title: Absence of metabolic cross-correction in Tay-Sachs cells: implications for gene therapy.
abstract: We have investigated the ability of a receptor-mediated gene transfer strategy (cross-correction) to restore ganglioside metabolism in fibroblasts from Tay-Sachs (TS) patients in vitro. TS disease is a GM2 gangliosidosis attributed to the deficiency of the lysosomal enzyme beta-hexosaminidase A (HexA) (beta-N-acetylhexosaminidase, EC ). The hypothesis is that transduced cells overexpressing and secreting large amounts of the enzyme would lead to a measurable activity in defective cells via a secretion-recapture mechanism. We transduced NIH3T3 murine fibroblasts with the LalphaHexTN retroviral vector carrying the cDNA encoding for the human Hex alpha-subunit. The Hex activity in the medium from transduced cells was approximately 10-fold higher (up to 75 milliunits) than observed in non-transduced cells. TS cells were cultured for 72 h in the presence of the cell medium derived from the transduced NIH3T3 cells, and they were analyzed for the presence and catalytic activity of the enzyme. Although TS cells were able to efficiently uptake a large amount of the soluble enzyme, the enzyme failed to reach the lysosomes in a sufficient quantity to hydrolyze the GM2 ganglioside to GM3 ganglioside. Thus, our results showed that delivery of the therapeutic HexA was not sufficient to correct the phenotype of TS cells.
authors.affiliation: Dipartimento di Scienze Biochimiche e Biotecnologie Molecolari, University of Perugia, 06126 Perugia, Italy. martino.sabata@hsr.it
authors.forename: Sabata
authors.initials: S
authors.lastname: Martino
authors.forename: Carla
authors.initials: C
authors.lastname: Emiliani
authors.forename: Brunella
authors.initials: B
authors.lastname: Tancini
authors.forename: Giovanni Maria
authors.initials: GM
authors.lastname: Severini
authors.forename: Vanna
authors.initials: V
authors.lastname: Chigorno
authors.forename: Claudio
authors.initials: C
authors.lastname: Bordignon
authors.forename: Sandro
authors.initials: S
authors.lastname: Sonnino
authors.forename: Aldo
authors.initials: A
authors.lastname: Orlacchio
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002478:Cells, Cultured; D018076:DNA, Complementary; D005678:G(M2) Ganglioside / Q000378:metabolism; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006801:Humans; D006868:Hydrolysis; D051379:Mice; D012190:Retroviridae / Q000235:genetics; D013661:Tay-Sachs Disease / Q000378:metabolism* / Q000473:pathology
chemical_list: D018076:DNA, Complementary; D005678:G(M2) Ganglioside