Photobiomodulation with 655-nm Laser Light to Induce the Differentiation of PC12 Cells

The healing effect of light at low power and energy density can be used as a treatment or alternative supportive method in various diseases. The photobiostimulation effect created on neural cells is also a very promising approach in the treatment of important neurodegenerative diseases such as Alzheimer’s disease. In this study, the response of PC12 cells to photobiomodulation was investigated as a result of the low level laser therapy with 655 nm diode laser after triple treatment. The red light at an energy density of 1, 3 and 5 J/cm2 was applied to PC12 cells three times with 24h intervals. The differentiation capacity of the cells and the elongation rates of neurites were assessed. The neurite lengths were calculated by analyzing the microscopic images of the cells. Neurite-forming capacity and differentiation rate of PC12 cells was at the maximum level after the application with 1 J/cm2 energy, nearly 2 times of the control group. 5 J/cm2 of energy density strongly inhibited the cell proliferation and the elongation of the neurites. The cell viability percentages of the cells showed that 5 J/cm2 energy density inhibited cell viability with a rate of nearly 30%. The outcomes of this study emphasized that the adjustment of light parameters in photobiomodulation applications may result in biostimulation or bioinhibition depending on the intensity and the irradiance levels applied on the cells.