Compression therapy in peripheral artery disease: a literature review.

OBJECTIVE: Our objective is to examine the pathophysiology of oedema in the ischaemic and post-revascularised limb, compare compression stockings to pneumatic compression devices, and summarise compression regimens in patients with severe peripheral artery disease (PAD) without revascularisation, after revascularisation, and in mixed arterial and venous disease. METHOD: A scoping literature review of the aforementioned topics was carried out using PubMed. RESULTS: Compression therapy has been shown to increase blood flow and aid in wound healing through a variety of mechanisms. Several studies suggest that intermittent pneumatic compression (IPC) devices can be used to treat critical limb ischaemia in patients without surgical options. Additionally, compression stockings may have a role in preventing oedema after peripheral artery bypass surgery, thereby diminishing pain and reducing the risk of surgical wound dehiscence. CONCLUSION: Oedema may occur in the ischaemic limb after revascularisation surgery, as well as in combination with venous disease. Clinicians should not fear using compression therapy in PAD.

Oxidant Signaling Mediated by Nox2 in Neutrophils Promotes Regenerative Myelopoiesis and Tissue Recovery following Ischemic Damage.

Ischemic tissue damage activates hematopoietic stem and progenitor cells (HSPCs) in the bone marrow (BM)-generating myeloid cells, and persistent HSPC activity may drive chronic inflammation and impair tissue recovery. Although increased reactive oxygen species in the BM regulate HSPC functions, their roles in myelopoiesis of activated HSPCs and subsequent tissue recovery during ischemic damage are not well understood. In this paper, we report that deletion of Nox2 NADPH oxidase in mice results in persistent elevations in BM HSPC activity and levels of inflammatory monocytes/macrophages in BM and ischemic tissue in a model of hindlimb ischemia. Ischemic tissue damage induces oxidants in BM such as elevations of hydrogen peroxide and oxidized phospholipids, which activate redox-sensitive Lyn kinase in a Nox2-dependent manner. Moreover, during tissue recovery after ischemic injury, this Nox2-ROS-Lyn kinase axis is induced by Nox2 in neutrophils that home to the BM, which inhibits HSPC activity and inflammatory monocyte generation and promotes tissue regeneration after ischemic damage. Thus, oxidant signaling in the BM mediated by Nox2 in neutrophils regulates myelopoiesis of HSPCs to promote regeneration of damaged tissue.

Baseline factors affecting closure of venous leg ulcers.

OBJECTIVE: The objective of this study was to characterize factors associated with closure of venous leg ulcers (VLUs) in a pooled analysis of subjects from three randomized clinical trials. METHODS: Closure of VLUs after treatment with HP802-247, an allogeneic living cell therapy consisting of growth-arrested human keratinocytes and fibroblasts, vs standard therapy with compression bandaging was evaluated in three phase 3 clinical trials of similar design. Two trials enrolled subjects with VLUs ranging from 2 cm2 to 12 cm2 in area with 12-week treatment periods; the third trial enrolled subjects with VLUs between >12 cm2 and ≤36 cm2 with a 16-week treatment period. The first trial went to completion but failed to demonstrate a benefit to therapy with HP802-247 compared with placebo, and because of this, the remaining trials were terminated before completion. On the basis of no differences in outcomes between groups, subjects from both HP802-247 and control groups were pooled across all three studies. Cox proportional hazards regression analysis was employed to evaluate factors associated with VLU closure. RESULTS: This analysis included data from 716 subjects with VLU. Factors evaluated for association with healing included age, gender, race, diabetes, glycated hemoglobin level, body mass index, treatment (HP802-247 vs compression alone), and ulcer characteristics including location and area and duration at baseline. In an initial model including all of these putative factors, the following were significant at the P < .10 level: diagnosis of diabetes mellitus, gender, wound location (ankle or leg), baseline wound area, and wound duration at baseline. In a final model including only these factors, all but diabetes mellitus were significant at the P < .05 level. Effect sizes were as follows (hazard ratio [95% confidence interval]): female gender (1.384 [1.134-1.690]), wound location on the leg (1.490 [1.187-1.871]), smaller wound area at baseline (0.907 [0.887-0.927]), and shorter wound duration at baseline (0.971 [0.955-0.987]). CONCLUSIONS: Factors associated with VLU lesions including location, area, and duration were important predictors of healing. Women were more likely than men to achieve wound closure. Factors including body mass index, the presence of diabetes mellitus, and higher concentrations of glycated hemoglobin were not significant independent predictors of wound closure in this analysis.

