Effects of Different Photobiomodulation Modes on the BJ-5ta-hTERT Fibroblasts Exposed to Ionizing Radiation

The aim of the work was to study the effects of photobiomodulation (PBM) in the red spectrum (640 nm) with fluences from 3 mJ/cm² to 2 J/cm² in combination with ionizing radiation (IR) at doses of 2-6 Gy against human BJ-5ta-hTERT - postnatal fibroblasts. The cells were exposed to low-intensity red light before or after their exposure to IR, the viability of the cells was determined by MTT 24 hours after the last exposure. It is shown that the effects of PBM depend on the fluence of PBM, the dose of IR and the sequence of the actions of these physical factors on cells. The adaptive effect of PBM was observed only for high fluences-1 and 2 J/cm² when exposed to PBM and subsequent (after 1 hour) irradiation of IR. At the same time, the stimulating effect of PBM was observed only for low fluences from 3 to 300 mJ/cm² under IR irradiation and subsequent (after 1 hour) exposure to PBM. These data should be taken into account when using PBM for the correction of adverse events of radiation therapy in an oncological clinic.