He-Ne laser has no effect on cell cycle phases of human colon adenocarcinoma cells.

The aim of this study is to investigate the effect of He-Ne continuous laser (12.6 mW, 632.8 nm), at low energy densities, on cell cycle synchronization of monolayer growing human colon adenocarcinoma cell line. The doubling time of cell culture was used as optimum time to verify laser effect. The monolayer cultures were exposed to single doses of different energy densities (0.042 J cm-2 to 1.68 J cm-2). The nuclear DNA content has been studied by flow cytometry to obtain the cell percentage in each cell cycle phase. Results show no effect of He-Ne laser irradiation on cell cycle short time synchronization under the previously mentioned conditions and cell type. Higher energy densities and multiple irradiations should be investigated.