Medical/biological Study (experimental study)

Clinical significance of different effects of static and pulsed electromagnetic fields on human osteoclast cultures. med./biol.

PubMed Entry

Journal web site

Aim of study (according to author)
To study whether static magnetic fields that are generated around spinal metal (titanium) devices could influence periprosthetic osteolysis modulating not only osteoblasts but also osteoclast cells function. Additionally, it was investigated whether pulsed electromagnetic fields that are usually used in clinical practice for nonunions could affect osteoclasts differentiation and activity.
Background/further details:
Primary osteoclast cells were isolated from primary human osteoclast precursor cells.

Endpoint

• osteoclast cell differentiation, cell morphology and activity, osteolysis

Exposure
General category: static magnetic field, low frequency field, signals/pulses, 50/60 Hz (AC), DC

Field characteristics	Parameters
field 1: DC/static exposure duration: continuous for 7, 10 or 14 days	magnetic flux density: 0.9 µT
field 2: 50 Hz exposure duration: continuous for 7, 10 or 14 days	magnetic flux density: 0.4 mT

Exposed system:
intact cell/cell culture (in vitro)

Methods
Endpoint/Measurement parameters/Methodology

• osteoclast cell differentiation, cell morphology (number of nuclei and cell distribution on the plastic surface; phase contrast microscopy) and activity (tartrate-resistent acid phosphatase (TRAP; expressed during osteoclast differentiation and regulating bone resorption) enzyme activity; spectrophotometry), osteolysis

Main outcome of study (according to author)
The static magnetic field-exposed cells showed a more differentiated phenotype, a higher number of differentiated cells and a significantly higher TRAP enzyme activity after 7 and 10 days of exposure with respect to a sham exposed cells. Pulsed electromagnetic field exposed cells have a less-differentiated phenotype after 7 days of exposure compared with the relative sham exposed control (no difference after 10 and 14 days), while the TRAP enzyme activity showed no statistically significant differences between exposed and control cells at any observation time.
The findings indicated that static magnetic fields of the same intensity of the one generated around spinal devices can affect osteoclast cell differentiation and activity. Aseptic loosening around titanium implants might be due in part to an increased osteoclast activity and cell differentiation. Pulsed electromagnetic fields of the same intensity than the one used for the management of nonunions can affect osteoclasts phenotype after 7 days of exposure, while osteoclasts TRAP enzyme activity is not affected by this kind of electromagnetic fields.

(Study character: medical/biological study, experimental study, pilot/exploratory/preliminary study)

Study funded by

• not stated/none

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