Inhibition Of Wound Healing Research Articles

Sulfur mustard downregulates iNOS expression to inhibit wound healing in a human keratinocyte model

Increased nitric oxide (NO) synthesized by inducible NO synthase (iNOS) is involved in inflammatory and pathological conditions. iNOS also regulates several biomarkers that accelerate normal wound healing. Effects of exposure to sulfur mustard (SM) on the skin include formation of blisters and slow-healing injuries. Promoting re-epithelialization is a challenging issue in the treatment of the delayed healing of SM-induced skin injuries. To clarify the role(s) of iNOS in wound healing and the effect of SM on iNOS expression in an in vitro wound assay to eventually develop therapies for SM skin injuries. A wound was created by scratching normal human epidermal keratinocytes grown in vitro. iNOS expression was monitored by Western blotting, fluorescence microscopy, and real-time RT-PCR. Wound healing was analyzed using digitalized image analysis software. The level of iNOS peaked 24-48h after wounding. SM exposure strongly reduced iNOS protein and mRNA levels. Fluorescence microscopy revealed that induction of iNOS expression by wounding and inhibition of iNOS expression by SM occurred not only in the cells at the wound edge but also in cells in the surrounding area, suggesting that wounding may induce and SM may inhibit release of cytokines that stimulate iNOS expression. iNOS-specific small interfering RNAs caused a marked decrease of iNOS expression irrespective of wounding. Gene silencing also completely inhibited wound healing. These results suggest that preventing SM-induced inhibition of iNOS may be a prospective strategy to promote wound healing in SM-exposed skin.

Guidelines for the treatment of venous ulcers

1. Co-chaired this panel2. University of South Florida, Tampa, FL3. Healthpoint Ltd., Fort Worth, TX4. University of California, San Francisco, CA5. University of Texas Medical Branch, Galveston, TX6. University of Cardiff, Cardiff, Wales, UK7. University of Pennsylvania, Philadelphia, PA8. Private practice, Warren, PA9. Private practice, Tamarac, FL10. University of Pittsburgh, Pittsburgh, PA11. St. Louis University, St. Louis, MO, and12. Washington University, St. Louis, MO

The extracellular adherence protein (Eap) of Staphylococcus aureus inhibits wound healing by interfering with host defense and repair mechanisms

AbstractStaphylococcus aureus is a major human pathogen interfering with host-cell functions. Impaired wound healing is often observed in S aureus–infected wounds, yet, the underlying mechanisms are poorly defined. Here, we identify the extracellular adherence protein (Eap) of S aureus to be responsible for impaired wound healing. In a mouse wound-healing model wound closure was inhibited in the presence of wild-type S aureus and this effect was reversible when the wounds were incubated with an isogenic Eap-deficient strain. Isolated Eap also delayed wound closure. In the presence of Eap, recruitment of inflammatory cells to the wound site as well as neovascularization of the wound were prevented. In vitro, Eap significantly reduced intercellular adhesion molecule 1 (ICAM-1)–dependent leukocyte-endothelial interactions and diminished the consequent activation of the proinflammatory transcription factor nuclear factor κB (NFκB) in leukocytes associated with a decrease in expression of tissue factor. Moreover, Eap blocked αv-integrin–mediated endothelial-cell migration and capillary tube formation, and neovascularization in matrigels in vivo. Collectively, the potent anti-inflammatory and antiangiogenic properties of Eap provide an underlying mechanism that may explain the impaired wound healing in S aureus–infected wounds. Eap may also serve as a lead compound for new anti-inflammatory and antiangiogenic therapies in several pathologies.

The Use of Hydrogen Peroxide for Achieving Dermal Hemostasis After Burn Excision in a Patient with Platelet Dysfunction

As a topical hemostatic agent, hydrogen peroxide (3%) has been applied to tangential excisions of burn patients. Hydrogen peroxide provides an adjunct to topical epinephrine for hemostasis and clinically has been most useful in patients with known platelet dysfunction. Hydrogen peroxide should be irrigated from the wound bed before the placement of skin grafting because of its potential to inhibit wound healing. In our experience, hydrogen peroxide (3%) soaks have not resulted in complications related to corrosive damage, oxygen gas formation, or lipid peroxidation that are associated with high concentrations of hydrogen peroxide (30%). We also have experienced excellent skin graft take at the wound bed after using hydrogen peroxide.

Retinoic Acid and Intestinal Wound Healing in Intra-operatively Irradiated Rat

Aim: This study was undertaken to assess the effect of intra-operative radiotherapy on intestinal wound healing and prevention of its side effects by retinoic acid.Materials and methods: Thirty Spraque-Dawley rats were divided into 3 groups of (n = 10). All the groups had laparotomies and terminal ileum exteriorization. Group I was the control group with no irradiation and no anastomosis; group II had both irradiation and anastomosis and group III rats had peroral retinoic acid conditioning and irradiation + anastomosis. On the seventh postoperative day, tensile strength and intestinal elongation measurements were to evaluate the effect of retinoic acid on wound healing.Results: Compared to the non-retinoic acid conditioned group, the retinoic acid conditioned group had statistically significant higher tensile strength and lower intestinal elongation values, revealing better wound healing. Conclusion: Peroral retinoic acid supplement administration has a preventive effect on radiation-induced wound-healing inhibition in intra-operative abdominopelvic irradiation and anastomoses.

