Noncontact, low-frequency ultrasound therapy enhances neovascularization and wound healing in diabetic mice

Ultrasound Induces Similar Temporal Endothelial Expression Patterns of eNOS and KLF2 as Normal Flow

OBJECTIVE

To determine the sensitivity of vascular endothelial cells to long durations of low-intensity pulsed ultrasound (LIPUS) compared to normal flow and identify the duration that maximizes expression of two mechanosensitive genes related to healthy endothelial function, endothelial nitric oxide synthase (eNOS) and Krüppel-like factor 2 (KLF2).

METHODS

Custom ultrasound exposure tanks were developed and the acoustic field was characterized. Human umbilical vein endothelial cells were seeded into culture plates and exposed to LIPUS at a frequency of 1 MHz and acoustic pressure of 217 kPa for 20 min, 1 h, 6 h, 9 h, or 24 h. As a comparator, other cells were exposed to normal flow. RT-qPCR was used to assess mRNA expression of eNOS and KLF2.

RESULTS

Maximum eNOS and KLF2 expression occurred at 6 h and was localized to the beam path. Both genes exhibited qualitatively similar patterns of expression under LIPUS compared to normal flow. LIPUS induced a more rapid beneficial response compared to normal flow, but flow induced higher expression of both genes. eNOS expression after 6 h of LIPUS was dependent on RNA yield and culture duration prior to experiments.

CONCLUSION

Endothelial cells exposed to longer durations of LIPUS than typically employed exhibited greater expression of beneficial genes. The temporal gene expression patterns resulting from LIPUS and normal flow suggest activation of similar signaling pathways. However, LIPUS also caused increased RNA yield that may be linked to proliferation, which would suggest more of a wound healing than atheroprotective phenotype.

Arterial Leg Ulcers in the Octogenarian

Arterial leg ulcers are a debilitating sequela of chronic ischemia, and their management, particularly in the octogenarian, is an immense challenge. ALUs are frequently a manifestation of end-stage peripheral arterial disease, and their presence portends a high morbidity and mortality. Management primarily relies on restoration of flow, but in the geriatric population, interventions may carry undue risk and pathologies may not be amenable. Adjunctive therapies that improve quality of life and decrease morbidity and mortality are therefore essential, and understanding their benefits and limitations is crucial in developing a multimodal treatment algorithm of care for the uniquely challenging octogenarian population.

Efficacy and safety of ultrasound-assisted wound debridement in the treatment of diabetic foot ulcers: a systematic review and meta-analysis of 11 randomized controlled trials

Objective

Research data suggests that ultrasound-assisted wound debridement (UAWD) can effectively promote the healing of diabetic foot ulcers (DFU). However, existing research is not consistent with this viewpoint. Therefore, we conducted this study to investigate the effect of UAWD on the healing of diabetic foot ulcers.

Methods

From the establishment of the database to January 2024, we searched 8 databases to study the effectiveness and safety of UAWD in the treatment of DFU. Two authors independently screened the qualifications of the articles, while two authors extracted relevant data. Statistical analysis was conducted using Review Manager 5.4 and STATA 18.0 software.

Results

A total of 11 randomized controlled studies were included, with 6 countries and 696 participants participating. Our findings showed that UAWD was associated with a significant benefit in healing rate (OR = 2.60, 95% CI: [1.67, 4.03], P < 0.0001, I2 = 25%), wound healing time (MD = -11.94, 95% CI: [-23.65, -0.23], P = 0.05, I2 = 99%), percentage reduction in wound size (MD = 14.2, 95% CI: [10.8, 17.6], P = 0.47, I2 = 32%), effectiveness of treatment (OR = 10.3, 95% CI: [4.68, 22.66], P < 0.00001, I2 = 0%). Moreover, UAWD did not cause any significant adverse reactions. However, there was no obvious difference in wound blood perfusion (MD = 0.25, 95% CI: [-0.01, 0.52], P = 0.06, I2 = 90%), transcutaneous oxygen partial pressure (MD = 14.34, 95% CI: [-10.03, 38.71], P = 0.25, I2 = 98%).

Conclusion

UAWD can significantly improve wound healing rate, shorten wound healing time, accelerate wound area reduction, and improve clinical treatment effectiveness without significant adverse reactions. Although there is no significant difference in transcutaneous oxygen pressure and wound blood flow perfusion between UAWD and SWC. So we look forward to more scientifically blinded, placebo-controlled, high-quality studies in the future, to enable researchers to obtain more complete and accurate analytical data, in order to improve the scientific and credibility of the evidence.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024501198.

Gene expression changes in therapeutic ultrasound-treated venous leg ulcers

Introduction

Low-frequency, low-intensity ultrasound has been previously shown to promote healing of chronic wounds in humans, but mechanisms behind these effects are poorly understood. The purpose of this study was to evaluate gene expression differences in debrided human venous ulcer tissue from patients treated with low-frequency (20 kHz), low-intensity (100 mW/cm2) ultrasound compared to a sham treatment in an effort to better understand the potential biological mechanisms.

