In vitro effects of low frequency electromagnetic fields on osteoblast proliferation and maturation in an inflammatory environment

Abstract

An in vitro model was set up to investigate the effects of low frequency pulsed electromagnetic fields (PEMF) and its induced electric fields on osteoblast cells under inflammatory conditions. Osteoblasts (7F2) were seeded on top of chitosan scaffolds and co-cultured with macrophage cells (RAW 264.7) growing on the bottom of culture wells, stimulated by lipopolysaccharide to release reactive oxygen species including nitric oxide (NO). The co-culture was exposed to PEMF (magnitude of the magnetic field = 1.5 mT; induced electric voltage = 2.5 mV; frequency = 75 Hz; pulse duration = 1.3 ms) for 9 h. The osteoblasts were examined for their proliferation, viability, alkaline phosphatase (ALP) activity, and genetic expressions of type I collagen (COL I) and osteocalcin (OC), immediately and 7 days after PEMF exposure (days 0 and 7). Macrophage cell viability and NO concentration in the medium were monitored before and after PEMF exposure. The PEMF-exposed co-culture released a significantly higher amount of NO (65 µM) compared to control (17 µM) on day 7. Despite the high level of NO in the medium that was reported to be cytotoxic, PEMF-exposed osteoblasts had enhanced cell proliferation (23%), viability (36%), and COL I mRNA expression (3.4-fold) compared to the controls. The osteoblasts subjected to the PEMF had 41% less ALP activity than the control, which was associated with the active cell proliferation and COL I expression. The expression of OC mRNA was not seen in either the PEMF or control group, indicating cells had not entered the mineralization stage by day 7.

Pulsed electromagnetic fields promote osteoblast mineralization and maturation needing the existence of primary cilia

“…We and others have reported that levels of intracellular Ca 2+ and nitric oxide (NO) increased following EMF exposure to stimulate osteogenesis in vitro or bone growth in vivo (Diniz et al, 2002;Fitzsimmons et al, 2008;Lin and Lin, 2011). Other studies have also implicated increased cGMP and protein kinase G activity (PKG) in EMF effect (Cheng et al, 2011;Pilla et al, 2011).…”

Osteoblast, fibroblast and in vivo biological response to poly(vinylidene fluoride) based composite materials

“…Further, research in tissue engineering has been working to develop new materials which could enhance or inhibit NO production due to its relevance to physiological functions. A cascade of events that prevents blood coagulation and thrombus formation was started with the NO production [38]. Nitric oxide production in bone cells has been linked to their proliferation and differentiation, than can be improved by the use of electro active materials due to the piezoelectricity of bone itself.…”

The Effects of Pulsed Electromagnetic Field (PEMF) on Osteoblast-Like Cells Cultured on Titanium and Titanium-Zirconium Surfaces

“…87 Their findings also demonstrated an ongoing proliferation on the seventh day in the PEMF-treated group. We have also observed that PEMF has increased cell proliferation on all of the surfaces, with the least effect on TiZr (Table 2).…”

“…In a recent study, Lin and Lin 87 have shown that osteoblast treated with PEMF had higher cell proliferations and higher viability. 87 Their findings also demonstrated an ongoing proliferation on the seventh day in the PEMF-treated group.…”