Eligibility Criteria for Active Ulcerative Pyoderma Gangrenosum in Clinical Trials: A Delphi Consensus on Behalf of the UPGRADE (Understanding Pyoderma Gangrenosum: Review and Assessment of Disease Effects) Group.

At present, there are no standardized guidelines for determining patient eligibility for pyoderma gangrenosum (PG) clinical trials. Thus, we aim to determine which clinical features, histopathological features, or laboratory features should be included in active ulcerative PG clinical trial eligibility criteria for treatment-naïve patients and patients already treated with immunomodulating medications (treatment-exposed patients). This study employed 4 rounds of the Delphi technique. Electronic surveys were administered to 21 international board-certified dermatologists and plastic surgeon PG experts (June 2022-December 2022). Our results demonstrated that for a patient to be eligible for a PG trial, they must meet the following criteria: (i) presence of ulcer(s) with erythematous/violaceous undermining wound borders, (ii) presence of a painful or tender ulcer, (iii) history/presence of rapidly progressing disease, (iv) exclusion of infection and other causes of cutaneous ulceration, (v) biopsy for H&E staining, and (vi) a presence/history of pathergy. These criteria vary in importance for treatment-naïve versus treatment-exposed patients. Given the international cohort, we were unable to facilitate live discussions between rounds. This Delphi consensus study provides a set of specific, standardized eligibility criteria for PG clinical trials, thus addressing one of the main issues hampering progress toward Food and Drug Administration approval of medications for PG.

Protease-Resistant Growth Factor Formulations for the Healing of Chronic Wounds.

Objective: Chronic wounds are long-term nonhealing wounds that are refractory to treatment. These wounds can present elevated protease levels, leading to rapid degradation of native and exogenously added growth factors. This work focused on developing a protease-resistant growth factor formulation for treatment of chronic wounds presented with high protease activity. Approach: This study developed protease-resistant growth factor formulations comprising elastin-like peptides (ELPs) fused with a known protease inhibitor peptide or growth factor. The ELP component of the fusion proteins allows assembly of heterogeneous nanoparticles (NPs) putting the inhibitor in close proximity to the growth factor to be protected. Results: We show successful preservation of growth factor activity in high human neutrophil elastase (HNE) environment and in human chronic wound fluid derived from patients. We further show that these NPs result in enhanced collagen remodeling and resolution of inflammation in a full thickness wound supplemented with HNE in genetically diabetic mice. Innovation: Development of heterogeneous NPs that put the protease inhibitor in close proximity of the growth factor. Moreover, the modular nature of the NPs allows for protection of multiple growth factors by the same inhibitor without changing the amino acid sequence of the growth factor. Conclusion: Our results indicate that the developed NPs hold tremendous promise in chronic wound healing therapy and may further help the translation of growth factor therapies to clinic. The customizable template for the NP design allows for multifaceted use across several fields in research and medicine.

Human Adipose-Derived Stem Cell Conditioned Media and Exosomes Containing MALAT1 Promote Human Dermal Fibroblast Migration and Ischemic Wound Healing.

