Effect of electrical stimulation on chronic wound healing: a meta-analysis

An Antibacterial, Conductive Nanocomposite Hydrogel Coupled with Electrical Stimulation for Accelerated Wound Healing

Background

Electrical stimulation (ES) can effectively promote skin wound healing; however, single-electrode-based ES strategies are difficult to cover the entire wound area, and the effectiveness of ES is often limited by the inconsistent mechanical properties of the electrode and wound tissue. The above factors may lead to ES treatment is not ideal.

Methods

A multifunctional conductive hydrogel dressing containing methacrylated gelatin (GelMA), Ti3C2 and collagen binding antimicrobial peptides (V-Os) was developed to improve wound management. Ti3C2 was selected as the electrode component due to its excellent electrical conductivity, the modified antimicrobial peptide V-Os could replace traditional antibiotics to suppress bacterial infections, and GelMA hydrogel was used due to its clinical applicability in wound healing.

Results

The results showed that this new hydrogel dressing (GelMA@Ti3C2/V-Os) not only has excellent electrical conductivity and biocompatibility but also has a durable and efficient bactericidal effect. The modified antimicrobial peptides V-Os used were able to bind more closely to GelMA hydrogel to exert long-lasting antibacterial effects. The results of cell experiment showed that the GelMA@Ti3C2/V-Os hydrogel dressing could enhance the effect of current stimulation and significantly improve the migration, proliferation and tissue repair related genes expression of fibroblasts. In vitro experiments results showed that under ES, GelMA@Ti3C2/V-Os hydrogel dressing could promote re-epithelialization, enhance angiogenesis, mediate immune response and prevent wound infection.

Conclusion

This multifunctional nanocomposite hydrogel could provide new strategies for promoting infectious wound healing.

Cold Atmospheric Pressure Plasma: A Growing Paradigm in Diabetic Wound Healing-Mechanism and Clinical Significance

Diabetes is one of the most significant causes of death all over the world. This illness, due to abnormal blood glucose levels, leads to impaired wound healing and, as a result, foot ulcers. These ulcers cannot heal quickly in diabetic patients and may finally result in amputation. In recent years, different research has been conducted to heal diabetic foot ulcers: one of them is using cold atmospheric pressure plasma. Nowadays, cold atmospheric pressure plasma is highly regarded in medicine because of its positive effects and lack of side effects. These conditions have caused plasma to be considered a promising technology in medicine and especially diabetic wound healing because studies show that it can heal chronic wounds that are resistant to standard treatments. The positive effects of plasma are due to different reactive species, UV radiation, and electromagnetic fields. This work reviews ongoing cold atmospheric pressure plasma improvements in diabetic wound healing. It shows that plasma can be a promising tool in treating chronic wounds, including ones resulting from diabetes.

3D Printed Polymer Piezoelectric Materials: Transforming Healthcare through Biomedical Applications

Three-dimensional (3D) printing is a promising manufacturing platform in biomedical engineering. It offers significant advantages in fabricating complex and customized biomedical products with accuracy, efficiency, cost-effectiveness, and reproducibility. The rapidly growing field of three-dimensional printing (3DP), which emphasizes customization as its key advantage, is actively searching for functional materials. Among these materials, piezoelectric materials are highly desired due to their linear electromechanical and thermoelectric properties. Polymer piezoelectrics and their composites are in high demand as biomaterials due to their controllable and reproducible piezoelectric properties. Three-dimensional printable piezoelectric materials have opened new possibilities for integration into biomedical fields such as sensors for healthcare monitoring, controlled drug delivery systems, tissue engineering, microfluidic, and artificial muscle actuators. Overall, this review paper provides insights into the fundamentals of polymer piezoelectric materials, the application of polymer piezoelectric materials in biomedical fields, and highlights the challenges and opportunities in realizing their full potential for functional applications. By addressing these challenges, integrating 3DP and piezoelectric materials can lead to the development of advanced sensors and devices with enhanced performance and customization capabilities for biomedical applications.

Designing a Biomaterial Approach to Control the Adaptive Response to a Skin Injury

The goal of this review is to explain how to design a biomaterial approach to control the adaptive response to injury, with an emphasis on skin wounds. The strategies will be selected based on whether they have a reasonable probability of meeting the desired clinical outcome vs. just comparing the pros and cons of different strategies. To do this, the review will look at the normal adaptive response in adults and why it does not meet the desired clinical outcome in most cases. In addition, the adaptive response will be looked at in cases where it does meet the clinical performance requirements including animals that regenerate and for fetal wound healing. This will lead to how biomaterials can be used to alter the overall adaptive response to allow it to meet the desired clinical outcome. The important message of the review is that you need to use the engineering design process, not the scientific method, to design a clinical treatment. Also, the clinical performance requirements are functional, not structural. The last section will give some specific examples of controlling the adaptive response for two skin injuries: burns and pressure ulcers. For burns, it will cover some preclinical studies used to justify a clinical study as well as discuss the results of a clinical study using this system. For pressure ulcers, it will cover some preclinical studies for two different approaches: electrical stimulation and degradable/regenerative scaffolds. For electrical stimulation, the results of a clinical study will be presented.

