Artikel
Extremely low frequency pulsed electromagnetic fields cause anti-oxidative defense mechanisms in human osteoblasts via induction of •O2 – and H2O2
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Autoren
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Sabrina Ehnert
- Siegfried Weller Institut für unfallmedizinische Forschung, Eberhard Karls Universität Tübingen, Tübingen, Germany
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Anne-Kristin Fentz
- Sachtleben GmbH, Hamburg, Germany
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Anna J. Schreiner
- Eberhard Karls Universität Tübingen, BG Unfallklinik Tübingen, Siegfried Weller Forschungsinstitut, Tübingen, Germany
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Johannes Birk
- Siegfried Weller Institut für unfallmedizinische Forschung, Eberhard Karls Universität Tübingen, Tübingen, Germany
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Benjamin Wilbrand
- Siegfried Weller Institut für unfallmedizinische Forschung, Eberhard Karls Universität Tübingen, Tübingen, Germany
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Patrick Ziegler
- BG Unfallklinik Tübingen, Tübingen, Germany
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Karsten Falldorf
- Sachtleben GmbH, Hamburg, Germany
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Andreas Nussler
- Siegfried Weller Institut für unfallmedizinische Forschung, Eberhard Karls Universität Tübingen, Tübingen, Germany
| Veröffentlicht: | 6. November 2018 |
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Gliederung
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Objectives: Recently, we identified a specific extremely low-frequency pulsed electromagnetic field (ELF-PEMF) that supports human osteoblast (hOBs) function in an ERK1/2-dependent manner, suggesting reactive oxygen species (ROS) being key regulators in this process. Thus, this study aimed at investigating how ELF-PEMF exposure can modulate hOBs function via ROS.
Methods: HOBs were isolated from spongy bone by collagenase digestion (ethical vote 387/2012BO2). During osteogenic differentiation cells were exposed to an ELF-PEMF with a fundamental frequency of 16 Hz (Somagen®, Sachtleben GmbH) for 7 min per day. ROS were detected with the help of fluorescent probes and radical scavengers. Osteoblast viability (mitochondrial activity and total protein content) and function (AP activity and matrix mineralization) were assessed. Furthermore, expression (qRT-PCR and Western blot) and function of mitochondrial antioxidative enzymes was measured. Data sets were compared by Kruskall Wallis test followed by Dunn's multiple comparison test.
Results and conclusion: Our results show that single exposure to ELF-PEMF induced ROS production in hOBs (~4-fold, p< 0.001), without reducing intracellular glutathione. Repetitive exposure (>3) to ELF-PEMF however reduced ROS-levels, suggesting alterations in the cells antioxidative stress response. The main ROS induced by ELF-PEMF were •O2− and H2O2, therefore expression and activity of antioxidative enzymes related to these ROS were further investigated. ELF-PEMF exposure induced expression of GPX3, SOD2, CAT and GSR on mRNA, protein and enzyme activity level. Scavenging •O2− and H2O2 diminished the ELF-PEMF effect on hOBs function (AP activity and mineralization). Challenging the hOBs with low amounts of H2O2 on the other hand improved hOBs function. In summary, our data show that ELF-PEMF treatment favors differentiation of hOBs by producing non-toxic amounts of ROS, which induces antioxidative defense mechanisms in these cells. Thus, ELF-PEMF treatment might represent an interesting adjunct to conventional therapy supporting bone formation under oxidative stress conditions, e.g. during fracture healing.