Objective: Chronically ill patients heal recalcitrant ulcerative wounds more slowly. Human adipose-derived stem cells (hADSCs) play an important role in tissue regeneration and exosomes secreted by hADSC contribute to their paracrine signaling. In addition to cytokines, lipids and growth factors, hADSC secrete mRNA, miRNA, and long noncoding (lnc) RNA into exosomes. In this study we examined the role of lncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), an abundant lncRNA in exosomes from conditioned media (CM), on cell migration and ischemic wound healing. Approach: CM and isolated exosomes from hADSC were applied to human dermal fibroblast (HDF) in scratch assays and electric cell-substrate impedance sensing (ECIS) assays. CM was also applied to a rat model of ischemic wound healing and wound closure was followed. Results: CM stimulated cell migration of HDFs in vitro by 48%. CM stimulated the closure of ischemic wounds in a rat model 50% faster than unconditioned media. The depletion of MALAT1 in adipose-derived stem cell (ADSC) CM significantly reduced cell migration. Since MALAT1 is secreted into exosomes, a purified population of exosomes was applied to HDF where they enhanced cell migration in a similar manner to FGF-2 or basic fibroblast growth factor (bFGF) in ECIS wound healing assays. The uptake of exosomes by HDF was shown using dynasore, an inhibitor that blocks clathrin- and caveolin-dependent endocytosis. Depletion of MALAT1 in hADSC with antisense oligonucleotides resulted in exosomes without MALAT1. These exosomes had an effect similar to the unconditioned, control media in ECIS assays. Innovation: Exosomes contain lncRNA MALAT1 and other factors that have the potential to stimulate HDF cell migration and angiogenesis involved in wound healing without applying stem cells to wounds. Conclusion: Our results show the potential of using topically applied ADSC-derived exosomes containing MALAT1 for treating ischemic wounds. This allows for harnessing the power of stem cell paracrine signaling capabilities without applying the cells.

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.

Modalities to Treat Venous Ulcers: Compression, Surgery, and Bioengineered Tissue.

BACKGROUND: Venous leg ulcers (VLUs) represent the most common ulcers of the lower extremity. VLUs are notorious for delayed and prolonged healing with high rates of recurrence. Most patients with VLUs also have significant comorbidities that interfere with primary wound healing. Thus, caring for patients with VLUs requires an interdisciplinary approach that addresses the abnormal venous anatomy and the downstream effects that lead to inflammation, ulceration, and a hostile wound microenvironment. METHODS: The current literature regarding venous ulcer treatment with an emphasis on compression, surgical options, and use of bioengineered tissue was reviewed. A combination of society guidelines, Cochrane reviews, and over 80 primary articles with high-level evidence were utilized to develop this summary and algorithm for an integrated approach to treating patients with venous ulcers. Details regarding compression modalities and venous diagnostic imaging are presented to help the clinician understand the rationale for using these technologies. RESULTS: The comprehensive approach to the patient with chronic venous insufficiency (CVI) includes advances in compression, diagnostics, minimally invasive surgical treatment of venous disease, wound bed preparation, and bioengineered skin and soft tissue substitutes. An algorithm that incorporates early treatment of the ulcer and the venous disease leading to healing with prevention of recurrence is presented. CONCLUSIONS: Utilizing guidelines that incorporate evidence-based modalities will lead to the highest quality outcomes with the most appropriate resource utilization. A proactive approach to treating venous disease will alleviate suffering and prevent the long-term sequelae of CVI.

Spinal Cord Injury survey to determine pressure ulcer vulnerability in the outpatient population.

Pressure ulcers are one of the most common causes of morbidity, mortality and rehospitalization for those living with Spinal Cord Injury (SCI). Literature examining risk and recurrence of pressure ulcers (PrUs) has primarily focused on the nursing home elderly who do not have SCI. More than 200 factors that increase PrU risk have been identified. Yet unlike the elderly who incur pressure ulcers in nursing homes or when hospitalized, most persons with SCI develop their pressure ulcers as outpatients, while residing in the community. The Veterans Health Administration (VHA) provides medical care for a large number of persons with chronic SCI. Included in the VHA SCI model of chronic disease management is the provision of an annual Comprehensive Preventive Health Evaluation, a tool that has potential to identify individuals at high risk for PrUs. This research was motivated by the clinical observation that some individuals appear to be protected from developing PrUs despite apparently 'risky' behaviors while others develop PrUs despite vigilant use of the currently known preventative measures. There is limited literature regarding protective factors and specific risk factors that reduce PrU occurrence in the community dwelling person with chronic SCI have not been delineated. The purpose of this study is to examine the preliminary hypothesis that there are biological and/or psychosocial factors that increase or reduce vulnerability to PrUs among persons with SCI. A limited number of refined hypotheses will be generated for testing in a prospective fashion. A retrospective cross-sectional survey of 119 randomly selected Veterans with SCI undergoing the Comprehensive Health Prevention Evaluation during the year 2009 was performed. Factors that differed between patients with 0, 1 or ⩾2 PrUs were identified and stratified, with an emphasis on modifiable risk factors. Three hypotheses generated from this study warrant further investigation: (1) cumulative smoking history increases the risk of PrUs independent of co-morbidities, (2) being moderately overweight, BMI>25, with or without spasticity, is a modifiable factor that may be protective and (3) increased use of a caregiver does not reduce PrU risk. Prospective studies that focus on these hypotheses will lead to evidence-based risk assessment tools and customized interventions to prevent PrUs in persons with SCI in the outpatient setting.

