Exposure to 16 Hz Pulsed Electromagnetic Fields Protect the Structural Integrity of Primary Cilia and Associated TGF-β Signaling in Osteoprogenitor Cells Harmed by Cigarette Smoke

Abstract

Cigarette smoking (CS) is one of the main factors related to avoidable diseases and death across the world. Cigarette smoke consists of numerous toxic compounds that contribute to the development of osteoporosis and fracture nonunion. Exposure to pulsed electromagnetic fields (PEMF) was proven to be a safe and effective therapy to support bone fracture healing. The aims of this study were to investigate if extremely low frequency (ELF-) PEMFs may be beneficial to treat CS-related bone disease, and which effect the duration of the exposure has. In this study, immortalized human mesenchymal stem cells (SCP-1 cells) impaired by 5% cigarette smoke extract (CSE) were exposed to ELF-PEMFs (16 Hz) with daily exposure ranging from 7 min to 90 min. Cell viability, adhesion, and spreading were evaluated by Sulforhodamine B, Calcein-AM staining, and Phalloidin-TRITC/Hoechst 33342 staining. A migration assay kit was used to determine cell migration. Changes in TGF-β signaling were evaluated with an adenoviral Smad2/3 reporter assay, RT-PCR, and Western blot. The structure and distribution of primary cilia were analyzed with immunofluorescent staining. Our data indicate that 30 min daily exposure to a specific ELF-PEMF most effectively promoted cell viability, enhanced cell adhesion and spreading, accelerated migration, and protected TGF-β signaling from CSE-induced harm. In summary, the current results provide evidence that ELF-PEMF can be used to support early bone healing in patients who smoke.

Modulation of Macrophage Activity by Pulsed Electromagnetic Fields in the Context of Fracture Healing

“…The device generates an AC magnetic field, here ELF-PEMF, via applicators (coils). Furthermore, the applicators distort the local earth magnetic DC-field, yielding inhomogeneous DC-field conditions [ 25 ]. In this study, 22 ELF-PEMF conditions have been tested in a blinded manner.…”

“…After washing, target proteins were visualized with an enhanced chemiluminescent (ECL) substrate solution (1.25 mM Luminol, 0.2 mM p-Coumaric acid, 0.03% H 2 O 2 in 100 mM TRIS, pH = 8.5), and the chemiluminescent signals were detected with a CCD camera. Signal intensities were quantified using ImageJ software [ 25 ].…”

“…Of the four ELF-PEMF (blinded), two ELF-PEMFs (termed A and B) showed opposing effects on macrophage function and were therefore further investigated for unblinding. [15,25,29] and field #4 was identified as the ELF-PEMF, which additionally stimulated osteoclast function in earlier studies [16]. Fields #3, #7, #15, and #20 were further investigated, of which #7 and #15 showed diverse effects on macrophage function-termed field A and field B in the following experiment.…”

“…Earlier reports suggested that each cell type responds to ELF-PEMFs with specific fundamental frequencies and pulse burst patterns. While an ELF-PEMF with a fundamental frequency of 16 Hz was shown to improve the function of osteoblasts [15,25],…”

“…Earlier reports suggested that each cell type responds to ELF-PEMFs with specific fundamental frequencies and pulse burst patterns. While an ELF-PEMF with a fundamental frequency of 16 Hz was shown to improve the function of osteoblasts [ 15 , 25 ], another ELF-PEMF (comparable intensity) with a fundamental frequency of 26 Hz also affected osteoclast function [ 16 ]. Studies on primary rat calvaria cells showed that not only the fundamental frequency but also the waveform and pulse burst pattern might be relevant [ 26 , 27 ].…”