Methods

Debrided venous ulcer tissue was collected from 32 subjects one week after sham treatment or low-frequency, low-intensity ultrasound treatment. Of these samples, 7 samples (3 ultrasound treated and 4 sham treated) yielded sufficient quality total RNA for analysis by ultra-high multiplexed PCR (Ampliseq) and expression of more than 24,000 genes was analyzed. 477 genes were found to be significantly differentially expressed between the ultrasound and sham groups using cut-off values of p < 0.05 and fold change of 2.

Results and Discussion

The top differentially expressed genes included those involved in regulation of cell metabolism, proliferation, and immune cell signaling. Gene set enrichment analysis identified 20 significantly enriched gene sets from upregulated genes and 4 significantly enriched gene sets from downregulated genes. Most of the enriched gene sets from upregulated genes were related to cell-cell signaling pathways. The most significantly enriched gene set from downregulated genes was the inflammatory response gene set. These findings show that therapeutic ultrasound influences cellular behavior in chronic wounds as early as 1 week after application. Considering the well-known role of chronic inflammation in impairing wound healing in chronic wounds, these results suggest that a downregulation of inflammatory genes is a possible biological mechanism of ultrasound-mediated venous chronic wound healing. Such increased understanding may ultimately lead to the enhancement of ultrasound devices to accelerate chronic wound healing and increase patient quality of life.

High-frequency noncontact low-intensity pulsed ultrasound modulates Ca2+-dependent transcription factors contributing to cell migration

Chronic wounds have negative physical and psychological effects on patients and increase the health care burden. Consequently, chronic wound in the elderly population is an important issue. Ultrasound can be a great modality for treating chronic wounds because of its noninvasive and safety characteristics; it can accelerate in vitro and in vivo wound healing. In this study, we developed a novel noncontact ultrasound for wound treatment. We stimulated human epidermal keratinocyte migration using low-intensity pulsed ultrasound (LIPUS) with a noncontact transducer to avoid direct contact with the wound. We also compared the effects of 15-min contact and noncontact transducer stimulation, where a 1-MHz contact transducer (intensity = 40 or 200 mW/cm²) and a 0.45-MHz noncontact transducer (intensity = 30 mW/cm²) were used. Both contact and noncontact LIPUS considerably increased cell migration and activated the calcium (Ca²⁺)-dependent transcription factors cAMP-responsive element-binding protein (CREB) and nuclear factor of activated T cells (NFAT). Furthermore, noncontact transducer stimulation did not cause cell death or affect cell proliferation but significantly increased the Ca²⁺ influx-mediated intracellular Ca²⁺ levels. Ca²⁺-free medium and Ca²⁺ channel blockers effectively inhibited LIPUS-induced Ca²⁺-dependent transcription factor activation and cell migration.

Adipose-derived mesenchymal stem cells and wound healing: Potential clinical applications in wound repair

Delayed and chronic wounds result from the dysregulation of molecular and cellular events associated with wound healing, including migration, inflammation, angiogenesis, extracellular matrix (ECM) remodeling, and re-epithelialization. Adipose tissue is an abundant, easily accessible, and rich source of mesenchymal stem cells (MSCs) with high therapeutic potential. In addition to their capability to differentiate into various lineages with specialized functions, adipose-derived MSCs (AMSCs) can mediate to the wound repair process through the secretion of different growth factors and mediators rather than making structural contribution alone. Adipose-derived MSCs mediate the formation of blood vessels, recruit progenitor cells, stimulate cell differentiation and ECM formation, and promote wound healing by releasing immune mediators and exosomes. Herein, we discuss and review the therapeutic potential of AMSCs for wound repair via acceleration of wound closure, re-epithelialization, enhancement of angiogenesis and immunomodulation of prolonged inflammatory responses, as well as the current challenges in clinical implementation.

Mesenchymal Stem Cell-Derived Exosomes Loaded with miR-155 Inhibitor Ameliorate Diabetic Wound Healing

Diabetic wounds are one of the debilitating complications that affect up to 20% of diabetic patients. Despite the advent of extensive therapies, the recovery rate is unsatisfactory, and approximately, 25% of patients undergo amputation, thereby demanding alternative therapeutic strategies. On the basis of the individual therapeutic roles of the miR-155 inhibitor and mesenchymal stem cells (MSC)-derived exosomes, we conjectured that the combination of the miR-155 inhibitor and MSC-derived exosomes would have synergy in diabetic wound healing. Herein, miR-155-inhibitor-loaded MSC-derived exosomes showed synergistic effects in keratinocyte migration, restoration of FGF-7 levels, and anti-inflammatory action, leading to accelerated wound healing mediated by negative regulation of miR-155, using an in vitro co-culture model and in vivo mouse model of the diabetic wound. Furthermore, treatment with miR-155-inhibitor-loaded MSC-derived exosomes led to enhanced collagen deposition, angiogenesis, and re-epithelialization in diabetic wounds. This study revealed the therapeutic potential of miR-155-inhibitor-loaded MSC-derived exosomes in diabetic wound healing and opened the doors for encapsulating miRNAs along with antibiotics within the MSC-derived exosomes toward improved management of chronic, nonhealing diabetic wounds.