The Kent hospital Wound Recovery and Hyperbaric Medicine Center: a brief overview, 1998-2013.

A brief description of the Wound Recovery and Hyperbaric Medicine Center, now in its second decade of service, will inform the general medical community of this valuable asset. Demand for wound care services is predicted to grow steadily over the next several decades. Kent Hospital's vision for wound care is embodied in its thriving Wound Recovery and Hyperbaric Medicine Center. New cost- effective wound healing therapies must be developed and evidence-based practices established. New physicians and support staff must be trained. Only through a blending of high quality clinical care with research and education will these objectives be achieved and future successes in the management of patients and their wounds be made possible.

Consequences of age on ischemic wound healing in rats: altered antioxidant activity and delayed wound closure.

Advertisements targeted at the elderly population suggest that antioxidant therapy will reduce free radicals and promote wound healing, yet few scientific studies substantiate these claims. To better understand the potential utility of supplemental antioxidant therapy for wound healing, we tested the hypothesis that age and tissue ischemia alter the balance of endogenous antioxidant enzymes. Using a bipedicled skin flap model, ischemic and non-ischemic wounds were created on young and aged rats. Wound closure and the balance of the critical antioxidants superoxide dismutase and glutathione in the wound bed were determined. Ischemia delayed wound closure significantly more in aged rats. Lower superoxide dismutase 2 and glutathione in non-ischemic wounds of aged rats indicate a basal deficit due to age alone. Ischemic wounds from aged rats had lower superoxide dismutase 2 protein and activity initially, coupled with decreased ratios of reduced/oxidized glutathione and lower glutathione peroxidase activity. De novo glutathione synthesis, to restore redox balance in aged ischemic wounds, was initiated as evidenced by increased glutamate cysteine ligase. Results demonstrate deficiencies in two antioxidant pathways in aged rats that become exaggerated in ischemic tissue, culminating in profoundly impaired wound healing and prolonged inflammation.

Computer simulation of pectoralis major muscle strain to guide exercise protocols for patients after breast cancer surgery.

STUDY DESIGN: Descriptive study. OBJECTIVES: To quantify and rank the order of strain (length change in proportion to the resting length) of 3 portions of the pectoralis major (PM) muscle during various exercises. BACKGROUND: A biomechanical foundation on which to base exercise prescriptions for patients after breast cancer surgery is lacking. METHODS: An interactive, 3-D, computer graphic simulation system, developed to study biomechanical properties of the musculoskeletal system, was used to simulate movements of the glenohumeral, scapulothoracic, and scapuloclavicular joints of the shoulder, and to estimate strain in 3 portions of the pectoralis major (PM) muscle throughout the motions. The computed tomography scans of 2 male cadavers and literature review formed the basis for the estimations used in the model. Strains in the clavicular, midsternum, and abdominal regions of the PM were expressed as percent strain: [(change in muscle length/resting length) × 100]. Exercise motions were based on PM muscle anatomy and published breast cancer rehabilitation protocols. RESULTS: Strains of the PM regions ranged from -21% shortening of the clavicular region during flexion to 55% lengthening of the abdominal region during the overhead stretch. Strain between adjacent regions was most uniform for the movement of abduction with external rotation, and least uniform with flexion. CONCLUSION: PM muscle lengthening estimates were not linearly proportioned to shoulder joint motions, and varied for 3 portions of the PM. This information may help clinicians and researchers to estimate lengthening of PM portions throughout measurable shoulder motions.

