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.

Characteristics of venous leg ulcer patients at a tertiary wound care center.

OBJECTIVE: The objective of this study was to assess patient, wound, care, and reflux characteristics of venous leg ulcers (VLUs) to update and improve knowledge of disease etiology, identify barriers to healing, and improve treatment. METHODS: Patients diagnosed with VLUs treated at the Stanford Advanced Wound Care Center between 2018 and 2019 were identified from the Healogics iHeal database. We identified 327 VLU entries, of which 133 were patients who had multiple or recurring wounds. An additional 27 patients were labeled as misdiagnosis, resulting in a final patient sample of 167. Patient demographics, wound, care, and ultrasound data for these patients were extracted from the Stanford electronic medical records regarding characteristics. The initial data analysis suggested possible differences in VLU characteristics depending on patient age and body mass index (BMI), which was then further analyzed. RESULTS: Of the 167 VLU patients assessed, 53.9% were male and 46.1% were female. The mean age was 74.7 years, and the average BMI was 30.2 kg/m2, including 41.1% of patients with a BMI over 30 kg/m2. Approximately 50% of wounds were presented in multiples, had cellulitis, or were recurring, and 39.5% were caused by trauma. Most common venous reflux patterns on duplex ultrasound examination were below-knee great saphenous vein reflux and calf perforator reflux, which was identified in 37.7% and 29.3% of the patients, respectively. Axial great saphenous vein reflux was detected in 14.4% of patients. When looking at the patient sample under 60 years of age, 67.7% were male, 61.3% presented with venous skin changes, and 51.6% had diabetes. In the patients older than 60, only 51.9% were male, 37.6% presented with venous skin changes, and 31.6% had diabetes. BMI was greater in the patients under age 60, with an average of 39.2 kg/m2, compared with 28.2 kg/m2 in those above 60. Of the patients with a BMI ≥30 kg/m2, 64.3% had multiple wounds, 61.4% had recurring wounds, and 56.5% had venous skin changes. In contrast, in patients with BMI <30 kg/m2, 47.4% had multiple wounds, 39.2% had recurring wounds, and 32.0% had venous skin changes. CONCLUSIONS: VLU pathology appears to differ depending on patient demographics and characteristics. Different drivers may influence disease cause, progression, and prognosis, making a standard approach to VLUs difficult. Our findings suggest that identifying different subtypes of VLUs and adapting an algorithm of care with a personalized treatment may help optimize management of these patients.

Clinical Vignettes Part I.

Patients with sickle cell disease and/or (rarely) trait are at increased risk for developing recurrent episodes of priapism, also known as stuttering priapism, and major ischemic priapism. Treatment of acute ischemic priapism is reactive; whereas ideal management consists of preventative approaches to ultimately promote the best improvement in patient's quality of life. Leg ulcers in patients with sickle cell disease (SCD) are quite common, with ∼20 % of patients with HBSS reporting either having an active or a past ucler. They can be confused with venous ulcers, with lower extremity hyperpigmentation confounding further the diagnosis. Several factors believed to contribute to the development of leg ulcers in patients with SCD are discussed in this article. Sickle cell liver disease (SCLD) occurs because of a wide variety of insults to the liver that happen during the lifetime of these patients. SCLD includes a range of complications of the hepatobiliary system and is increasing in prevalence with the aging adult sickle population. Liver nodular regenerative hyperplasia (NRH) is more common than realized and underappreciated as a diagnosis and requires liver biopsy with reticulin staining. Undiagnosed, the insidious damage from liver NRH can lead to noncirrhotic portal hypertension or cirrhosis.

Atypical ulcers: a stepwise approach for clinicians.

Chronic ulcers are associated with significant morbidity and mortality. Typical ulcers are due to venous insufficiency, diabetes, ischemia, pressure, and lymphedema. A chronic ulcer that does not respond to standard therapies should be reevaluated for potential atypical etiologies. Atypical ulcers are less common and more difficult to diagnose due to a wide range of possible etiologies, including inflammatory (autoimmune), neoplastic, vasculopathy, hematologic, infectious, drug-induced, or external. No standardized approach to the management of complex atypical ulcers exists. In this review, a stepwise approach to atypical ulcers is proposed with the aim of assisting physicians in their identification and diagnosis. If perfusion is adequate and there are no signs of infection, then the authors recommend obtaining an ulcer biopsy for microbiologic, DIF, and histopathologic evaluation as the criterion standard for diagnosis. Laboratory testing, including an autoimmune panel, a hypercoagulable panel, and an infectious diseases panel, can further aid in diagnosis. Atypical ulcers often require multidisciplinary care, with input from specialists in rheumatology, dermatology, infectious diseases, wound care, vascular surgery, hematology, and oncology. Effective communication within the health care team is essential for accurate diagnosis and management of atypical ulcers. Active dialogue between providers can improve consult efficiency and ultimately lower the cost of care.

