P.17.9 AAV9 vector encoding hGAA improves synaptic pathology of the neuromuscular junction in Pompe disease

Abstract

Pompe disease is caused by the deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA) and results in a progressive accumulation of lysosomal glycogen. This impacts cellular architecture and function and leads to progressive respiratory insufficiency and motoneuron dysfunction. We have developed an adeno-associated virus (AAV) vector strategy to express long-term therapeutic levels of human GAA in cardiac, skeletal muscle, and the CNS resulting in improved cardiorespiratory function. However, an incomplete restoration of skeletal muscle function or activation still remains. We tested the hypothesis that an AAV9 vector encoding hGAA would result in retrograde transport and restore neuromuscular junction integrity and reverse axonal pathology in Pompe disease. 20 month old Pompe mice (Gaa−/−) were randomized to the following groups: untreated (Gaa−/−), AAV9-CMV-hGAA, or AAV9-DES-hGAA. AAV9 treated animals received a single injection of 1 × 1011vg in the right tibialis anterior (TA) muscle. One month post injection, the TA muscle and lumbar spinal cord were analyzed for vector genome copy number and GAA activity. Significant levels of vector genomes were detected in the TA (AAV9-DES-hGAA 1.5 × 105 ± 3.1 × 104 vg/ug DNA; AAV9-CMV-hGAA 8.4 × 104 ± 1.7 × 104 vg/ug DNA) and lumbar spinal cord (AAV9-DES-hGAA 1.5 × 103 ± 1.7 × 102 vg/ug DNA; AAV9-CMV-hGAA 2.5 × 103 ± 1.3 × 103 vg/ug DNA) suggesting efficient transduction of skeletal muscle and retrograde transport of AAV9. Activity of GAA in TA lysates was 2396% and 1770% above wild-type in AAV9-DES-hGAA and AAV9-CMV-hGAA animals, respectively ( p