The Effect of Laser Photobiomodulation on Periodontal Ligament Stem Cells

Photobiomodulation (PBM) is considered as a noninvasive procedure with the potential of inducing favorable changes in cellular behavior. In this study, we aimed to evaluate the effects of near-infrared low-intensity laser PBM on proliferation, viability and osteogenic differentiation of stem cells isolated from human periodontal ligament. A 940-nm diode laser with an energy density of 4 J cm^-2 in a 100-mW continuous wave was used for irradiation in 3 sessions every 48h. Cell viability was measured 24, 48 and 72 h after irradiation. The effects of laser on mineralized tissue deposition were evaluated by using Alizarin red staining after dividing cells into three groups of nonosteogenic medium (C-), an osteogenic medium without laser (C+), and an osteogenic medium with laser irradiation (L+). Gene expression levels were also evaluated by real-time PCR. Our results showed no significant difference between MTT levels of the study and control groups. After 14 and 21 days, both L+ and C+ groups showed an increase in mineralized tissue formation compared to the C- group. There was an increase in VEGF and BMP expressions compared to C-. In conclusion, the irradiation setting used in this study may be able to improve mineralized tissue deposition.