The effect of induced biphasic pulsed currents on re-epithelialization of a novel wound healing model

The effects of electrical stimulation on diabetic ulcers of foot and lower limb: A systematic review

Diabetic foot ulcer (DFU) is a life-threatening condition affecting a third of diabetic patients. Many adjuvant therapies aimed at improving the healing rate (HR) and accelerating healing time are currently under investigation. Electrical stimulation (ES) is a physical-based therapy able to increase cells activity and migration into wound bed as well as inhibiting bacterial activity. The aim of this paper was to collect and analyse findings on the effects of ES used in combination with standard wound care (SWC) in the treatment of diabetic foot ulceration compared with SWC alone. A systematic review was performed to synthesise data from quantitative studies from eight databases. Article quality was assessed using the Crowe critical appraisal tool. Seven articles out of 560 publications met the inclusion criteria. A meta-analysis was not performed due to the heterogeneity of the studies and the results were narratively synthetised. Findings showed that HR appears to be higher among diabetic ulcers treated with ES; however, the reliability of these findings is affected by the small sample sizes of the studies. Furthermore, four studies are considered as moderate or high risk of bias. The evidence to suggest the systematic usage of ES in the treatment of DFUs is still insufficient.

Electrical Stimulation to Enhance Wound Healing

Electrical stimulation (ES) can serve as a therapeutic modality accelerating the healing of wounds, particularly chronic wounds which have impaired healing due to complications from underlying pathology. This review explores how ES affects the cellular mechanisms of wound healing, and its effectiveness in treating acute and chronic wounds. Literature searches with no publication date restrictions were conducted using the Cochrane Library, Medline, Web of Science, Google Scholar and PubMed databases, and 30 full-text articles met the inclusion criteria. In vitro and in vivo experiments investigating the effect of ES on the general mechanisms of healing demonstrated increased epithelialization, fibroblast migration, and vascularity around wounds. Six in vitro studies demonstrated bactericidal effects upon exposure to alternating and pulsed current. Twelve randomized controlled trials (RCTs) investigated the effect of pulsed current on chronic wound healing. All reviewed RCTs demonstrated a larger reduction in wound size and increased healing rate when compared to control groups. In conclusion, ES therapy can contribute to improved chronic wound healing and potentially reduce the financial burden associated with wound management. However, the variations in the wound characteristics, patient demographics, and ES parameters used across studies present opportunities for systematic RCT studies in the future.

High glucose inhibits ClC-2 chloride channels and attenuates cell migration of rat keratinocytes

Background

Accumulating evidence has demonstrated that migration of keratinocytes is critical to wound epithelialization, and defects of this function result in chronic delayed-healing wounds in diabetes mellitus patients, and the migration has been proved to be associated with volume-activated chloride channels. The aim of the study is to investigate the effects of high glucose (HG, 25 mM) on ClC-2 chloride channels and cell migration of keratinocytes.

Methods

Newborn Sprague Dawley rats were used to isolate and culture the keratinocyte in this study. Immunofluorescence assay, real-time polymerase chain reaction, and Western blot assay were used to examine the expression of ClC-2 protein or mRNA. Scratch wound assay was used to measure the migratory ability of keratinocytes. Transwell cell migration assay was used to measure the invasion and migration of keratinocytes. Recombinant lentivirus vectors were established and transducted to keratinocytes. Whole-cell patch clamp was used to perform the electrophysiological studies.

Results

We found that the expression of ClC-2 was significantly inhibited when keratinocytes were exposed to a HG (25 mM) medium, accompanied by the decline of volume-activated Cl⁻ current (I_Cl,vol), migration potential, and phosphorylated PI3K as compared to control group. When knockdown of ClC-2 by RNAi or pretreatment with wortmannin, similar results were observed, including I_Cl,vol and migration keratinocytes were inhibited.

Conclusion

Our study proved that HG inhibited ClC-2 chloride channels and attenuated cell migration of rat keratinocytes via inhibiting PI3K signaling.

Mesenchymal stem cell-conditioned medium improves the proliferation and migration of keratinocytes in a diabetes-like microenvironment

The impairment of wound healing in diabetic patients is an important clinical problem. Proper keratinocyte migration and proliferation are the crucial steps during reepithelialization, and these steps may be impaired in diabetes mellitus (DM) due to hyperglycemia and chronic inflammation in wound site. In this study, we explored the effects of diabetes-like microenvironment with high glucose (HG) and intense inflammation on the migration and proliferation of keratinocytes in vitro. We found that the migration and proliferation of rat keratinocytes were reduced with HG and lipopolysaccharide (LPS) stimulation via Erk signaling pathway in a reactive oxygen species (ROS)-dependent manner. Nevertheless, mesenchymal stem cell-conditioned medium (MSC-CM) counteracts the effects of HG and LPS. Treatment of rat keratinocyte with MSC-CM decreased HG- and/or LPS-induced ROS overproduction. Furthermore, MSC-CM reversed the downregulation of phosphorylation of MEK1/2 and Erk 1/2, which was induced by HG and/or LPS without affecting total levels. Our results may provide a possible mechanism for delayed wound healing in DM and provide a foundation to develop MSC-CM as an alternative therapeutic strategy to ameliorate the poor wound-healing conditions.