Treatment of eccrine carcinoma of the chin via submental island flap.

BACKGROUND: The submental artery island flap is a reliable reconstructive option for lower face defects. Advantages of this flap include suppleness of tissue, excellent color and texture match to facial skin, a wide arc of rotation, prominent blood supply, and a well-hidden donor site scar. METHODS: This article describes a 61-year-old man with eccrine carcinoma of the chin necessitating extensive excision. A submental artery island flap was used for the reconstruction of the extended chin subunit. RESULTS: The operation resulted in excellent aesthetic outcome and maintenance of oral competence. CONCLUSION: The submental artery island flap utilizes loose tissue of the submental area to effectively and reliably reconstruct the soft tissue subunits of the chin and is a superb option for sizable defects. The flap is sufficiently well vascularized to tolerate postoperative radiation therapy without significant fibrosis or retraction.

Study of the neural and vascular anatomy of the anterolateral thigh flap.

UNLABELLED: The purpose of this study was to perform a detailed investigation of the vascular and neural structures of the anterolateral thigh (ALT) flap, with emphasis on the peripheral neurovascular system of the subcutaneous adipofascial layer. METHODS: Ten cadavers were examined after injection of latex into the bilateral external iliac arterial system. The nutrient vessels of the femoral cutaneous nerves and the relationship between these vessels and the adjacent tissue were studied. RESULTS: The intrinsic and extrinsic neurocutaneous vascular systems surrounding the cutaneous nerves in the deep adipofascial layer were explored. The extrinsic neurocutaneous vascular system consisted of chain-like anastomoses formed by segmental arteries derived from perforators and revealed a distinct axial course along the nerves. The first segmental artery of the extrinsic neurocutaneous system was found to be the longest and to have the greatest diameter. The three-dimensional vascular structure of the ALT flap resembled a tree, in that the nutrient vessels arborised in each layer with their length and diameter decreasing from the deep adipofascial layer to the superficial adipofascial layer. Two categories of branch vessels connect the suprafascial plexus and subdermal plexus in the ALT flap: (1) large branches derived directly from the perforator ascend obliquely or vertically to the skin and (2) small branches arise from the nerve's nutrient artery and ascend to the skin. CONCLUSIONS: The ALT flap is ideal for soft-tissue reconstruction in the Asian population. Preservation of the large branch vessels ensures flap survival during primary defatting, allowing for improved contour in single-stage reconstructions. It is also possible to design a proximally pedicled neurocutaneous flap based on the cutaneous nerve in the thigh and its corresponding vascular system. This neurocutaneous flap may offer a novel advantage for sensate reconstruction of the perineum.

Proteolytic activity in wound fluids and tissues derived from chronic venous leg ulcers.

Venous leg ulcers affect approximately 1% of the general population and 3.6% of those over the age of 65. The goal of the research described herein is to shorten the time to healing by developing wound care alternatives that are based on a comprehensive understanding of the venous ulcer wound environment. The proteolytic and inflammatory components in wound fluids and tissue biopsy samples were characterized in subjects with documented long-standing venous ulcers that had showed resistance to standard therapy. All wounds showed polymicrobial colonization with greater than 10(6) CFU/g. Myeloperoxidase, a measure of leukocyte infiltration, was also markedly elevated in these wounds. Zymography revealed the presence of both pro-matrix metalloproteinase (MMP)-2 and pro-MMP-9 in wound fluids and to a lesser extent in tissue biopsies. Using an immunocapture activity assay we reveal a sevenfold excess of MMP-9 in wound fluid as compared to tissue, with 73% in the activated form. In contrast, MMP-8 total protein levels were nearly equal in wound fluids and biopsies. Fibronectin, a critical component of the extracellular matrix, was shown to be degraded in both wound fluids and biopsy samples. Finally, the potential of a novel wound dressing to neutralize several constituents of this hostile wound environment is shown.

Characterization of a preclinical model of chronic ischemic wound.

