Combined effects of 450, 635 and 980 nm LASER wavelengths on proliferation and migration of human periodontal ligament mesenchymal stem cells

This in vitro investigation was conducted to compare the efficacy of various wavelengths individually [450 nm (G1), 635 nm (G2), 980 nm (G3)] or in combination [450 nm + 635 nm (G4); 450 nm + 980 nm (G5); 635 nm + 980 nm (G6); and 450 nm + 635 nm + 980 nm (G7)] on cellular viability, proliferation, and migration of human periodontal ligament stem cells (hPDLSCs). In combined-wavelengths groups (G4, G5, G6, G7), laser irradiation was performed simultaneously through a single probe. All groups received 10 uninterrupted seconds of irradiation with each wavelengths set at 4 J/cm 2 energy density and 200 mW power. MTT assay, DAPI staining, scratch migration assay, Ki67 marker expression, Annexin V/PI assay (apoptosis), and proliferatory/migratory factors through ELISA (SDF-1, VEGF and TGF-β1) were utilized from 1 to 6 days post-irradiation. All groups were compared against each-other and a control negative (no laser therapy) group. The statistical analysis was evaluated using Two-way ANOVA ( P < 0.05). MTT and DAPI assays showed significantly higher metabolic activity/viability rates for G1, G5 and G7. The expression rate of Ki67 and its mean fluorescent intensity were both superior in G7. G7 had the most stable outcomes in apoptosis tests. hPDLSCs had the greatest migratory capability in G6 and G7 in the first 2 days. The highest concentrations of SDF-1, VEGF and TGF- β1 were observed in G1, G5 and G7, respectively. It is worth noting that combined-wavelength groups had overall higher energy densities and powers than individual-wavelength groups. Given the outstanding proliferative and migrative outcomes of blue light (450 nm) individually or in combination with red and near-infrared wavelengths on hPDLSCs, further studies must incorporate blue light lasers in photobiomodulation therapy. All wavelengths were set at 4 J/cm 2 ; further dose-matched studies must be conducted to reach firm conclusions.