Despite advances in standard wound care (SWC), only approximately 60%–70% of diabetic foot ulcers (DFUs) heal within 12–20 weeks, leaving a substantial number of patients at risk of chronic progression [1,2]. This underscores the need for adjunctive strategies that target the biological wound microenvironment beyond conventional mechanical and infection-focused approaches. Bioelectric signaling plays a critical role in tissue repair, providing an essential regulatory mechanism for cell behavior and tissue organization. Endogenous electric fields generated by ionic flux across disrupted epithelium create spatial potential gradients that guide keratinocyte and fibroblast migration (electrotaxis) and support epithelial regeneration [3,4].

Because the attenuation of these signals in chronic wounds is closely associated with impaired healing [5], electrical stimulation has been explored as a strategy to reinforce bioelectric cues, accelerate cell migration, and improve microcirculatory dynamics [3,4,6]. However, the clinical role of electrical stimulation in DFUs remains insufficiently defined, particularly in early-stage disease. High-voltage microcurrent therapy (HVMT) is a noninvasive modality capable of generating localized electric fields with minimal current intensity.

Therefore, this study aimed to evaluate the feasibility and safety of adjunct HVMT in early-stage DFUs under SWC, and to describe wound progression within a hypothesis-generating physiological framework through a retrospective descriptive case series based on anonymized clinical records and photographs obtained during routine clinical care.

Patients were not prospectively enrolled according to a predefined research protocol, and no additional intervention or procedure was performed for research purposes. Therefore, this work was considered a retrospective case series based on routine clinical practice rather than a prospective human-subject research study. Written informed consent for publication of clinical information and photographs was obtained from all patients. Regarding the device, the ELCURE 1000 system (Regentech Co., Ltd.) is a commercially available Class II medical device approved by the Korean Ministry of Food and Drug Safety (MFDS) as an electric potential generator (A16040.01). Its approved intended use is the improvement of blood circulation through the application of alternating electric fields to the human body.

The following descriptive case series included five patients with DFUs who had shown insufficient improvement from prior treatment. Previous management consisted of wound dressings, antibiotic therapy, and glycemic control. Most ulcers were classified as Wagner grade 1–2, indicating early-stage disease. Baseline vascular assessment was performed prior to treatment initiation. Arterial perfusion was evaluated using Doppler ultrasonography (SonoDop 5000; Sonotechnik GmbH), with assessment of the dorsalis pedis artery at the dorsum of the foot, the posterior tibial artery posterior to the medial malleolus, and the peroneal artery along the lateral aspect of the lower leg at standard anatomical landmarks. In all patients, audible pulsatile flow signals were detected in the major pedal arteries, demonstrating preserved macrovascular perfusion. No additional vascular interventions were performed during the treatment period. All patients received SWC in accordance with established clinical guidelines [1,2,7], including routine wound cleansing, appropriate dressings, infection control, pressure off-loading, and metabolic management. Surgical debridement was not performed because the eschars were dry, stable, and non-infected. Instead, granulation tissue developed beneath the eschars, leading to natural separation, and only loosened portions were selectively trimmed during routine dressings. Although considered a standard off-loading modality [7], total contact casting was omitted due to practical limitations, such as patient discomfort, restricted mobility, and cost considerations. Instead, conservative off-loading strategies were implemented, including the use of pressure-relieving footwear, limitation of ambulation, reduction of weight-bearing, and application of protective padding.

Adjunct HVMT was administered using the ELCURE 1000 system (Regentech Co., Ltd.). Pulsed high-voltage microcurrent stimulation (peak voltage, 1,000–3,000 V; average current, 100–250 μA) was applied for 20–40 minutes per session. Surface electrodes were positioned proximally and distally relative to the ulcer to avoid direct contact with the wound bed (Fig. 1). Treatment was initiated once weekly and subsequently adjusted based on clinical response. During the treatment period, clinical parameters including ischemic deterioration, infection progression, tissue necrosis, and delayed wound healing were monitored. Safety-related parameters, including potential device-related adverse events such as electrical or thermal injury, electrode-site pain, stinging sensation, irritation, discomfort, and skin erythema, were also continuously assessed.

SWC remains the cornerstone of DFU management; however, delayed healing and recurrence continue to represent a substantial unmet clinical need despite advances in multidisciplinary care [1,2]. In real-world practice, even in the absence of critical limb ischemia, many early-stage DFUs fail to follow the expected healing trajectory, highlighting the importance of factors beyond macrovascular perfusion. In this case series, adjunct HVMT applied alongside standard care was associated with a consistent pattern of wound progression, including reduced exudate, granulation tissue formation, wound contraction, and epithelialization. All patients demonstrated preserved macrovascular perfusion on Doppler ultrasonography, suggesting that impaired healing may be more closely related to microcirculatory dysfunction and local wound microenvironmental factors rather than large-vessel insufficiency [1,2].

To interpret these findings, we propose a hypothesis-generating framework focused on the wound microenvironment. The concept of “lymph sludge,” defined as the accumulation of protein-rich interstitial fluid that may impair microcirculatory dynamics, is introduced as a clinically derived construct distinct from established models. While preliminary, this framework may help explain persistent healing delays observed in patients without overt macrovascular compromise (Fig. 7).

Mechanistically, HVMT generates localized electric fields within the microampere range that may interact with disrupted endogenous bioelectric signals. Such fields have been shown to promote electrotaxis of keratinocytes, fibroblasts, and endothelial cells, facilitating coordinated cell migration during tissue repair, as demonstrated in studies by Zhao and Nuccitelli [3,4,6]. In addition, electrotransport mechanisms, including iontophoresis, have been described to influence interstitial fluid dynamics and the redistribution of charged molecules within tissues [8]. Electrical stimulation has also been associated with enhanced nitric oxide (NO) bioavailability, endothelial activation, and vascular endothelial growth factor-mediated angiogenesis, as well as modulation of inflammatory pathways [6,9-12]. Furthermore, microcurrent stimulation has been reported to enhance ATP production, protein synthesis, and membrane transport, particularly in the seminal work of Cheng et al. [13]. Taken together, HVMT may function as a multi-target, microenvironment-modulating approach, rather than a single-mechanism therapy. This integrative effect may be particularly relevant in DFU, where impaired healing arises from complex interactions among microcirculatory dysfunction, interstitial alterations, and disrupted bioelectric signaling.

This study has several limitations. As an uncontrolled descriptive case series, it does not permit causal inference or determination of therapeutic efficacy. In addition, no direct measurements of microcirculation, lymphatic function, or biochemical markers were performed, and the observed clinical course may reflect multifactorial effects of comprehensive wound care.

Despite the use of high-voltage stimulation, the delivered current remained within the microampere range (<1 mA), which is generally considered physiologically safe and comparable to endogenous bioelectric currents [4,6,13]. In this series, no device-related adverse events or clinically relevant complications–including infection aggravation, ischemic deterioration, or tissue necrosis–were observed, supporting the safety and tolerability of HVMT in real-world clinical settings. Given the persistent gap between standard care and optimal healing outcomes in DFU, a noninvasive and well-tolerated adjunctive modality that can be integrated into existing treatment protocols has clear clinical relevance.

These observations describe wound healing outcomes in a small retrospective case series of patients who received adjunct HVMT during routine clinical care. Rather than targeting a single pathway, HVMT may represent a clinically scalable strategy for modulating the wound microenvironment at multiple levels. While causal inference cannot be established, the observed clinical course combined with a favorable safety profile warrants further evaluation in controlled, mechanism-driven clinical studies to clarify its potential role as an adjunctive therapy.