Increasing interest has been observed in the use of photobiomodulation (PBM) to enhance the proliferation of stem cells and induce their differentiation. The effects of PBM at two different wavelengths (635 and 809 nm) with three different energy densities (0.5, 1 and 2 J/cm2) on the osteogenic differentiation of adipose-derived stem cells (ADSC) were investigated. Cell viability and proliferation were evaluated by MTT and Alamar Blue assays. Osteoblast differentiation were assessed by alkaline phosphatase (ALP) activity, Alizarin red staining and reverse-transcription polymerase chain reaction (RT-PCR) for the expression of collagen type I (COL1A), ALP and osteocalcin. 635 nm and 809 nm laser irradiation had no effect on the cell viability on days 7 and 14, except for 0.5 J/cm2 group at 14th day after 635 nm irradiation (p < 0.05). Cell proliferation was not changed significantly. Mineralization was increased significantly in 809 nm laser groups but no enhancement was detected in the osteogenic differentiation by ALP activity and gene expression results. In 0.5 and 1 J/cm2 groups, ALP and COL1A expressions were down regulated at day 7 after 809 nm laser exposure. These results suggest that PBM may alter osteogenic differentiation of ADSC and increase mineralization but further investigation is needed to define adequate parameters.

中文翻译：

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光生物调节对脂肪干细胞成骨分化的影响。

在使用光生物调节（PBM）来增强干细胞的增殖并诱导其分化方面，人们的兴趣日益浓厚。研究了两种不同波长（635和809 nm），三种能量密度（0.5、1和2 J / cm2）的PBM对脂肪干细胞（ADSC）的成骨分化的影响。通过MTT和Alamar Blue测定法评估细胞活力和增殖。通过碱性磷酸酶（ALP）活性，茜素红染色和逆转录聚合酶链反应（RT-PCR）评估成骨细胞的分化，以表达I型胶原（COL1A），ALP和骨钙蛋白。635 nm和809 nm激光照射在第7天和第14天对细胞活力没有影响，除了在635 nm照射后第14天使用0.5 J / cm2组时（p <0.05）。细胞增殖没有明显改变。在809 nm激光组中，矿化作用显着增加，但通过ALP活性和基因表达结果未检测到成骨分化的增强。在0.5和1 J / cm2组中，在809 nm激光照射后第7天，ALP和COL1A表达下调。这些结果表明，PBM可能会改变ADSC的成骨分化并增加矿化作用，但需要进一步研究以定义适当的参数。