Ultrasound-based Techniques as Alternative Treatments for Chronic Wounds: A Comprehensive Review of Clinical Applications

Accelerating cutaneous healing in a rodent model of type II diabetes utilizing non-invasive focused ultrasound targeted at the spleen

Healing of wounds is delayed in Type 2 Diabetes Mellitus (T2DM), and new treatment approaches are urgently needed. Our earlier work showed that splenic pulsed focused ultrasound (pFUS) alters inflammatory cytokines in models of acute endotoxemia and pneumonia via modulation of the cholinergic anti-inflammatory pathway (CAP) (ref below). Based on these earlier results, we hypothesized that daily splenic exposure to pFUS during wound healing would accelerate closure rate via altered systemic cytokine titers. In this study, we applied non-invasive ultrasound directed to the spleen of a rodent model [Zucker Diabetic Sprague Dawley (ZDSD) rats] of T2DM with full thickness cutaneous excisional wounds in an attempt to accelerate wound healing via normalization of T2DM-driven aberrant cytokine expression. Daily (1x/day, Monday-Friday) pFUS pulses were targeted externally to the spleen area for 3 min over the course of 15 days. Wound diameter was measured daily, and levels of cytokines were evaluated in spleen and wound bed lysates. Non-invasive splenic pFUS accelerated wound closure by up to 4.5 days vs. sham controls. The time to heal in all treated groups was comparable to that of healthy rats from previously published studies (ref below), suggesting that the pFUS treatment restored a normal wound healing phenotype to the ZDSD rats. IL-6 was lower in stimulated spleen (-2.24 ± 0.81 Log2FC, p = 0.02) while L-selectin was higher in the wound bed of stimulated rodents (2.53 ± 0.72 Log2FC, p = 0.003). In summary, splenic pFUS accelerates healing in a T2DM rat model, demonstrating the potential of the method to provide a novel, non-invasive approach for wound care in diabetes.

Technological Improvement Rates and Evolution of Energy-Based Therapeutics

This paper examines the field of energy-based medical therapies based on the analysis of patents. We define the field as the use of external stimuli to achieve biomedical modifications to treat disease and to increase health. Based upon distinct sets of patents, the field is subdivided into sub-domains for each energy category used to achieve the stimulation: electrical, magnetic, microwave, ultrasound, and optical. Previously developed techniques are used to retrieve the relevant patents for each of the stimulation modes and to determine main paths along the trajectory followed by each sub-domain. The patent sets are analyzed to determine key assignees, number of patents, and dates of emergence of the sub-domains. The sub-domains are found to be largely independent as to patent assignees. Electrical and magnetic stimulation patents emerged earliest in the 1970s and microwave most recently around 1990. The annual rate of improvement of all sub-domains (12-85%) is found to be significantly higher than one we find for an aggregate pharmaceutical domain (5%). Overall, the results suggest an increasingly important role for energy-based therapies in the future of medicine.

Time- and Dose-Dependent Effects of Pulsed Ultrasound on Dermal Repair in Diabetic Mice

Chronic wounds, including diabetic, leg and pressure ulcers, impose a significant health care burden worldwide. Some evidence indicates that ultrasound can enhance soft tissue repair. However, therapeutic responses vary among individuals, thereby limiting clinical translation. Here, effects of pulsed ultrasound on dermal wound healing were assessed using a murine model of chronic, diabetic wounds. An ultrasound exposure system was developed to provide daily ultrasound exposures to full-thickness, excisional wounds in genetically diabetic mice. Wounds were exposed to 1 MHz ultrasound (2 ms pulse, 100 Hz pulse repetition frequency, 0-0.4 MPa) for 2 or 3 wk. Granulation tissue thickness and wound re-epithelialization increased as a function of increasing ultrasound pressure amplitude. At 2 wk after injury, significant increases in granulation tissue thickness and epithelial ingrowth were observed in response to 1 MHz pulsed ultrasound at 0.4 MPa. Wounds exposed to 0.4 MPa ultrasound for 3 wk were characterized by collagen-dense, revascularized granulation tissue with a fully restored, mature epithelium. Of note, only half of wounds exposed to 0.4 MPa ultrasound showed significant granulation tissue deposition after 2 wk of treatment. Thus, the db⁺/db⁺ mouse model may help to identify biological variables that influence individual responses to pulsed ultrasound and accelerate clinical translation.