Chronic ischemic wounds presenting at wound clinics are heterogeneous with respect to etiology, age of the wound, and other factors complicating wound healing. In addition, there are ethical challenges associated with collecting repeated biopsies from a patient to develop an understanding of the temporal dynamics of the mechanisms underlying chronic wounds. The need for a preclinical model of ischemic wound is therefore compelling. The porcine model is widely accepted as an excellent preclinical model for human wounds. A full-thickness bipedicle flap approach was adopted to cause skin ischemia. Closure of excisional wounds placed on ischemic tissue was severely impaired resulting in chronic wounds. Histologically, ischemic wounds suffered from impaired re-epithelialization, delayed macrophage recruitment and poorer endothelial cell abundance and organization. Compared with the pair-matched nonischemic wound, unique aspects of the ischemic wound biology were examined on days 3, 7, 14, and 28 by systematic screening of the wound tissue transcriptome using high-density porcine GeneChips. Ischemia markedly potentiated the expression of arginase-1, a cytosolic enzyme that metabolizes the precursor of nitric oxide l-arginine. Ischemia also induced the SOD2 in the wound tissue perhaps as survival response of the challenged tissue. Human chronic wounds also demonstrated elevated expression of SOD2 and arginase-1. This study provides a thorough database that may serve as a valuable reference tool to develop novel hypotheses aiming to elucidate the biology of ischemic chronic wounds in a preclinical setting.

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.

Successful incorporation of tissue-engineered porcine small-intestinal submucosa as substitute flexor tendon graft is mediated by elevated TGF-beta1 expression in the rabbit.

PURPOSE: Ideal tendon repair materials combine minimal donor-site morbidity and ready availability with excellent healing and postoperative function. Bioengineered porcine small-intestinal submucosa (SIS) was compared with tendon autografts as a potential human flexor tendon graft substitute. METHODS: Rabbit zone II flexor digitorum profundus segments were excised in 40 rabbits. Randomized tendon repair consisted of either interposition reversed autograft or SIS, passed beneath the A2 and A4 pulleys. Forepaws were statically splinted for 3 weeks followed by unrestricted motion. Animals were killed at 7, 14, 28, and 56 days. Specimens were analyzed for hydroxyproline content (absorption spectroscopy) and tensile strength. Hematoxylin-eosin and Movat-stained sections of the central graft and distal repair site were semiquantitatively scored for total cellularity, inflammatory cell content, foreign-body reaction, vascularity, mature collagen content, and new collagen deposition. Transforming growth factor-beta (TGF-beta1) and TGF-beta1 receptor immunostaining was performed. RESULTS: At week 1, SIS hydroxyproline content was significantly reduced compared with autograft hydroxyproline content. However, week 2 SIS hydroxyproline content increased to equivalent values. Collagen deposition was evident in SIS by week 1 but negligible in autograft. More rapid total and inflammatory cell increases occurred in SIS by 4 weeks. A stronger early inflammatory reaction also occurred. More rapid SIS neovascularization occurred despite a greater foreign-body reaction. Small-intestinal submucosa vascularity was markedly greater at weeks 1 and 2 and equivalent thereafter. At week 4, SIS intrinsic tensile strength (suture removed) exceeded that of both autograft and suture material. Preoperative TGF-beta1 immunostaining in SIS was less than that of autograft but greater during weeks 2 and 4. CONCLUSIONS: Earlier neovascularization, increased TGF-beta1 levels, and increased collagen deposition, along with greater intrinsic repair strength relative to both autograft and suture strength at week 4, make SIS a promising flexor tendon graft substitute. Future studies examining tendon excursion are planned.

Hyperbaric oxygen attenuates apoptosis and decreases inflammation in an ischemic wound model.