Case report: Successful treatment of human diabetic foot ulcer using low-intensity diagnostic ultrasound combined with microbubbles: Two cases

BACKGROUND

Diabetic foot ulcer (DFU) is one of the serious complications of diabetes, which has high disability rate and mortality. Low-intensity ultrasound combined with microbubbles in blood circulation can enhance the blood perfusion effect of local soft tissue, which has the potential to promote the healing of diabetic ulcer. Here, we report how this method was used to help the healing of two patients with chronic refractory DFUs.

CASE PRESENTATION

In case 1, a 56-year-old man with 3-years history of type 2 diabetes had a 3.0×2.0 cm ulcer which infected with staphylococcus aureus on his right calf for more than half a month. In case 2, a 70-year-old man with 10-years history of type 2 diabetes presented with an 8-month right heel ulcer that developed to 7.5×4.6 cm. And he also had hyperlipidemia, hypertension, and renal impairment. Both patients were enrolled in our study to receive treatment of low-intensity diagnostic ultrasound (LIDUS) combined with microbubbles. They were discharged after a 20-minute daily standard treatment for 7 consecutive days. The ulcers in both cases completely healed in 60 days and 150 days, respectively, and haven't recurred for more than one year of follow-up.

CONCLUSION

It is feasible, safe, and effective to use commercial LIDUS combined with commercial microbubbles in the treatment of diabetic lower extremity ulcers. This study may provide an innovative and non-invasive method for the treatment of DFUs.

Teaching Seasoned Doctors New Technology: An Intervention to Reduce Barriers and Improve Comfort With Clinical Ultrasound

Introduction Although clinical ultrasound (CUS) is a core skill that is a requirement for emergency medicine (EM) residency graduation, only a fraction of EM practitioners who trained prior to this requirement are certified in CUS. The objective of the study was to implement a CUS workshop for practicing EM physicians, identify barriers to utilization, and assess comfort with the machine, obtaining and interpreting images, and incorporating CUS into clinical practice. Methods This was a prospective descriptive cohort study of EM physician faculty who participated in an interactive 5-hour CUS workshop intervention that introduced four core CUS modalities via didactics and hands-on scanning stations. Pre- and post-surveys were administered to identify barriers to utilization and assess perceived comfort with CUS using a 5-point Likert scale. Results were analyzed using Fisher's exact and paired t-tests. Results Thirty-five EM physicians participated with a 100% survey response rate. Only five of the physicians were ultrasound certified at the time of the workshop. On average, physicians were 16 years post-residency. Prior to the workshop, 29% had minimal ultrasound experience and 43% had not performed more than 50 ultrasounds. In the pre-course survey, every physician expressed at least one barrier to CUS utilization. Post-workshop, physicians felt significantly more comfortable using the ultrasound machine (p=0.0008), obtaining and interpreting images (p=0.0009 and p=0.0004), and incorporating CUS into clinical practice (p=0.002). Conclusion This workshop is an effective tool to expose practicing physicians to core concepts of CUS, improve their comfort level, and reduce barriers to ultrasound utilization.

Ultrasonic-assisted wound debridement: report from a closed panel meeting

Mechanical debridement can be considered as an alternative to surgical debridement if surgery is not available, or is considered impractical or too high risk. One form of selective mechanical debridement is ultrasonic-assisted wound (UAW) debridement. As the published evidence on this is limited, a closed international expert meeting was held to review the existing evidence base on it, present preliminary findings of research currently in progress and discuss individual cases selected from the clinical experts' own practice. The panel also explored the potential barriers to the implementation of UAW debridement and how these might be addressed. It concluded there is sufficient evidence that UAW debridement is an effective method of cleansing and debriding almost all hard-to-heal wounds. Patients who are most likely to benefit from it are not medically stable, on anticoagulants, unable to visit a hospital for wound treatment, and/or have wounds with a poor vascular supply or are close to critical structures. The panel also observed that UAW debridement can be used to prepare the wound for negative pressure wound therapy (NPWT) or as an adjunctive to it. Given the potential to experience pain during the procedure, the panel considered that patients will benefit from topical analgesia. The panel noted that health professionals, patients and visitors must be protected from the aerosolisation associated with UAW, to reduce risk of cross-contamination.

