Lack of recovery from oxygen-induced damage to colony formation and DNA synthesis in senescent human diploid fibroblasts.

The colony formation and DNA synthesis of cultured human fibroblasts were inhibited under hyperbaric oxygen. When maintained in a growth-arrested state for a few days after oxygen exposure, early passage diploid and SV-40-transformed cells repaired the oxygen-induced damage, while late passage diploid cells did not. In early passage cells to which cycloheximide, a protein synthesis inhibitor, was administered, no recovery from the damage to colony formation was found, indicating that de novo protein synthesis is necessary to the repair process. The repair function of the late passage cells against oxidative damage seems to be impaired. Oxidative stress may be involved in cellular ageing.