The identification of the most efficient method for whole central nervous system targeting that is translatable to humans and the safest route of adeno-associated virus (AAV) administration is a major concern for future applications in clinics. Additionally, as many AAV serotypes were identified for gene introduction into the brain and the spinal cord, another key to human gene-therapy success is to determine the most efficient serotype. In this study, we compared lumbar intrathecal administration through catheter implantation and intracerebroventricular administration in the cynomolgus macaque. We also evaluated and compared two AAV serotypes that are currently used in clinical trials: AAV9 and AAVrh10. We demonstrated that AAV9 lumbar intrathecal delivery using a catheter achieved consistent transgene expression in the motor neurons of the spinal cord and in the neurons/glial cells of several brain regions, whereas AAV9 intracerebroventricular delivery led to a consistent transgene expression in the brain. In contrast, AAVrh10 lumbar intrathecal delivery led to rare motor neuron targeting. Finally, we found that AAV9 efficiently targets respiratory and skeletal muscles after injection into the cerebrospinal fluid (CSF), which represents an outstanding new property that can be useful for the treatment of diseases affecting both the central nervous system and muscle.

Pompe disease is a lysosomal storage disorder caused by acid-α-glucosidase (GAA) deficiency, leading to glycogen storage. The disease manifests as a fatal cardiomyopathy in infantile form. Enzyme replacement therapy (ERT) has recently prolonged the lifespan of these patients, revealing a new natural history. The neurologic phenotype and the persistence of selective muscular weakness in some patients could be attributed to the central nervous system (CNS) storage uncorrected by ERT. GAA-KO 6neo/6neo mice were treated with a single intrathecal administration of adeno-associated recombinant vector (AAV) mediated gene transfer of human GAA at 1 month and their neurologic, neuromuscular, and cardiac function was assessed for 1 year. We demonstrate a significant functional neurologic correction in treated animals from 4 months onward, a neuromuscular improvement from 9 months onward, and a correction of the hypertrophic cardiomyopathy at 12 months. The regions most affected by the disease i.e. the brainstem, spinal cord, and the left cardiac ventricular wall all show enzymatic, biochemical and histological correction. Muscle glycogen storage is not affected by the treatment, thus suggesting that the restoration of muscle functionality is directly related to the CNS correction. This unprecedented global and long-term CNS and cardiac cure offer new perspectives for the management of patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-017-0464-2) contains supplementary material, which is available to authorized users.

Adeno-associated virus (AAV) gene therapy constitutes a powerful tool for the treatment of neurodegenerative diseases. While AAVs are generally administered systemically to newborns in preclinical studies of neurological disorders, in adults the maturity of the blood-brain barrier (BBB) must be considered when selecting the route of administration. Delivery of AAVs into the cerebrospinal fluid (CSF) represents an attractive approach to target the central nervous system (CNS) and bypass the BBB. In this study, we investigated the efficacy of intra-CSF delivery of a single-stranded (ss) AAV9-CAG-GFP vector in adult mice via intracisternal (iCist) or intralumbar (it-Lumb) administration. It-Lumb ssAAV9 delivery resulted in greater diffusion throughout the entire spinal cord and green fluorescent protein (GFP) expression mainly in the cerebellum, cortex and olfactory bulb. By contrast, iCist delivery led to strong GFP expression throughout the entire brain. Comparison of the transduction efficiency of ssAAV9-CAG-GFP versus ssAAV9-SYN1-GFP following it-Lumb administration revealed widespread and specific GFP expression in neurons and motoneurons of the spinal cord and brain when the neuron-specific synapsin 1 (SYN1) promoter was used. Our findings demonstrate that it-Lumb ssAAV9 delivery is a safe and highly efficient means of targeting the CNS in adult mice.