Enzymatic correction and cross-correction of mucopolysaccharidosis type I fibroblasts by adeno-associated virus-mediated transduction of the alpha-L-iduronidase gene

Mucopolysaccharidosis type I (MPS I), a deficiency in the lysosomal enzyme alpha-L-iduronidase (IDUA), is characterized by skeletal abnormalities, hep atosplenomegaly and neurological dysfunction, To evaluate the potential for treatment of the disease using a gene delivery approach, recombinant adeno -associated virus (rAAV) vectors were constructed and evaluated for express ion of the human IDUA cDNA in transduced cells. 293 cells transduced with t hese AAV vectors contained IDUA activity at 0.5 to 1.4 mu mol/mg hr, 50- to 140-fold above background (control-transduced) levels. In time course stud ies of transduced 293 cells, IDUA activity levels peaked 1 week after trans duction and persisted at 50% of the peak level for at least 6 weeks, Transd uced MPS I fibroblasts also expressed high levels of IDUA activity (114-290 nmol/mg hr), which persisted for at least 3 weeks in the absence of select ion, In addition, transduced MPS I fibroblasts were capable of clearing int racellular radiolabeled glycosaminoglycan (GAG). As a test of the ability o f these vectors to mediate metabolic cross-correction, transduced HuH7 huma n hepatoma cells were demonstrated to release enzyme that was subsequently taken up by nontransduced MPS I fibroblasts, These results illustrate the e ffectiveness of AAV vectors for delivery and expression of human IDUA gene sequences and for potential treatment of MPS I.