| Mucopolysaccharidosis type I (MPS I), an autosomal recessive deficiency of the lysosomal enzyme α-L-iduronidase (IDUA), is characterized by skeletal abnormalities, hepatosplenomegaly 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 expression of the human IDUA cDNA. Cultures of 293 cells transduced with these AAV vectors contained 0.5 to 1.4 μmol/mg-hr of IDUA activity, 50- to 140-fold above background (control-transduced) levels. Transduced 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 selection. In addition, transduced MPS I fibroblasts were capable of clearing intracellular radiolabelled glycosaminoglycan (GAG). As a test of the ability of these vectors to mediate metabolic cross correction, transduced HuH7 human hepatoma cells were demonstrated to release enzyme which was subsequently taken up by non-transduced MPS I fibroblasts.; To determine the potential for treatment of MPS I using a gene delivery approach, a recombinant adeno-associated virus (AAV) vector vTRCA1, was constructed and 1 × 1010 particles were injected intravenously into 1 day-old Idua −/− mice. High levels of IDUA activity were present in the plasma of vTRCA1-treated animals that persisted for the 5 month duration of the study, with heart and lung of this group demonstrating the highest tissue levels of gene transfer and enzyme activity overall. VTRCA1-treated Idua (−/−) animals with measurable plasma IDUA activity exhibited histopathological evidence of reduced lysosomal storage in a number of peripheral tissues and certain regions of the brain and were normalized with respect to urinary GAG excretion, craniofacial boney parameters, and body weight. In an open field test, vTRCA1-treated Idua −/− animals exhibited a significant reduction in total squares covered and a trend of normalization in rearing events and grooming time compared to control-treated MPS I animals. We conclude that AAV-mediated transduction of the IDUA gene in newborn Idua −/− mice was sufficient to have a major curative impact on several of the most important parameters of the disease. |
