Research for gene therapy of α-glucosidase deficiency using adenoviral vector

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α-glucsidase deficiency (acid maltase deficiency: AMD) causes a lysosomal glycogenosis inherited as an autosomal recessive trait. The infantile type of AMD (Pompe disease) leads to early death due to severe dysfunction of cardiac and respiratory muscles and no effective therapy is available. Replication-defective adenovirus vectors offer a promising tool for in vivo gene delivery and gene therapy. We constructed a recombinant adenovirus containing the human α-glucosidase cDNA downstream of the CAG promoter, composed of modified chicken β-actin promoter and CMV-IE enhancer (AxCANAM). We used two animal models to estimate the effects of AxCANAM; naturally generated Japanese quail with AMD and α-glucosidase knockout (AM-KO) mice.First, we used Japanese quail with AMD. When cultured fibroblasts from AMD quails were infected with AxCANAM, α-glucosidase activity in the cells increased in proportion to multiplicity of infection (MOI). When AxCANAM was injected into unilateral superficial pect … More oral muscle of AMD quails, PAS staining showed that glycogenosomes disappeared and stainability of acid phosphatase was reduced in the injected area as compared to the contralateral muscle of the same birds. Biochemically, α-glucosidase activity increased and glycogen content decreased in the injected muscle. Western blot analysis showed that AMD quail muscle injected with AxCANAM expressed human α-glucosidase protein processed to active forms. These results suggest that the human α-glucosidase cDNA transferred by an adenovirus vector was sufficiently expressed, leading to a marked reduction of the glycogen accumulation in the skeletal muscle of AMD quails.Second, we used knockout mice, which was generated with exon 6 of α-glucosidase gene deleted. When AxCANAM was injected into cardiac cavity of AM-KO mice, α-glucosidase activity increased and glycogen content decreased in skeletal muscle, heart, and liver. Stainability of PAS and acid phosphatase was reduced in these tissues. After the injection, α-glucosidase was expressed mainly in liver, but it was thought that the precurcer protein was presumably secreted into blood, uptaked by peripheral tissues, such as muscle, and processed to active α-glucosidase in lysosomes, thereby leading to systemic effects. Less