He: Ne laser irradiation induced survival and cell cycle progression effects on human circulating mononuclear cells in vitro

ABSTRACT

The biostimulation and therapeutic effects of low-power laser radiation of different wavelengths and light doses are well known, but the exact mechanism of action of the laser radiation with living cells is not yet understood. The aim of the present study was to investigate whether HeNe laser irradiation induced mitogenic stimulation on human blood circulating mononuclear cells in vitro displays peculiar features of cell cycle regulation. Buffy-coat human leukocytes were irradiated with He-Ne [10 mW] at energy densities of 1, 2.5 and 5 J/cm[2] and cultured in medium 199 without any supplements in the absence and presence of phytohaemagglutinin for120 hours. Detailed analysis of viability percentage, telomerase activity and gene p53 mRNA expression was performed and compared with a similar analysis of phytohaemagglutinin stimulated and non-stimulated mononuclear cells. Results showed that laser induced telomerase activity in blood mononuclear cells throughout the five consecutive days post laser irradiation, reaching its highest level at 72 hours post laser irradiation and was significantly higher in PHA stimulated cells compared to laser irradiated cells, where 5 J/cm[2] displayed the highest activity. There were no changes in gene p53 mRNA expression at zero compared to 72 hours post laser irradiation. However, it was non-significantly higher in PHA stimulated cells compared to laser stimulated cells. Results threw some light over the mechanism encountered by lymphocytes in the process of He-Ne laser induced biostimulation