A comparative evaluation of the effects of 635 nm laser on cell proliferation and osteogenic differentiation of buccal fat pad mesenchymal stem cells.

The purpose of this study was to evaluate the effects of 635 nm diode laser with different powers on undifferentiated mesenchymal stem cells obtained from buccal fat pad. Human buccal fat stem cells were cultured in DMEM containing 10% FBS, penicillin, and streptomycin under 5% CO₂ and 95% humidity. Cells were cultured in 96-well plate and 24 h later, laser irradiation with 635 nm diode laser was performed in four groups of 200, 300, 400, and 500 mW powers in addition to the control group with the same energy density of 4 J/cm². MTT and flow cytometry assay was performed to evaluate cell proliferation and viability on 2 and 4 days after irradiation. Alizarin red assay and real-time PCR (OPN, OCN, ALP, and RUNX-2 genes) was performed to evaluate osteogenic differentiation. According to the MTT assay, none of the mentioned powers of 635 nm diode laser had significant effect on cell proliferation. Cells irradiated with power of 400 mW and 500 mW significantly showed a greater number of necrotic cells compared to the control group in Day 4. Cells irradiated with 300 mW power significantly exhibited a greater amount of nodule formation compared to all groups. Results of this study indicated that 635 nm diode laser with energy density of 4 J/cm² has a positive effect inducing osteogenic differentiation when applying with a power of 300 mW in buccal fat pad mesenchymal stem cells.