The molecular mechanisms whereby hyperbaric oxygen (HBO) improves ischemic wound healing remain elusive. In this study, a rat model of wound ischemia was used to test the hypothesis that HBO enhances wound healing by modulating hypoxia-inducible factor-1alpha (HIF-1alpha) signaling. Male Sprague-Dawley rats underwent creation of a previously validated ischemic flap. Three groups underwent daily treatment: HBO (90 minutes, 2.4 atm); systemic administration of the free radical scavenger, N-acetylcysteine (NAC 150 mg kg(-1) intraperitoneal); control (neither HBO nor NAC). HBO treatment improved healing of the ischemic wounds. Analysis of ischemic wound tissue extracts demonstrated significantly reduced expression of HIF-1alpha, p53, and BNip3. Additionally, HBO increased expression of Bcl-2 while decreasing cleaved caspase-3. DNA fragmentation was abolished and the number of TUNEL-positive cells was reduced compared to the other groups. Vascular endothelial growth factor, cyclooxygenase-2, and neutrophil infiltration were reduced in ischemic wounds treated with HBO. These results indicate that HBO improves ischemic wound healing by downregulation of HIF-1alpha and subsequent target gene expression with attenuation of cell apoptosis and reduction of inflammation.

Clinical and experimental applications of NIR-LED photobiomodulation.

This review presents current research on the use of far-red to near-infrared (NIR) light treatment in various in vitro and in vivo models. Low-intensity light therapy, commonly referred to as "photobiomodulation," uses light in the far-red to near-infrared region of the spectrum (630-1000 nm) and modulates numerous cellular functions. Positive effects of NIR-light-emitting diode (LED) light treatment include acceleration of wound healing, improved recovery from ischemic injury of the heart, and attenuated degeneration of injured optic nerves by improving mitochondrial energy metabolism and production. Various in vitro and in vivo models of mitochondrial dysfunction were treated with a variety of wavelengths of NIR-LED light. These studies were performed to determine the effect of NIR-LED light treatment on physiologic and pathologic processes. NIRLED light treatment stimulates the photoacceptor cytochrome c oxidase, resulting in increased energy metabolism and production. NIR-LED light treatment accelerates wound healing in ischemic rat and murine diabetic wound healing models, attenuates the retinotoxic effects of methanol-derived formic acid in rat models, and attenuates the developmental toxicity of dioxin in chicken embryos. Furthermore, NIR-LED light treatment prevents the development of oral mucositis in pediatric bone marrow transplant patients. The experimental results demonstrate that NIR-LED light treatment stimulates mitochondrial oxidative metabolism in vitro, and accelerates cell and tissue repair in vivo. NIR-LED light represents a novel, noninvasive, therapeutic intervention for the treatment of numerous diseases linked to mitochondrial dysfunction.

Optimization and validation of an ischemic wound model.

Localized tissue ischemia is a key factor in the development and poor prognosis of chronic wounds. Currently, there are no standardized animal models that provide sufficient tissue to evaluate the effect of modalities that may induce angiogenesis, and in vitro models of angiogenesis do not mimic the complexity of the ischemic wound bed. Therefore, we set out to develop a reproducible ischemic model for use in wound-healing studies. Male Sprague-Dawley rats underwent creation of dorsal bipedicle skin flaps with centrally located excisional wounds. Oxygen tension, wound-breaking strength, wound area, lactate, and wound vascular endothelial growth factor (VEGF) were compared in flaps measuring 2.5 and 2.0 x 11 cm with and without an underlying silicone sheet. We found that the center of the 2.0 cm flap with silicone remains in the critically ischemic range up to 14 days without tissue necrosis (33+/-4 vs. 49+/-6 mmHg in controls). Wound healing and breaking strength were significantly impaired and tissue lactate from the center of this flap was 2.9 times greater than tissue from either nonischemic controls and 2.5 cm flap (0.23+/-0.05 mg/dL/mg sample vs. 0.09+/-0.02 and 0.08+/-0.02, respectively). Vascular endothelial growth factor was 2 times greater than the nonischemic control. This ischemic wound model is relatively inexpensive, easy to perform, reproducible, and reliable. The excisional wounds provide sufficient tissue for biochemical and histologic analysis, and are amenable to the evaluation of topical and systemic therapies that may induce angiogenesis or improve wound healing.