[Effects of static magnetic field at different times on the proliferation and differentiation of osteoblasts in vitro].

Abstract

OBJECTIVE: To investigate the effect of exposure to static magnetic fields (SMFs) of 3.9 mT on proliferation and differentiation of osteoblasts in vitro. METHODS: The newborn rat calvarial osteoblasts were isolated by enzyme digestion and randomly divided into 9 groups after one passage. The intensity of the SMFs was 3.9 mT. The cells were exposed in the SMFs for 0 (control group), 0.5, 1.0, 1.5, 2.0, 2.5, 3, 3.5 and 4.0 h groups respectively. They were observed under the contrast phase microscope each day. After 48 h, cell proliferation was assayed by MTT method. The alkaline phosphatase (Alkaline Phosphatase, ALP) activities and calcium content were measured after 3, 6, 9, and 12 days exposed with SMFs. The ALP positive colonies were histochemically stained after 8 days and the calcified nodules were stained by Alizarin Bordeaux after 10 days; BMP-2, Runx-2 and Opg mRNA expression were measured after SMFs treatment in 0, 24, 48 and 72 h. RESULTS: Contrast with control group, all SMFs groups enhanced cell proliferation (P < 0.01 or P < 0.05), and they promoted maturation and mineralization of the osteoblasts. The results showed that SMFs improved the ALP activity, promoted calcium content, boost BMP-2, Runx -2 and Opg mRNA expression. CONCLUSION: The cells exposed to the SMFs of 3.9 mT at 2.5 h apparently promote proliferation and differentiation of osteoblasts in vitro.

AI evidence extraction

Main findings

Compared with control, all static magnetic field (3.9 mT) exposure groups showed increased osteoblast proliferation and promoted maturation/mineralization. SMF exposure increased ALP activity, calcium content, and BMP-2, Runx-2, and Opg mRNA expression; 2.5 h exposure was reported as apparently promoting proliferation and differentiation.

Outcomes measured

• Cell proliferation (MTT at 48 h)
• Alkaline phosphatase (ALP) activity (3, 6, 9, 12 days)
• Calcium content (3, 6, 9, 12 days)
• ALP-positive colonies (histochemical staining at 8 days)
• Calcified nodules/mineralization (Alizarin Bordeaux staining at 10 days)
• mRNA expression of BMP-2, Runx-2, Opg (0, 24, 48, 72 h)

Limitations

• In vitro study (newborn rat osteoblasts); applicability to humans not addressed in abstract
• Sample size not reported in abstract
• Only one field intensity tested (3.9 mT)

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "static",
        "source": null,
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "0–4.0 h exposure (groups: 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3, 3.5, 4.0 h); outcomes assessed up to 12 days"
    },
    "population": "Newborn rat calvarial osteoblasts (in vitro)",
    "sample_size": null,
    "outcomes": [
        "Cell proliferation (MTT at 48 h)",
        "Alkaline phosphatase (ALP) activity (3, 6, 9, 12 days)",
        "Calcium content (3, 6, 9, 12 days)",
        "ALP-positive colonies (histochemical staining at 8 days)",
        "Calcified nodules/mineralization (Alizarin Bordeaux staining at 10 days)",
        "mRNA expression of BMP-2, Runx-2, Opg (0, 24, 48, 72 h)"
    ],
    "main_findings": "Compared with control, all static magnetic field (3.9 mT) exposure groups showed increased osteoblast proliferation and promoted maturation/mineralization. SMF exposure increased ALP activity, calcium content, and BMP-2, Runx-2, and Opg mRNA expression; 2.5 h exposure was reported as apparently promoting proliferation and differentiation.",
    "effect_direction": "benefit",
    "limitations": [
        "In vitro study (newborn rat osteoblasts); applicability to humans not addressed in abstract",
        "Sample size not reported in abstract",
        "Only one field intensity tested (3.9 mT)"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "static magnetic field",
        "SMF",
        "3.9 mT",
        "osteoblast",
        "proliferation",
        "differentiation",
        "ALP",
        "mineralization",
        "BMP-2",
        "Runx-2",
        "Opg",
        "rat calvarial cells"
    ],
    "suggested_hubs": []
}

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