Irwin Schafer

Study of the Hurler syndrome using cell culture: definition of the biochemical phenotype and the effect of ascorbic acid on the mutant cell

Fibroblasts from patients with Hurler syndrome retain a distinctive biochemical phenotype when grown in culture which is characterized by increased synthesis of both nonsulfated and sulfated glycosaminoglycans. Ascorbic acid reinforces the phenotypic expression of the biochemical abnormality, producing not only increased synthesis of sulfated glycosaminoglycans, but selective retention of sulfated glycosaminoglycans within the cell. Although the synthesis of nonsulfated glycosaminoglycans is also increased, these compounds, particularly hyaluronic acid are not retained by the cell but are secreted into the medium. Analyses of urine from patients with Hurler syndrome show increased absolute concentrations of nonsulfated glycosaminoglycans in addition to the expected increase in sulfated glycosaminoglycans. This indicates that the biochemical phenotype as defined in cell culture is not an artifact of the experimental model but reflects the biochemical defect in the patient. Redefinition of the biochemical defect to include nonsulfated as well as sulfated glycosaminoglycans contradicts explanations of this disease which are based on a single structural gene mutation.

Vitamin C-Induced Increase of Dermatan Sulfate in Cultured Hurler's Fibroblasts

In fibroblasts taken from patients witli Hurlers syndromne and grown in cultlure, dermatan sulfate constituted a larger percentage of the total sulfated glycosaminoglycans than it did in cultured fibroblasts from unaffected individuals. Moreover, the addition of ascorbic acid (vitamnin C) to the culture medium markedly increased the concentration of dermatan sulfate in the Hurlers fibroblasts but not in the normal fibroblasts. The biochemical phenotype of the Hurlers cells persisted during 28 weeks of serial culture.