Cellular Proliferation, Dermal Repair, and Microbiological Effectiveness of Ultrasound-Assisted Wound Debridement (UAW) Versus Standard Wound Treatment in Complicated Diabetic Foot Ulcers (DFU): An Open-Label Randomized Controlled Trial

We aimed to evaluate the effects of ultrasound-assisted wound (UAW) debridement on cellular proliferation and dermal repair in complicated diabetic foot ulcers as compared to diabetic foot ulcers receiving surgical/sharp wound debridement. A randomized controlled trial was performed involving 51 outpatients with complicated diabetic foot ulcers that either received surgical debridement (n = 24) or UAW debridement (n = 27) every week during a six-week treatment period. Compared to patients receiving surgical debridement, patients treated with UAW debridement exhibited significantly improved cellular proliferation, as determined by CD31 staining, Masson’s trichrome staining, and actin staining. Bacterial loads were significantly reduced in the UAW debridement group compared to the surgical group (UAW group 4.27 ± 0.37 day 0 to 2.11 ± 0.8 versus surgical group 4.66 ± 1.21 day 0 to 4.39 ± 1.24 day 42; p = 0.01). Time to healing was also significantly lower (p = 0.04) in the UAW group (9.7 ± 3.8 weeks) compared to the surgical group (14.8 ± 12.3 weeks), but both groups had similar rates of patients that were healed after six months of follow-up (23 patients (85.1%) in the UAW group vs. 20 patients (83.3%) in the surgical group; p = 0.856). We propose that UAW debridement could be an effective alternative when surgical debridement is not available or is contraindicated for use on patients with complicated diabetic foot ulcers.

Low-intensity ultrasound combined with allogenic adipose-derived mesenchymal stem cells (AdMSCs) in radiation-induced skin injury treatment

Mesenchymal stem cells are mechano-sensitive cells with the potential to restore the function of damaged tissues. Low-intensity ultrasound has been increasingly considered as a bioactive therapeutic apparatus. Optimizing transplantation conditions is a critical aim for radiation-induced skin tissue injury. Therefore, the therapeutic function of adipose-derived mesenchymal stem cells to ultrasound stimulus was examined based on the mechanical index (MI). Mesenchymal stem cells were isolated from the adipose tissues of mature guinea pigs. An ultrasound system (US) was constructed with a 40 kHz frequency. The radiation-induced skin injury model was produced on the abdominal skin of guinea pigs by 60 Gy of radiation. Then, they were divided to 7 groups (n = 42): control, sham, US (MI = 0.7), AdMSCs injection, US AdMSCs (AdMSCs, under US with MI = 0.2), AdMSCs + US (AdMSCs transplantation and US with MI = 0.7) and US AdMSCs + US (combining the last two groups). The homing of stem cells was verified with fluorescence imaging. The groups were followed with serial photography, ultrasound imaging, tensiometry, and histology. The thickness of the skin was analyzed. Functional changes in skin tissue were evaluated with Young's modulus (kPa). One-way ANOVA tests were performed to analyze differences between treatment protocols (p < 0.05). The results of Kumar's score showed that radiation injury was significantly lower in the treatment groups of US AdMSCs and US AdMSCs + US than other groups after 14 days (p < 0.05). There was a significant difference in skin thickness between treatment groups with control, sham, and US groups after 60 Gy radiation and were closer to the thickness of healthy skin. Young's modulus in US AdMSCs + US, US AdMSCs, and AdMSCs + US groups demonstrated a significant difference with the other groups (p < 0.05). Young's modulus in US AdMSCs + US and US AdMSCs treatment groups were closer to Young's modulus of the healthy skin. The histological results confirmed the improvement of acute radiation damage in the combined treatment method, especially in US AdMSCs + US and US AdMSCs groups with increasing the epithelialization and formation of collagen. An ultrasonic treatment plan based on a mechanical index of the target medium could be used to enhance stem cell therapy.

Vibrational stress affects extracellular signal-regulated kinases activation and cytoskeleton structure in human keratinocytes

As the outermost organ, the skin can be damaged following injuries such as wounds and bacterial or viral infections, and such damage should be rapidly restored to defend the body against physical, chemical, and microbial assaults. However, the wound healing process can be delayed or prolonged by health conditions, including diabetes mellitus, venous stasis disease, ischemia, and even stress. In this study, we developed a vibrational cell culture model and investigated the effects of mechanical vibrations on human keratinocytes. The HaCaT cells were exposed to vibrations at a frequency of 45 Hz with accelerations of 0.8g for 2 h per day. The applied mechanical vibration did not affect cell viability or cell proliferation. Cell migratory activity did increase following exposure to vibration, but the change was not statistically significant. The results of immunostaining (F-actin), western blot (ERK1/2), and RT-qPCR (FGF-2, PDGF-B, HB-EGF, TGF-β1, EGFR, and KGFR) analyses demonstrated that the applied vibration resulted in rearrangement of the cytoskeleton, leading to activation of ERK1/2, one of the MAPK signaling pathways, and upregulation of the gene expression levels of HB-EGF and EGFR. The results suggest that mechanical vibration may have wound healing potential and could be used as a mechanical energy-based treatment for enhancing wound healing efficiency.