Smart piezoelectric biomaterials for tissue engineering and regenerative medicine: a review

Due to the presence of electric fields and piezoelectricity in various living tissues, piezoelectric materials have been incorporated into biomedical applications especially for tissue regeneration. The piezoelectric scaffolds can perfectly mimic the environment of natural tissues. The ability of scaffolds which have been made from piezoelectric materials in promoting cell proliferation and regeneration of damaged tissues has encouraged researchers in biomedical areas to work on various piezoelectric materials for fabricating tissue engineering scaffolds. In this review article, the way that cells of different tissues like cardio, bone, cartilage, bladder, nerve, skin, tendon, and ligament respond to electric fields and the mechanism of tissue regeneration with the help of piezoelectric effect will be discussed. Furthermore, all of the piezoelectric materials are not suitable for biomedical applications even if they have high piezoelectricity since other properties such as biocompatibility are vital. Seen in this light, the proper piezoelectric materials which are approved for biomedical applications are mentioned. Totally, the present review introduces the recent materials and technologies that have been used for tissue engineering besides the role of electric fields in living tissues.

Effectiveness of combined modulated ultrasound and electric current stimulation to treat diabetic foot ulcers

OBJECTIVE

The use of combined ultrasound and electrostimulation (CUSECS) as an adjunct therapy for diabetic foot ulcers (DFUs) is a relatively new concept. This study aimed to investigate if combined ultrasound and electrostimulation is an effective adjunctive treatment for hard-to-heal DFUs when compared with standard wound care.

METHODS

A randomised controlled pilot study design was used. Patients with hard-to-heal DFUs from two centres were sequentially randomised. For 8 weeks, the experimental group received CUSECS and standard wound care treatment twice a week. The control group received standard wound care treatment once a week. Wound changes were documented using photography, which also facilitated wound size measurement. Self-efficacy, economic cost, quality of life and reoccurrence rates were analysed as secondary objectives.

RESULTS

The experimental group (n=6) achieved a higher rate of mean wound healing (mean difference (MD): 0.49) when compared to the control group (n=5, MD: 0.01). Two participants completed full healing in the experimental group and one in the control group. There were no statistically significant findings because of the small sample size. There were no direct adverse reactions to this therapy. Quality of life scores improved in the treatment group. There was no significant change in self-efficacy scores. Costs were higher in the experimental group; however, the healing rate was quicker, which could be extrapolated to cost reductions over time.

CONCLUSION

Results suggest that CUSECS may be a useful adjunctive therapy for treatment of hard-to-heal DFUs. Further large-scale studies are needed to ascertain the effectiveness of CUSECS. The findings here are inconclusive but indicate that CUSECS may offer promise as a treatment.

Direct Current Electrical Fields Improve Experimental Wound Healing by Activation of Cytokine Secretion and Erk1/2 Pathway Stimulation

There is growing evidence that cell behaviors can be influenced by the direct current electric fields (EFs). Some behaviors may influence wound healing directly. This study aimed to investigate the effects of EF (200 mV/mm) on immortalized nontumorigenic human epidermal (HaCaT) cells. We established a setup that can transmit an EF and maintain a stable cell culture environment. An EF was applied to HaCaT cells, and scratch-assays were performed as a model of wound healing to observe cell migration. Proliferation was evaluated by mitochondrial activity, total protein, and DNA content. Secretion of healing-associated cytokines was evaluated via cytokine arrays, and Western blot was applied to investigate signaling pathway alterations. Compared with the control group, the migration of cells exposed to EFs significantly increased (p < 0.01). After 7 days, the changes in proliferation also increased significantly (p < 0.05). The cytokine arrays revealed that granulocyte-macrophage colony-stimulating factor (GM-CSF) was the most abundant factor secreted by HaCaT following EF exposure. The signals for phospho-Erk1/2 showed a significant (p < 0.0001) increase following EF exposure. The results demonstrate that exposure of HaCaT cells to EFs has positive effects on migration, proliferation, and cytokine secretion—three important steps in wound healing—and these effects may be partially mediated by activation of the Erk1/2 signaling pathway.

Electrical stimulation for pain reduction in hard-to-heal wound healing

OBJECTIVE

Despite treatment advances over the past 30 years, the societal impact of hard-to-heal wounds is increasingly burdensome. An unresolved issue is wound pain, which can make many treatments, such as compression in venous leg ulcers, intolerable. The aim of this review is to present the evidence and stimulate thinking on the use of electrical stimulation devices as a treatment technology with the potential to reduce pain, improve adherence and thus hard-to-heal wound outcomes.

METHOD

A literature search was conducted for clinical studies up to August 2020 reporting the effects of electrical stimulation devices on wound pain. Devices evoking neuromuscular contraction or direct spinal cord stimulation were excluded.

RESULTS

A total of seven publications (three non-comparative and four randomised trials) were identified with four studies reporting a rapid (within 14 days) reduction in hard-to-heal wound pain. Electrical stimulation is more widely known for accelerated healing and is one of the most evidence-based technologies in wound management, supported by numerous in vitro molecular studies, five meta-analyses, six systematic reviews and 30 randomised controlled trials (RCTs). Despite this wealth of supportive evidence, electrical stimulation has not yet been adopted into everyday practice. Some features of electrical stimulation devices may have hampered adoption in the past.

CONCLUSION

As new, pocket-sized, portable devices allowing convenient patient treatment and better patient adherence become more widely available and studied in larger RCTs, the evidence to date suggests that electrical stimulation should be considered part of the treatment options to address the challenges of managing and treating painful hard-to-heal wounds.

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.

