scAAV9 Intracisternal Delivery Results in Efficient Gene Transfer to the Central Nervous System of a Feline Model of Motor Neuron Disease

Abstract

On the basis of previous studies suggesting that vascular endothelial growth factor (VEGF) could protect motor neurons from degeneration, adeno-associated virus vectors (serotypes 1 and 9) encoding VEGF (AAV.vegf) were administered in a limb-expression 1 (LIX1)-deficient cat-a large animal model of lower motor neuron disease-using three different delivery routes to the central nervous system. AAV.vegf vectors were injected into the motor cortex via intracerebral administration, into the cisterna magna, or intravenously in young adult cats. Intracerebral injections resulted in detectable transgene DNA and transcripts throughout the spinal cord, confirming anterograde transport of AAV via the corticospinal pathway. However, such strategy led to low levels of VEGF expression in the spinal cord. Similar AAV doses injected intravenously resulted also in poor spinal cord transduction. In contrast, intracisternal delivery of AAV exhibited long-term transduction and high levels of VEGF expression in the entire spinal cord, yet with no detectable therapeutic clinical benefit in LIX1-deficient animals. Altogether, we demonstrate (i) that intracisternal delivery is an effective AAV delivery route resulting in high transduction of the entire spinal cord, associated with little to no off-target gene expression, and (ii) that in a LIX1-deficient cat model, however, VEGF expressed at high levels in the spinal cord has no beneficial impact on the disease course.

Intracisternal delivery of AAV9 results in oligodendrocyte and motor neuron transduction in the whole central nervous system of cats

“…The vector transduced neurons in the cerebellum, thalamus, striatum, motor and sensory cortex of both newborn (data not shown) and young injected cats, as we previously showed. 29 In addition to GFP-positive neurons, transduced astrocytes were also seen in the cerebral cortex of newborn and young cats (Figure 2), indicating that IC injection of AAV9 resulted in both neuronal and astrocytic transduction in the gray matter of the brain, consistent with recent reports in primates 17,18 or in dogs. 21 More surprisingly, glial fibrillary acidic protein (GFAP)-positive fibrous astrocytes in the brain and a significant number of oligodendrocytes throughout both the corona radiata in the brain and the white matter all along the spinal cord expressed GFP (Figure 2).…”

Plastin-3 extends survival and reduces severity in mouse models of spinal muscular atrophy

“…PLS3 levels were elevated compared with baseline levels following a single injection via the facial vein of 1 × 10 11 vector genomes of the AAV9-PLS3 vector. Widespread distribution from a single peripheral injection has been reported extensively in SMA and related fields (16)(17)(18)(19); therefore, achieving spinal cord expression from a peripheral injection was expected. Collectively, these results provide proof-of-concept evidence that increasing PLS3 levels could be an alternative approach for reducing the severity in milder forms of SMA.…”

“…To investigate the therapeutic potential of a genetic modifier of the SMA phenotype, we utilized adeno-associated virus serotype 9 (AAV9) to deliver the PLS3 cDNA. AAV9 exhibits a broad tropism for tissues within the CNS and within peripheral tissues (16)(17)(18)(19). Importantly, AAV9-mediated delivery enters disease-relevant cells and is able to quickly express the transgene, as evidenced by the significant rescue of the SMA phenotype following AAV9-SMN delivery (18,(20)(21)(22)(23) …”

Optogenetic Brain Interfaces

“…Delivery of drugs and/or viruses across the blood-brain barrier (BBB) is typically difficult. One option for gene delivery might be direct injection into the brain parenchyma or ventricles/cisterna to circumvent such difficulties [230]. There is recent evidence that some serotypes of AAV may cross the BBB, and could therefore be delivered via intravenous injection [231], [232].…”