Epidermal Potentiation of Dermal Fibrosis: Lessons from Occlusion and Mucosal Healing.

Fibrotic skin conditions, such as hypertrophic and keloid scars, frequently result from injury to the skin and as sequelae to surgical procedures. The development of skin fibrosis may lead to patient discomfort, limitation in range of motion, and cosmetic disfigurement. Despite the frequency of skin fibrosis, treatments that seek to address the root causes of fibrosis are lacking. Much research into fibrotic pathophysiology has focused on dermal pathology, but less research has been performed to understand aberrations in fibrotic epidermis, leading to an incomplete understanding of dermal fibrosis. Herein, literature on occlusion, a treatment modality known to reduce dermal fibrosis, in part through accelerating wound healing and regulating aberrant epidermal inflammation that otherwise drives fibrosis in the dermis, is reviewed. The review focuses on epidermal-dermal crosstalk, which contributes to the development and maintenance of dermal fibrosis, an underemphasized interplay that may yield novel strategies for treatment if understood in more detail.

Amnion membranes support wound granulation in a delayed murine excisional wound model.

Chronic or delayed healing wounds constitute an ever-increasing burden on healthcare providers and patients alike. Thus, therapeutic modalities that are tailored to particular deficiencies in the delayed wound healing response are of critical importance to improve clinical outcomes. Human amnion-derived viable and devitalized allografts have demonstrated clinical efficacy in promoting the closure of delayed healing wounds, but the mechanisms responsible for this efficacy and the specific wound healing processes modulated by these tissues are not fully understood. Here, we utilized a diabetic murine excisional wound model in which healing is driven by granulation and re-epithelialization, and we applied viable (vHAMA) or devitalized (dHAMA) amnion-derived allografts to the wound bed in order to determine their effects on wound healing processes. Compared to control wounds that were allowed to heal in the absence of treatment, wounds to which vHAMA or dHAMA were applied demonstrated enhanced deposition of granulation tissue accompanied by increased cellular proliferation and increased de novo angiogenesis, while vHAMA-treated wounds also demonstrated accelerated re-epithelialization. Taken together, these data suggest that both vHAMA and dHAMA facilitate wound healing through promoting processes critical to granulation tissue formation. Further understanding of the cellular and tissue mechanisms underlying the effects of tissue-derived matrices on wound healing will enable tailored prescription of their use in order to maximize clinical benefit.

Knockdown of sodium channel Nax reduces dermatitis symptoms in rabbit skin.

The skin plays a critical role in maintenance of water homeostasis. Dysfunction of the skin barrier causes not only delayed wound healing and hypertrophic scarring, but it also contributes to the development of various skin diseases. Dermatitis is a chronic inflammatory skin disorder that has several different subtypes. Skin of contact dermatitis and atopic dermatitis (AD) show epidermal barrier dysfunction. Nax is a sodium channel that regulates inflammatory gene expression in response to perturbation of barrier function of the skin. We found that in vivo knockdown of Nax using RNAi reduced hyperkeratosis and keratinocyte hyperproliferation in rabbit ear dermatitic skin. Increased infiltration of inflammatory cells (mast cells, eosinophils, T cells, and macrophages), a characteristic of dermatitis, was reduced by Nax knockdown. Upregulation of PAR-2 and thymic stromal lymphopoietin (TSLP), which induce Th2-mediated allergic responses, was inhibited by Nax knockdown. In addition, expression of COX-2, IL-1ß, IL-8, and S100A9, which are downstream genes of Nax and are involved in dermatitis pathogenesis, were also decreased by Nax knockdown. Our data show that knockdown of Nax relieved dermatitis symptoms in vivo and indicate that Nax is a novel therapeutic target for dermatitis, which currently has limited therapeutic options.

The sodium channel NaX : Possible player in excitation-contraction coupling.