Identification and content validation of wound therapy clinical endpoints relevant to clinical practice and patient values for FDA approval. Part 1. Survey of the wound care community.

Wounds that exhibit delayed healing add extraordinary clinical, economic, and personal burdens to patients, as well as to increasing financial costs to health systems. New interventions designed to ease such burdens for patients with cancer, renal, or ophthalmologic conditions are often cleared for approval by the U.S. Food and Drug Administration (FDA) using multiple endpoints but the requirement of complete healing as a primary endpoint for wound products impedes FDA clearance of interventions that can provide other clinical or patient-centered benefits for persons with wounds. A multidisciplinary group of wound experts undertook an initiative, in collaboration with the FDA, to identify and content validate supporting FDA criteria for qualifying wound endpoints relevant to clinical practice (CP) and patient-centered outcomes (PCO) as primary outcomes in clinical trials. As part of the initiative, a research study was conducted involving 628 multidisciplinary expert wound clinicians and researchers from 4 different groups: the interdisciplinary core advisory team; attendees of the Spring 2015 Symposium on Advanced Wound Care (SAWC); clinicians employed by a national network of specialty clinics focused on comprehensive wound care; and Association for the Advancement of Wound Care (AAWC) and Wound Healing Society (WHS) members who had not previously completed the survey. The online survey assessed 28 literature-based wound care endpoints for their relevance and importance to clinical practice and clinical research. Fifteen of the endpoints were evaluated for their relevance to improving quality of life. Twenty-two endpoints had content validity indexes (CVI) ≥ 0.75, and 15 were selected as meriting potential inclusion as additional endpoints for FDA approval of future wound care interventions. This study represents an important first step in identifying and validating new measurable wound care endpoints for clinical research and practice and for regulatory evaluation.

Advanced Technologies to Improve Wound Healing: Electrical Stimulation, Vibration Therapy, and Ultrasound-What Is the Evidence?

BACKGROUND: Cellular energy is required for the healing cascade to occur. A combination of cells, cytokines, chemokines, tissue perfusion, an extracellular matrix, and local forces are also required to allow for human tissue repair to proceed. Although there are many examples of treatment options, energy-based therapies are the least understood, appreciated, and employed by practicing wound care physicians. The recent growth of tissue engineering has encouraged researchers to employ both electrical stimulation and therapeutic ultrasound (US) to stimulate cells, induce migration, and modify tissue constructs. METHODS: The authors have reviewed the literature on electrical stimulation, US, and vibrational therapy and are providing an update to a prior 2007 publication on this topic. The hope was to provide a broad exposure to these treatments but not to create a comprehensive review. A table of evidence was generated from the recent literature to help guide treatment decisions for the clinician. RESULTS: In the current literature, there is much debate over which treatment modality, dosage levels, and timing are optimal. There are numerous in-vitro-based publications that describe mechanism of action and several clinical articles that describe effectiveness of electrical stimulation and US, but few well-controlled and/or randomized trials. The absence of level one evidence has hindered the adoption of these techniques throughout the years. Three energy-based treatment options, electrical stimulation, vibration, and US, will be reviewed along with possible clinical applications CONCLUSIONS: : Although most trials are underpowered with inconsistent treatment settings, physical therapy modality use is increasing in the clinical community. Recent guidelines reference the use of these treatments with increasing evidence level recommendations. At the present time, electrical stimulation carries the greatest level of evidence for clinical use.

Macrophage PPARγ and impaired wound healing in type 2 diabetes.

