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Stem Cells International
Volume 2017 (2017), Article ID 2450327, 17 pages
https://doi.org/10.1155/2017/2450327
Research Article

Pulsed Electromagnetic Field Regulates MicroRNA 21 Expression to Activate TGF-β Signaling in Human Bone Marrow Stromal Cells to Enhance Osteoblast Differentiation

1Department of Biotechnology, School of Bioengineering, SRM University, Kattankulathur, Tamil Nadu, India
2Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY, USA
3Department of Cell Biology, New York University School of Medicine, New York, NY, USA

Correspondence should be addressed to Nicola C. Partridge; ude.uyn@432pcn

Received 23 September 2016; Revised 5 January 2017; Accepted 12 February 2017; Published 23 April 2017

Academic Editor: Elisabetta A. Cavalcanti-Adam

Copyright © 2017 Nagarajan Selvamurugan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Pulsed electromagnetic fields (PEMFs) have been documented to promote bone fracture healing in nonunions and increase lumbar spinal fusion rates. However, the molecular mechanisms by which PEMF stimulates differentiation of human bone marrow stromal cells (hBMSCs) into osteoblasts are not well understood. In this study the PEMF effects on hBMSCs were studied by microarray analysis. PEMF stimulation of hBMSCs’ cell numbers mainly affected genes of cell cycle regulation, cell structure, and growth receptors or kinase pathways. In the differentiation and mineralization stages, PEMF regulated preosteoblast gene expression and notably, the transforming growth factor-beta (TGF-β) signaling pathway and microRNA 21 (miR21) were most highly regulated. PEMF stimulated activation of Smad2 and miR21-5p expression in differentiated osteoblasts, and TGF-β signaling was essential for PEMF stimulation of alkaline phosphatase mRNA expression. Smad7, an antagonist of the TGF-β signaling pathway, was found to be miR21-5p’s putative target gene and PEMF caused a decrease in Smad7 expression. Expression of Runx2 was increased by PEMF treatment and the miR21-5p inhibitor prevented the PEMF stimulation of Runx2 expression in differentiating cells. Thus, PEMF could mediate its effects on bone metabolism by activation of the TGF-β signaling pathway and stimulation of expression of miR21-5p in hBMSCs.