Loss of electron-dense lamellar material from Fabry's disease fibroblasts after enzyme replacement.

Cultured fibroblasts from a patient with Fabry's disease were treated with alpha-galactosidase A. The cells internalized the enzyme via a receptor-mediated transport system, resulting in the uptake of enzyme to 50% of the activity of normal cells. Following uptake of the enzyme and incubation for 9 days, a loss of electron-dense lamellar material within membrane-bound residual bodies was detected by electron microscopy. Morphometric analysis of electron micrographs showed that the percentage volume of cytoplasm occupied by electron-dense lamellar material in Fabry's disease fibroblasts decreased to near normal after treatment with enzyme. These results indicate that the ultrastructural abnormalities of Fabry's disease cells can be corrected by enzyme replacement, at least in cultured fibroblasts.