Skin stem cell hypotheses and long term clone survival--explored using agent-based modelling

Epithelial renewal in skin is achieved by the constant turnover and differentiation of keratinocytes. Three popular hypotheses have been proposed to explain basal keratinocyte regeneration and epidermal homeostasis: 1) asymmetric division (stem-transit amplifying cell); 2) populational asymmetry (progenitor cell with stochastic fate); and 3) populational asymmetry with stem cells. In this study, we investigated lineage dynamics using these hypotheses with a 3D agent-based model of the epidermis. The model simulated the growth and maintenance of the epidermis over three years. The offspring of each proliferative cell was traced. While all lineages were preserved in asymmetric division, the vast majority were lost when assuming populational asymmetry. The third hypothesis provided the most reliable mechanism for self-renewal by preserving genetic heterogeneity in quiescent stem cells, and also inherent mechanisms for skin ageing and the accumulation of genetic mutation.

Pulsed electric current induces the differentiation of human keratinocytes

Although normal human keratinocytes are known to migrate toward the cathode in a direct current (DC) electric field, other effects of the electric stimulation on keratinocyte activities are still unclear. We have investigated the keratinocyte differentiation under monodirectional pulsed electric stimulation which reduces the electrothermal and electrochemical hazards of a DC application. When cultured keratinocytes were exposed to the electric field of 3 V (ca. 100 mV/mm) or 5 V (ca. 166 mV/mm) at a frequency of 4,800 Hz for 5 min a day for 5 days, cell growth under the 5-V stimulation was significantly suppressed as compared with the control culture. Expression of mRNAs encoding keratinocyte differentiation markers such as keratin 10, involucrin, transglutaminase 1, and filaggrin was significantly increased in response to the 5-V stimulation, while the 3-V stimulation induced no significant change. After the 5-V stimulation, enhanced immunofluorescent stainings of involucrin and filaggrin were observed. These results indicate that monodirectional pulsed electric stimulation induces the keratinocyte differentiation with growth arrest.

Physical reparative treatment in reptiles

BACKGROUND

The tissue growth necessary to achieve a complete or partial restitution ad integrum as a result of injury to soft tissue and/or hard times in reptiles is variable and often needs long time in relation to the species, to the habitat and to their intrinsic physiological characteristics. The purpose of this work was to see if the tissue optimization (TO) treatment with radio electric asymmetric conveyer (REAC) provided good results in these animals and whether its use translates into reduced time of tissue repair. This paper describes preliminary results with in promoting the tissue repair in reptiles.

CASES PRESENTATION

A 5 year old male Testudo graeca (Leo) and Trachemys scripta scripta (Mir) and a 15 year old female Testudo hermanni (Juta) were evaluated because of soft tissue injuries. A female 25 year old Trachemys scripta elegans (Ice), a female 2.5 year old Trachemys scripta scripta (Penelope) as well as a 50 year old male Testudo graeca (Margherito) were evaluated because of wounds of the carapace. Following debridement and traditional therapies, Leo, Penelope and Margherito were exposed to the radio electric asymmetric conveyer (REAC) device, with a specific treatment protocol, named tissue optimization-basic (TO-B). Also Ice and Mir were subjected to REAC treatment after wounds debridement. Juta was treated only with REAC treatment. Complete wound healing was evident after 17 days for Leo, 7 days for Penelope, 27 days for Mir, 78 days for Ice and after 14 days for Margherito. Juta showed a considerable tissue activation in 2 days and complete wound healing in 5 days.

CONCLUSION

Our findings suggest that REAC TO-B treatment may provide advantages over other traditional methods after complete wound healing in Leo, and also suitable healing in the other patients. Then REAC device with its specific treatment TO-B protocol, which induces tissue repair without causing severe stress to the patient, could be a potential therapy for tissue damage healing in reptiles. Further studies still need to be conducted to support our observations.

Radio electric tissue optimization in the treatment of surgical wounds

Purpose

To report preliminary results with the tissue optimization (TO) treatment with a radio electric asymmetric conveyer (REAC) in promoting the repair of surgical wounds.