Association of wound healing with quality and continuity of care and sociodemographic characteristics.

OBJECTIVES: To evaluate the association between clinics' wound healing performance and clinic-level measures of care continuity, clinical quality, and sociodemographic characteristics of the population in their catchment areas. STUDY DESIGN: In this cross-sectional analysis, we analyzed electronic health records for 180,336 chronic wounds from 480 wound care clinics during the 2018 calendar year. METHODS: We measured healing performance using a clinic's observed to expected (O/E) ratio, which is based on the rate at which chronic wounds were predicted to heal within 12 weeks given its case mix and the actual healing rate. We compared the top and bottom quintiles, in terms of the O/E ratio, of clinics. Multivariable regression was used to estimate the effect of the clinic-level measures on the O/E ratio. RESULTS: Clinics in the top quintile had higher rates of care continuity and quality measures, as well as a lower proportion of disadvantaged populations in their catchment areas. In the regression model, 10% increases in a clinic's rate of weekly provider visits, nurse visits, and debridement were associated with 2.5%, 3.0% and 0.7% increases, respectively, in the O/E ratio. The weekly provider visit rate had a greater marginal effect when the proportion of African American residents in the clinic's catchment area was larger. CONCLUSIONS: Clinic-level measures of care continuity, clinical quality, and sociodemographic composition of their catchment areas' population explain a meaningful part of differences in clinics' wound healing performance. Better care continuity appears to have a greater beneficial effect in disadvantaged populations.

Outpatient Wound Clinics During COVID-19 Maintained Quality but Served Fewer Patients.

OBJECTIVE: To evaluate the impact of COVID-19-related disruptions on care continuity and outcomes of chronic wounds. DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: Electronic medical records for 152,225 chronic wounds from a network of 488 wound care clinics in 45 US states and the District of Columbia. METHODS: Wound and patient characteristics, the number of chronic wounds newly seen at the clinics, and 12-week healing rates were compared between the first 2 quarters of 2019 and 2020. Multivariable regression models were constructed to evaluate whether the pandemic was associated with a statistically significant change in the probability of 12-week wound healing after risk adjustment. RESULTS: During the pandemic, wound and patient characteristics did not change compared to the previous year. Case volume dropped as much as 40% in April 2020 but returned to the previous year's level by June. No systematic changes in measures of care continuity were observed. Unadjusted 12-week healing rates remained stable at 0.502 in 2019 and 0.503 in 2020. Likewise, risk-adjusted 12-week healing rates were 0.504 and 0.505 in 2019 and 2020, respectively, but the difference was not statistically significant. States with stricter lockdowns saw a greater decline in case volume. However, the pandemic was not associated with a statistically significant change in the probability of 12-week wound healing in most states. The percentage of wounds with 1 or more telehealth visits increased from 0.14% in 2019 to 1.04% in 2020. CONCLUSIONS AND IMPLICATIONS: Despite COVID-19-related disruptions, our results suggest that wound care clinics maintained standards of care and outcomes for patients who sought care. This positive result should not detract from the problem that the number of new wounds seen at the clinics dropped sharply. Further research should evaluate outcomes in patients with unattended chronic wounds.

Development of a Model to Predict Healing of Chronic Wounds Within 12 Weeks.

Objective: Chronic wounds represent a highly prevalent but little recognized condition with substantial implications for patients and payers. While better wound care products and treatment modalities are known to improve healing rates, they are inconsistently used in real-world practice. Predicting healing rates of chronic wounds and comparing to actual rates could be used to detect and reward better quality of care. We developed a prediction model for chronic wound healing. Approach: We analyzed electronic medical records (EMRs) for 620,356 chronic wounds of various etiologies in 261,398 patients from 532 wound care clinics in the United States. Patient-level and wound-level parameters influencing wound healing were identified from prior research and clinician input. Logistic regression and classification tree models to predict the probability of wound healing within 12 weeks were developed using a random sample of 70% of the wounds and validated in the remaining data. Results: A total of 365,659 (58.9%) wounds were healed by week 12. The logistic and classification tree models predicted healing with an area under the curve of 0.712 and 0.717, respectively. Wound-level characteristics, such as location, area, depth, and etiology, were more powerful predictors than patient demographics and comorbidities. Innovation: The probability of wound healing can be predicted with reasonable accuracy in real-world data from EMRs. Conclusion: The resulting severity adjustment model can become the basis for applications like quality measure development, research into clinical practice and performance-based payment.

