[Time effect of sinusoidal electromagnetic field on enhancing the maturation and mineralization of osteoblasts in vitro].

Abstract

The present research was to investigate the time effect of sinusoidal electromagnetic fields (SEMFs) at different exposure time on the proliferation and differentiation of osteoblasts (OB) in vitro. The newborn rat calvarial OB were isolated by enzyme digestion and divided randomly into 7 groups after one passage. The exposure times of the SEMFs were 0.5 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h and 3.0 h, respectively, and the frequency was 50 Hz. The cells were exposed in the SEMFs of 1.8 mT. Those without SEMFs exposure were used as the control group. 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 were measured after the exposure of SEMFs for 3 d, 6 d, 9 d and 12 d, respectively. The calcified nodules were stained by Alizarin Bordeaux after 10 d. The cells exposed in the SEMFs were arranged in Spiral appearance after 8 d. The SEMFs exposure time at 2.0 h, 2.5 h and 3.0 h significantly inhibited cell proliferation (P < 0.01) and 0.5 h, 1.0 h, 1.5 h groups more significantly than control groups (P < 0.05). When the 3 d, 6 d and 12 d the ALP activities of the 0.5 h, 1.0 h, 1.5 h and 2.0 h, times group were significantly higher than those in the control group (P < 0.05), and after 9 d the 1.0 h, 1.5 h and 2.0 h activity of ALP higher significantly than control and other groups (P < 0.01). Other groups had no effect on the ALP activity. Alizarin Bordeaux staining result showed the amounts of calcified nodules 1.0 h, 1.5 h and 2.0 h higher than control groups. The SEMFs at 50 Hz, 1.8 mT different time exposure groups inhibits the proliferation of OB, but they enhances the maturation and mineralization of the OB and SEMFs at 1.8 mT of the 1.5 h has the strongest activity.

AI evidence extraction

Main findings

Osteoblasts exposed to 50 Hz, 1.8 mT sinusoidal electromagnetic fields showed time-dependent effects: exposure at 2.0–3.0 h significantly inhibited proliferation, while shorter exposures (0.5–1.5 h) also differed from control. ALP activity was significantly increased versus control at several time points for 0.5–2.0 h exposure groups (with 1.0–2.0 h notably higher at day 9), and calcified nodules were increased in the 1.0–2.0 h groups. The authors conclude SEMF inhibits proliferation but enhances maturation and mineralization, with 1.5 h reported as strongest.

Outcomes measured

• Osteoblast proliferation (MTT at 48 h)
• Alkaline phosphatase (ALP) activity (3 d, 6 d, 9 d, 12 d)
• Calcified nodule formation/mineralization (Alizarin Bordeaux staining after 10 d)
• Cell morphology/arrangement (phase contrast microscopy)

Limitations

• In vitro study (newborn rat calvarial osteoblasts), not directly generalizable to humans
• Sample size not reported in abstract
• Only one field strength (1.8 mT) and one frequency (50 Hz) tested
• Exposure regimen details beyond daily exposure time (e.g., number of days of exposure per group) not fully specified in abstract

Suggested hubs

• elf-emf (0.9)
  Exposure is 50 Hz (ELF) sinusoidal electromagnetic field at 1.8 mT.

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "ELF",
        "source": null,
        "frequency_mhz": 0.05000000000000000277555756156289135105907917022705078125,
        "sar_wkg": null,
        "duration": "0.5 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h, 3.0 h (exposure time groups)"
    },
    "population": "Newborn rat calvarial osteoblasts (in vitro)",
    "sample_size": null,
    "outcomes": [
        "Osteoblast proliferation (MTT at 48 h)",
        "Alkaline phosphatase (ALP) activity (3 d, 6 d, 9 d, 12 d)",
        "Calcified nodule formation/mineralization (Alizarin Bordeaux staining after 10 d)",
        "Cell morphology/arrangement (phase contrast microscopy)"
    ],
    "main_findings": "Osteoblasts exposed to 50 Hz, 1.8 mT sinusoidal electromagnetic fields showed time-dependent effects: exposure at 2.0–3.0 h significantly inhibited proliferation, while shorter exposures (0.5–1.5 h) also differed from control. ALP activity was significantly increased versus control at several time points for 0.5–2.0 h exposure groups (with 1.0–2.0 h notably higher at day 9), and calcified nodules were increased in the 1.0–2.0 h groups. The authors conclude SEMF inhibits proliferation but enhances maturation and mineralization, with 1.5 h reported as strongest.",
    "effect_direction": "mixed",
    "limitations": [
        "In vitro study (newborn rat calvarial osteoblasts), not directly generalizable to humans",
        "Sample size not reported in abstract",
        "Only one field strength (1.8 mT) and one frequency (50 Hz) tested",
        "Exposure regimen details beyond daily exposure time (e.g., number of days of exposure per group) not fully specified in abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "sinusoidal electromagnetic field",
        "SEMF",
        "50 Hz",
        "1.8 mT",
        "osteoblast",
        "proliferation",
        "differentiation",
        "alkaline phosphatase",
        "mineralization",
        "calcified nodules",
        "in vitro",
        "rat"
    ],
    "suggested_hubs": [
        {
            "slug": "elf-emf",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Exposure is 50 Hz (ELF) sinusoidal electromagnetic field at 1.8 mT."
        }
    ]
}

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