Patients and methods

Two subjects, a 54-year-old male with a tear bruise on the upper third of the leg and a 19-year-old female with a stab wound to the hand, were treated with 12 REAC-TO treatment sessions.

Results

In both patients, the wounds showed shorter healing time compared with the time usually required for similar wounds, and good repair quality.

Conclusion

REAC device with its specific treatment protocols may be an alternative therapy for wound healing.

A comparison of imaging methodologies for 3D tissue engineering

Imaging of cells in two dimensions is routinely performed within cell biology and tissue engineering laboratories. When biology moves into three dimensions imaging becomes more challenging, especially when multiple cell types are used. This review compares imaging techniques used regularly in our laboratory in the culture of cells in both two and three dimensions. The techniques reviewed include phase contrast microscopy, fluorescent microscopy, confocal laser scanning microscopy, electron microscopy, and optical coherence tomography. We compare these techniques to the current "gold standard" for imaging three-dimensional tissue engineered constructs, histology.

Production of tissue-engineered skin and oral mucosa for clinical and experimental use

Since the early 1990s, our understanding of how epithelial and stromal cells interact in 3D tissue-engineered constructs has led to tissue-engineered skin and oral mucosa models, which are beginning to deliver benefit in the clinic (usually in small-scale reconstructive surgery procedures) but have a great deal to offer for in vitro investigations. These 3D tissue-engineered models can be used for a wide variety of purposes such as dermato- and mucotoxicity, wound healing, examination of pigmentation and melanoma biology, and in particular, a recent development from this laboratory, as a model of bacterially infected skin. Models can also be used to investigate specific skin disease processes. In this chapter, we describe the basic methodology for producing 3D tissue-engineered skin and oral mucosa based on de-epidermised acellular human dermis, and we give examples of how these models can be used for a variety of applications.

Development of a calcium-chelating hydrogel for treatment of superficial burns and scalds

Aims: Superficial burns and scalds are usually managed conservatively with traditional dressings. Failure to heal within 3 weeks leads to their management by skin grafting. Our aim was to develop a biomaterial to actively promote keratinocyte migration in superficial burns by modulating local cation concentrations to accelerate keratinocyte migration and deter wounds from contracting, thus potentially reducing the number of such wounds requiring grafting. Materials & methods: We investigated polymeric hydrogels for their Ca2+ chelating properties and enhancement of keratinocyte migration in human tissue-engineered skin models. Results: Dimethylaminoethyl methacrylate:methacrylic acid hydrogel coupled with elevated [Mg2+] reduced media [Ca2+], potentiating keratinocyte migration in tissue-engineered skin models, it also significantly reduced wound model contraction. Conclusion: Dimethylaminoethyl methacrylate:methacrylic acid hydrogels could promote wound healing and reduce wound contraction, a significant complication in burn wound healing.

Hyperglycaemic conditions decrease cultured keratinocyte mobility: implications for impaired wound healing in patients with diabetes

BACKGROUND

Elevated blood glucose in patients with diabetes mellitus (DM) leads to complications including poor wound healing. Proper keratinocyte migration and proliferation are the crucial steps during re-epithelialization. We hypothesize that the impaired wound healing in patients with DM is due to the disruption of proper re-epithelialization.

OBJECTIVES

We aimed to explore the effects of high glucose on keratinocytes in terms of cell migration and proliferation.

METHODS

Keratinocytes were cultivated in normal and high glucose conditions. Their viability was evaluated by MTS assay. Transwell migration and in vitro scratch assays were used to evaluate their mobility. The mRNA expressions and activities of matrix metalloproteinase (MMP)-2 and MMP-9 were determined. The mRNA of their respective physiological inhibitors, tissue inhibitor of MMP (TIMP)-1 and TIMP-2, was also evaluated. Immunofluorescent staining and Western blotting were used to examine the expression of phosphorylated focal adhesion kinase (pp125(FAK)). The impacts of high glucose on keratinocyte proliferation were assessed by 5-bromo-2'-deoxyuridine incorporation assay.

RESULTS

High glucose treatment did not affect keratinocyte viability up to 3 days. In contrast, the mobility of keratinocytes, the activities and gene expressions of MMP-2 and MMP-9, the expression of pp125(FAK), and the cell proliferation after 5 days were significantly downregulated after hyperglycaemic treatments while the mRNA expression of TIMP-1 increased.

CONCLUSIONS

Under hyperglycaemic conditions, keratinocytes demonstrate reduced migration and decreased proliferation capacities. These impairments of keratinocyte functions are likely to result in inadequate re-epithelialization. These defective physiological events provide a reasonable explanation for the poor wound healing commonly observed in patients with DM.