAV-Mediated Gene Expression.

Techniques to localize vector transgenes in cells and tissues are essential in order to fully characterize gene therapy outcomes. In situ hybridization (ISH) uses synthesized complementary RNA or DNA nucleotide probes to localize and detect sequences of interest in fixed cells, tissue sections, or whole tissue mounts. Variations in techniques include adding labels to probes, such as fluorophores, which can allow for the simultaneous visualization of multiple targets.