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.

Use of a National Electronic Health Record Network to Describe Characteristics and Healing Patterns of Sickle Cell Ulcers.

Objective: Sickle cell ulcers affect as many as 15% of patients with sickle cell disease in the United States and severely impact quality of life. An understanding of baseline healing patterns is important to inform study design for future trials that test therapies for this disease. Approach: In this study, an electronic wound management system was leveraged to analyze retrospective data on 133 unique sickle cell patients who were treated across 114 wound healing centers, and to describe their characteristics and healing patterns as compared with those of venous ulcer patients. The data included 198 care episodes for 427 wounds. Results: Patients with sickle cell ulcers were younger and had fewer comorbid diseases than those with venous ulcers. Larger size and longer duration were predictors of poor healing. Between the first and fourth assessments, mean change in area for sickle cell ulcers showed a 58% increase, compared with a 13% decrease for venous ulcers. Kaplan-Meier curves showed poorer healing in sickle cell ulcers than in venous ulcers across all categories of size and duration. Patients with sickle cell ulcers had longer care episodes and were more likely to re-present for care. Innovation: This study reports on the largest data set of sickle cell ulcer patients analyzed to date in the published literature to provide a more detailed understanding of wound healing patterns of this disease. Conclusion: A national network of electronic health records can effectively identify a large number of patients with sickle cell ulcers to support analysis of epidemiology, healing patterns, and health care utilization.

Impact of Hyperbaric Oxygen on More Advanced Wagner Grades 3 and 4 Diabetic Foot Ulcers: Matching Therapy to Specific Wound Conditions.

Objective: The goal of this research was to identify a population of diabetic foot ulcer patients who demonstrate a significant response to hyperbaric oxygen therapy (HBOT) using a large sample size to provide guidance for clinicians when treating these complicated patients. Approach: The effect of HBOT on diabetic foot ulcers, Wagner grades 3 and 4, was evaluated using a retrospective observational real-world data set. The study reported on the overall healing rate, (74.2%) at the population level, for >2 million wounds. Results: When a subgroup of patients of only foot ulcers with a Wagner grade 3 or 4 were considered, the healing rate was only 56.04%. The use of HBOT, without filtering for the number of treatments received, improved the healing rate to 60.01% overall. Healing rates for this same subgroup, however, were improved to 75.24% for patients who completed the prescribed number of hyperbaric treatments. Innovation: This observational study discusses the importance of reporting at the population level, specific wound etiology level, a risk-stratified level, and to then overlay the effect of treatment adherence on those outcomes to provide clinicians with a comprehensive understanding of when to prescribe an advanced modality such as hyperbaric oxygen. Conclusion: The authors provide healing outcomes data from several prior HBOT studies as well as other advanced modalities that have been used in diabetic foot ulcer care for comparison and context.

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.

Wound healing outcomes: Using big data and a modified intent-to-treat method as a metric for reporting healing rates.

Chronic wounds are increasing in prevalence and are a costly problem for the US healthcare system and throughout the world. Typically outcomes studies in the field of wound care have been limited to small clinical trials, comparative effectiveness cohorts and attempts to extrapolate results from claims databases. As a result, outcomes in real world clinical settings may differ from these published studies. This study presents a modified intent-to-treat framework for measuring wound outcomes and measures the consistency of population based outcomes across two distinct settings. In this retrospective observational analysis, we describe the largest to date, cohort of patient wound outcomes derived from 626 hospital based clinics and one academic tertiary care clinic. We present the results of a modified intent-to-treat analysis of wound outcomes as well as demographic and descriptive data. After applying the exclusion criteria, the final analytic sample includes the outcomes from 667,291 wounds in the national sample and 1,788 wounds in the academic sample. We found a consistent modified intent to treat healing rate of 74.6% from the 626 clinics and 77.6% in the academic center. We recommend that a standard modified intent to treat healing rate be used to report wound outcomes to allow for consistency and comparability in measurement across providers, payers and healthcare systems.

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.