Electrokinetic Perfusion Through Three-Dimensional Culture Reduces Cell Mortality

Cell proliferation and survival are dependent on mass transfer. In vivo, fluid flow promotes mass transfer through the vasculature and interstitial space, providing a continuous supply of nutrients and removal of cellular waste products. In the absence of sufficient flow, mass transfer is limited by diffusion and poses significant challenges to cell survival during tissue engineering, tissue transplantation, and treatment of degenerative diseases. Artificial perfusion may overcome these challenges. In this work, we compare the efficacy of pressure driven perfusion (PDP) with electrokinetic perfusion (EKP) toward reducing cell mortality in three-dimensional cultures of Matrigel extracellular matrix. We characterize electro-osmotic flow through Matrigel to identify conditions that generate similar interstitial flow rates to those induced by pressure. We also compare changes in cell mortality induced by continuous or pulsed EKP. We report that continuous EKP significantly reduced mortality throughout the perfusion channels more consistently than PDP at similar flow rates, and pulsed EKP decreased mortality just as effectively as continuous EKP. We conclude that EKP has significant advantages over PDP for promoting tissue survival before neovascularization and angiogenesis. Impact statement Interstitial flow helps promote mass transfer and cell survival in tissues and organs. This study generated interstitial flow using pressure driven perfusion (PDP) or electrokinetic perfusion (EKP) to promote cell viability in three-dimensional cultures. EKP through charged extracellular matrices possesses significant advantages over PDP and may promote cell survival during tissue engineering, transplantations, and treatment of degenerative diseases.

Cold Atmospheric Pressure Plasma in Wound Healing and Cancer Treatment

Plasma medicine is gaining increasing attention and is moving from basic research into clinical practice. While areas of application are diverse, much research has been conducted assessing the use of cold atmospheric pressure plasma (CAP) in wound healing and cancer treatment—two applications with entirely different goals. In wound healing, a tissue-stimulating effect is intended, whereas cancer therapy aims at killing malignant cells. In this review, we provide an overview of the latest clinical and some preclinical research on the efficacy of CAP in wound healing and cancer therapy. Furthermore, we discuss the current understanding of molecular signaling mechanisms triggered by CAP that grant CAP its antiseptic and tissue regenerating or anti-proliferative and cell death-inducing properties. For the efficacy of CAP in wound healing, already substantial evidence from clinical studies is available, while evidence for therapeutic effects of CAP in oncology is mainly from in vitro and in vivo animal studies. Efforts to elucidate the mode of action of CAP suggest that different components, such as ultraviolet (UV) radiation, electromagnetic fields, and reactive species, may act synergistically, with reactive species being regarded as the major effector by modulating complex and concentration-dependent redox signaling pathways.

A Narrative Review of the Use of Neuromuscular Electrical Stimulation in Individuals With Diabetic Foot Ulceration

This review aims to summarize the evidence reported on the use of neuromuscular electrical stimulation (NMES) in individuals with diabetic foot ulceration (DFU). A systematic search of EMBASE and MEDLINE databases was performed in February 2019, using search terms relating to the domains DFU and NMES. All primary evidence assessing outcomes of NMES in DFU were included. Of 344 references obtained from database searching, 7 met the inclusion criteria and included a total of 140 participants, 77 of whom had DFU. All included studies used prospective designs. Two studies demonstrated improvements in chronic ulcer healing with NMES use; however, in each study, only 3 of the included participants had DFU and subgroup analyses based on ulcer etiology was omitted. The remaining 5 studies were produced by the same research group and positive effects of NMES (in combination with heat therapy) on DFU healing were consistently demonstrated. They reported significantly better healing rates with NMES in DFU than in nondiabetic wounds of a similar grade (healing rate: 70.0 ± 32.3% in DFU vs 38.4 ± 22.3% in nondiabetic ulcers [ P < .01]). These studies did not provide data assessing the isolated effects of NMES without concomitant heat exposure. Data on device tolerability and compliance were lacking. The existing data support a potential role for NMES in individuals with DFU; however, the identified studies inadequately controlled for confounding and were underpowered. Given the significant morbidity and mortality associated with DFU, higher quality evidence is needed to assess the adjunctive role for NMES in this group.

Electrical stimulation for treating pressure ulcers

BACKGROUND

Pressure ulcers (also known as pressure sores, decubitus ulcers or bedsores) are localised injuries to the skin or underlying tissue, or both. Pressure ulcers are a disabling consequence of immobility. Electrical stimulation (ES) is widely used for the treatment of pressure ulcers. However, it is not clear whether ES is effective.

OBJECTIVES

To determine the effects (benefits and harms) of electrical stimulation (ES) for treating pressure ulcers.

SEARCH METHODS

In July 2019 we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies as well as reviews, meta-analyses and health technology reports to identify additional studies. We did not impose any restrictions with respect to language, date of publication or study setting.

SELECTION CRITERIA

We included published and unpublished randomised controlled trials (RCTs) comparing ES (plus standard care) with sham/no ES (plus standard care) for treating pressure ulcers.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, extracted data, and assessed risk of bias. We assessed the certainty of evidence using GRADE.

