Effect of photobiomodulation therapy on the morphology, intracellular calcium concentration, free radical generation, apoptosis and necrosis of human mesenchymal stem cells-an in vitro study.

Abstract

The aim of the study was to investigate the impact of multiwave locked system (MLS M1) emitting synchronized laser radiation at 2 wavelength simultaneous (λ = 808nm, λ = 905nm) on the mesenchymal stem cells (MSCs). Human MSCs were exposed to MLS M1 system laser radiation with the power density 195-318 mW/cm2 and doses of energy 3-20J, in continuous wave emission (CW) or pulsed emission (PE). After irradiation exposure in doses of energy 3J, 10J (CW, ƒ = 1000Hz), and 20J (ƒ = 2000Hz), increased proliferation of MSCs was observed. Significant reduction of Fluo-4 Direct™ Ca2+ indicator fluorescence over controls after CW and PE with 3J, 10J, and 20J was noticed. A decrease in fluorescence intensity after the application of radiation with a frequency of 2000Hz in doses of 3J, 10J, and 20J was observed. In contrary, an increase in DCF fluorescence intensity after irradiation with laser radiation of 3J, 10J, and 20J (CW, ƒ = 1000Hz and ƒ = 2000Hz) was also shown. Laser irradiation at a dose of 20J, emitted at 1000Hz and 2000Hz, and 3J emitted at a frequency of 2000Hz caused a statistically significant loss of MSC viability. The applied photobiomodulation therapy induced a strong pro-apoptotic effect dependent on the laser irradiation exposure time, while the application of a sufficiently high-energy dose and frequency with a sufficiently long exposure time significantly increased intracellular calcium ion concentration and free radical production by MSCs.