The sodium channel NaX (encoded by the SCN7A gene) was originally identified in the heart and skeletal muscle and is structurally similar to the other voltage-gated sodium channels but does not appear to be voltage gated. Although NaX is expressed at high levels in cardiac and skeletal muscle, little information exists on the function of NaX in these tissues. Transcriptional profiling of ion channels in the heart in a subset of patients with Brugada syndrome revealed an inverse relationship between the expression of NaX and NaV 1.5 suggesting that, in cardiac myocytes, the expression of these channels may be linked. We propose that NaX plays a role in excitation-contraction coupling based on our experimental observations. Here we show that in cardiac myocytes, NaX is expressed in a striated pattern on the sarcolemma in regions corresponding to the sarcomeric M-line. Knocking down NaX expression decreased NaV 1.5 mRNA and protein and reduced the inward sodium current (INa+ ) following cell depolarization. When the expression of NaV 1.5 was knocked down, ~85% of the INa+ was reduced consistent with the observations that NaV 1.5 is the main voltage-gated sodium channel in cardiac muscle and that NaX likely does not directly participate in mediating the INa+ following depolarization. Silencing NaV 1.5 expression led to significant upregulation of NaX mRNA. Similar to NaV 1.5, NaX protein levels were rapidly downregulated when the intracellular [Ca2+ ] was increased either by CaCl2 or caffeine. These data suggest that a relationship exists between NaX and NaV 1.5 and that NaX may play a role in excitation-contraction coupling.

Liposome-encapsulated statins reduce hypertrophic scarring through topical application.

Hypertrophic scar is an important clinical problem with limited therapeutic options. Aside from their roles as 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, statins have also been demonstrated to decrease scarring by reducing connective tissue growth factor (CTGF) expression. However, poor penetrative ability limits their utility as topical treatments for hypertrophic scar. Here, we aim to develop novel statin formulations using liposomes to enhance dermal penetrative ability and to evaluate their efficacy against formation of hypertrophic scar utilizing our validated rabbit ear hypertrophic scar model. Liposomal simvastatin or pravastatin were compounded using a novel, flexible liposomal formulation and applied topically to rabbit ear hypertrophic scars daily from postoperation day (POD) 14 until POD 25. Scar color, including erythema and melanin, was measured using reflectance spectrophotometry on POD 28, and scar tissue was harvested for evaluation of scar elevation index as well as gene and protein expression. Human foreskin fibroblasts were also treated with statin formulations and CCN2 expression was determined by quantitative PCR. Both simvastatin and pravastatin were efficiently encapsulated in liposomes, forming nanometer-scale particles possessing highly negative charges. Topical treatment with liposomal simvastatin and pravastatin at 6.5% concentration significantly reduced scar elevation index and decreased type I/III collagen content and myofibroblast persistence in the wound. The erythema/vascularity of scars was reduced by liposomal statin treatment, with concomitant decrease of CD31 expression as measured histologically. Expression levels of transcripts encoding CTGF, collagen I, and collagen III collagen in scar tissue were also decreased by liposomal pravastatin treatment, as were myofibroblast persistence and the type I/III collagen ratio as assessed by immunofluorescence and picrosirus red staining, respectively. Treatment of human foreskin fibroblasts with simvastatin or with liposome-encapsulated pravastatin resulted in decreased expression of transcript encoding CTGF. Overall, our novel statin formulations encapsulated in liposomes were successfully delivered through topical application, significantly reducing hypertrophic scarring in a rabbit ear model.

Invited Discussion On: Efficacy and Safety of Intralesional Triamcinolone Versus Combination of Triamcinolone with 5-Fluorouracil in the Treatment of Keloids and Hypertrophic Scars: A Systematic Review and Meta-Analysis.

Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Imiquimod-induced skin inflammation is relieved by knockdown of sodium channel Nax.

Nax is an atypical sodium channel that mediates inflammatory pathways in pathological conditions of the skin. In this study, we developed a skin inflammation model in the rabbit ear through application of imiquimod (IMQ). Knockdown of Nax using RNAi attenuated IMQ-induced skin inflammation, including skin erythema, scaling and papule formation. Histologic analysis showed that thickening and insufficient differentiation of the epidermis found in psoriasis-like skin were normalized by administration of Nax -RNAi. Excessive infiltration of inflammatory cells found in inflammatory lesions, such as mast cells, eosinophils, neutrophils, T cells and macrophages, was reduced by Nax -RNAi. Expression of S100A9, which is a downstream gene of Nax and a mediator of inflammation, was decreased by Nax -RNAi. Our results demonstrated that knockdown of Nax ameliorated IMQ-induced psoriasis-like skin inflammation in vivo. Thus, targeting of Nax may represent a potential therapeutic option for the treatment of psoriasis.

