Electrical Stimulation and Cutaneous Wound Healing: A Review of Clinical Evidence

A Comparative Study of the Effects of Vibration and Electrical Stimulation Therapies on the Acceleration of Wound Healing in Diabetic Ulcers

Introduction: Diabetic ulcers accompanied by ischemia is difficult to treat. Such ulcers require therapy that can improve the blood flow. Previous studies have revealed that two therapies could improve blood flow and accelerate the healing of diabetic ulcers; vibration and electrical stimulation (ES). However, it is unknown which of these two therapies is best at accelerating wound healing in diabetic ulcers. The purpose of this study was to compare both therapies in relation to accelerating the wound healing of diabetic ulcers. Methods: This study was an experimental study involving diabetic rats. The rats were divided into two groups: vibration and ES. Vibration and ES were applied for 10 minutes per day for 7 days. Wound size, inflammation, intensity of fibroblast infiltration, area of necrosis and degree of re-epithelialisation were compared. The difference in wound size was analysed using an independent t-test, while the histological data were analysed using a Mann-Whitney U-test. Results: On day 5 onwards, there was a thin slough in the ES group which was not present in the vibration group. Day 4 onwards and the wound size was significantly smaller in the vibration group than in the ES group. The intensity of inflammation was significantly less, and the degree of fibroblast infiltration was significantly higher in the vibration group compared with the ES group. Re-epithelialisation was more advanced in the vibration group than the ES group. Conclusions: Our study revealed that wound healing in diabetic ulcers following vibration was better than after ES. We suggest that nurses should use vibration rather than ES in clinical settings.

Bone-healing capacity of conditioned medium derived from three-dimensionally cultivated human mesenchymal stem cells and electrical stimulation on collagen sponge

Continuing from our previous study, we hypothesized that combining electrical stimulation (ES) and three-dimensional (3D) culture would be a useful strategy to obtain more bioactive factors in conditioned medium (CM) derived from human mesenchymal stem cells (hMSC). Our aim in this study was to investigate the bone-healing capacity of CM derived from hMSC after 4 days of culture on a collagen sponge-exposed (CM-ES) or unexposed (CM-control; CM-CON) to ES in comparison with that of hMSC implantation. A cytokine assay of both CMs revealed the presence of cytokines, growth factors, and trophic factors. In vitro evaluation of both CMs showed increased cell growth and alkaline phosphatase activity of the hMSC, with little difference between CMs. We investigated the bone-healing effect using two bone disease models: bone defect and inflammatory bone loss. The calvaria defect was implanted with whole CM or 3D-precultured hMSC unexposed to ES. Microcomputed tomography analysis after 4 weeks indicated a twofold greater bone volume in the CM-CON and CM-ES groups than in the hMSC and vehicle groups, though we found no difference between the CM groups. However, CM-ES enhanced the bone healing of interleukin-1-induced bone loss to a level comparable with hMSC, whereas CM-CON did not. These results show that 3D-cultured CM had a greater or similar capacity for bone healing as treatment using hMSC transplantation, and CM-ES was especially effective against inflammatory bone loss. Thus, 3D-cultured CM with or without ES presents an encouraging alternative to MSC-based bone healing. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 311-320, 2018.

Studying Electrotaxis in Microfluidic Devices

Collective cell migration is important in various physiological processes such as morphogenesis, cancer metastasis and cell regeneration. Such migration can be induced and guided by different chemical and physical cues. Electrotaxis, referring to the directional migration of adherent cells under stimulus of electric fields, is believed to be highly involved in the wound-healing process. Electrotactic experiments are conventionally conducted in Petri dishes or cover glasses wherein cells are cultured and electric fields are applied. However, these devices suffer from evaporation of the culture medium, non-uniformity of electric fields and low throughput. To overcome these drawbacks, micro-fabricated devices composed of micro-channels and fluidic components have lately been applied to electrotactic studies. Microfluidic devices are capable of providing cells with a precise micro-environment including pH, nutrition, temperature and various stimuli. Therefore, with the advantages of reduced cell/reagent consumption, reduced Joule heating and uniform and precise electric fields, microfluidic chips are perfect platforms for observing cell migration under applied electric fields. In this paper, I review recent developments in designing and fabricating microfluidic devices for studying electrotaxis, aiming to provide critical updates in this rapidly-growing, interdisciplinary field.

Modulation of cell function by electric field: a high-resolution analysis

Regulation of cell function by a non-thermal, physiological-level electromagnetic field has potential for vascular tissue healing therapies and advancing hybrid bioelectronic technology. We have recently demonstrated that a physiological electric field (EF) applied wirelessly can regulate intracellular signalling and cell function in a frequency-dependent manner. However, the mechanism for such regulation is not well understood. Here, we present a systematic numerical study of a cell-field interaction following cell exposure to the external EF. We use a realistic experimental environment that also recapitulates the absence of a direct electric contact between the field-sourcing electrodes and the cells or the culture medium. We identify characteristic regimes and present their classification with respect to frequency, location, and the electrical properties of the model components. The results show a striking difference in the frequency dependence of EF penetration and cell response between cells suspended in an electrolyte and cells attached to a substrate. The EF structure in the cell is strongly inhomogeneous and is sensitive to the physical properties of the cell and its environment. These findings provide insight into the mechanisms for frequency-dependent cell responses to EF that regulate cell function, which may have important implications for EF-based therapies and biotechnology development.

Advanced Therapeutic Dressings for Effective Wound Healing--A Review

Advanced therapeutic dressings that take active part in wound healing to achieve rapid and complete healing of chronic wounds is of current research interest. There is a desire for novel strategies to achieve expeditious wound healing because of the enormous financial burden worldwide. This paper reviews the current state of wound healing and wound management products, with emphasis on the demand for more advanced forms of wound therapy and some of the current challenges and driving forces behind this demand. The paper reviews information mainly from peer-reviewed literature and other publicly available sources such as the US FDA. A major focus is the treatment of chronic wounds including amputations, diabetic and leg ulcers, pressure sores, and surgical and traumatic wounds (e.g., accidents and burns) where patient immunity is low and the risk of infections and complications are high. The main dressings include medicated moist dressings, tissue-engineered substitutes, biomaterials-based biological dressings, biological and naturally derived dressings, medicated sutures, and various combinations of the above classes. Finally, the review briefly discusses possible prospects of advanced wound healing including some of the emerging physical approaches such as hyperbaric oxygen, negative pressure wound therapy and laser wound healing, in routine clinical care.

Feasibility of an electrostimulation system treatment for wound healing: a case series of patients with chronic ulcers in Barbados

Major advances have been made in the development of new therapies for chronic wounds. Fenzian™, an electrostimulation system (ES), has been clinically used for a variety of conditions. The ES was recently tested in the Barbadian population for tolerability and acceptability by asthma patients, with encouraging results. Barbados has an estimated 170 people with diabetes having some form of lower-extremity amputation annually. Here, we describe a case series of 21 chronic ulcer patients with diabetes recruited as inpatients (n = 10) and outpatients (n = 11) in a pilot study to evaluate the feasibility and acceptability of ES in the Barbadian population. Results showed statistically significant improvement among those in the inpatient- versus outpatient-recruited group for wound perimeter (P = 0·04), wound surface area (P = 0·03) and wound volume (P = 0·08). We also demonstrate that the improvement continued after cessation of ES treatment. Participants reported increased levels of pain at the end of treatment, and there was no statistically significant change in the reported quality of life. Our results showed greater improvements in reduction of ulcer size for participants from the inpatient- versus outpatient-recruited group.