Correction of Sanfilippo A skin fibroblasts by retroviral vector-mediated gene transfer

The recent cloning of the sulfamidase gene has made possible the consideration of gene-based therapies for Sanfilippo A syndrome (mucopolysaccharidosis type IIIA), one of the most common of the mucopolysaccharidoses, In this paper, me present the construction of a retroviral vector in which a sulfamidase cDNA is under the transcriptional control of the Moloney murine leukemia virus long terminal repeat, This construct was used to make a high-titer (4 x 10(5) colony-forming units/ml) producer cell line, PA317/LNSSN#19, in the amphotropic packaging cell line PA317. This producer cell line was shown to be helper virus free using an assay for horizontal spread of virus, Virus supernatant from PA317/LNSSN#19 was used to transduce Sanfilippo A fibroblasts, resulting in complete correction of both the enzymatic defect and the storage phenotype as assessed by intracellular accumulation of (SO4-)-S-35-labeled material, Phenotypic correction was seen even when the levels of viral transduction were low, These results show that gene therapy of the Sanfilippo A syndrome is practicable, although the nature of the disorder suggests that careful consideration needs to be given to the choice of the cellular target for gene transfer.