Pulsed electromagnetic field (PEMF) transiently stimulates the rate of mineralization in a 3-dimensional ring culture model of osteogenesis

Abstract

Pulsed Electromagnetic Field (PEMF) has shown efficacy in bone repair and yet the optimum characteristics of this modality and its molecular mechanism remain unclear. To determine the effects of timing of PEMF treatment, we present a novel three-dimensional culture model of osteogenesis that demonstrates strong de novo generation of collagen and mineral matrix and exhibits stimulation by PEMF in multiple stages over 62 days of culture. Mouse postnatal day 2 calvarial pre-osteoblasts were cast within and around Teflon rings by polymerization of fibrinogen and cultured suspended without contact with tissue culture plastic. Ring constructs were exposed to PEMF for 4h/day for the entire culture (Daily), or just during Day1-Day10, Day11-Day 27, or Day28-Day63 and cultured without PEMF for the preceding or remaining days, and compared to no-PEMF controls. PEMF was conducted as HF Physio, 40.85 kHz frequency with a 67 ms burst period and an amplitude of 1.19 mT. Osteogenesis was kinetically monitored by repeated fluorescence measurements of continuously present Alizarin Red S (ARS) and periodically confirmed by micro-CT. PEMF treatment induced early-onset and statistically significant transient stimulation (~4-fold) of the mineralization rate when PEMF was applied Daily, or during D1-D10 and D11-D27. Stimulation was apparent but not significant between D28-D63 by ARS but was significant at D63 by micro-CT. PEMF also shifted the micro-CT density profiles to higher densities in each PEMF treatment group. Ring culture generated tissue with a mineral:matrix ratio of 2.0 by thermogravimetric analysis (80% of the calvaria control), and the deposited crystal structure was 50% hydroxyapatite by X-ray diffraction (63% of the calvaria and femur controls), independent of PEMF. These results were consistent with backscatter, secondary electron, and elemental analysis by scanning electron microscopy. Thus, in a defined, strong osteogenic environment, PEMF applied at different times was capable of further stimulation of osteogenesis with the potential to enhance bone repair.

Ion channels as molecular targets of glioblastoma electrotherapy

“…This DC-EF effect was sensitive to verapamil, a blocker of L-and T-type voltage-gated Ca 2+ Ca v channels (Bergson et al, 2011) suggesting an involvement of Ca v channels in the transduction of the static electric field into Ca 2+ signaling. 10.3389/fncel.2023.1133984 Pulsed EMF (PEMF) have been demonstrated in vitro to stimulate osteogenesis (Petecchia et al, 2015;Benya et al, 2021;Kar et al, 2021;He et al, 2022). Polycystin-2 (TRPP2, PKD-2), a voltage-dependent Ca 2+ -permeable cation channel of the polycystic subfamily of the transient receptor proteins (TRP), harbors a voltage sensor domain similar to other voltage-gated ion channels (Shen et al, 2016) and is expressed in rat osteoblasts.…”

Do magnetic field applications lead to improved bone union in light of Evidence- Based Medicine principles? Analysis of the scientific evidence from basic science to clinical research

“…Thus, as can be seen from the above rationales, it is difficult at the level of basic research to determine the optimal value of magnetic field strength for promoting bone union. For example, He et al [14] suggest beneficial effects under magnetic induction of 0.6 mT, Benya et al [15] 1.18 mT, Ma et al [16] 2 mT [16], and Lin et al [17] even more than 10 mT, showing a lack of consensus in this regard.…”

“…Similarly, the time for a single treatment is a wide spectrum, ranging from 10 minutes to as much as several hours [8][9][10][11][12][13][14][15][16][17]. However, other technical parameters seem to be similar, i.e., rectangular shape of the field, and the treatment series is 14-30 days.…”

Design, fabrication, and characterization of a multimodal reconfigurable bioreactor for bone tissue engineering

“…Along with mechanical stimulations, electrical stimulations have also been studied to promote bone regeneration, and it is currently administered by using three different approaches: direct current (DC) (Khaw et al, 2021; Srirussamee et al, 2021; Y. Zhang et al, 2021), pulsed electromagnetic field (PEMF) (Benya et al, 2021; Diniz et al, 2002; Dong et al, 2021), and capacitive coupled (CC) (Chalidis et al, 2011). The main problems affecting the application of these methods in vitro are due to the lack of standardization of cell types, models and protocols, the high risk of contamination, and the invasiveness and high costs of the surgical procedures that would follow in vivo (Bhavsar et al, 2020).…”