The Hurler syndrome: treatment of cultured Hurler fibroblasts with normal human serum.

Prolonged replacement of fetal calf serum by normal human serum for the enrichment of medium during tissue culture of Hurler fibroblasts resulted in increased acid mucopolysaccharides in the cells and in the medium. The predominant intracellular mucopolysaccharide had the characteristics of dermatan sulfate when Hurler cells were treated with either serum. Normal human serum contains a nonspecific coreective factor capable of augmenting the loss of 35SO4-AMPS from Hurler cells, but not from normal cells. Fetal calf serum and Hurler serum have similar corrective factor activity for labeled Hurler cells. The corrective factor activity of all three sera was recovered from reconstituted dialyzed ammonium sulfate precipitates. The corrective factor of normal human serum did not increase degradation of mucopolysaccharide, but increased secretion of macromolecular and large oligosaccharide components. Failure of the corrective factor of normal human serum to effectively decrease the dermatan sulfate content of Hurler cells during prolonged exposure may be a quantitative phenomenon due partly to the brief duration of corrective factor activity and partly to increased synthesis of mucopolysaccharide.