MAIN RESULTS

We included 20 studies with 913 participants. The mean age of participants ranged from 26 to 83 years; 50% were male. ES was administered for a median (interquartile range (IQR)) duration of five (4 to 8) hours per week. The chronicity of the pressure ulcers was variable, ranging from a mean of four days to more than 12 months. Most of the pressure ulcers were on the sacral and coccygeal region (30%), and most were stage III (45%). Half the studies were at risk of performance and detection bias, and 25% were at risk of attrition and selective reporting bias. Overall, the GRADE assessment of the certainty of evidence for outcomes was moderate to very low. Nineteen studies were conducted in four different settings, including rehabilitation and geriatric hospitals, medical centres, a residential care centre, and a community-based centre. ES probably increases the proportion of pressure ulcers healed compared with no ES (risk ratio (RR) 1.99, 95% confidence interval (CI) 1.39 to 2.85; I² = 0%; 11 studies, 501 participants (512 pressure ulcers)). We downgraded the evidence to moderate certainty due to risk of bias. It is uncertain whether ES decreases pressure ulcer severity on a composite measure compared with no ES (mean difference (MD) -2.43, 95% CI -6.14 to 1.28; 1 study, 15 participants (15 pressure ulcers) and whether ES decreases the surface area of pressure ulcers when compared with no ES (12 studies; 494 participants (505 pressure ulcers)). Data for the surface area of pressure ulcers were not pooled because there was considerable statistical heterogeneity between studies (I² = 96%) but the point estimates for the MD of each study ranged from -0.90 cm² to 10.37 cm². We downgraded the evidence to very low certainty due to risk of bias, inconsistency and imprecision. It is uncertain whether ES decreases the time to complete healing of pressure ulcers compared with no ES (hazard ratio (HR) 1.06, 95% CI 0.47 to 2.41; I² = 0%; 2 studies, 55 participants (55 pressure ulcers)). We downgraded the evidence to very low certainty due to risk of bias, indirectness and imprecision. ES may be associated with an excess of, or difference in, adverse events (13 studies; 586 participants (602 pressure ulcers)). Data for adverse events were not pooled but the types of reported adverse events included skin redness, itchy skin, dizziness and delusions, deterioration of the pressure ulcer, limb amputation, and occasionally death. We downgraded the evidence to low certainty due to risk of selection and attrition bias and imprecision. ES probably increases the rate of pressure ulcer healing compared with no ES (MD 4.59% per week, 95% CI 3.49 to 5.69; I² = 25%; 12 studies, 561 participants (613 pressure ulcers)). We downgraded the evidence to moderate certainty due to risk of bias. We did not find any studies that looked at quality of life, depression, or consumers' perception of treatment effectiveness.

AUTHORS' CONCLUSIONS

ES probably increases the proportion of pressure ulcers healed and the rate of pressure ulcer healing (moderate certainty evidence), but its effect on time to complete healing is uncertain compared with no ES (very low certainty evidence). It is also uncertain whether ES decreases the surface area of pressure ulcers. The evidence to date is insufficient to support the widespread use of ES for pressure ulcers outside of research. Future research needs to focus on large-scale trials to determine the effect of ES on all key outcomes.

Percutaneous tibial nerve stimulation (PTNS): an alternative treatment option for chronic therapy resistant anal fissure

BACKGROUND

The aim of the present study was to evaluate percutaneous tibial nerve stimulation (PTNS) for treatment resistant chronic anal fissure.

METHODS

Consecutive patients with chronic anal fissure were treated with neuromodulation via the posterior tibial nerve between October 2013 and January 2014. Patients had PTNS for 30 min on 10 consecutive days. All patients had failed conventional medical treatment. The visual analogue scale (VAS) score, St. Marks score, Wexner's constipation score, Brief Pain Inventory (BPI-SF), bleeding and mucosal healing were evaluated before treatment, at termination, after 3 months, and then yearly for 3 years.

RESULTS

Ten patients (4 males and 6 females; mean age 49.8 years) were identified but only 9 were evaluated as one patient's fissure healed before PTNS was started. At 3-year follow-up, fissures had remained completely healed in 5 out of 9 patients. All patients stopped bleeding and were almost completely pain-free at 3 years (VAS p = 0.010) and pain relief improved from 50% at completion to 90% at 3 years. The patients' Wexner constipation scores improved significantly (p = 0.007).

CONCLUSIONS

In this small series, PTNS enhanced healing of chronic anal fissure and reduced pain and bleeding with an associated improvement in bowel function.

Disposable Patterned Electroceutical Dressing (PED-10) Is Safe for Treatment of Open Clinical Chronic Wounds

Objective: To evaluate if patterned electroceutical dressing (PED) is safe for human chronic wounds treatment as reported by wound care providers. Approach: This work reports a pilot feasibility study with the primary objective to determine physically observable effects of PED application on host tissue response from a safety evaluation point of view. For this pilot study, patients receiving a lower extremity amputation with at least one open wound on the part to be amputated were enrolled. Patients were identified through the Ohio State University Wexner Medical Center (OSUWMC) based on inclusion and exclusion criteria through prescreening through the Comprehensive Wound Center's (CWC) Limb Preservation Program and wound physicians and/or providers at OSUWMC. Wounds were treated with the PED before amputation surgery. Results: The intent of the study was to identify if PED was safe for clinical application based on visual observations of adverse or lack of adverse events on skin and wound tissue. The pilot testing performed on a small cohort (N = 8) of patients showed that with engineered voltage regulation of current flow to the open wound, the PED can be used with little to no visually observable adverse effects on chronic human skin wounds. Innovation: The PED was developed as a second-generation tunable electroceutical wound care dressing, which could potentially be used to treat wounds with deeper infections compared with current state of the art that treats wounds with treatment zone limited to the surface near topical application. Conclusion: Technology advances in design and fabrication of electroceutical dressings were leveraged to develop a tunable laboratory prototype that could be used as a disposable low-cost electroceutical wound care dressing on chronic wounds. Design revisions of PED-1 (1 kΩ ballast resistor) circumvented previously observed adverse effects on the skin in the vicinity of an open wound. PED-10 (including a 10 kΩ ballast resistor) was well tolerated in the small cohort of patients (N = 8) on whom it was tested, and the observations reported here warrant a larger study to determine the clinical impact on human wound healing and infection control.

