Extensive β -Glucuronidase Activity in Murine Central Nervous System after Adenovirus-Mediated Gene Transfer to Brain

Abdi Ghodsi; Colleen Stein; Todd Derksen; Gongyu Yang; Richard D. Anderson; Beverly L. Davidson

doi:10.1089/hum.1998.9.16-2331

ABSTRACT Mucopolysaccharidosis type VII (MPS VII), caused by β-glucuronidase deficiency, is a classic lysosomal storage disease. In the central nervous system (CNS), there is widespread pathology with distention of vacuoles in neurons and glia. An approach to therapy for MPS VII would require extensive delivery of enzyme to the CNS and subsequent uptake by the affected cells. In this study we show that intrastriatal injection of recombinant adenovirus encoding β-glucuronidase (Adβgluc) to MPS VII or wild-type mice results in focal, intense β-glucuronidase mRNA expression near the injection site. Further, histochemical staining for enzyme activity showed that β-glucuronidase activity extended well beyond transduced cells. Activity was detected throughout the ipsilateral striatum as well as in the corpus callosum, ventricles, and bilateral neocortex. Similarly, after injection into the right lateral ventricle or cisterna magna, enzyme activity was present in the ependymal cells of the ventricles, in the subarachnoid spaces, and also in the underlying cortex (150–500 μm from ependyma). The distribution of enzyme was most extensive 21 days after gene transfer to normal mouse brain, with more than 50% of the hemisphere positive for β-glucuronidase activity. Eighty-four days after adenovirus injection a substantial level of enzyme expression remained (>40% of hemisphere positive for β-glucuronidase activity). Histological sections from striatum of β-glucuronidase-deficient mice injected with Adβgluc showed a marked reduction in the number of distended vacuoles in both neurons and glia, as compared with uninjected striatum. Importantly, correction was noted in both hemispheres. Our finding that a relatively small number of transduced cells produce enzyme that reaches a large proportion of the CNS has favorable implications in developing direct gene transfer therapies for lysosomal storage disorders. Overview summary Mucopolysaccharidosis type VII (MPS VII) is a lysosomal storage disease (LSD) with multi-organ involvement. Others have shown that bone marrow transplant, with appropriate donor cells, alleviates systemic manifestations, but disease in the eye and the brain is not significantly attenuated. One approach to correct the CNS disease is by direct gene transfer. We show in this study that gene transfer to adult MPS VII mice, via a recombinant adenoviral vector, caused extensive production of enzyme, even though few cells produced the gene product. The correction of the characteristic lysosomal inclusion bodies was evident by 3 weeks in both hemispheres. These results have favorable implications for all vector delivery systems for treatment of CNS deficits of the LSDs.

Extensive β -Glucuronidase Activity in Murine Central Nervous System after Adenovirus-Mediated Gene Transfer to Brain

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