School of Dentistry, College of Medical and Dental Sciences, Institute of Clinical Sciences, University of Birmingham, Birmingham, UK.
School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK.
J Biophotonics. 2019 Jun;12(6):e201800411. doi: 10.1002/jbio.201800411. Epub 2019 Feb 20.
Photobiomodulation (PBM) is the application of light to promote tissue healing. Current indications suggest PBM induces its beneficial effects in vivo through upregulation of mitochondrial activity. However, how mitochondrial content influences such PBM responses have yet to be evaluated. Hence, the current study assessed the biological response of cells to PBM with varying mitochondrial contents.
DNA was isolated from myoblasts and myotubes (differentiated myoblasts), and mitochondrial DNA (mtDNA) was amplified and quantified using a microplate assay. Cells were seeded in 96-wellplates, incubated overnight and subsequently irradiated using a light-emitting diode array (400, 450, 525, 660, 740, 810, 830 and white light, 24 mW/cm , 30-240 seconds, 0.72-5.76J/cm ). The effects of PBM on markers of mitochondrial activity including reactive-oxygen-species and real-time mitochondrial respiration (Seahorse XFe96) assays were assessed 8 hours post-irradiation. Datasets were analysed using general linear model followed by one-way analysis of variance (and post hoc-Tukey tests); P = 0.05).
Myotubes exhibited mtDNA levels 86% greater than myoblasts (P < 0.001). Irradiation of myotubes at 400, 450 or 810 nm induced 53%, 29% and 47% increases (relative to non-irradiated control) in maximal respiratory rates, respectively (P < 0.001). Conversely, irradiation of myoblasts at 400 or 450 nm had no significant effect on maximal respiratory rates.
This study suggests that mitochondrial content may influence cellular responses to PBM and as such explain the variability of PBM responses seen in the literature.
光生物调节（PBM）是一种应用光来促进组织愈合的方法。目前的研究表明，PBM 通过上调线粒体活性来诱导其体内的有益作用。然而，线粒体含量如何影响这种 PBM 反应尚未得到评估。因此，本研究评估了具有不同线粒体含量的细胞对 PBM 的生物学反应。
从成肌细胞和肌管（分化的成肌细胞）中分离 DNA，并使用微孔板测定法扩增和定量线粒体 DNA（mtDNA）。将细胞接种于 96 孔板中，孵育过夜，然后使用发光二极管阵列（400、450、525、660、740、810、830 和白光，24mW/cm2，30-240 秒，0.72-5.76J/cm2）进行辐照。辐照后 8 小时，评估 PBM 对线粒体活性标志物（包括活性氧和实时线粒体呼吸（ Seahorse XFe96 ）测定）的影响。使用一般线性模型进行数据集分析，然后进行单因素方差分析（和事后 Tukey 检验）；P=0.05）。
肌管的 mtDNA 水平比成肌细胞高 86%（P<0.001）。400、450 或 810nm 辐照肌管分别诱导最大呼吸速率增加 53%、29%和 47%（与未辐照对照相比）（P<0.001）。相反，400 或 450nm 辐照成肌细胞对最大呼吸速率没有显著影响。
本研究表明，线粒体含量可能影响细胞对 PBM 的反应，从而解释了文献中观察到的 PBM 反应的可变性。
