Polychromatic visible and infrared light (480-3400 nm) downregulates the growth of hepatoma MH22a in mice

Abstract

We studied the effect of polychromatic visible (380-750 nm) (VIS) and combined with the visible infrared (480-3400 nm) (VIS-IR) radiation on the growth of hepatoma in mice. In the first series of experiments on C3HA mice with subcutaneously transplanted syngeneic hepatoma MH22a it was shown 1.5-4 times inhibition of tumor volume after irradiation of tumor-bearing mice with VIS-infrared light at a dose 4.8 J/ cm2. Mice irradiation at doses of 9.6 J/cm2 and 38.4 J/cm2 had no effect on the rate of tumor growth. Exposition to VIS and IR-light in all doses we used an increase of the surviveness of animals in the 1.5 and 2 times respectively was observed. In a second series of experiments we investigated the effect VIS-IR radiation on tumor cells in vitro with subsequent inoculation to intact mice. After implantation in mice irradiated cells at a dose of 4.8 J/cm2 9.6 J/cm2 inhibition of tumor growth during the first 25 days at 3-12 times as compared to control and increased survival in mice 1.5-2 respectively was observed. The main results of this study consists in the fact that none of the doses used VIS and a IR-radiation has not been shown to stimulate tumor growth both in irradiated mice with tumors, and the irradiation of MH22a hepatoma cells under in vitro conditions prior to transplantation of intact mice. Furthermore it was detected dose range VIS-IR light (4.8-9.6 Joules/cm2) when the rate of growth of hepatoma MH22a decreased and increased surviveness of animals.