Renal dysfunction aggravated impaired cutaneous wound healing in diabetic mice.

Renal dysfunction has been associated with poor outcomes of wound healing in the diabetic population. The purpose of this study was to create an excisional wound healing model in diabetic mice with renal dysfunction to investigate the combined effects of diabetes and nephropathy on cutaneous ulcers. Renal impairment was introduced in diabetic db/db mice through unilateral nephrectomy and electrocoagulation of the contralateral kidney. Renal function was subsequently monitored with assays of blood urea nitrogen and spot urinary protein/creatinine ratio. After 8 weeks, splinted, full-thickness excisional wounds were created on the dorsal skin and harvested on postoperative days 7 and 14 for further evaluation of wound healing. Renal injury promoted the increase of blood urea nitrogen 3 weeks after initial operation, which was maintained at double the control level throughout the study, concomitantly leading to a significant increase of spot urinary protein excretion. Diabetic mice with renal injury displayed notably impaired wound healing processes, concurrent with reductions in cellular proliferation and angiogenesis, as well as increases in M1 polarized macrophages, infiltrated neutrophils, oxidative stress, and cellular apoptosis. Furthermore, quantitative polymerase chain reaction (qPCR) results displayed corresponding changes of related genes (TNF-α, IL-1ß, SOD2) in the wounds of renal injured db/db mice. Renal manipulation in this study accelerated the progress of renal impairment, which was demonstrated to aggravate impaired cutaneous wound healing in diabetic mice.

S100A8 and S100A9 Are Induced by Decreased Hydration in the Epidermis and Promote Fibroblast Activation and Fibrosis in the Dermis.

The most critical function of the epidermis is to prevent water loss and maintain skin homeostasis. Disruption of the functional skin barrier causes delayed wound healing, hypertrophic scarring, and many skin diseases. Herein, we show that reduced hydration increases the expression of S100 protein family members, S100A8/S100A9, in stratified keratinocyte culture and human ex vivo skin culture. Immunohistological analyses show that S100A8/A9 are highly expressed in the epidermis of human hypertrophic scar and keloid tissues. Reduced hydration demonstrates activation of fibroblasts in the keratinocyte-fibroblast co-culture. In contrast, knockdown of S100A8 or S100A9 by RNA interference in keratinocytes failed to activate fibroblasts. Pretreatment with pharmacological blockers of S100A8/A9 receptors, Toll-like receptor 4 and receptor for advanced glycation end products, inhibits fibroblast activation induced by recombinant S100A8/A9 proteins. Moreover, we observe that local delivery of S100A8 protein results in a marked increase in hypertrophic scarring in the in vivo rabbit ear scar model. Our results indicate that hydration status promotes fibroblast activation and fibrosis by directly affecting the expression of inflammatory signaling in keratinocytes, thereby strongly suggesting S100A8/A9 to be novel targets in preventing scarring.

Thermal injury model in the rabbit ear with quantifiable burn progression and hypertrophic scar.

Hypertrophic scar is a major clinical outcome of deep-partial thickness to full thickness thermal burn injury. Appropriate animal models are a limitation to burn research due to the lack of, or access to, animal models which address the endpoint of hypertrophic scar. Lower species, such as rodents, heal mainly by contracture, which limits the duration of study. Higher species, such as pigs, heal more similarly to humans, but are associated with high cost, long duration for scar development, challenges in quantifying scar hypertrophy, and poor manageability. Here, we present a quantifiable deep-partial thickness burn model in the rabbit ear. Burns were created using a dry-heated brass rod for 10 and 20 seconds at 90 °C. At the time of eschar excision on day 3, excisional wounds were made on the contralateral ear for comparison. Burn wound progression, in which the wound size expands over time is a major distinction between excisional and thermal injuries, was quantified at 1 hour and 3 days after the injuries using calibrated photographs and histology and the size of the wounds was found to be unchanged from the initial wound size at 1 hour, but 10% in the 20 seconds burn wounds at 3 days. A quantifiable hypertrophic scar, measured by histology as the scar elevation index, was present in both 20 seconds burn wounds and excisional wounds at day 35. ImageJ measurements revealed that the 20 seconds burn wound scars were 22% larger than the excisional wound scars and the 20 seconds burn scar area measurements from histology were 26% greater than in the excisional wound scar. The ability to measure both burn progression and scar hypertrophy over a 35-day time frame suits this model to screening early intervention burn wound therapeutics or scar treatments in a burn-specific scar model.