Macrophages undergo a transition from pro-inflammatory to healing-associated phenotypes that is critical for efficient wound healing. However, the regulation of this transition during normal and impaired healing remains to be elucidated. In our studies, the switch in macrophage phenotypes during skin wound healing was associated with up-regulation of the peroxisome proliferator-activated receptor (PPAR)γ and its downstream targets, along with increased mitochondrial content. In the setting of diabetes, up-regulation of PPARγ activity was impaired by sustained expression of IL-1ß in both mouse and human wounds. In addition, experiments with myeloid-specific PPARγ knockout mice indicated that loss of PPARγ in macrophages is sufficient to prolong wound inflammation and delay healing. Furthermore, PPARγ agonists promoted a healing-associated macrophage phenotype both in vitro and in vivo, even in the diabetic wound environment. Importantly, topical administration of PPARγ agonists improved healing in diabetic mice, suggesting an appealing strategy for down-regulating inflammation and improving the healing of chronic wounds.

Calcinosis cutis presenting in the context of long-term therapy for chronic myeloid leukemia: a case report and review of the literature.

Calcinosis cutis is a poorly understood process in which calcium salts deposit in the skin and subcutaneous tissues. Due to its multifactorial pathogenesis, several subtypes and potential etiologies have been described. Presented here is a case of bilateral pretibial calcinosis cutis in a patient on long-term tyrosine kinase inhibitor therapy for chronic myeloid leukemia. The patient initially presented with a right tibial ulceration treated with multiple surgical debridements, antibiotics, and negative pressure wound therapy. The wound was ultimately closed with a split-thickness skin graft. Relevant literature is examined and several possible mechanisms are discussed.

Low-intensity vibration improves angiogenesis and wound healing in diabetic mice.

Chronic wounds represent a significant health problem, especially in diabetic patients. In the current study, we investigated a novel therapeutic approach to wound healing--whole body low-intensity vibration (LIV). LIV is anabolic for bone, by stimulating the release of growth factors, and modulating stem cell proliferation and differentiation. We hypothesized that LIV improves the delayed wound healing in diabetic mice by promoting a pro-healing wound environment. Diabetic db/db mice received excisional cutaneous wounds and were subjected to LIV (0.4 g at 45 Hz) for 30 min/d or a non-vibrated sham treatment (controls). Wound tissue was collected at 7 and 15 d post-wounding and wound healing, angiogenesis, growth factor levels and wound cell phenotypes were assessed. LIV increased angiogenesis and granulation tissue formation at day 7, and accelerated wound closure and re-epithelialization over days 7 and 15. LIV also reduced neutrophil accumulation and increased macrophage accumulation. In addition, LIV increased expression of pro-healing growth factors and chemokines (insulin-like growth factor-1, vascular endothelial growth factor and monocyte chemotactic protein-1) in wounds. Despite no evidence of a change in the phenotype of CD11b+ macrophages in wounds, LIV resulted in trends towards a less inflammatory phenotype in the CD11b- cells. Our findings indicate that LIV may exert beneficial effects on wound healing by enhancing angiogenesis and granulation tissue formation, and these changes are associated with increases in pro-angiogenic growth factors.

Sustained inflammasome activity in macrophages impairs wound healing in type 2 diabetic humans and mice.

The hypothesis of this study was that sustained activity of the Nod-like receptor protein (NLRP)-3 inflammasome in wounds of diabetic humans and mice contributes to the persistent inflammatory response and impaired healing characteristic of these wounds. Macrophages (Mp) isolated from wounds on diabetic humans and db/db mice exhibited sustained inflammasome activity associated with low level of expression of endogenous inflammasome inhibitors. Soluble factors in the biochemical milieu of these wounds are sufficient to activate the inflammasome, as wound-conditioned medium activates caspase-1 and induces release of interleukin (IL)-1ß and IL-18 in cultured Mp via a reactive oxygen species-mediated pathway. Importantly, inhibiting inflammasome activity in wounds of db/db mice using topical application of pharmacological inhibitors improved healing of these wounds, induced a switch from proinflammatory to healing-associated Mp phenotypes, and increased levels of prohealing growth factors. Furthermore, data generated from bone marrow-transfer experiments from NLRP-3 or caspase-1 knockout to db/db mice indicated that blocking inflammasome activity in bone marrow cells is sufficient to improve healing. Our findings indicate that sustained inflammasome activity in wound Mp contributes to impaired early healing responses of diabetic wounds and that the inflammasome may represent a new therapeutic target for improving healing in diabetic individuals.

