A response of HeLa Kyoto tumor cells to a combination of photobiomodulation and ionizing radiation

The aim of the work was studying the effects of photobiomodulation in doses of less than 1 J/cm2 in combination with gamma-irradiation to Hela Kyoto cells. Tumor cells were irradiated with 640 nm LED at different energy densities before and after to gamma-irradiation. Cells viability was determined 24 h after exposure for each gamma-irradiation dose and PBM mode. There was a statistically significant decrease in a number of viable tumor cells for samples that were exposed to PBM prior to gamma-irradiation and a statistically significant increase in a number of viable tumor cells for samples that were exposed to PBM after gamma-irradiation.