Noncontact Phased-Array Ultrasound Facilitates Acute Wound Healing in Mice

Supplemental Digital Content is available in the text.

Background:

The authors developed a noncontact low-frequency ultrasound device that delivers high-intensity mechanical force based on phased-array technology. It may aid wound healing because it is likely to be associated with lower risks of infection and heat-induced pain compared with conventional ultrasound methods. The authors hypothesized that the microdeformation it induces accelerates wound epithelialization. Its effects on key wound-healing processes (angiogenesis, collagen accumulation, and angiogenesis-related gene transcription) were also examined.

Methods:

Immediately after wounding, bilateral acute wounds in C57BL/6J mice were noncontact low-frequency ultrasound– and sham-stimulated for 1 hour/day for 3 consecutive days (10 Hz/90.6 Pa). Wound closure (epithelialization) was recorded every 2 days as the percentage change in wound area relative to baseline. Wound tissue was procured on days 2, 5, 7, and 14 (five to six per time point) and subjected to histopathology with hematoxylin and eosin and Masson trichrome staining, CD31 immunohistochemistry, and quantitative polymerase-chain reaction analysis.

Results:

Compared to sham-treated wounds, ultrasound/phased-array–treated wounds exhibited significantly accelerated epithelialization (65 ± 27 percent versus 30 ± 33 percent closure), angiogenesis (4.6 ± 1.7 percent versus 2.2 ± 1.0 percent CD31⁺ area), and collagen deposition (44 ± 14 percent versus 28 ± 13 percent collagen density) on days 5, 2, and 5, respectively (all p < 0.05). The expression of Notch ligand delta-like 1 protein (Dll1) and Notch1, which participate in angiogenesis, was transiently enhanced by treatment on days 2 and 5, respectively.

Conclusions:

The authors’ noncontact low-frequency ultrasound phased-array device improved the wound-healing rate. It was associated with increased early neovascularization that was followed by high levels of collagen-matrix production and epithelialization. The device may expand the mechanotherapeutic proangiogenesis field, thereby helping stimulate a revolution in infected wound care.

Differentiation of Menstrual Blood Stem Cells into Keratinocyte-Like Cells on Bilayer Nanofibrous Scaffold

Skin tissue engineering is a high-throughput technology to heal the wounds. Already, considerable advances have been achieved using stem cells for wound healing applications. Menstrual blood stem cell (MenSC) is an available and accessible source of stem cells that have differentiation potential into a wide range of lineages like keratinocytes. Extracellular matrix like substratum plays an impressive role in skin regeneration as an attachment site for stem cells by transmitting the bioactive signals and provoking stem cells to differentiate into keratinocyte lineage. The biomimetic nanofibrous scaffold especially in bilayer format has been extensively utilized to develop skin equivalents. This chapter explains detailed protocols of keratinocyte differentiation of MenSCs on bilayer scaffold comprising amniotic membrane and fibroin nanofibers. The isolated MenSCs are seeded on the nanofibers and subsequently differentiated into keratinocyte lineage in co-culture with foreskin-derived keratinocytes. Immunofluorescence staining is used to evaluate the development of seeded MenSCs in bilayer scaffold into keratinocyte-like cells.

Efficacy and Safety of Low-Frequency, Noncontact Airborne Ultrasound Therapy (Glybetac) For Neuropathic Diabetic Foot Ulcers: A Randomized, Double-Blind, Sham-Control Study

The diabetic foot ulcer (DFU) healing rates remain dismally low. Therefore, many adjunctive therapies have been evaluated including ultrasound therapy. The prior studies with noncontact, low-frequency ultrasound were retrospective, single arm, unblinded, or with historical controls. The aim of the present study was to compare the efficacy of noncontact, low-frequency airborne ultrasound (Glybetac) therapy with sham therapy added to standard treatment in patients with neuropathic, clinically infected, or noninfected DFU (wound size >2 cm²), Wagner grades 2 and 3. Patients received ultrasound or sham therapy for 28 days dosed daily for first 6 days followed by twice a week for next 3 weeks along with standard of care. The primary outcome was percentage of patients with at least >50% decrease in wound area at 4 week of intervention. Fifty-eight patients completed the study protocol. The duration of wound was 15.8 ± 11.2 weeks and 12.1 ± 10.9 weeks and wound area of 11.3 ± 8.2 cm² and 14.8 ± 13.8 cm² ( P = .507) in the ultrasound and sham groups, respectively. A >50% reduction in wound area was observed in 97.1% and 73.1% subjects ( P = .042) in ultrasound and sham groups, respectively. Wound contraction was faster in the first 2 weeks with ultrasound therapy, 5.3 cm², compared with 3.0 cm² ( P = .025) with sham treatment. Overall, wound area reduction of 69.4 ± 23.2% and 59.6 ± 24.9% ( P = .126) was observed at 4 weeks in the ultrasound and sham groups, respectively. We conclude that the airborne low-frequency ultrasound therapy improves and hastens the healing of chronic neuropathic DFU when combined with standard wound care.