Conductive polymers to modulate the post-stroke neural environment

Despite the prevalence of stroke, therapies to augment recovery remain limited. Here we focus on the use of conductive polymers for cell delivery, drug release, and electrical stimulation to optimize the post-stroke environment for neural recovery. Conductive polymers and their interactions with in vitro and in vivo neural systems are explored. The ability to continuously modify the neural environment utilizing conductive polymers provides applications in directing stem cell differentiation and increasing neural repair. This exciting class of polymers offers new approaches to optimizing the post-stroke brain to improve functional recovery.

The impact of a muscle pump activator on incisional wound healing compared to standard stockings and compression devices in kidney and kidney-pancreas transplant recipients: A randomized controlled trial

INTRODUCTION

We aimed to evaluate the impact of thrombo-embolic-deterrent + intermittent pneumatic compression (TED + IPC) vs. muscle pump activator (MPA) on incisional wound healing in kidney and simultaneous pancreas- kidney (SPK) transplant recipients.

METHODS

We conducted a single-centre, randomized controlled trial in which 104 patients (kidney n=94; SPK n=10) were randomly assigned to wear TED + IPC (n= 52) or MPA (n=52) for the first six days following surgery. Patient demographics, postoperative outcomes, and incisional wound images were taken using a HIPAA-compliant application on postoperative days (POD) 3, 5, and 30, and assessed using the validated Southampton Wound Care Score.

RESULTS

There were no demographic differences between the groups. The MPA group had a significant improvement in wound healing on POD 3 (p=0.04) that persisted until POD 5 (p=0.0003). At POD 30, both groups were similar in wound healing outcomes (p=0.51). Bayesian inferential analysis revealed that the use of TED + IPC following transplantation had inferior outcomes compared to the use of MPA with sequential moderate evidence. The rate of complex wound infections was significantly greater in the TED + IPC group compared to the MPA group (29% vs. 12%, respectively; p=0.03). Patients were more satisfied with the use of a MPA device than TED + IPC. No major complications were encountered in either group.

CONCLUSIONS

The use of a MPA device in the immediate postoperative period leads to a significant improvement in immediate and early wound healing, and decreased number of complex wound infections following kidney and SPK transplantation compared to standard TED + IPC therapy. Patients were more satisfied with the use of a MPA device than TED + IPC.

The Feasibility of Using Pulsatile Electromagnetic Fields (PEMFs) to Enhance the Regenerative Ability of Dermal Biomaterial Scaffolds

Degradable regenerative scaffolds usually require adjunctive treatment to meet the clinical healing performance requirements. This study was designed to look at pulsatile electromagnetic fields (PEMF) as an adjunctive therapy for these scaffolds in skin wounds; however, no scaffold was used in this study in order to isolate the effects of PEMF alone. In this study, New Zealand rabbits received four full-thickness defects with a size of 3 cm × 3 cm on the dorsolateral aspect. The rabbits in the treatment group were placed in a chamber and subjected to a PEMF at six different predetermined frequency and intensity combinations for 2 h a day for a 2-week period. At the end of the 2-week period, the animals were sacrificed and tissue samples were taken. Half of each tissue sample was used for histomorphometric analysis and the other half was for tensile testing. The study showed an increased healing response by all the PEMF treatments compared to that in the control, although different combinations led to increases in different aspects of the healing response. This suggests that although some treatments are better for the critical clinical parameter—healing rate, it might be beneficial to use treatments in the early stages to increase angiogenesis before the treatment is switched to the one best for the healing rate to get an even better haling rate.

High-Voltage Electrical Stimulation Versus Ultrasound in the Treatment of Pressure Ulcers

OBJECTIVE

The aim of this study was to assess and compare the efficacy of high-voltage electrical stimulation (HVES) with ultrasound (US) in treating Stage II through Stage IV pressure ulcers (PrUs)* of hospitalized patients.

DESIGN

This study was designed as a prospective, controlled trial in which patients were randomly assigned to 2 groups.

PARTICIPANTS AND SETTINGS

A total of 27 patients (22 male, 5 female) hospitalized for neurologic rehabilitation in the Clinic of Physical Medicine and Rehabilitation with Stage II through Stage IV PrUs were included in this study. The patients were randomly assigned to either HVES or US treatment group, and all patients underwent standard wound care. Over 4 to 12 weeks, HVES was applied for 60 minutes 3 times per week, and US was applied 3 times per week.

MAIN OUTCOME MEASURES

Properties of the PrUs were noted during pre- and posttreatment.

RESULTS

The PrUs of patients in the HVES and US groups healed at a mean rate of 43% and 63%, respectively. There was no statistically significant intergroup difference in healing found after treatment. Regression analysis was performed for the factors that could influence the wound surface areas, and significant effects were detected among the level of ambulation, pretreatment stage, and smoking.

CONCLUSIONS

Both HVES and US are promising methods for wound healing, and both electrotherapy modalities have been demonstrated to support the healing of PrUs.

Effectiveness of Transcutaneous Electrical Nerve Stimulation Energy in Older Adults: A Pilot Clinical Trial

OBJECTIVE

To evaluate the effectiveness of a transcutaneous electric nerve stimulation (TENS) device typically used for pain suppression (analgesia) during pressure injury (PI) healing, peripheral vascularization, and secondary pain in older adults with chronic PIs and cognitive impairment.