Clinical interventions for venous leg ulcers: Proposals to improve the quality of clinical leg ulcer research.

The present status of clinical leg ulcer healing research was reviewed by 25 experts over 2 days on September 28 and 29, 2015. Multiple clinical effectiveness reviews were presented suggesting that published clinical wound healing research often does not meet present (2015) evidence based standards. Specific areas requiring remediation were highlighted and approaches to overcoming existing challenges were proposed. Participants using anonymous voting technology developed an action plan to resolve perceived deficiencies. Statements were accepted if 75% of participants agreed. Older patients with a high frequency of comorbid conditions posed particular difficulties in designing clinical research protocols and better diagnostic categorization is necessary A standardized model template for collecting information about diagnosis and evaluation of the effect of interventions on healing of all types of leg ulcers was considered a high priority. Such a model template could be modified depending on the specific etiology of the leg ulcers. Generally agreed on quantifiable standards to establish degree of morbidity was considered a high priority. There was universal agreement that sources of funding and conflicts of interest needed to be disclosed in presentations and all publications. All clinical research studies should be registered with appropriate authorities. There was substantial enthusiasm for a clinical research network with quality standards for membership and an advisory research core available to investigators. Such a network should be funded and actively managed to insure long-term viability. The governance of such an entity needs to be established by the wound care community. The present trend to integrate patients into the clinical research process was endorsed and there was enthusiasm to develop patient advocacy for wound healing research.

Diabetes medications: Impact on inflammation and wound healing.

Chronic wounds are a common complication in patients with diabetes that often lead to amputation. These non-healing wounds are described as being stuck in a persistent inflammatory state characterized by accumulation of pro-inflammatory macrophages, cytokines and proteases. Some medications approved for management of type 2 diabetes have demonstrated anti-inflammatory properties independent of their marketed insulinotropic effects and thus have underappreciated potential to promote wound healing. In this review, the potential for insulin, metformin, specific sulfonylureas, thiazolidinediones, and dipeptidyl peptidase-4 inhibitors to promote healing is evaluated by reviewing human and animal studies on inflammation and wound healing. The available evidence indicates that diabetic medications have potential to prevent wounds from becoming arrested in the inflammatory stage of healing and to promote wound healing by downregulating pro-inflammatory cytokines, upregulating growth factors, lowering matrix metalloproteinases, stimulating angiogenesis, and increasing epithelization. However, no clinical recommendations currently exist on the potential for specific diabetic medications to impact healing of chronic wounds. Thus, we encourage further research that may guide physicians on providing personalized diabetes treatments that achieve glycemic goals while promoting healing in patients with chronic wounds.

A treatment algorithm to identify therapeutic approaches for leg ulcers in patients with sickle cell disease.

Sickle cell leg ulcers (SCLUs) are a common complication of sickle cell disease (SCD). Patients who develop ulcers appear to have a more severe haemolysis-associated vasculopathy than individuals who do not develop them, and manifest other complications such as priapism and pulmonary hypertension. SCLUs are slow to heal and often recur, affecting both the emotional and physical well-being of patients. Here we summarise what is known about the pathophysiology of SCLUs, describe available treatment options and propose a treatment algorithm.

Amniotic membrane is a potential regenerative option for chronic non-healing wounds: a report of five cases receiving dehydrated human amnion/chorion membrane allograft.

A case series of five patients with a total of six chronic non-healing wounds (>30 day duration) were non-randomly selected to evaluate the performance, safety and handling properties of dehydrated human amnion/chorion membrane allograft, an amniotic membrane scaffolding product. The patients had lower extremity wounds that had previously failed standard of care within a university outpatient/inpatient wound healing programme. Five wounds treated with dehydrated amnion/chorion membrane allograft showed a mean 43% area reduction from baseline (51% median) at 3 weeks into treatment and completely healed with a 64-day median time to closure (SD ±27·6 days). One wound worsened at 3 weeks and was found to have a complete central vein obstruction that was treated with long-term mild compression but still eventually healed at 6 months. Removing this outlier, the four responding wounds had a 72% mean and 69% median change in area from baseline, at the 3 week point. All five patients received only one application of dehydrated human amnion/chorion membrane allograft, and there were no adverse events. The product was easy to use, administer and handle. In summary, dehydrated human amnion/chorion membrane allograft appears to be a safe, effective and easy to use therapy for chronic non-healing wounds. This study describes the details of these clinical cases and provides an overview of the current evidence on the use of amniotic tissue in clinical practice.

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.