Transdermal Delivery of Enfuvirtide in a Porcine Model Using a Low-Frequency, Low-Power Ultrasound Transducer Patch

Ultrasound-mediated transdermal delivery is a promising parenteral administration method for large-molecule or unstable medications. This study evaluated skin health and systemic delivery when administering enfuvirtide, an injectable anti-retroviral medication, over a 1-mo period in a porcine model using a low-frequency cymbal transducer. Three groups received twice-daily treatments: (i) enfuvirtide injection control (n = 12); (ii) saline ultrasound control (n = 6); and (iii) enfuvirtide ultrasound treatment (n = 13). Ultrasound parameters were as follows: 30-min exposure, 90 mW/cm², 24-26 kHz and 15% duty cycle. No statistical difference in trans-epidermal water loss, a measure of skin health and function, was seen between ultrasound-treated and control skin sites for either saline (p = 0.50) or enfuvirtide (p = 0.29) groups. Average trough plasma concentrations of enfuvirtide were 0.6 ± 0.2 and 2.8 ± 0.8 μg/mL for ultrasound and injection, respectively. Tolerability and efficacy results indicate that chronic, low-frequency ultrasound exposure can be a practical means for transdermal delivery of medications such as enfuvirtide.

Efficacy of Biophysical Energies on Healing of Diabetic Skin Wounds in Cell Studies and Animal Experimental Models: A Systematic Review

We have systematically assessed published cell studies and animal experimental reports on the efficacy of selected biophysical energies (BPEs) in the treatment of diabetic foot ulcers. These BPEs include electrical stimulation (ES), pulsed electromagnetic field (PEMF), extracorporeal shockwave (ECSW), photo energies and ultrasound (US). Databases searched included CINAHL, MEDLINE and PubMed from 1966 to 2018. Studies reviewed include animal and cell studies on treatment with BPEs compared with sham, control or other BPEs. Information regarding the objective measures of tissue healing and data was extracted. Eighty-two studies were eventually selected for the critical appraisal: five on PEMF, four each on ES and ECSW, sixty-six for photo energies, and three about US. Based on the percentage of original wound size affected by the BPEs, both PEMF and low-level laser therapy (LLL) demonstrated a significant clinical benefit compared to the control or sham treatment, whereas the effect of US did not reveal a significance. Our results indicate potential benefits of selected BPEs in diabetic wound management. However, due to the heterogeneity of the current clinical trials, comprehensive studies using well-designed trials are warranted to confirm the results.

Bilayer Amniotic Membrane/Nano-fibrous Fibroin Scaffold Promotes Differentiation Capability of Menstrual Blood Stem Cells into Keratinocyte-Like Cells

The skin provides a dynamic barrier separating and protecting human body from the exterior world, and then immediate repair and rebuilding of the epidermal barrier is crucial after wound and injury. Wound healing without scars and complete regeneration of skin tissue still remain as a clinical challenge. The demand to engineer scaffolds that actively promote regeneration of damaged areas of the skin has been increased. In this study, menstrual blood-derived stem cells (MenSCs) have been induced to differentiate into keratinocytes-like cells in the presence of human foreskin-derived keratinocytes on a bilayer scaffold based on amniotic membrane and silk fibroin. Based on the findings, newly differentiated keratinocytes from MenSCs successfully expressed the keratinocytes specific markers at both mRNA and protein levels judged by real-time PCR and immunostaining techniques, respectively. We could show that the differentiated cells over bilayer composite scaffolds express the keratinocytes specific markers at higher levels when compared with those cultured in conventional 2D culture system. Based on these findings, bilayer amniotic membrane/nano-fibrous fibroin scaffold represents an efficient natural construct with broad applicability to generate keratinocytes from MenSCs for stem cell-based skin wounds healing and regeneration.

Acceleration of Diabetic Wound Healing with PHD2- and miR-210-Targeting Oligonucleotides

