ARYLSULFATASE-A ACTIVITIES AND GLYCOSAMINOGLYCAN LEVELS IN RETROVIRALLY TRANSDUCED MUCOPOLYSACCHARIDOSIS TYPE-VI CELLS - PROSPECTS FOR GENE-THERAPY

Mucopolysacchariodosis type VI (MPS VI) is the lysosomal storage disor der caused by the deficient activity of arylsulfatase B (ASB; N-acetyl galactosamine 4-sulfatase) and the subsequent accumulation of the glyc osaminoglycan (GAG), dermatan sulfate. In this study, a retroviral vec tor containing the full-length human ASB cDNA was constructed and used to transduce skin fibroblasts, chondrocytes, and bone marrow cells fr om human patients, cats, or rats with MPS VI. The ASB vector expressed high levels of enzymatic activity in each of the cell types tested an d, in the case of cat and rat cells, enzymatic expression led to compl ete normalization of (SO4)-S-35 incorporation. In contrast, overexpres sion of ASB in human MPS VI skin fibroblasts did not lead to metabolic correction. High-level ASB expression was detected for up to eight we eks in transduced MPS VI cat and rat bone marrow cultures, and PCR ana lysis demonstrated retroviral-mediated gene transfer to similar to 30- 50% of the CFU GM-derived colonies. Notably, overexpression of ASB in bone marrow cells led to release of the enzyme into the media and upta ke by MPS VI cat and rat skin fibroblasts and/or chondrocytes via the mannose-6-phosphate receptor system, leading to metabolic correction. Thus, these studies provide important rationale for the development of gene therapy for this disorder and lay the frame-work for future in v ivo studies in the animal model systems.