Therapeutic strategy for Fabry disease by intravenous administration of adeno-associated virus 2 or 9 in α-galactosidase A-deficient mice

Abstract

Background: Fabry disease (FD) is an inherited lysosomal storage disease caused by deficiency of α-galactosidase A (α-Gal A) encoded by the GLA gene. The symptoms of FD occur as a result of the accumulation of globotriaosylceramide (Gb3), comprising a substrate of α-Gal A, in the organs. Adeno-associated virus (AAV)-mediated gene therapy is a promising treatment for FD.

Methods: α-Gal A knockout (GLAko) mice were injected intravenously with AAV2 (1 × 10¹¹ viral genomes [vg]) or AAV9 (1 × 10¹¹ or 2 × 10¹² vg) vectors carrying human GLA (AAV-hGLA), and plasma, brain, heart, liver and kidney were tested for α-Gal A activity. The vector genome copy numbers (VGCNs) and Gb3 content in each organ were also examined.

Results: The plasma α-Gal A enzymatic activity was three-fold higher in the AAV9 2 × 10¹² vg group than wild-type (WT) controls, which was maintained for up to 8 weeks after injection. In the AAV9 2 × 10¹² vg group, the level of α-Gal A expression was high in the heart and liver, intermediate in the kidney, and low in the brain. VGCNs in the all organs of the AAV9 2 × 10¹² vg group significantly increased compared to the phosphate-buffered-saline (PBS) group. Although Gb3 in the heart, liver and kidney of the AAV9 2 × 10¹² vg was reduced compared to PBS group and AAV2 group, and the amount of Gb3 in the brain was not reduced.

Conclusions: Systemic injection of AAV9-hGLA resulted in α-Gal A expression and Gb3 reduction in the organs of GLAko mice. To expect a higher expression of α-Gal A in the brain, the injection dosage, administration route and the timing of injection should be reconsidered.

Keywords: Fabry disease; adeno-associated virus vector; gene therapy; mouse; systemic administration; α-galactosidase A deficiency.