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.

中文翻译：

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激光光生物调制对牙周膜干细胞的影响

光生物调节 (PBM) 被认为是一种非侵入性程序，具有诱导细胞行为发生有利变化的潜力。在本研究中，我们旨在评估近红外低强度激光 PBM 对人牙周膜干细胞增殖、活力和成骨分化的影响。能量密度为 4 J cm ^{-2的 940 nm 二极管激光器}每 48 小时使用 100 mW 连续波进行 3 次照射。在照射后 24、48 和 72 小时测量细胞活力。在将细胞分为三组非成骨培养基 (C-)、无激光成骨培养基 (C+) 和激光照射成骨培养基 (L+) 后，使用茜素红染色评估激光对矿化组织沉积的影响。还通过实时PCR评估基因表达水平。我们的结果显示，研究组和对照组的 MTT 水平没有显着差异。14 天和 21 天后，与 C- 组相比，L+ 和 C+ 组均显示矿化组织形成增加。与 C-相比，VEGF 和 BMP 表达增加。综上所述，