Exposure of primary osteoblasts to combined magnetic and electric fields induced spatiotemporal endochondral ossification characteristic gene- and protein expression profiles

Abstract

Purpose Molecular processes in primary osteoblasts were analyzed in response to magnetic and electric field exposure to examine its potential impact on bone healing. Methods Primary osteoblasts were exposed to a combination of a magnetic field and an additional electric field (EFMF) (20 Hz, 700 mV, 5 mT, continuous sinusoids) in vitro. mRNA- and protein-expressions were assessed during a time interval of 21 days and compared with expression data obtained from control osteoblasts. Results We observed an autonomous osteoblast differentiation process in vitro under the chosen cultivation conditions. The initial proliferative phase was characterized by a constitutively high mRNA expression of extracellular matrix proteins. Concurrent EFMF exposure resulted in significanly increased cell proliferation (fold change: 1.25) and reduced mRNA-expressions of matrix components (0.5–0.75). The following reorganization of the extracellular matrix is prerequisite for matrix mineralization and is characterised by increased Ca2+ deposition (1.44). On molecular level EFMF exposure led to a significant decreased thrombospondin 1 (THBS1) mRNA- (0.81) and protein- (0.54) expression, which in turn reduced the TGFß1-dependent mRNA- (0.68) and protein- (0.5) expression of transforming growth factor beta induced (ßIG-H3) significantly, an inhibitor of endochondral ossification. Consequently, EFMF exposure stimulated the expression of genes characteristic for endochondral ossification, such as collagen type 10, A1 (1.50), osteopontin (1.50) and acellular communication network factor 3 (NOV) (1.45). Conclusions In vitro exposure of osteoblasts to EFMF supports cell differentiation and induces gene- and protein-expression patterns characteristic for endochondral ossification during bone fracture healing in vivo.

Combined electric and magnetic field therapy for bone repair and regeneration: an investigation in a 3-mm and an augmented 17-mm tibia osteotomy model in sheep

“…This study demonstrated the effect of CEMF therapy on the acceleration and enhancement of the bone healing process overall in a standardized osteotomy model in sheep, resulting in more mature new bone structure, callus morphology and superior biomechanical properties. It was hypothesized, based on in vitro findings using the CEMF technology [ 26 ], that CEMF treatment would enhance bone healing in vivo. The CEMF technology showed a significant effect in the 17-mm at 12 weeks compared to the 3-mm model at 9 weeks, in which means may have been higher in the CEMF group, but higher variability in responses rendered the differences not statistically significant.…”

“…It may involve a spectrum of responses, as the therapy was applied starting at day 4 postoperatively and therefore bridged various stages of bone healing, from inflammation to remodeling [ 4 ]. In vitro tests performed on the same CEMF technology showed evidence of enhanced osteoblast proliferation and osteogenic protein expression [ 26 ], which merit future investigation in a large animal model. Another limitation was the sample size ( n = 6), which, combined with the biological variability expected in sheep, made it difficult to detect statistical differences, particularly in the 3-mm gap model.…”

Combined electric and magnetic field therapy enhances bone repair and regeneration in two tibia osteotomy models in sheep.

“…It may involve a spectrum of responses, as the therapy was applied starting at day 4 post-operatively and therefore bridged various stages of bone healing, from in ammation to remodeling (4). In vitro tests performed on the same CEMF technology showed evidence of enhanced osteoblast proliferation and osteogenic protein expression (29), which merit future investigation in a large animal model. A methodological limitation to note was that some semi-quantitative scores were not designed to distinguish between various advanced stages of maturation in bone healing and exhibited a ceiling effect.…”

Homo sapiens—A Species Not Designed for Space Flight: Health Risks in Low Earth Orbit and Beyond, Including Potential Risks When Traveling beyond the Geomagnetic Field of Earth

“…A large number of studies have attempted to better understand the effects of a variety of electromagnetic field intensities over variable periods of time on animals [ 134 , 135 , 136 , 137 , 138 , 139 , 140 ], animal tissues [ 141 ], and cells [ 142 , 143 ]. The recent review by Lee et al [ 140 ] provides an excellent summary of much of the animal literature in this regard.…”