Blocking interleukin-1ß induces a healing-associated wound macrophage phenotype and improves healing in type 2 diabetes.

Diabetes is associated with persistent inflammation and defective tissue repair responses. The hypothesis of this study was that interleukin (IL)-1ß is part of a proinflammatory positive feedback loop that sustains a persistent proinflammatory wound macrophage phenotype that contributes to impaired healing in diabetes. Macrophages isolated from wounds in diabetic humans and mice exhibited a proinflammatory phenotype, including expression and secretion of IL-1ß. The diabetic wound environment appears to be sufficient to induce these inflammatory phenomena because in vitro studies demonstrated that conditioned medium of both mouse and human wounds upregulates expression of proinflammatory genes and downregulates expression of prohealing factors in cultured macrophages. Furthermore, inhibiting the IL-1ß pathway using a neutralizing antibody and macrophages from IL-1 receptor knockout mice blocked the conditioned medium-induced upregulation of proinflammatory genes and downregulation of prohealing factors. Importantly, inhibiting the IL-1ß pathway in wounds of diabetic mice using a neutralizing antibody induced a switch from proinflammatory to healing-associated macrophage phenotypes, increased levels of wound growth factors, and improved healing of these wounds. Our findings indicate that targeting the IL-1ß pathway represents a new therapeutic approach for improving the healing of diabetic wounds.

Stem Cells and Healing: Impact on Inflammation.

SIGNIFICANCE: The number of patients with nonhealing wounds has rapidly accelerated over the past 10 years in both the United States and worldwide. Some causative factors at the macro level include an aging population, epidemic numbers of obese and diabetic patients, and an increasing number of surgical procedures. At the micro level, chronic inflammation is a consistent finding. RECENT ADVANCES: A number of treatment modalities are currently used to accelerate wound healing, including energy-based modalities, scaffoldings, the use of mechano-transduction, cytokines/growth factors, and cell-based therapies. The use of stem cell therapy has been hypothesized as a potentially useful adjunct for nonhealing wounds. Specifically, mesenchymal stem cells (MSCs) have been shown to improve wound healing in several studies. Immune modulating properties of MSCs have made them attractive treatment options. CRITICAL ISSUES: Current limitations of stem cell therapy include the potentially large number of cells required for an effect, complex preparation and delivery methods, and poor cell retention in targeted tissues. Comparisons of published in-vitro and clinical trials are difficult due to cell preparation techniques, passage number, and the impact of the micro-environment on cell behavior. FUTURE DIRECTIONS: MSCs may be more useful if they are preactivated with inflammatory cytokines such as tumor necrosis factor alpha or interferon gamma. This article will review the current literature with regard to the use of stem cells for wound healing. In addition the anti-inflammatory effects of MSCs will be discussed along with the potential benefits of stem cell preactivation.

Current status of the use of modalities in wound care: electrical stimulation and ultrasound therapy.

Wound healing is a complex pathway that requires cells, an appropriate biochemical environment (i.e., cytokines, chemokines), an extracellular matrix, perfusion, and the application of both macrostrain and microstrain. The process is both biochemically complex and energy dependent. Healing can be assisted in difficult cases through the use of physical modalities. In the current literature, there is much debate over which treatment modality, dosage level, and timing is optimal. The mechanism of action for both electrical stimulation and ultrasound are reviewed along with possible clinical applications for the plastic surgeon.

Maintenance debridement in the treatment of difficult-to-heal chronic wounds. Recommendations of an expert panel.