The use of desiccation to treat Staphylococcus aureus biofilm-infected wounds.

Chronic wounds colonized with biofilm present a major burden to our healthcare system. While the current paradigm for wound healing is to maintain a moist environment, we sought to evaluate the effects of desiccation, and the ability of honey to desiccate wounds, on wound healing characteristics in Staphylococcus aureus biofilm wounds. In vivo biofilm wound healing after exposure to open-air desiccation, honey, molasses, and saline was analyzed using a rabbit ear model of S. aureus biofilm wounds previously developed by our group. Wound morphology was examined using scanning electron microscopy and granulation tissue deposition was measured using light microscopy with hematoxylin and eosin staining. Viable bacterial counts in rabbit ear biofilm wounds and scabs were measured using a drop dilution method. In vitro S. aureus growth curves were established using tryptic soy broth containing honey and glycerol. Gene expression analysis of rabbit ear wounds was performed using reverse transcription quantitative PCR. Rabbit ear S. aureus biofilm wounds exposed to open-air desiccation, honey, and molasses developed a dry scab, which displaced the majority of biofilm bacteria off of the wound bed. Wounds treated with open-air desiccation, honey, and molasses expressed lower levels of the inflammatory markers tumor necrosis factor-α and interleukin-1ß at postoperative day 12 compared with wounds treated with saline, and had increased levels of granulation tissue formation. In vitro growth of S. aureus in tryptic soy broth was inhibited by the presence of honey to a greater extent than by the presence of osmolality-matched glycerol. Desiccation of chronic wounds colonized with biofilm via exposure to open air or honey leads to improved wound healing by decreasing bacterial burden and inflammation, and increasing granulation tissue formation. The ability of honey to help heal chronic wounds is at least in part due to its ability to desiccate bacterial biofilm, but other factors clearly contribute.

Systemic administration of hemoglobin improves ischemic wound healing.

BACKGROUND: Oxygen plays multifaceted roles in wound healing, including effects on cell proliferation, collagen synthesis, angiogenesis, and bacterial killing. Oxygen deficit is a major factor in the pathogenesis of chronic wounds. MATERIALS AND METHODS: We present a novel mechanism for oxygen delivery to ischemic wounds by systemic administration of an oxygen carrier substitute derived from bovine hemoglobin (IKOR 2084) in our ischemic rabbit ear wound model. The wound healing indexes, including epithelial gap and neo-granulation tissue area, were histologically analyzed. In situ expression of endothelial cells (CD31+) and proliferative cells (Ki-67+) were examined by immunohistochemistry analysis. The messenger RNA expression of collagen I, III, and vascular endothelial growth factor was measured by quantitative RT-PCR. Sirius Red staining was implemented for detection of collagen deposition, and terminal deoxynucleotidyl transferase dUTP nick end labeling analysis was performed to examine dermal cellular apoptosis. RESULTS: Systemic administration of IKOR 2084 significantly improved oxygen tension of ischemic tissue. When compared with saline controls, IKOR 2084 treatment enhanced wound repair as demonstrated by a reduced epithelial gap and increased granulation tissue area. The expression of Ki-67+, CD31+, vascular endothelial growth factor and collagen was also enhanced by IKOR 2084 administration. Moreover, apoptosis analysis in the wounds showed that cell survival in the dermis was increased by systemic IKOR 2084 administration. CONCLUSIONS: Our study suggests that systemic delivery of IKOR 2084 ameliorates hypoxic state, subsequently promotes angiogenesis, cellular proliferation, and collagen synthesis, attenuates hypoxia-induced apoptosis, and improved ischemic wound healing.

