title: Differentiation of osteoprogenitor cells is induced by high-frequency pulsed electromagnetic fields.
abstract: Craniofacial defect repair is often limited by a finite supply of available autologous tissue (ie, bone) and less than ideal alternatives. Therefore, other methods to produce bony healing must be explored. Several studies have demonstrated that low-frequency pulsed electromagnetic field (PEMF) stimulation (ie, 5-30 Hz) of osteoblasts enhances bone formation. The current study was designed to investigate whether a Food and Drug Administration-approved, high-frequency PEMF-emitting device is capable of inducing osteogenic differentiation of osteoprogenitor cells. Osteoprogenitor cells (commercially available C3H10T1/2 and mouse calvarial) in complete Dulbecco modified Eagle medium were continuously exposed to PEMF stimulation delivered by the ActiPatch at a frequency of 27.1 MHz. Markers of cellular proliferation and early, intermediate, and terminal osteogenic differentiation were measured and compared with unstimulated controls. All experiments were performed in triplicate. High-frequency PEMF stimulation increases alkaline phosphatase activity in both cell lines. In addition, high-frequency PEMF stimulation augments osteopontin and osteocalcin expression as well as mineral nodule formation in C3H10T1/2 cells, indicating late and terminal osteogenic differentiation, respectively. Cellular proliferation, however, was unaffected by high-frequency PEMF stimulation. Mechanistically, high-frequency PEMF-stimulated osteogenic differentiation is associated with elevated mRNA expression levels of osteogenic bone morphogenetic proteins in C3H10T1/2 cells. Our findings suggest that high-frequency PEMF stimulation of osteoprogenitor cells may be explored as an effective tissue engineering strategy to treat critical-size osseous defects of the craniofacial and axial skeleton.
  
  
  BACKGROUND
  ALP, alkaline phosphatase; BMP, bone morphogenetic protein; ERK-1, extracellular signal-regulated kinase 1; iCALs, immortalized calvarial cells; IHC, immunohistochemical; MAP, mitogen-activated protein; MSC, mesenchymal stem cell; OCN, osteocalcin; OPN, osteopontin; p38α, p38-reactivating kinase; PBS, phosphate-buffered saline; PEMF, pulsed electromagnetic field.
authors.affiliation: Laboratory of Craniofacial Biology & Development, Section of Plastic and Reconstructive Surgery, The University of Chicago Medical Center, Chicago, Illinois 60637, USA.
authors.forename: Chad M
authors.initials: CM
authors.lastname: Teven
authors.forename: Matthew
authors.initials: M
authors.lastname: Greives
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Natale
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Su
authors.forename: Qing
authors.initials: Q
authors.lastname: Luo
authors.forename: Bai-Cheng
authors.initials: BC
authors.lastname: He
authors.forename: Deana
authors.initials: D
authors.lastname: Shenaq
authors.forename: Tong-Chuan
authors.initials: TC
authors.lastname: He
authors.forename: Russell R
authors.initials: RR
authors.lastname: Reid
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000528:radiation effects*; D002478:Cells, Cultured; D004574:Electromagnetic Fields; D007124:Immunoenzyme Techniques; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism / Q000528:radiation effects*; D015675:Osteocalcin / Q000378:metabolism; D053495:Osteopontin / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012886:Skull / Q000166:cytology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; D015675:Osteocalcin; D053495:Osteopontin; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C487737:mitogen-activated protein kinase 11, mouse; D048051:p38 Mitogen-Activated Protein Kinases; D000469:Alkaline Phosphatase