Study type: Medical/biological study (experimental study)

Different electromagnetic field waveforms have different effects on proliferation, differentiation and mineralization of osteoblasts in vitro. med./bio.

Published in: Bioelectromagnetics 2014; 35 (1): 30-38

Aim of study (acc. to author)

To study the effects of different waveforms on cell proliferation, differentiation and mineralization of rat osteoblasts.

Background/further details

Four different waveforms and an untreated control were examined: sinusoidal, triangular, rectangular and sawtooth.
Osteoblasts (primary cells) were isolated from skull bones of neonatal rats.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 30 min/day for up to 12 days
Exposure 2: 50 Hz
Exposure duration: 30 min/day for up to 12 days
triangular
Exposure 3: 50 Hz
Exposure duration: 30 min/day for up to 12 days
Exposure 4: 50 Hz
Exposure duration: 30 min/day for up to 12 days

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 30 min/day for up to 12 days
Exposure setup
Exposure source
Chamber osteoblasts placed in 60 mm culture dishes inside the solenoid
Setup solenoid consisting of three series-connected coils and the core cylinder was an acrylic tube (inner diameter = 18 cm, height = 21 cm); solenoid positioned in an incubator at 37°C
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.8 mT effective value measured - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Exposure duration 30 min/day for up to 12 days
Additional info triangular
Additional info Signal form: triangular
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.8 mT effective value measured - -

Exposure 3

Main characteristics
Frequency 50 Hz
Type
Waveform
  • rectangular
Exposure duration 30 min/day for up to 12 days
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.8 mT effective value measured - -

Exposure 4

Main characteristics
Frequency 50 Hz
Type
Waveform
  • sawtooth-shaped
Exposure duration 30 min/day for up to 12 days
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.8 mT effective value measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Compared to the untreated control, sinusoidal magnetic field exposure significantly inhibited osteoblast proliferation while rectangular magnetic field exposure significantly increased the proliferation.
After 9 and 12 days of exposure, the enzyme activity of the alkaline phosphatase was significantly higher in the sinusoidal and triangular waveform exposed cultures compared to the control cultures. The amount of alkaline phosphatase positive colonies was significantly higher in the sinusoidal, triangular and sawtooth waveform exposed cultures than in the control cultures.
Regarding mineralization, after 9 and 12 days of exposure to sinusoidal and triangular waveforms (and amount of calcium also sawtooth after 12 days), the amount of calcium and the number of calcified nodules were significantly higher than in the control cultures.
In comparison to the control cultures, the gene expression of Runx-2 and Opg was significantly upregulated after 1 day of exposure to a sinusoidal, triangular and sawtooth waveform, whereas the gene expression of Igf-1 was significantly increased after 3 and 4 days.
While rectangular magnetic fields increased the proliferation and did not effect the differentiation of osteoblasts, sinusoidal fields inhibited the proliferation but promoted osteogenic differentiation. The authors conclude that the influence of magnetic fields on proliferation, differentiation and mineralization of rat osteoblasts is dependent on the waveform.

Study character:

Study funded by

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