Hypertrophic scars and keloids are two different manifestations of excessive dermal fibrosis and are caused by an alteration in the normal wound-healing process. Treatment with radiofrequency (RF)-based therapies has proven to be useful in reducing hypertrophic scars. In this study, the effect of one of these radiofrequency therapies, Capacitive Resistive Electrical Transfer Therapy (CRET) on biomarkers of skin fibrosis was investigated. For this, in cultures of human myofibroblasts treated with CRET therapy or sham-treated, proliferation (XTT Assay), apoptosis (TUNEL Assay), and cell migration (Wound Closure Assay) were analyzed. Furthermore, in these cultures the expression and/or localization of extracellular matrix proteins such as α-SMA, Col I, Col III (immunofluorescence), metalloproteinases MMP1 and MMP9, MAP kinase ERK1/2, and the transcription factor NFκB were also investigated (immunoblot). The results have revealed that CRET decreases the expression of extracellular matrix proteins, modifies the expression of the metalloproteinase MMP9, and reduces the activation of NFκB with respect to controls, suggesting that this therapy could be useful for the treatment of fibrotic pathologies.

Androgenic alopecia (AGA) is the most common type of alopecia and its treatments involve drugs that have various adverse effects and are not completely effective. Radiofrequency-based therapies (RF) are an alternative for AGA treatment. Although there is increasing clinical evidence of the effectiveness of RF for alopecia, its effects at the tissue and cellular level have not been studied in detail. The objective of this study was to analyze ex vivo the potential effect of RF currents used in capacitive resistive electrical transfer (CRET) therapy on AGA. Hair follicles (HFs) were donated by patients with AGA and treated with CRET. AGA-HFs were exposed in vitro to intermittent 448 kHz electric current in subthermal conditions. Cell proliferation (Ki67), apoptosis (TUNEL assay), differentiation (β-catenin), integrity (collagen and MMP9), thickness of the epidermis surrounding HF, proportion of bulge cells and melanoblasts in AGA-HF were analyzed by immunohistochemistry. CRET increased proliferation and decreased death of different populations of AGA-HF cells. In addition, the melanoblasts increased in bulge and the epidermis surrounding the hair follicle thickened. These results support the effectiveness of RF-based therapies for the treatment of alopecia. However, clinical trials are necessary to know the true effectiveness of CRET therapy and other RF therapies for AGA treatment.

Wound healing consists of a sequence of coordinated phases: inflammation, proliferation, and remodeling. In skin lesions, neutrophils and keratinocytes are the main cell types participating in the inflammatory phase, during which the release of mediators intervening in the regulation of the subsequent regenerative phases takes place. These mediators are involved in tissue regeneration through induction of transendothelial migration, enzyme secretion, cell adhesion, and T-Cell activation and cytotoxicity, as well as neutrophil accumulation at the wound site. Among these mediators, the keratinocyte-synthesized chemokines RANTES, MCP-1, MIP-1, and IL-8 stand out. Although therapies applying electromagnetic fields or electric currents have been shown to have anti-inflammatory effects in a variety of experimental models and in patients through reduced production of proinflammatory cytokines such as IFN-Υ and increased production of IL-10, the knowledge on the biological basis of these effects is still limited. Previous studies by our group have shown that subthermal treatment with radiofrequency (RF) currents used in capacitive-resistive electric transfer (CRET) therapy promotes the proliferation and migration of various cell types, such as human ADSC (stem cells), fibroblasts or keratinocytes, involved in skin regeneration. This study investigates the effects of in vitro treatment with CRET currents on cytokine production by HaCat human keratinocytes. The results reveal that, compared to sham-exposed controls, RF stimulation induces decreased production of IL-8 and RANTES and increased MCP-1, without significantly affecting other chemokines such as MIP-1. Taken together, our results indicate that due to the RF effects on the production of chemokines involved in the modulation of the inflammatory phase of wound regeneration, CRET therapy could be effective in the treatment of skin wounds.

Keratinocytes play an essential role in the inflammatory phase of wound regeneration. In addition to migrating and proliferating for tissue regeneration, they produce a large amount of cytokines that modulate the inflammatory process. Previous studies have shown that subthermal treatment with radiofrequency (RF) currents used in capacitive resistive electric transfer (CRET) therapy promotes the proliferation of HaCat keratinocytes and modulates their cytokine production. Although physical therapies have been shown to have anti-inflammatory effects in a variety of experimental models and in patients, knowledge of the biological basis of these effects is still limited. The aim of this study was to investigate the effect of CRET on keratinocyte proliferation, cytokine production (IL-8, MCP-1, RANTES, IL-6, IL-11), TNF-α secretion, and the expression of MMP9, MMP1, NF-κB, ERK1/2, and EGFR. Human keratinocytes (HaCat) were treated with an intermittent 448 kHz electric current (CRET signal) in subthermal conditions and for different periods of time. Cell proliferation was analyzed by XTT assay, cytokine and TNF-α production by ELISA, NF-κB expression and activation by immunofluorescence, and MMP9, MMP1, ERK1/2, and EGF receptor expression and activation by immunoblot. Compared to a control, CRET increases keratinocyte proliferation, increases the transient release of MCP-1, TNF-α, and IL-6 while decreasing IL-8. In addition, it modifies the expression of MMPs and activates EGFR, NF-κB, and ERK1/2 proteins. Our results indicate that CRET reasonably modifies cytokine production through the EGF receptor and the ERK1/2/NF-κB pathway, ultimately modulating the inflammatory response of human keratinocytes.

Cutaneous mycoses are common infections whose treatment has become more complex due to increasing antifungal resistance and the need for prolonged therapies, hindering patient adherence and increasing the incidence of adverse effects. Consequently, the use of physical therapies, especially photodynamic therapy (PDT), has increased for the treatment of onychomycosis due to its antimicrobial capacity being mediated by the production of reactive oxygen species. This study investigates the in vitro effect of applying blue light (448 nm) or red light (645 nm), alone or together with terbinafine, on the viability of human keratinocytes and the production of reactive oxygen species. The combination of terbinafine and blue light significantly increases ROS production and caspase-3 expression, while red light together with terbinafine increases catalase, superoxide dismutase (SOD) and PPARγ expression, which reduces the amount of ROS in the cultures. The effect of both treatments could be useful in clinical practice to improve the response of cutaneous mycoses to pharmacological treatment, reduce their toxicity and shorten their duration.

Hydroxychloroquine (HCQ), an antimalarial commonly used in autoimmune and dermatological conditions, may exert photoprotective effects, though its role against high-energy visible light (HEVL) remains underexplored. This study evaluated HCQ’s impact on cell viability and oxidative stress in human keratinocytes (HaCat cells) exposed to HEVL blue light. Cells were treated with HCQ (1, 2.5, or 5 µM) and irradiated with blue light doses (4.5–72 J/cm²). Assays assessed cell viability (XTT), reactive oxygen species (ROS) production, and the expression of oxidative stress-related enzymes: superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT). Results showed that low blue light doses triggered endogenous protective responses, which HCQ enhanced, potentially via SOD activation. However, higher irradiation levels caused extensive cellular damage that overwhelmed HCQ’s protective capacity. These findings suggest HCQ may confer in vitro photoprotection against sublethal HEVL exposure by modulating oxidative stress responses, although this effect diminishes beyond a certain damage threshold.