Effect of cell donor age on the synthetic properties of fibroblasts obtained from phenytoin-induced gingival hyperplasia.

Diploid fibroblasts obtained from explants of human gingiva and maintained in vitro undergo a several-fold decrease in protein and collagen synthesis as a function of increasing donor age. Using drug-induced gingival hyperplasia as a model, we performed experiments to learn whether fibroblasts derived from hyperplastic tissue behave in a similar manner. Fibroblast strains were established from explants of hyperplastic gingiva obtained from 10 patients chronically ingesting phenytoin and ranging in age from 9 to 45 years. Protein production and degradation were compared to previously reported data similarly obtained from periodontally normal donors ranging in age from 12 to 68 yr. The total quantity of protein and collagen produced by the phenytoin cells was significantly greater than previously reported for cells from normal gingiva. No donor age-related decrease in protein and collagen production nor in the proportion of cell synthetic activity committed to collagen production was observed for cultures of phenytoin cells. The gross pattern of proteins produced, as assessed by 2-dimensional gel electrophoresis, was unrelated to donor age in both normal and phenytoin cells, but three polypeptides ranging in size from about 20 kD to 40 kD that were not found in the cultures of normal cells were produced by five of seven phenytoin cells strains. The observations demonstrate that the phenytoin cells do not undergo the donor age-dependent decrease in synthesis observed for normal cells. This abnormality may account in part for the phenytoin-induced hyperplasia. The phenytoin cells appear to be a unique phenotype.

Effects of donor age on protein and collagen synthesis in vitro by human diploid fibroblasts.

Diploid fibroblast strains were established from explants of normal gingiva from donors ranging in age from 12 to 68 years. By using labeled amino acid precursors, we measured protein and collagen production, and intra- and extracellular protein degradation. Qualitative assessment of the patterns of protein production was performed by two-dimensional gel electrophoresis and detection of labeled components by fluorography. Protein and collagen production decreased more than 5-fold as a function of increasing donor age over the age range studied while protein degradation remained unaffected by donor age. The pattern of proteins produced was unaffected by donor age. These data demonstrate a large statistically significant slowdown in general protein synthesis with increasing donor age. This slowdown is not selective, but appears to affect all of the proteins being produced.