Polyphenols: A Promising Avenue in Therapeutic Solutions for Wound Care

In chronic wounds, the regeneration process is compromised, which brings complexity to the therapeutic approaches that need to be adopted, while representing an enormous loss in the patients’ quality of life with consequent economical costs. Chronic wounds are highly prone to infection, which can ultimately lead to septicemia and morbidity. Classic therapies are increasing antibiotic resistance, which is becoming a critical problem beyond complex wounds. Therefore, it is essential to study new antimicrobial polymeric systems and compounds that can be effective alternatives to reduce infection, even at lower concentrations. The biological potential of polyphenols allows them to be an efficient alternative to commercial antibiotics, responding to the need to find new options for chronic wound care. Nonetheless, phenolic compounds may have some drawbacks when targeting wound applications, such as low stability and consequent decreased biological performance at the wound site. To overcome these limitations, polymeric-based systems have been developed as carriers of polyphenols for wound healing, improving its stability, controlling the release kinetics, and therefore increasing the performance and effectiveness. This review aims to highlight possible smart and bio-based wound dressings, providing an overview of the biological potential of polyphenolic agents as natural antimicrobial agents and strategies to stabilize and deliver them in the treatment of complex wounds. Polymer-based particulate systems are highlighted here due to their impact as carriers to increase polyphenols bioavailability at the wound site in different types of formulations.

Therapeutic ultrasound associated with essential oils of copaiba and tea tree for healing skin lesions

Objective: to evaluate the effectiveness of low-frequency ultrasound associated with copaiba and tea tree oil gel in healing skin lesions. Method: quasi-experimental study with pre and post-tests in a single group, carried out in a public hospital in Ceará, Brazil, from March to September 2017, with 14 participants who received 10 treatment sessions. Results: there was an average reduction of more than 20 cm² from the 1st to the 5th application. The reduction in the initial size for the 10th session was over 50%. There was statistical significance (p = 0.0043) between the initial evaluation and the 10th therapy evaluation, with an average reduction of 37 cm². There was a reduction in the intensity of pain reported by the participants and 62.5% were free of pain after applying the therapy. Conclusion: the use of the gel with copaiba and tea tree oil points to an alternative coverage associated with biostimulators such as ultrasound. The composition of the gel oil helped in the application and in the reduction of the maceration of the edge of the wounds, as well as the control of the exudate of the lesion.

Ultrassom terapêutico associado a óleos essenciais de copaíba e melaleuca na cicatrização de lesões de pele

Objetivo: avaliar a eficácia do ultrassom de baixa frequência associado ao gel de óleos de copaíba e melaleuca na cicatrização de lesões de pele. Método: estudo quase-experimental com pré e pós-testes em grupo único, realizado em hospital público no Ceará, Brasil, no período de março a setembro de 2017, com 14 participantes que receberam 10 sessões de tratamento. Resultados: houve redução média de mais de 20 cm2 da 1ª para 5ª aplicação. A redução no tamanho inicial para a 10ª sessão foi superior a 50%. Houve significância estatística (p=0,0043) entre a avaliação inicial e a 10ª avaliação da terapia, com redução média de 37 cm2. Houve redução na intensidade da dor relatada pelos participantes e 62,5% estavam livres da dor após aplicação da terapia. Conclusão: o uso do gel com óleo de copaíba e melaleuca aponta para uma alternativa de cobertura associada a bioestimuladores como o ultrassom. A composição do óleo em gel auxiliou na aplicação e na redução de maceração do bordo das feridas bem como o controle do exsudato da lesão.