Extremely low frequency pulsed electromagnetic fields cause antioxidative defense mechanisms in human osteoblasts via induction of •O2 − and H2O2

Abstract

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. Our results show that single exposure to ELF-PEMF induced ROS production in hOBs, 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/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.

Electromagnetic Field and Temozolomide Increase Differentiation of Human Glioblastoma Cell Line; concise view of mechanism

“…We found SOD and p53 were increased to combat ROS increasing. Our results seem to support the report of Ehnert et al, that extremely low-frequency electromagnetic fields cause antioxidant defense mechanisms [66].…”

The cellular effects of Pulsed Electromagnetic Fields on osteoblasts: A review

“…On the contrary, but possibly consistent with a proliferative phenotype, ALP activity and Osteocalcin expression were decreased in cultures exposed to PEMFs [Lin and Lin, ]. Increased resistance to oxidative stress was further investigated in a recent study by Ehnert et al [] using primary human osteoblasts (hOBs) exposed to 0.6 Hz, 0.28 mT PEMF bursts of 16 Hz pulses for 7 min/day, using a stimulation regime that was shown to be able to increase cell differentiation in the same cell model [Ehnert et al, ]. The authors demonstrated that EMFs induced the generation of Reactive Oxygen Species (ROS) in hOBs, most noticeably O 2 − (superoxide anion) and H 2 O 2 (hydrogen peroxide), and also induced the expression of antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase.…”

“…The authors demonstrated that EMFs induced the generation of Reactive Oxygen Species (ROS) in hOBs, most noticeably O 2 − (superoxide anion) and H 2 O 2 (hydrogen peroxide), and also induced the expression of antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. Most interestingly, they showed that the induction of non‐toxic levels of ROS was required for PEMF‐induced osteoblast differentiation [Ehnert et al, ].…”

Physical Stimulations for Bone and Cartilage Regeneration

“…Ehnert et al identified a specific extremely low-frequency pulsed electromagnetic field (ELFPEMF) (10 to 90.6 Hz) that supports human osteoblast function in an ERK1/2-dependent manner. The ELF-PEMF by producing non-toxic amounts of reactive oxygen species (ROS), induced antioxidative defense mechanisms in these cells [63, 64]. …”