Abstract
Summary: We studied survival of normal (n=4) and cystinotic (n=3) fibroblast strains in selective (cystine-free) medium, with or without dithiothreitol (DTT)-thiol or disulfide. Cells were plated at low density first in maintenance medium (Contining cystine), then washed and exposed to selective medium for 24 hr or longer. Cultures were trypsinized at specified times and the cells counted. Selective medium caused progressive detachment (>90% by 72 hr) of control and cystinotic cells; DTT-disulfide (4 mM) and DTT-thiol (0.5 mM) both protected cystinotic cells (p <0.02) but not control cells in selective medium. DTT-thiol (0.5 mM) and DTT-disulfide (4 mM) both depleted the intracellular cystine pool were not protected by DTT in selective medium. Toxicity, measured by cell survivial in maintenance medium containing various concentrations of DTT, was less with DTT-disulfide than with DTT-thiol. These findings imply that mobilization of intracellular cystine protects cystinotic cells in selective medium; cystinotic fibroblasts can utilize DTT-disulfide as well as DTT0-thiol to mobilize cystine.
Speculation: The ability of DTT-disulfide to deplete intracellular cystine in cystinotic fibroblasts, and to protect these cells in selective (cystine-free) medium, implies that they retain a capacity to reduce disulfide. Implications for clinical treatment trials in vivo, with oxidised DTT which is odorless and tasteless, are evident in our findings.
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Lancaster, G., Scriver, C. CYSTINOTIC AND NORMAL FIBROBLASTS: DIFFERENTIAL PROTECTION IN CYSTINE-FREE MEDIUM BY DITHIOTHREITOL. Pediatr Res 16 (Suppl 1), 86–88 (1982). https://doi.org/10.1203/00006450-198201001-00019
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DOI: https://doi.org/10.1203/00006450-198201001-00019