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

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.