The differentiation of normal and transformed human fibroblasts in vitro is influenced by electromagnetic fields.

Abstract

We studied the effect of symmetric, biphasic sinusoidal electromagnetic fields (EMF) (20 Hz, 6 mT) on the differentiation of normal human skin fibroblasts (HH-8), normal human lung fibroblasts (WI38), and SV40-transformed human lung fibroblasts (WI38SV40) in in vitro cultures. Cells were exposed up to 21 days for 2 x 6 h per day to EMF. Normal mitotic human skin and lung fibroblasts could be induced to differentiate into postmitotic cells upon exposure to EMF. Concomitantly, the synthesis of total collagen as well as total cellular protein increased significantly by a factor of 5-13 in EMF-induced postmitotic cells. As analyzed by two-dimensional gel electrophoresis of [35S]methionine-labeled polypeptides, EMF-induced postmitotic cells express the same differentiation-dependent and cell type-specific marker proteins as their spontaneously arising counterparts. In SV40-transformed human lung fibroblasts (cell line WI38SV40) the exposure to EMF induced the differentiation of mitotic WI38SV40 cells into postmitotic and degenerating cells in subpopulations of WI38SV40 cell cultures. Other subpopulations of WI38SV40 cells did not show any effect of EMF on cell proliferation and differentiation. These results indicate that long-term EMF exposure of fibroblasts in vitro induces the differentiation of mitotic to postmitotic cells that are characterized by differentiation-specific proteins and differentiation-dependent enhanced metabolic activities.

AI evidence extraction

Main findings

Exposure to symmetric, biphasic sinusoidal EMF (20 Hz, 6 mT) for up to 21 days induced differentiation of normal human skin and lung fibroblasts from mitotic to postmitotic cells, with significantly increased total collagen and total cellular protein (reported 5–13-fold). In SV40-transformed WI38SV40 cultures, EMF induced differentiation into postmitotic and degenerating cells in some subpopulations, while other subpopulations showed no effect on proliferation and differentiation.

Outcomes measured

• Cell differentiation (mitotic to postmitotic)
• Cell proliferation
• Collagen synthesis
• Total cellular protein synthesis
• Expression of differentiation-dependent and cell type-specific marker proteins
• Cell degeneration (in SV40-transformed subpopulations)

Limitations

• In vitro study (cell culture), limiting direct inference to human health outcomes
• Sample size not reported in abstract
• Heterogeneous response in transformed cell line (subpopulations with no observed effect)

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "ELF",
        "source": null,
        "frequency_mhz": 0.0200000000000000004163336342344337026588618755340576171875,
        "sar_wkg": null,
        "duration": "Up to 21 days; 2 × 6 h/day"
    },
    "population": "Normal human skin fibroblasts (HH-8), normal human lung fibroblasts (WI38), and SV40-transformed human lung fibroblasts (WI38SV40) in vitro cultures",
    "sample_size": null,
    "outcomes": [
        "Cell differentiation (mitotic to postmitotic)",
        "Cell proliferation",
        "Collagen synthesis",
        "Total cellular protein synthesis",
        "Expression of differentiation-dependent and cell type-specific marker proteins",
        "Cell degeneration (in SV40-transformed subpopulations)"
    ],
    "main_findings": "Exposure to symmetric, biphasic sinusoidal EMF (20 Hz, 6 mT) for up to 21 days induced differentiation of normal human skin and lung fibroblasts from mitotic to postmitotic cells, with significantly increased total collagen and total cellular protein (reported 5–13-fold). In SV40-transformed WI38SV40 cultures, EMF induced differentiation into postmitotic and degenerating cells in some subpopulations, while other subpopulations showed no effect on proliferation and differentiation.",
    "effect_direction": "mixed",
    "limitations": [
        "In vitro study (cell culture), limiting direct inference to human health outcomes",
        "Sample size not reported in abstract",
        "Heterogeneous response in transformed cell line (subpopulations with no observed effect)"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "extremely low frequency",
        "ELF",
        "electromagnetic fields",
        "20 Hz",
        "6 mT",
        "fibroblasts",
        "HH-8",
        "WI38",
        "WI38SV40",
        "SV40-transformed",
        "differentiation",
        "postmitotic",
        "collagen",
        "protein synthesis",
        "two-dimensional gel electrophoresis"
    ],
    "suggested_hubs": []
}

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