Does low‐energy helium‐neon laser irradiation alter “in vitro” replication of human fibroblasts?

Cultured human fibroblasts were treated in a controlled, randomized manner to assess the effect of low‐energy (0.9 mW) helium‐neon (HeNe) laser irradiation on cellular proliferation. Two trials were performed: one with fibroblasts in the third to fourth passage and the other with fibroblasts in the 13th to 14th passage. In each trial, separate plasticpetri dishes were inoculated with the cells, maintained in a 5% CO₂‐95% air atmosphere, and nourished with HB 102 media. Treatment began 48 h after inoculation with daily 60‐s irradiations of the “treated” cultures over a 5‐d period. Control cultures underwent the same handling but were not irradiated. A significant stimulative, or inhibitive, effect on replication was not found in either trial.