Many inborn errors of connective tissue metabolism have as a sequelae of the disorder a severe and often devastating neurologic component. Representative of such disorders are the mucopolysaccharidoses (MPS), and, specifically, beta-glucuronidase deficiency or MPS VII (Sly syndrome). Therapies directed toward correction of the MPS usually have either no effect (direct enzyme replacement, fibroblast transplantation or amnion membrane transplantation) or questionable effects (bone marrow transplantation) on the CNS involvement. Presumably this is due to difficulties in delivering enzymes or cells across the blood/brain barrier. Enzyme replacement to the CNS may therefore be more effectively approached by the direct delivery of transgenes. Previous attempts to direct gene replacement to the brain have involved the use of recombinant herpes simplex virus vectors, retroviruses, plasmids, or liposome/plasmids, but technical problems have limited the usefulness of these systems to date. More recently, however, we have achieved high levels of long term gene transfer and transgene expression in murine brain using replication defective recombinant adenoviruses (greater than 2 months). This proposal outlines a series of experiments that will use recombinant adenoviruses containing the cDNA for human beta-glucuronidase to direct regional gene transfer to the CNS of homozygous deficient gus (mps) mice. The goal of these experiments will be the metabolic correction of the CNS involvement in these MPSVII mice via regional expression of transgenic beta- glucuronidase. Several anatomically and functionally defined brain regions will be targeted for gene transfer. Analysis of enzyme production in brain will be determined by in situ enzymatic histochemistry, quantitative analysis of enzyme activity i tissue lysates, measurement of glycosaminoglycan storage products in brain, and transmission electron microscopy. Long-term safety issues will also be addressed, as will the therapeutic response of Adbeta-gluc gene transfer to the CNS of gus(mps) mice. Studies on the most effective of the Adbeta-gluc viruses in mice will be extended to non-human primates for further critical evaluation. However, these experiments are not included within the current proposal. The experiments described will determine the general applicability of recombinant adenoviruses for the therapeutic correction of MPS in the CNS.
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