In vitro correction of iduronate-2-sulfatase deficiency by adenovirus-mediated gene transfer

Hunter syndrome is a lethal lysosomal storage disorder caused by the deficiency of iduronate-2-sulfatase and characterized by severe skeletal and neurological symptoms. Only symptomatic treatments are available and, although bone marrow transplantation has been suggested, no encouraging results have been obtained so far. Therefore, gene therapy might be a route to be pursued for treatment of the disease. In this respect, one major goal to achieve is the generation of an overexpressing vector able to correct, in particular, central nervous system (CNS) cells. Adenoviruses have been shown to infect CNS cells efficiently with minor or even absent immunological response. We describe the generation of a replication-defective adenoviral vector, AdRSVIDS, which is able to express in vitro high levels of iduronate-2-sulfatase. After infection, accumulation of mucopolysaccharides in treated Hunter cells was normalized. Furthermore, endocytosis of the transduced IDS did occur via the mannose-6-phosphate (M6P) receptor. Since no animal model for the disease is available, we developed a system based on the generation of derma-equivalents which enabled us to verify the expression of high levels of sulfatase up to 30 days after infection.