Case Studies supporting PEMF benefits for Bone
A Comparative Analysis of the In Vitro Effects of Pulsed Electromagnetic Field Treatment on Osteogenic Differentiation of Two Different Mesenchymal Cell Lineages
AbstractHuman mesenchymal stem cells (MSCs) are a promising candidate cell type for regenerative medicine and tissue engineering applications. Exposure of MSCs to physical stimuli favors early and rapid activation of the tissue repair process. In this study we investigated the in vitro effects of pulsed electromagnetic field (PEMF) treatment on the proliferation and osteogenic differentiation of bone marrow MSCs (BM-MSCs) and adipose- tissue MSCs (ASCs), to assess if both types of MSCs could be indifferently used in combination with PEMF exposure for bone tissue healing. We compared the cell viability, cell matrix distribution, and calcified matrix production in unstimulated and PEMF-stimulated (magnetic field: 2 mT, amplitude: 5mV) mesenchymal cell lineages. After PEMF exposure, in comparison with ASCs, BM-MSCs showed an increase in cell proliferation ( p < 0.05) and an enhanced deposition of extracellular matrix components such as decorin, fibronectin, osteocalcin, osteonectin, osteopontin, and type-I and -III collagens ( p < 0.05). Calcium deposition was 1.5-fold greater in BM-MSC–derived osteoblasts ( p < 0.05). The immunofluorescence related to the deposition of bone matrix proteins and calcium showed their colocalization to the cell-rich areas for both types of MSC-derived osteoblast. Alkaline phosphatase activity increased nearly 2-fold ( p < 0.001) and its protein content was 1.2-fold higher in osteoblasts derived from BM-MSCs. The quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis revealed up-regulated transcription specific for bone sialoprotein, osteopontin, osteonectin, and Runx2, but at a higher level for cells differentiated from BM-MSCs. All together these results suggest that PEMF promotion of bone extracellular matrix deposition is more efficient in osteoblasts differentiated from BM-MSCs.
Electrical Bone Growth Stimulation of the Appendicular Skeleton
In the appendicular skeleton, electrical stimulation (with either implantable electrodes or noninvasive surface stimulators) has been investigated for the treatment of delayed union, nonunion, and fresh fractures.
Electrical and electromagnetic fields can be generated and applied to bones through the following methods:
- Surgical implantation of a cathode at the fracture site with the production of direct current electrical stimulation. Invasive devices require surgical implantation of a current generator in an intramuscular or subcutaneous space, while an electrode is implanted within the fragments of bone graft at the fusion site. The implantable device typically remains functional for 6 to 9 months after implantation, and, although the current generator is removed in a second surgical procedure when stimulation is completed, the electrode may or may not be removed. Implantable electrodes provide constant stimulation at the nonunion or fracture site but carry increased risks associated with implantable leads.
- Noninvasive electrical bone growth stimulators generate a weak electrical current within the target site using pulsed electromagnetic fields, capacitive coupling, or combined magnetic fields. In capacitive coupling, small skin pads/electrodes are placed on either side of the fusion site and worn for 24 hours per day until healing occurs or up to 9 months. In contrast, pulsed electromagnetic fields are delivered via treatment coils that are placed over the skin and are worn for 6 to 8 hours per day for 3 to 6 months. Combined magnetic fields deliver a time-varying magnetic field by superimposing the time-varying magnetic field onto an additional static magnetic field. This device involves a 30-minute treatment per day for 9 months. Patient compliance may be an issue with externally worn devices.
- Semi-invasive (semi-implantable) stimulators use percutaneous electrodes and an external power supply obviating the need for a surgical procedure to remove the generator when treatment is finished.
In the appendicular skeleton, electrical stimulation has been primarily used to treat tibial fractures, and thus this technique has often been thought of as a treatment of the long bones. According to orthopedic anatomy, the skeleton consists of long bones, short bones, flat bones, and irregular bones. Long bones act as levels to facilitate motion, while short bones function to dissipate concussive forces. Short bones include those composing the carpus and tarsus. Flat bones, such as the scapula or pelvis, provide a broad surface area for attachment of muscles. Despite their anatomic classification, all bones are composed of a combination of cortical and trabecular (also called cancellous) bone. Each bone, depending on its physiologic function, has a different proportion of cancellous to trabecular bone. At a cellular level, however, both bone types are composed of lamellar bone and cannot be distinguished microscopically.
Effects of Pulsed Electromagnetic Field Frequencies on the Osteogenic Differentiation of Human Mesenchymal Stem Cells
The purpose of this study was to evaluate the effect of different frequencies of pulsed electromagnetic fields on the osteogenic differentiation of human mesenchymal stem cells. Third-generation human mesenchymal stem cells were irradiated with different frequencies of pulsed electromagnetic fields, including 5, 25, 50, 75, 100, and 150 Hz, with a field intensity of 1.1 mT, for 30 minutes per day for 21 days. Changes in human mesenchymal stem cell morphology were observed using phase contrast microscopy. Alkaline phosphatase activity and osteocalcin expression were also determined to evaluate human mesenchymal stem cell osteogenic differentiation.
Different effects were observed on human mesenchymal stem cell osteoblast induction following exposure to different pulsed electromagnetic field frequencies. Levels of human mesenchymal stem cell differentiation increased when the pulsed electromagnetic field frequency was increased from 5 hz to 50 hz, but the effect was weaker when the pulsed electromagnetic field frequency was increased from 50 Hz to 150 hz. The most significant effect on human mesenchymal stem cell differentiation was observed at of 50 hz.
The results of the current study show that pulsed electromagnetic field frequency is an important factor with regard to the induction of human mesenchymal stem cell differentiation. Furthermore, a pulsed electromagnetic field frequency of 50 Hz was the most effective at inducing human mesenchymal stem cell osteoblast differentiation in vitro.
Electromagnetic Fields for Bone Healing
Electrical stimulation has been applied in a number of different ways to influence tissue healing. Most of the early work was carried out by orthopedic surgeons looking for new ways of enhancing fracture healing, particularly those fractures that had developed into nonunions. Electrical energy can be supplied to a fracture by direct application of electrodes or inducing current by use of pulsed electromagnetic field or capacitive coupling. Many of these techniques have not been standardized, so interpretation of the literature can be difficult and misleading. Despite this, there have been a few good laboratory and clinical studies to investigate the effect of electrical stimulation on fracture healing, which are reviewed. These do not permit recommendation or rejection of the technique per se; however, there is some room for optimism. The authors present some of the guidelines for using this treatment modality but suggest that all treatment should be carried out as part of a clinical trial in order to generate reliable data.
Case Study Reference Source:
1. A Comparative Analysis of the In Vitro Effects of Pulsed Electromagnetic Field Treatment on Osteogenic Differentiation of Two Different Mesenchymal Cell Lineages
(Authors: Gabriele Ceccarelli, Nora Bloise, Melissa Mantelli, Giulia Gastaldi, Lorenzo Fassina, Maria Gabriella Cusella De Angelis, Davide Ferrari, Marcello Imbriani and Livia Visai)
2. Electrical Bone Growth Stimulation of the Appendicular Skeleton
3. Effects of Pulsed Electromagnetic Field Frequencies on the Osteogenic Differentiation of Human Mesenchymal Stem Cells
(Authors: Fei Luo, PhD; Tianyong Hou, PhD; Zehua Zhang, PhD; Zhao Xie, PhD; Xuehui Wu, PhD;Jianzhong Xu, PhD)
4. Electromagnetic Fields for Bone Healing
(Authors: S.A.W. Pickering, FRCS, and B. E. Scammell, DM, FRCS)