Effects of 50 Hz sinusoidal electromagnetic fields of different intensities on proliferation, differentiation and mineralization potentials of rat osteoblasts.

Bone · 2011 · Mixed · Low evidence

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MixedLow evidencePaper 4453

Study snapshot

PublicationBone · 2011

Study typein_vitro

Reported directionMixed

Evidence ratingLow

Abstract

Electromagnetic fields (EMFs) have been used clinically to slow down osteoporosis and promote fracture healing for many years. However, the underlying action mechanisms and optimal parameters of the EMF applications are unclear. In this study, we investigated the effects of treatment for different durations with 50 Hz sinusoidal electromagnetic fields (SEMFs) at different intensities on proliferation, differentiation and mineralization potentials of rat osteoblasts. Osteoblasts isolated from neonatal rats were treated with SEMFs (50 Hz at 0.9 mT-4.8 mT, 0.3 mT interval, 30 min/day up to 15 days). Compared to untreated control, SEMFs inhibited osteoblast proliferation (after 3 days' treatment) but increased alkaline phosphatase (ALP) activity (after treatment for 9 days) from 0.9 mT to 1.8 mT, declined from 1.8 mT until 3.0 mT, and then increased again from 3.0 mT to 3.6 mT and decreased once again from 3.6 mT to 4.8 mT. Numbers of colonies stained positive for ALP after 8 days and mineralized nodules stained by Alizarin red after 10 days showed the same bimodal tendency as with the ALP activity, with two peaks at 1.8 mT and 3.6 mT. SEMFs also bimodally increased Runx-2, Col1α2 and Bmp-2 mRNA expression levels in osteoblasts at 12, 24 and 96 h after exposure. The results indicated that while exposure to 50 Hz SEMFs inhibits the osteoblast proliferation, it significantly promotes differentiation and mineralization potentials of osteoblasts in an intensity-dependent manner with peak activity at 1.8 mT and 3.6 mT.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typein_vitro

Effect directionmixed

PopulationRat osteoblasts isolated from neonatal rats

Sample sizeNot supplied

ExposureELF · 0.05 MHz · 30 min/day up to 15 days

Evidence strengthLowConfidence: 86% · Peer reviewed: yes

Main findings

Neonatal rat osteoblasts exposed to 50 Hz sinusoidal electromagnetic fields (0.9–4.8 mT; 30 min/day) showed inhibited proliferation after 3 days compared with untreated controls. Differentiation and mineralization-related outcomes (ALP activity, ALP-positive colonies, mineralized nodules, and Runx-2/Col1α2/Bmp-2 mRNA expression) were increased in a bimodal, intensity-dependent pattern with peaks at 1.8 mT and 3.6 mT.

Outcomes measured

Osteoblast proliferation
Alkaline phosphatase (ALP) activity
ALP-positive colony numbers
Mineralized nodule formation (Alizarin red staining)
Runx-2 mRNA expression
Col1α2 mRNA expression
Bmp-2 mRNA expression

Limitations

In vitro study in rat osteoblasts; generalizability to humans/clinical outcomes not addressed in abstract
Sample size not reported in abstract
Mechanisms and optimal parameters noted as unclear in background

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 0.05,
    "sar_wkg": null,
    "duration": "30 min/day up to 15 days"
  },
  "population": "Rat osteoblasts isolated from neonatal rats",
  "sample_size": null,
  "outcomes": [
    "Osteoblast proliferation",
    "Alkaline phosphatase (ALP) activity",
    "ALP-positive colony numbers",
    "Mineralized nodule formation (Alizarin red staining)",
    "Runx-2 mRNA expression",
    "Col1α2 mRNA expression",
    "Bmp-2 mRNA expression"
  ],
  "main_findings": "Neonatal rat osteoblasts exposed to 50 Hz sinusoidal electromagnetic fields (0.9–4.8 mT; 30 min/day) showed inhibited proliferation after 3 days compared with untreated controls. Differentiation and mineralization-related outcomes (ALP activity, ALP-positive colonies, mineralized nodules, and Runx-2/Col1α2/Bmp-2 mRNA expression) were increased in a bimodal, intensity-dependent pattern with peaks at 1.8 mT and 3.6 mT.",
  "effect_direction": "mixed",
  "limitations": [
    "In vitro study in rat osteoblasts; generalizability to humans/clinical outcomes not addressed in abstract",
    "Sample size not reported in abstract",
    "Mechanisms and optimal parameters noted as unclear in background"
  ],
  "evidence_strength": "low",
  "confidence": 0.86,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "50 Hz",
    "sinusoidal electromagnetic fields",
    "SEMF",
    "ELF-EMF",
    "osteoblast",
    "proliferation",
    "differentiation",
    "mineralization",
    "alkaline phosphatase",
    "Runx-2",
    "Bmp-2",
    "Col1α2",
    "intensity-dependent",
    "bimodal response"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1016/j.bone.2011.06.026
PubMed: 21726678

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