Short Exposures to an Extremely Low-Frequency Magnetic Field (ELF MF) Enhance Protein but not mRNA Alkaline Phosphatase Expression in Human Osteosarcoma Cells.

Tania Rescigno,Anna Capasso,Mario Felice Tecce,Bruno Bisceglia

doi:10.2174/1874091x01812010065

Abstract

Background:Among electromagnetic fields treatments used in orthopedics, extremely low-frequency magnetic fields (ELF MF) need more detailed information about the molecular mechanisms of their effects and exposure conditions.Objective:Evaluation of the effects of an ELF MF exposure system, recently introduced among current clinical treatments for fracture healing and other bone diseases, on Alkaline Phosphatase (ALP) activity and expression in a human osteosarcoma cell line (SaOS-2), as marker typically associated to osteogenesis and bone tissue regeneration.Method:Cells were exposed to the ELF MF physical stimulus (75 Hz, 1.5 mT) for 1h. Cell viability, enzymatic activity, protein and mRNA expression of alkaline phosphatase were then measured at different times after exposure (0, 4 and 24 h).Results:Data demonstrate that this signal is active on an osteogenic process already one hour after exposure. Treatment was, in fact, capable, even after an exposure shorter than those commonly used in clinical applications, to significantly up-regulate alkaline phosphatase enzymatic activity. This regulation is produced essentially through an increase of ALP protein level, without changes of its mRNA concentration, while assessed magnetic field did not affect cell growth and viability and did not produce temperature variations.Conclusion:Tested low-frequency magnetic field affects cellular ALP expression with a posttranslational mechanism, without the involvement of regulations at gene transcription and mRNA level. This molecular effect is likely produced even within treated tissues during therapies with this signal and may be implicated in the induction of observed effects in treated patients.

Highlights

Practical use of Electro-magnetic Fields (EMF) in the treatment of several pathological conditions, including bone diseases, has attracted the attention of recent literature and clinical applications of electro-magnetic stimulation are becoming frequent [1 - 3]
SaOS-2 cells were treated with extremely low-frequency magnetic fields (ELF MF) for 1 h and Methyl Thiazolyl blue Tetrazolium (MTT) assay was performed at different times (0, 6, 24, 30, 46, 52, and 144 h) after exposure
While our work was mostly aimed to study the effect of the apparatus on cell related to bone tissues, the use of MCF-7 and SK-BR-3, both derived from breast cancers, but with different degree of malignancy was intended to test our signal with different cell lines, essentially showing in this case absence of toxicity

Summary

Introduction

Practical use of Electro-magnetic Fields (EMF) in the treatment of several pathological conditions, including bone diseases, has attracted the attention of recent literature and clinical applications of electro-magnetic stimulation are becoming frequent [1 - 3]. Low-Frequency (ELF) Electro-Magnetic Fields (EMF), along with pulsed EMF, have been shown to positively affect osteogenic processes [9 - 11]. PEMF seem to affect osteogenesis stimulating proliferation and differentiation of bone cells in vitro, increasing bone marker genes expression and inducing bone mineralization processes [15, 16]. Among electromagnetic fields treatments used in orthopedics, extremely low-frequency magnetic fields (ELF MF) need more detailed information about the molecular mechanisms of their effects and exposure conditions

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