Activity of imipenem against Klebsiella pneumoniae biofilms in vitro and in vivo.

Encapsulated Klebsiella pneumoniae has emerged as one of the most clinically relevant and more frequently encountered opportunistic pathogens in combat wounds as the result of nosocomial infection. In this report, we show that imipenem displayed potent activity against established K. pneumoniae biofilms under both static and flow conditions in vitro. Using a rabbit ear model, we also demonstrated that imipenem was highly effective against preformed K. pneumoniae biofilms in wounds.

In vitro characterization of scaffold-free three-dimensional mesenchymal stem cell aggregates.

Mesenchymal stem cells (MSCs) are capable of self-renewal and differentiation along multiple cell lineages and have potential applications in a wide range of therapies. These cells are commonly cultured as monolayers on tissue culture plastic but possibly lose their cell-specific properties with time in vitro. There is growing interest in culturing adherent cells via three-dimensional (3D) techniques in order to recapitulate 3D in vivo conditions. We describe a novel method for generating and culturing rabbit MSCs as scaffold-free 3D cell aggregates by using micropatterned wells via a forced aggregation technique. The viability and proliferative capability of MSC aggregates were assessed via Live/Dead staining and 5-ethynyl-2'-deoxyuridine (EdU) incorporation. Enzyme-linked immunosorbent assay and antibody-based multiplex protein assays were used to quantify released growth factors and chemokines. The gene expression profile of MSCs as 3D aggregates relative to MSCs grown as monolayers was evaluated via quantitative real-time polymerase chain reaction. The rabbit MSCs were able to form compact cell aggregates and remained viable in 3D culture for up to 7 days. We also demonstrated enhanced gene and protein expression related to angiogenesis and wound healing in MSCs cultured under 3D conditions. In vitro tube formation and scratch assay revealed superior neovessel formation and greater cell recovery and migration in response to 3D conditioned media after wounding. Our data further suggest that adipose-derived stem cell aggregates have greater potential than dermal fibroblasts or bone-marrow-derived MSCs in accelerating wound healing and reducing scarring.

Response of human mature adipocytes to hypoxia-reoxygenation.

BACKGROUND AIMS: Adipocytes are metabolically active cells and have endocrine functions, such as cytokine secretion. Notably, adipocytes are found underneath skin and are thought to be involved in the body's response to ischemia-reperfusion (I-R). I-R injury is an important factor in the pathogenesis of chronic skin wounds. In this study, we investigated the response of human adipocytes to hypoxia-reoxygenation (H-R), the in vitro equivalent of I-R. METHODS: We cultured human mature adipocytes by enclosing them in hydrogel composed of hyaluronan and collagen and analyzed their proliferation and response to H-R. RESULTS: The average diameter of mature adipocytes isolated from abdominal subcutaneous fat tissue was between 60 and 109 µm, and a positive correlation was found between adipocyte size and body mass index. Hydrogel-enclosed human adipocytes displayed viability in in vitro culture and were capable of expressing foreign genes for at least 1 month. Proliferation analysis revealed 5-bromo-2'-deoxy-uridine labeling and positive Ki67 signaling. vascular endothelial growth factor expression was differentially altered in adipocytes in response to hypoxia and H-R. Adipocyte messenger RNA expression of pro-inflammatory cytokines, such as interleukin-1, interleukin-8 and tumor necrosis factor-α, was upregulated in response to H-R. In addition, the expression of heat shock protein 70, a cytoprotective gene, and inducible nitric oxide synthase, a proapoptotic gene, were both increased in H-R. Survival of hydrogel-enclosed adipocytes was found at 2 months after delivery into athymic mice. CONCLUSIONS: These and previous results from our group show that mature adipocytes can be cultured in vitro within a matrix and that they are functionally active cells that respond to environmental changes.

Intravenous curcumin efficacy on healing and scar formation in rabbit ear wounds under nonischemic, ischemic, and ischemia-reperfusion conditions.

