Fetal Tay-Sachs disease brain cells in culture: lack of turnover in [(14)C]glucosamine-labeled G(M2)

Tay-Sachs disease and normal cerebellar cells in culture: elevated levels of lysosomal enzymes in Tay-Sachs disease cells

Tay-Sachs disease and normal fetal cerebellar cells were maintained in culture for up to four weeks. Elevated levels of the lysosomal enzymes hexosaminidase B, beta-galactosidase, and acid phosphatase were observed in the Tay-Sachs cells in long term cultures although elevated lysosomal enzyme levels were not observed in the normal cultures. Similarly, elevated lysosomal enzyme activities were observed in Tay-Sachs cultures which had been treated with Concanavalin A.

Long-term intracellular retention of hexosaminidase A by Tay-Sachs disease brain and lung cells in vitro

Enzyme-replacement treatment for metabolic storage disorders has been widely studied using model cell culture systems. This study determines the long-term fate of human hexosaminidase A supplied to Tay-Sachs disease brain and lung cells. Hex A retention studies showed that the incorporated Hex A is retained in undiminished quantity by TSD lung cells maintained in stationary culture for 14 days. Tay-Sachs disease brain cells similarly followed for 28 days in stationary culture showed an initial reduction in Hex A for 3 days, after which the Hex A level stabilized and remained relatively constant for the next 25 days. Hexosaminidase B isoenzyme was found to accumulate in both cell lines during extended cultivation, despite the observation that significant amounts were excreted into the extracellular environment. The demonstration of long-term intracellular retention of exogenously supplied therapeutic enzyme by the target cells offers additional evidence for the feasibility of an enzyme-replacement approach for study and treatment of lysosomal storage disorders.

Enzyme replacement treatment for Tay-Sachs disease brain cells in culture utilizing concanavalin A-mediated hexosaminidase A uptake: biochemical and morphological evidence of GM2 mobilization

When Concanavalin A (Con A) is bound to the cell membrane, it functions as an artificial enzyme receptor, mediating the binding and intracellular incorporation of significant amounts of exogenous hexosaminidase A (Hex A) into Tay-Sachs disease (TSD) glia cells. The treated cells retained almost 50% of incorporated Hex A activity after 3 days incubation in Hex A free medium. Hex A was released from Con A within the cell and was available as free enzyme. Biochemical analysis of gangliosides in Con A and Hex A treated cells depicted a greater than 50% reduction in stored GM2 ganglioside and a fourfold reduction in GM2 label (14C) when compared to controls. Ultrastructural evidence of GM2 breakdown is presented which supports the biochemical and labeling studies.

Tay-Sachs disease brain cells in culture: mobilization of stored GM2 after concanavalin A-mediated uptake of hexosaminidase A

A human Tay-Sachs disease (TSD) fetal-brain-cell line is a useful model for the disease since the cells lack hexosaminidase A and accumulate the ganglioside, GM2. This brain-cell line was used to assess the effect of hexosaminidase A treatment on GM2 storage material. Entry of placental hexosaminidase A into the cells was obtained by pretreatment of the cultures with concanavalin A. Cells were analyzed periodically during six days. During the course of the experiment, GM2 in the cells decreased by approximately 50%. A substantial amount of hexosaminidase A was maintained in the cultures throughuot the experiment. This strategy was successful in mobilizing stored GM2 in TSD brain-cell cultures. Therefore, the activating factor needed for hexosaminidas A activity must be present in TSD-cultured brain cells.