Lysosomal enzymes in medium from cultured skin fibroblasts from normal individuals and patients with lysosomal diseases

Abstract

The release of acid hydrolases from cultured skin fibroblasts into the cell culture medium was studied in several lysosomal storage disorders (GM1-gangliosidosis, Fabry's disease, Hurler's disease, mannosidosis, and mucolipidosis). The levels of different activities were proportional to time (up to 44 h after medium change) and cell density with the exception of beta-glucosidase, which was not released. Culture medium from the fibroblasts of mucolipidosis patients exhibited higher activity of acid hydrolases than medium from cells of patients with GM1-gangliosidosis, Fabry's disease, Hurler's disease, and mannosidosis. These cells, however, exhibited somewhat higher levels of enzyme activity in their culture medium than control fibroblasts. The total production of acid hydrolases was yet rather similar in fibroblasts from controls and patients. Differential centrifugation showed that the highest specific activity of acid hydrolases was seen, as expected, in the lysosomal fraction, except in fibroblasts from patients with mucolipidosis, where the supernatant exhibited most activity. beta-Glucosidase, however, showed a normal differential centrifugation pattern also in fibroblasts from these patients.