Electric currents of 448 kHz upregulate anti-­ senescence pathways in human dermal fibroblasts

Background / Purpose

Skin aging is characterized by loss of elasticity, thinning, and reduced collagen synthesis caused by senescence of dermal fibroblasts. This in-vitro study explored whether subthermal Capacitive-Resistive Electric Transfer (CRET) currents at 448 kHz can counteract fibroblast senescence, enhance proliferation and migration, and promote extracellular matrix (ECM) renewal. Both standard (non-modulated) and modulated (20 kHz – 40%) 448 kHz signals were compared to clarify biological mechanisms underlying Tecar therapy’s rejuvenating effects.

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Methods

Three human dermal fibroblast models were analyzed:

• HFn: neonatal fibroblasts
• HFs: replicative-senescent fibroblasts
• HFa: adult fibroblasts (> 40 yrs)

Cells were treated with subthermal electric pulses (100 μA/mm²) for up to 48 hours using an INDIBA Deep Care Elite NS generator. Evaluations included:

• Cell proliferation (XTT assay, flow cytometry)
• Migration (wound-closure assay, vinculin staining)
• Senescence markers: β-galactosidase, vimentin, p53, p21
• ECM synthesis: fibronectin, collagen I, hyaluronic acid (ELISA / immunofluorescence)
• MMP-1 and MMP-9 expression (western blot).

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Results

Cell proliferation: CRET-Standard (Std) significantly increased proliferation in neonatal (HFn) and adult (HFa) fibroblasts (p < 0.01) by ≈ 25–35%, while senescent (HFs) remained unchanged. CRET-Modulated (Mod) showed no effect.

Migration: CRET-Std accelerated wound closure by ≈ 20–30% at 6–12 hours in all cell types, indicating enhanced motility independent of age.

Senescence markers: (Cellular aging)

• β-galactosidase activity decreased ≈ 30–40% in adult and senescent fibroblasts (p < 0.05).
• Vimentin expression fell significantly in HFn and HFa (p < 0.05).
• p21 and p53 protein levels decreased in HFn and HFs (≈ 20–30%), reflecting anti-senescence pathway activation.

ECM production:

• Fibronectin rose significantly (+25%, p < 0.05) in HFn after CRET-Std.
• Collagen I slightly decreased after 24 h, possibly due to transient MMP-1 upregulation before new collagen formation.
• Hyaluronic acid decreased in HFn but was unchanged in HFa and HFs.

Matrix metalloproteinases: MMP-9 was downregulated in all fibroblast types (12–24 h), suggesting reduced tissue degradation and inflammation.

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Conclusion

Subthermal Tecar stimulation at 448 kHz activates anti-senescence pathways, enhancing fibroblast proliferation and migration while reducing key aging biomarkers (β-gal, vimentin, p21, p53). CRET therapy also modulates ECM metabolism by increasing fibronectin and temporarily regulating collagen turnover via MMP signaling. These results demonstrate that even under non-thermal conditions, Tecar currents promote cellular rejuvenation and tissue regeneration potential in human dermal fibroblasts. Therefore, the use of this CRET therapy to reduce the signs of dermal aging and to promote tissue regeneration could be of interest.