INTRODUCTION: Maintenance debridement has been proposed as a therapeutic intervention to address the problem of chronic wounds characterized by an adequate wound bed but absent or slow healing. A panel of experts convened to address the rationale and method of maintenance debridement. PURPOSE: The goals of the panel were to summarize the scientific rationale for maintenance debridement, discuss the biochemical and cellular abnormalities in the wound bed, and provide a working algorithm for how maintenance debridement should be used. METHODS: A multidisciplinary panel of wound healing and wound care experts comprising the fields of nursing, dermatology, internal medicine, and surgery was assembled to address maintenance debridement from different points of view and offer a unified approach. FINDINGS: The chronic wound contains a number of microbial, biochemical, and cellular features and abnormalities that prevent or slow its progression to healing despite a seemingly adequate wound bed. Under these circumstances, maintenance debridement is proposed as a way to remove tissues that are colonized with an excessive bacterial burden and diminish what can be described as a biochemical and cellular burden that impairs healing. A working clinical algorithm is proposed. CONCLUSION: Maintenance debridement is a proactive way to "jump-start" the wound and keep it in a healing mode, even when traditional debridement may not appear necessary because of a seemingly "healthy" wound bed.

Push-pull theory: using mechanotransduction to achieve tissue perfusion and wound healing in complex cases.

Wound healing has evolved from gauze therapy to the use of proteomics, gene therapy, and cellular-based therapies in the short time span of 45 years. Education for health care providers has not kept pace with the logarithmic acceleration in technology development and treatment options. A patient with a non-healing wound requires a comprehensive work-up, including a focus on six primary points of interest. These points include the status of tissue perfusion, role of bacterial contamination, pressure applied to the tissue, the immune status of the host, co-morbid medical conditions including the patient's psychosocial status, and lastly, the status of the wound itself. Even after re-establishing macrovascular flow, many wounds either fail to improve or paradoxically worsen. Potential mechanisms for these unexpected findings include reperfusion injury, no-reflow, and the presence of stunned/hibernating tissue. Using the concept of mechanotransduction, the clinician can simulate normal pulsatile blood flow and re-establish adequate microvascular perfusion. Treatment regimens may include negative pressure therapy, electrical stimulation, ultrasound therapy, and other energy-based modalities.

Surgical palliative care of advanced wounds.

The history of surgery is rich with accomplishments in wound care, a legacy that recently has been abandoned by many surgeons only to be taken up by nonsurgical providers. When dealing with advanced wounds at the end of life, such as pressure ulcers or venous stasis ulcers, goals of treatment are relief of pain, elimination of odor, and control of wound exudates and infection. Benefits and risks of surgical intervention must be discussed with the patient and family in terms of the patient's perceived prognosis, extent of tissue necrosis and infection, the rate of deterioration, and the underlying wound pathogenesis. When appropriate, the role of surgery looms large in the treatment of chronic, advanced wounds, especially when minimally invasive surgical techniques are used.

Ultrasound therapy for recalcitrant diabetic foot ulcers: results of a randomized, double-blind, controlled, multicenter study.

An estimated 15% of patients with diabetes will develop a foot ulcer sometime in their life, making them 30 to 40 times more likely to undergo amputation due to a non-healing foot ulcer than the non-diabetic population. To determine the safety and efficacy of a new, non-contact, kilohertz ultrasound therapy for the healing of recalcitrant diabetic foot ulcers - as well as to evaluate the impact on total closure and quantitative bacterial cultures and the effect on healing of various levels of sharp/surgical debridement - a randomized, double-blinded, sham-controlled, multicenter study was conducted in hospital-based and private wound care clinics. Patients (55 met criteria for efficacy analysis) received standard of care, which included products that provide a moist environment, offloading diabetic shoes and socks, debridement, wound evaluation, and measurement. The "therapy" was either active 40 KHz ultrasound delivered by a saline mist or a "sham device" which delivered a saline mist without the use of ultrasound. After 12 weeks of care, the proportion of wounds healed (defined as complete epithelialization without drainage) in the active ultrasound therapy device group was significantly higher than that in the sham control group (40.7% versus 14.3%, P = 0.0366, Fisher's exact test). The ultrasound treatment was easy to use and no difference in the number and type of adverse events between the two treatment groups was noted. Of interest, wounds were debrided at baseline followed by a quantitative culture biopsy. The results of these cultures demonstrated a significant bioburden (greater than 10(5)) in the majority of cases, despite a lack of clinical signs of infection. Compared to control, this therapeutic modality was found to increase the healing rate of recalcitrant, diabetic foot ulcers.