DESIGN AND SETTING

This pilot clinical trial followed patients from 6 nursing homes.

PATIENTS AND INTERVENTION

Twenty-two patients with PIs in the distal third of their lower limbs (7 men, 15 women) were included in this study. The control group completed standard wound care (SWC), whereas the experimental group received SWC and TENS. A total of 20 sessions were conducted for each group over 2 months, 3 times a week.

MAIN OUTCOME MEASURE

PI area, PI healing rate, blood flow, skin temperature, oxygen saturation, and level of pain at baseline and posttreatment.

MAIN RESULTS

Significant improvements were achieved in PI area (mean difference, 0.92; 95% confidence interval [CI], 0.15-1.67; P =.024), healing rate (3; 95% CI, 1-4.99; P =.009), skin temperature (1.82; 95% CI, 0.35-3.28; P =.021), and pain (1.44; 95% CI, 0.49-2.39; P =.008) in the experimental group, whereas none of the variables revealed a significant change in the control group.

CONCLUSIONS

The effect of local and spinal TENS combined with the SWC for PI produced a significant improvement in size, healing, skin temperature, and pain levels.

Electric Pulses Can Influence Galvanotaxis of Dictyostelium discoideum

Galvanotaxis, or electrotaxis, plays an essential role in wound healing, embryogenesis, and nerve regeneration. Up until now great efforts have been made to identify the underlying mechanism related to galvanotaxis in various cells under direct current electric field (DCEF) in laboratory studies. However, abundant clinical research shows that non-DCEFs including monopolar or bipolar electric field may also contribute to wound healing and regeneration, although the mechanism remains elusive. Here, we designed a novel electric stimulator and applied DCEF, pulsed DCEF (pDCEF), and bipolar pulse electric field (bpEF) to the cells of Dictyostelium discoideum. The cells had better directional performance under asymmetric 90% duty cycle pDCEF and 80% duty cycle bpEF compared to DCEF, with 10 Hz frequency electric fields eliciting a better cell response than 5 Hz. Interestingly, electrically neutral 50% duty cycle bpEF triggered the highest migration speed, albeit in random directions. The results suggest that electric pulses are vital to galvanotaxis and non-DCEF is promising in both basic and clinical researches.

Reversing the direction of galvanotaxis with controlled increases in boundary layer viscosity

Weak external electric fields (EFs) polarize cellular structure and direct most migrating cells (galvanotaxis) toward the cathode, making it a useful tool during tissue engineering and for healing epidermal wounds. However, the biophysical mechanisms for sensing weak EFs remain elusive. We have reinvestigated the mechanism of cathode-directed water flow (electro-osmosis) in the boundary layer of cells, by reducing it with neutral, viscous polymers. We report that increasing viscosity with low molecular weight polymers decreases cathodal migration and promotes anodal migration in a concentration dependent manner. In contrast, increased viscosity with high molecular weight polymers does not affect directionality. We explain the contradictory results in terms of porosity and hydraulic permeability between the polymers rather than in terms of bulk viscosity. These results provide the first evidence for controlled reversal of galvanotaxis using viscous agents and position the field closer to identifying the putative electric field receptor, a fundamental, outside-in signaling receptor that controls cellular polarity for different cell types.

Developing a Model of Care for Healing Pressure Ulcers With Electrical Stimulation Therapy for Persons With Spinal Cord Injury

Background: Electrical stimulation therapy (EST) has been shown to be an effective therapy for managing pressure ulcers in individuals with spinal cord injury (SCI). However, there is a lack of uptake of this therapy, and it is often not considered as a first-line treatment, particularly in the community. Objective: To develop a pressure ulcer model of care that is adapted to the local context by understanding the perceived barriers and facilitators to implementing EST, and to describe key initial phases of the implementation process. Method: Guided by the Knowledge-to-Action (KTA) and National Implementation Research Network (NIRN) frameworks, a community-based participatory research (CBPR) approach was used to complete key initial implementation processes including (a) defining the practice, (b) identifying the barriers and facilitators to EST implementation and organizing them into implementation drivers, and (c) developing a model of care that is adapted to the local environment. Results: A model of care for healing pressure ulcers with EST was developed for the local environment while taking into account key implementation barriers including lack of interdisciplinary collaboration and communication amongst providers between and across settings, inadequate training and education, and lack of resources, such as funding, time, and staff. Conclusions: Using established implementation science frameworks with structured planning and engaging local stakeholders are important exploratory steps to achieve a successful sustainable best practice implementation project.

Using a Modified ADAPTE Process to Enable Effective Implementation of Electrical Stimulation Therapy for Treating Pressure Ulcers in Persons With Spinal Cord Injury

Objectives:

To apply a modified ADAPTE process to adapt best practices to a local context for successful implementation of electrical stimulation therapy (EST) for treating pressure injuries in persons with spinal cord injury (SCI).

Participants:

An expert team of health care professionals and a consumer participated in a 2-day workshop to assist in the development of the locally adapted EST document in Southwest Ontario, Canada.

Results:

A process map illustrating the flow of activities to initiate EST for treating pressure injuries in persons with SCI based on the challenges and opportunities existing within this region was created. The team also developed a summary of roles and responsibilities delineating tasks specific to providing EST and identified a set of challenges likely to be encountered.

Conclusions:

The modified ADAPTE process provided a clear and flexible structure to adaptation when used for implementation planning. This article shares some challenges associated with using this process for local adaptation and shares strategies of improvement for future studies aimed at adapting a practice to their local environment.