Curcumin, a spice found in turmeric, is widely used in alternative medicine for its purported anti-inflammatory and antioxidant activities. The goal of this study was to test the curcumin efficacy on rabbit ear wounds under nonischemic, ischemic, and ischemia-reperfusion conditions. Previously described models were utilized in 58 New Zealand White rabbits. Immediately before wounding, rabbits were given intravenous crude or pure curcumin (6 µg/kg, 30 µg/kg, or 60 µg/kg) dissolved in 1% ethanol. Specimens were collected at 7-8 days to evaluate the effects on wound healing and at 28 days to evaluate the effects on hypertrophic scarring. Student's t test was applied to screen difference between any treatment and control group, whereas analysis of variance was applied to further analyze for all treatment groups in aggregate in some specific experiments. Treatment with crude curcumin suggested accelerated wound healing that reached significance for reepithelialization in lower and medium doses and granulation tissue formation in lower dose. Purified curcumin became available and was used for all later experiments. Treatment with pure curcumin suggested accelerated wound healing that reached significance for reepithelialization in lower and medium doses and granulation tissue formation in lower dose. Treatment with pure curcumin significantly promoted nonischemic wound healing in a dose-response fashion compared with controls as judged by increased reepithelialization and granulation tissue formation. Improved wound healing was associated with significant decreases in pro-inflammatory cytokines interleukin (IL)-1 and IL-6 as well as the chemokine IL-8. Curcumin also significantly reduced hypertrophic scarring. The effects of curcumin were examined under conditions of impaired healing including ischemic and ischemia-reperfusion wound healing, and beneficial effects were also seen, although the dose response was less clear. Systemically administrated pure curcumin significantly promotes nonischemic wound healing and reduces hypertrophic scarring. Improvements in wound healing were associated with decreased inflammatory markers in wounds. Further study is needed to optimize dosing in ischemic and ischemia-reperfusion wound healing. In aggregate, the studies strongly support the systemic administration of curcumin to improve wound healing.

Impact of a novel, antimicrobial dressing on in vivo, Pseudomonas aeruginosa wound biofilm: quantitative comparative analysis using a rabbit ear model.

The importance of bacterial biofilms to chronic wound pathogenesis is well established. Different treatment modalities, including topical dressings, have yet to show consistent efficacy against wound biofilm. This study evaluates the impact of a novel, antimicrobial Test Dressing on Pseudomonas aeruginosa biofilm-infected wounds. Six-mm dermal punch wounds in rabbit ears were inoculated with 10(6) colony-forming units of P. aeruginosa. Biofilm was established in vivo using our published model. Dressing changes were performed every other day with either Active Control or Test Dressings. Treated and untreated wounds were harvested for several quantitative endpoints. Confirmatory studies were performed to measure treatment impact on in vitro P. aeruginosa and in vivo polybacterial wounds containing P. aeruginosa and Staphylococcus aureus. The Test Dressing consistently decreased P. aeruginosa bacterial counts, and improved wound healing relative to Inactive Vehicle and Active Control wounds (p < 0.05). In vitro bacterial counts were also significantly reduced following Test Dressing therapy (p < 0.05). Similarly, improvements in bacterial burden and wound healing were also achieved in polybacterial wounds (p < 0.05). This study represents the first quantifiable and consistent in vivo evidence of a topical antimicrobial dressing's impact against established wound biofilm. The development of clinically applicable therapies against biofilm such as this is critical to improving chronic wound care.

Dermal wound transcriptomic responses to Infection with Pseudomonas aeruginosa versus Klebsiella pneumoniae in a rabbit ear wound model.

