865. An Ex Vivo Gene Therapy Approach for Metachromatic Leukodystrophy Using Neural Progenitor Cells

Abstract

Metachromatic leukodystrophy(MLD) is an autosomal recessive inherited disease caused by mutations of the gene encoding the lysozomal enzyme, arylsulfatase A(ASA). Accumulation of the substrate, sulfated glycoprotein, in both the central and peripheral nervous system results in progressive motor and mental deterioration. No effective therapy has been developed yet. Neural progenitor cells are thought to be useful for cell replacement therapy and also cell mediated gene therapy of neurodegenerative diseases. In the present study, we examined the feasibility of ex vivo gene therapy for MLD using neural progenitor cells. Neural progenitor cells (neurospheres) were prepared from the striatum of E14 embryo MLD knockout mice or GFP transgenic mice and transduced with the VSV pseudotyped HIV vector carrying the ASA gene (HIV-ASA). HIV vector transduced progenitor cells retained the potential for differentiation into neurons, astrocytes, and oligodendrocytes in vitro. Expression of ASA in neurospheres transduced with HIV-ASA was confirmed by the spectrophotometric enzyme assay and Western blotting. When neurospheres from GFP mice were transduced with HIV-ASA and inoculated into the brain parenchyma of adult MLD mice, GFP positive cells were detectable one month after injection. Those cells include GFAP positive astrocytes and undifferentiated cells. Immunohistochemistry using anti-ASA antibody demonstrated that ASA was localized in both GFP positive and negative cells, suggesting that ASA was secreted from the transduced cells and taken up by the surrounding cells. These results hold promise for the use of genetically engineered neural stem cells for ex vivo therapy of MLD.