Influence of in-house rehabilitation on the postoperative outcome of dogs with intervertebral disk herniation

OBJECTIVE

To determine the influence of in-house rehabilitation on the postoperative outcome of dogs with intervertebral disk herniation (IVDH).

DESIGN

Retrospective cohort study.

ANIMALS

Dogs (n = 248) under 20 kg of weight, with single site, thoracolumbar, Hansen Type I IVDH.

PROCEDURES

Medical records of non-ambulatory dogs with IVDH treated via hemilaminectomy were reviewed. Dogs were classified in 2 groups depending on whether their postoperative management included an in-house rehabilitation program. Preoperative and sequential postoperative modified Frankel scores (MFSs) were recorded. Time to ambulation, time to normal conscious proprioception, final MFS, and complications were compared between the groups.

RESULTS

More dogs returned to full neurologic function (final MFS of Grade 5) when in-house rehabilitation was included in the postoperative management (33% compared to 9%). Normal conscious proprioception and ambulation returned earlier in the control group (42 days and 14 days, respectively) compared to the group with rehabilitation (49 days and 28 days, respectively). The complication rate was higher in the control group (29%) compared with the group with rehabilitation (16%).

CONCLUSIONS AND CLINICAL RELEVANCE

In-house rehabilitation should be included in the postoperative management in dogs after surgical treatment of IVDH to improve neurologic function and reduce postoperative complications.

ANALYTICAL STUDY OF ELECTRO-OSMOSIS MODULATED CAPILLARY PERISTALTIC HEMODYNAMICS

A mathematical model is developed to analyze electro-kinetic effects on unsteady peristaltic transport of blood in cylindrical vessels of finite length. The Newtonian viscous model is adopted. The analysis is restricted under Debye–Hückel linearization (i.e., wall zeta potential [Formula: see text] 25[Formula: see text]mV) is sufficiently small). The transformed, nondimensional conservation equations are derived via lubrication theory and long wavelength and the resulting linearized boundary value problem is solved exactly. The case of a thin electric double layer (i.e., where only slip electro-osmotic velocity considered) is retrieved as a particular case of the present model. The response in pumping characteristics (axial velocity, pressure gradient or difference, volumetric flow rate, local wall shear stress) to the influence of electro-osmotic effect (inverse Debye length) and Helmholtz–Smoluchowski velocity is elaborated in detail. Visualization of trapping phenomenon is also included and the bolus dynamics evolution with electro-kinetic effects examined. A comparative study of train wave propagation and single wave propagation is presented under the effects of thickness of EDL and external electric field. The study is relevant to electrophoresis in haemotology, electrohydrodynamic therapy and biomimetic electro-osmotic pumps.

Electrical stimulation therapy for the treatment of pressure ulcers in individuals with spinal cord injury: a systematic review and meta-analysis

To conduct a systematic review and meta-analysis on the effects of electrical stimulation therapy (EST) on healing pressure ulcers in individuals with spinal cord injury (SCI). CINAHL, The Cochrane Library, PubMed, SCOPUS, EMBASE, Nursing & Allied Health and Dissertation & Theses databases were searched for relevant English language articles from the date of inception to 31 January 2014. Separate searches were conducted in Google Scholar and academic journals specialised in wound care. Two reviewers independently assessed study eligibility. Studies were included if EST was used to treat pressure ulcers in individuals with SCI. A total of 599 articles were screened, and 15 studies met the inclusion criteria. A meta-analysis with five studies demonstrated that EST significantly decreased the ulcer size by 1·32%/day [95% confidence interval (CI): 0·58-2·05, P < 0·001] compared to standard wound care (SWC) or sham EST. Another meta-analysis conducted with four studies showed that EST increased the risk of wound healing by 1·55 times compared with standard wound care or sham EST (95% CI: 1·12 to 2·15, P < 0·0001). Because of the wide array of outcome measures across studies, a single meta-analysis could not be conducted. EST appears to be an effective adjunctive therapy to accelerate and increase pressure ulcer closure in individuals with SCI.

Kcnh2 and Kcnj8 interactively regulate skin wound healing and regeneration

Previous studies indicate that ion channels are mediators of bioelectricity promoting wound closure/regeneration in nonmammalian, lower vertebrate systems. The role of ion channels however in regeneration of wounds in mammalian systems that do not regenerate as adults is not yet defined. Using a mammalian model system that allows us to determine differentially expressed genes when skin regenerates and when skin does not regenerate after wound induction, we identified two potassium channels, kcnh2 and kcnj8, to be (1) differentially expressed between the two states and (2) highly expressed after wound induction at the nonregenerative state. We also found that kcnh2 small molecule inhibitor enhanced wound healing while kcnj8 small molecule inhibitor did not. In contrast, kcnj8 activator accelerated wound healing and even augmented the effect of kcnh2 inhibition. These results provide evidence for the first time that potassium channels may mediate skin wound healing and regeneration interactively.