In diabetes-associated chronic wounds, the normal response to hypoxia is impaired and many cellular processes involved in wound healing are hindered. Central to the hypoxia response is hypoxia-inducible factor-1α (HIF-1α), which activates multiple factors that enhance wound healing by promoting cellular motility and proliferation, new vessel formation, and re-epithelialization. Prolyl hydroxylase domain-containing protein 2 (PHD2) regulates HIF-1α activity by targeting it for degradation under normoxia. HIF-1α also upregulates microRNA miR-210, which in turn regulates proteins involved in cell cycle control, DNA repair, and mitochondrial respiration in ways that are antagonistic to wound repair. We have identified a highly potent short synthetic hairpin RNA (sshRNA) that inhibits expression of PHD2 and an antisense oligonucleotide (antimiR) that inhibits miR-210. Both oligonucleotides were chemically modified for improved biostability and to mitigate potential immunostimulatory effects. Using the sshRNA to silence PHD2 transcripts stabilizes HIF-1α and, in combination with the antimiR targeting miR-210, increases proliferation and migration of keratinocytes in vitro. To assess activity and delivery in an impaired wound healing model in diabetic mice, PHD2-targeting sshRNAs and miR-210 antimiRs both alone and in combination were formulated for local delivery to wounds using layer-by-layer (LbL) technology. LbL nanofabrication was applied to incorporate sshRNA into a thin polymer coating on a Tegaderm mesh. This coating gradually degrades under physiological conditions, releasing sshRNA and antimiR for sustained cellular uptake. Formulated treatments were applied directly to splinted full-thickness excisional wounds in db/db mice. Cellular uptake was confirmed using fluorescent sshRNA. Wounds treated with a single application of PHD2 sshRNA or antimiR-210 closed 4 days faster than untreated wounds, and wounds treated with both oligonucleotides closed on average 4.75 days faster. Markers for neovascularization and cell proliferation (CD31 and Ki67, respectively) were increased in the wound area following treatment, and vascular endothelial growth factor (VEGF) was increased in sshRNA-treated wounds. Our results suggest that silencing of PHD2 and miR-210 either together or separately by localized delivery of sshRNAs and antimiRs is a promising approach for the treatment of chronic wounds, with the potential for rapid clinical translation.

Ultrasound-Mediated EGF-Coated-Microbubble Cavitation in Dressings for Wound-Healing Applications

The feasibility of ultrasound (US) controlled cavitation for transdermal drug delivery (TDD) using gas-filled microbubbles (MBs) has been explored. However, liquid or gel-type MBs is not easy used for TDD. The present study investigated a new treatment model for evaluating the US-mediated liquid-type epidermal growth factor (EGF)-coated lysozyme microbubble (LYMB) cavitation in a wound dressing for enhancing wound healing. The maximum loading efficacy of EGF onto LYMBs was 19.40 ± 0.04%. In terms of the in vitro treatment efficacy, the growth of Staphylococcus aureus was inhibited by 97.50 ± 1.50% in the group with LYMBs exposed to 3 W/cm² US. During 21 days in vivo wound healing experiments, the recovery rate during the first 6 days was significant higher in the group with EGF-LYMB dressings and US exposure (day 6: 54.28 ± 3.26%) than in the control group (day 6: 26.36 ± 3.34%) (p < 0.05). Our results show that the new model can significantly reduce the treatment duration during wound healing.

Platelet Rich Plasma: New Insights for Cutaneous Wound Healing Management

The overall increase of chronic degenerative diseases associated with ageing makes wound care a tremendous socioeconomic burden. Thus, there is a growing need to develop novel wound healing therapies to improve cutaneous wound healing. The use of regenerative therapies is becoming increasingly popular due to the low-invasive procedures needed to apply them. Platelet-rich plasma (PRP) is gaining interest due to its potential to stimulate and accelerate the wound healing process. The cytokines and growth factors forming PRP play a crucial role in the healing process. This article reviews the emerging field of skin wound regenerative therapies with particular emphasis on PRP and the role of growth factors in the wound healing process.

Comparison of the effects of 1MHz and 3MHz therapeutic ultrasound on endothelium-dependent vasodilation of humans: a randomised clinical trial

OBJECTIVE

To compare the effects of different waveforms of 1MHz and 3MHz therapeutic ultrasound on endothelial function in healthy subjects.

DESIGN

Randomised placebo-controlled, crossover study with concealed allocation and assessor blinding.

SETTING

Imaging Centre of the University Hospital.

PARTICIPANTS

Thirty volunteers aged between 18 and 35 years were divided into two homogeneous groups (1MHz and 3MHz).

INTERVENTIONS

Continuous (CUT; 0.4W/cm^2SATA), pulsed (PUT; 20% duty cycle, 0.08W/cm^2SATA) and placebo waveforms (equipment off) of ultrasound (1MHz and 3MHz) were randomized and applied over the brachial artery for 5minutes.

MAIN OUTCOME MEASURES

Endothelial function was evaluated using the flow-mediated dilation (FMD) technique.

RESULTS

Both 1MHz [CUT: mean difference 4%, 95% confidence interval (CI) 2 to 6%, P<0.001; PUT: mean difference 4%, 95% CI 2 to 6%, P<0.001] and 3MHz (CUT: mean difference 4%, 95% CI 2 to 6%, P<0.001; PUT: mean difference 4%, 95% CI 2 to 6%, P<0.001) of therapeutic ultrasound increased %FMD by approximately 4% compared with the placebo waveforms. The endothelium-dependent vasodilator responses were the same for both types of waves and frequencies. No differences in baseline diameter, hyperaemic flow, and nitroglycerin-mediated diameter and vasodilation were observed between groups.