BACKGROUND: Bacterial infections of wounds impair healing and worsen scarring. We hypothesized that transcriptome analysis of wounds infected with Klebsiella pneumoniae (K.p.) or Pseudomonas aeruginosa (P.a.) would indicate host-responses associated with the worse healing of P.a.- than K.p.-infected wounds. METHODS: Wounds created on post-operative day (POD) 0 were infected during the inflammatory phase of healing on POD3 and were harvested on POD4 for microarray and transcriptome analysis. Other wounds received topical antibiotic after infection for 24 hours to promote biofilm development, and were harvested on POD6 or POD12. RESULTS: Wounds infected for 24 hours, relative to uninfected wounds, elevated transcripts of immune-response functions characteristic of infiltrating leukocytes. But P.a.-infected wounds elevated many more transcripts and to higher levels than K.p.-infected wounds. Coincidently, suppressed transcripts of both wounds enriched into stress-response pathways, including EIF2 signaling; however, this was more extensive for P.a.-infected wounds, including many-fold more transcripts enriching in the 'cell death' annotation, suggesting resident cutaneous cell toxicity in response to a more damaging P.a. inflammatory milieu. The POD6 wounds were colonized with biofilm but expressed magnitudes fewer immune-response transcripts with no stress-response enrichments. However, elevated transcripts of P.a.-infected wounds were inferred to be regulated by type I interferons, similar to a network unique to P.a.-infected wounds on POD4. On POD12, transcripts that were more elevated in K.p.-infected wounds suggested healing, while transcripts more elevated in P.a.-infected wounds indicated inflammation. CONCLUSIONS: An extensive inflammatory response of wounds was evident from upregulated transcripts 24 hours after infection with either bacterium, but the response was more intense for P.a.- than K.p.-infected wounds. Coincidently, more extensive down-regulated transcripts of P.a.-infected wounds indicated a stronger "integrated stress response" to the inflammatory milieu that tipped more toward cutaneous cell death. Unique to P.a.-infected wounds on POD4 and POD6 were networks inferred to be regulated by interferons, which may result from intracellular replication of P.a. These data point to specific downregulated transcripts of cells resident to the wound as well as upregulated transcripts characteristic of infiltrating leukocytes that could be useful markers of poorly healing wounds and indicators of wound-specific treatments for improving outcomes.

Updated international clinical recommendations on scar management: part 2--algorithms for scar prevention and treatment.

BACKGROUND: In 2002, an international advisory panel was convened to assess the scientific literature and develop evidence-based guidance for the prevention and treatment of pathologic scarring. Emerging clinical data, new treatment options, and technical advances warranted a renewed literature search and review of the initial advisory panel recommendations. OBJECTIVE: To update the management algorithm for pathologic scarring to reflect best practice standards at present. MATERIALS AND METHODS: Management recommendations were derived from clinical evidence amassed during a comprehensive literature search and from the clinical experience and consensus opinion of advisory panel members. RESULTS: A combination approach using multiple modalities provides the maximum potential for successful treatment of hypertrophic scars and keloids. The advisory panel advocates a move toward more aggressive initial management of keloids, including earlier application of 5-fluorouracil. A growing body of clinical research supports a place in therapy for newer agents (e.g., bleomycin, onion extract, imiquimod, mitomycin C) and laser therapy (pulsed-dye, fractional) for scar management. CONCLUSION: Prevention and treatment of pathologic scarring requires individualized care built upon the principles of evidence-based medicine and continues to evolve in step with technological and scientific advances.

Evaluating the effects of subclinical, cyclic ischemia-reperfusion injury on wound healing using a novel device in the rabbit ear.

OBJECTIVE: This study aimed to evaluate the effect of cyclic ischemia-reperfusion (IR) injury on wound healing using a novel rabbit ear model. MATERIALS AND METHODS: A lightweight clamp apparatus was developed for reversible occlusion of the central ear artery. Ventral ear wounds were analyzed postoperatively for epithelialization and granulation as well as gene expression after 3 consecutive days of IR cycling. RESULTS: By postoperative day #7, ears showed no gross tissue necrosis, but histologic analysis of wounds confirmed a significant impairment in epithelial and granulation tissue gaps as well as total epithelial and granulation tissue areas (P < 0.001). Quantitative polymerase chain reaction analysis of IR wounds indicated significant up-regulation of heat shock protein-70 and down-regulation of superoxide dismutase 1 relative to sham controls (P < 0.05). CONCLUSIONS: A novel rabbit ear model for the induction of subclinical, cyclic IR injury in cutaneous tissue has been developed that will serve as a valuable tool for the testing of new therapeutics.