Sine-wave electrical stimulation initiates a voltage-gated potassium channel-dependent soft tissue response characterized by induction of hemocyte recruitment and collagen deposition

Soft tissue repair is a complex process that requires specific communication between multiple cell types to orchestrate effective restoration of physiological functions. Macrophages play a critical role in this wound healing process beginning at the onset of tissue injury. Understanding the signaling mechanisms involved in macrophage recruitment to the wound site is an essential step for developing more effective clinical therapies. Macrophages are known to respond to electrical fields, but the underlying cellular mechanisms mediating this response is unknown. This study demonstrated that low‐amplitude sine‐wave electrical stimulation (ES) initiates a soft tissue response in the absence of injury in Procambarus clarkii. This cellular response was characterized by recruitment of macrophage‐like hemocytes to the stimulation site indicated by increased hemocyte density at the site. ES also increased tissue collagen deposition compared to sham treatment (P < 0.05). Voltage‐gated potassium (K_V) channel inhibition with either 4‐aminopyridine or astemizole decreased both hemocyte recruitment and collagen deposition compared to saline infusion (P < 0.05), whereas inhibition of calcium‐permeable channels with ruthenium red did not affect either response to ES. Thus, macrophage‐like hemocytes in P. clarkii elicit a wound‐like response to exogenous ES and this is accompanied by collagen deposition. This response is mediated by K_V channels but independent of Ca²⁺ channels. We propose a significant role for K_V channels that extends beyond facilitating Ca²⁺ transport via regulation of cellular membrane potentials during ES of soft tissue.

Biochemical and Biophysical Cues in Matrix Design for Chronic and Diabetic Wound Treatment

Progress in biomaterial science and engineering and increasing knowledge in cell biology have enabled us to develop functional biomaterials providing appropriate biochemical and biophysical cues for tissue regeneration applications. Tissue regeneration is particularly important to treat chronic wounds of people with diabetes. Understanding and controlling the cellular microenvironment of the wound tissue are important to improve the wound healing process. In this study, we review different biochemical (e.g., growth factors, peptides, DNA, and RNA) and biophysical (e.g., topographical guidance, pressure, electrical stimulation, and pulsed electromagnetic field) cues providing a functional and instructive acellular matrix to heal diabetic chronic wounds. The biochemical and biophysical signals generally regulate cell-matrix interactions and cell behavior and function inducing the tissue regeneration for chronic wounds. Some technologies and devices have already been developed and used in the clinic employing biochemical and biophysical cues for wound healing applications. These technologies can be integrated with smart biomaterials to deliver therapeutic agents to the wound tissue in a precise and controllable manner. This review provides useful guidance in understanding molecular mechanisms and signals in the healing of diabetic chronic wounds and in designing instructive biomaterials to treat them.

The strategy and method in modulating finger regeneration

The tip of the human finger can regenerate if the amputation is distal to the nail bed, usually in young children. Studies in regeneration of rodent digits have shown that regeneration occurs if the amputation is distal to the mid-third phalanx for certain ages. The digit contains many different components, such as muscle, tendon, bone, skin, nerves and blood vessels, which must all be regrown in the proper location in order to restore functionality. The mechanism behind the complex healing/regeneration processes is still under investigation; however, improvements in injured finger regeneration have been gradually developing in animal models over the past few years. This review discusses a few strategies and methods to possibly enhance digit regeneration beyond current natural limits, focusing on aspects including scarless wound healing, cell-based treatments, tissue engineering and electrical stimulation.

ElectroTaxis-on-a-Chip (ETC): an integrated quantitative high-throughput screening platform for electrical field-directed cell migration

Both endogenous and externally applied electrical stimulation can affect a wide range of cellular functions, including growth, migration, differentiation and division. Among those effects, the electrical field (EF)-directed cell migration, also known as electrotaxis, has received broad attention because it holds great potential in facilitating clinical wound healing. Electrotaxis experiment is conventionally conducted in centimetre-sized flow chambers built in Petri dishes. Despite the recent efforts to adapt microfluidics for electrotaxis studies, the current electrotaxis experimental setup is still cumbersome due to the needs of an external power supply and EF controlling/monitoring systems. There is also a lack of parallel experimental systems for high-throughput electrotaxis studies. In this paper, we present a first independently operable microfluidic platform for high-throughput electrotaxis studies, integrating all functional components for cell migration under EF stimulation (except microscopy) on a compact footprint (the same as a credit card), referred to as ElectroTaxis-on-a-Chip (ETC). Inspired by the R-2R resistor ladder topology in digital signal processing, we develop a systematic approach to design an infinitely expandable microfluidic generator of EF gradients for high-throughput and quantitative studies of EF-directed cell migration. Furthermore, a vacuum-assisted assembly method is utilized to allow direct and reversible attachment of our device to existing cell culture media on biological surfaces, which separates the cell culture and device preparation/fabrication steps. We have demonstrated that our ETC platform is capable of screening human cornea epithelial cell migration under the stimulation of an EF gradient spanning over three orders of magnitude. The screening results lead to the identification of the EF-sensitive range of that cell type, which can provide valuable guidance to the clinical application of EF-facilitated wound healing.

The role of CXCL12 and CCL7 chemokines in immune regulation, embryonic development, and tissue regeneration

Chemotactic factors direct the migration of immune cells, multipotent stem cells, and progenitor cells under physiologic and pathologic conditions. Chemokine ligand 12 and chemokine ligand 7 have been identified and investigated in multiple studies for their role in cellular trafficking in the setting of tissue regeneration. Recent early phase clinical trials have suggested that these molecules may lead to clinical benefit in patients with chronic disease. Importantly, these two proteins may play additional significant roles in directing the migration of multipotent cells, such as mesenchymal stem cells and hematopoietic progenitor cells. This article reviews the functions of these two chemokines, focusing on recruitment to sites of injury, immune function modulation, and contributions to embryonic development. Additional research would provide valuable insight into the potential clinical application of these two proteins in stem cell therapy.