CONCLUSION

Both CUT and PUT ultrasound waveforms improved endothelial function. The 1MHz and 3MHz frequencies of therapeutic ultrasound led to similar improvement in endothelial function in healthy volunteers. Clinical trial registration number RBR-4z5z3t.

A Cooperative Copper Metal-Organic Framework-Hydrogel System Improves Wound Healing in Diabetes

Chronic non-healing wounds remain a major clinical challenge that would benefit from the development of advanced, regenerative dressings that promote wound closure within a clinically relevant time frame. The use of copper ions has shown promise in wound healing applications possibly by promoting angiogenesis. However, reported treatments that use copper ions require multiple applications of copper salts or oxides to the wound bed, exposing the patient to potentially toxic levels of copper ions and resulting in variable outcomes. Herein we set out to assess whether copper metal organic framework nanoparticles (HKUST-1 NPs) embedded within an antioxidant thermoresponsive citrate-based hydrogel would decrease copper ion toxicity and accelerate wound healing in diabetic mice. HKUST-1 and poly-(polyethyleneglycol citrate-co-N-isopropylacrylamide) (PPCN) were synthesized and characterized. HKUST-1 NP stability in a protein solution with and without embedding them in PPCN hydrogel was determined. Copper ion release, cytotoxicity, apoptosis, and in vitro migration processes were measured. Wound closure rates and wound blood perfusion were assessed in vivo using the splinted excisional dermal wound diabetic mouse model. HKUST-1 NP disintegrated in protein solution while HKUST-1 NPs embedded in PPCN (H-HKUST-1) were protected from degradation and copper ions were slowly released. Cytotoxicity and apoptosis due to copper ion release were significantly reduced while dermal cell migration in vitro and wound closure rates in vivo were significantly enhanced. In vivo, H-HKUST-1 induced angiogenesis, collagen deposition, and re-epithelialization during wound healing in diabetic mice. These results suggest that a cooperatively stabilized, copper ion-releasing H-HKUST-1 hydrogel is a promising innovative dressing for the treatment of chronic wounds.

Mesenchymal Stem Cells and Cutaneous Wound Healing: Current Evidence and Future Potential

Human skin is a remarkable organ that sustains insult and injury throughout life. The ability of skin to expeditiously repair wounds is paramount to survival. With an aging global population, coupled with a rise in the prevalence of conditions such as diabetes, chronic wounds represent a significant biomedical burden. Mesenchymal stem cells (MSC), a progenitor cell population of the mesoderm lineage, have been shown to be significant mediators in inflammatory environments. Preclinical studies of MSC in various animal wound healing models point towards a putative therapy. This review examines the body of evidence suggesting that MSC accelerate wound healing in both clinical and preclinical studies and also the possible mechanisms controlling its efficacy. The delivery of a cellular therapy to the masses presents many challenges from a safety, ethical, and regulatory point of view. Some of the issues surrounding the introduction of MSC as a medicinal product are also delineated in this review.

Prospective Randomized Controlled Trial Comparing the Effects of Noncontact Low-Frequency Ultrasound with Standard Care in Healing Split-Thickness Donor Sites

BACKGROUND

Skin graft donor sites are notoriously painful, with potential complications of fluid loss, delayed healing, infection, and hypertrophic scarring, particularly in patients with burns or traumatic injury. In this population, rapid epithelialization is critical to reducing morbidity and cost.

STUDY DESIGN

This prospective, randomized controlled trial compared the effects of 40-kHz noncontact low-frequency ultrasound (NLFU) in addition to standard care (SC) with SC alone in subjects with split-thickness donor sites of 20 to 200 cm(2). Standard care consisted of cleansing and moist wound dressings. Outcomes measured were time to healing, defined as absence of drainage and full epithelialization; pain and itching scores; and recidivism rates.

RESULTS

Of 33 patients enrolled; 27 were randomized and received a minimum of 4 study treatments. Median age was 49 years, 69% were male, and 84% were burn patients. Comorbidities included hypertension (31%), coronary artery disease (22%), pulmonary disease (38%), anemia (31%), and diabetes (16%). Median donor site area was 136.0 cm(2). Noncontact low-frequency ultrasound and SC compared with SC demonstrated a mean time to heal of 12.1 days vs 21.3 days (p = 0.04). All NLFU+SC subjects had epithelialized by 4 weeks compared with only 71% in SC. Recidivism rates were 8% for NLFU+SC compared with 45% for SC. Pain scores were reduced and significant differences in itching were observed.

CONCLUSIONS

Noncontact low-frequency ultrasound and SC compared with SC alone in the treatment of split-thickness donor sites demonstrated significant accelerated healing and reduced pain and itching. Noncontact low-frequency ultrasound subjects experienced a better quality of healing with less incidence of infection and recidivism.