Surgical Resection After Downsizing of Colorectal Liver Metastasis in the Era of Bevacizumab

During the last 5 years, numerous publications have demonstrated the potential value of chemotherapy in downstaging patients with hepatic metastasis from colorectal cancer (CRC). Improvements in fluorouracil (FU) -based chemotherapy by the addition of irinotecan or oxaliplatin has led to resectability rates of 12% to 22% in those patients who were initially deemed unresectable. Patients who subsequently undergo resection can achieve a respectable 5-year survival rate (30% to 35%). The addition of bevacizumab, a monoclonal antibody to vascular endothelial growth factor A (VEGF-A), and other targeted therapies (such as cetuximab) to cytotoxic chemotherapy improves response rates further, and it certainly is possible that this could increase the rate of resection. However, this brings one to question the effect of targeted therapies, with or without cytotoxic chemotherapy, on wound healing and hepatic regeneration in patients who undergo liver resection after neoadjuvant therapy. Well-designed preclinical studies have demonstrated that inhibition of angiogenesis can inhibit wound healing. Interestingly, there are no published studies examining the effect of anti-VEGF therapy on liver regeneration. One of the reasons for this lack of data is the fact that studies on liver regeneration in murine models cannot be done with bevacizumab because this antibody specifically recognizes the human form of VEGF and not murine VEGF. It must be remembered that VEGF-A binds to both VEGF receptor 2 (VEGFR2) and VEGFR1, which mediate distinct functions on endothelial cells and other cell types. Bevacizumab, therefore, theoretically can inhibit the activity of both receptors that likely play a role in liver regeneration. In the pivotal phase III clinical trial comparing bolus FU/leucovorin/irinotecan with or without bevacizumab as first-line therapy of advanced CRC, patients who underwent surgery while receiving bevacizumab had a slightly higher (yet not statistically significant) complication rate than those receiving chemotherapy alone (six of 39 v one of 25). A subsequent analysis of pooled data confirmed the increased incidence of complications in patients undergoing surgery while receiving bevacizumab-containing regimens for metastatic CRC. Although these numbers are small, one must recognize the fact that anti-VEGF therapy does inhibit wound healing. Potential inhibition of normal hepatic regeneration becomes even more important when patients are being considered for hepatic resection after downstaging while receiving, or shortly after being treated with bevacizumab-containing regimens. VEGF plays a critical role in liver regeneration after partial hepatectomy or chemical injury. VEGF not only regulates angiogenesis in the regenerating liver, but also mediates a paracrine pathway by which other cytokines can be upregulated in liver sinusoidal endothelial cells. For example, activation of VEGFR1 on liver sinusoidal endothelial cells leads to induction of hepatocyte growth factor that, in turn, mediates liver repair. Interestingly, in regenerating livers in animals with hepatic steatosis, the angiogenic response is impaired. Cytotoxic chemotherapy drugs can induce hepatic steatosis. In patients with CRC metastases who undergo downstaging of their disease by chemotherapy, hepatic steatosis can be present in up to 45% of patients. Therefore, in patients who undergo hepatic resection after treatment with bevacizumab-containing regimens, one must be cognizant of the fact that hepatic regeneration may be impaired due to several mechanisms. Regardless of the mechanism of impaired hepatic regeneration, it is critical to determine the appropriate timing of surgery in patients presenting with CRC metastases who are being considered for liver resection after being treated with bevacizumab-containing chemotherapeutic regimens. In contrast to standard chemotherapeutic agents, the half-life of bevacizumab is relatively long. In pharmacokinetic studies, the mean half-life of bevacizumab is approximately 20 days, but the range varies between 11 and 50 days. Males and patients with large tumor burden seem to JOURNAL OF CLINICAL ONCOLOGY COMMENTS AND CONTROVERSIES VOLUME 23 NUMBER 22 AUGUST 1 2005

Molecular Pathogenesis of Chronic Wounds: The Role of β-Catenin and c- myc in the Inhibition of Epithelialization and Wound Healing

Lack of understanding of the molecular mechanisms and pathogenesis of impaired healing in chronic ulcers is a serious health issue that contributes to excessive limb amputations and mortality. Here we show that beta-catenin and its downstream targets in keratinocytes, c-myc, and keratins K6 and K16, play important roles in the development of chronic wounds. In contrast to normal epidermis, we observed a significant nuclear presence of beta-catenin and elevated c-myc expression at the nonhealing wound edge of chronic ulcers from 10 patients. In vitro studies indicated that stabilization of nuclear beta-catenin inhibited wound healing and keratinocyte migration by blocking epidermal growth factor response, inducing c-myc and repressing the K6/K16 keratins (cytoskeletal components important for migration). The molecular mechanism of K6/K16 repression involved beta-catenin and arginine methyltransferase (CARM-1) acting as co-repressors of glucocorticoid receptor monomers. We conclude that activation of the beta-catenin/c-myc pathway(s) contributes to impaired healing by inhibiting keratinocyte migration and altering their differentiation. The presence of activated beta-catenin and c-myc in the epidermis of chronic wounds may serve as a molecular marker of impaired healing and may provide future targets for therapeutic intervention.

Mitomycin C bei oberflächlichen Hornhautablationen mit dem Excimer-Laser: Eigene Erfahrungen und Literaturübersicht

Haze formation with loss of corneal transparency and surface irregularities and myopic regression are the major complications after corneal refractive surface surgery. The use of mitomycin C (MMC) with its antibiotic and antineoplastic properties is intended to inhibit wound healing mechanisms leading to subepithelial fibrosis. We report the use of MMC to achieve visual rehabilitation in the re-treatment of 3 eyes of 2 patients following refractive corneal surgery. According to the literature, the local use of MMC 0.02 % for 2 minutes is safe and enables one to treat and prevent stromal haze and myopic regression and allows a reduction of the postoperative topical pharmacotherapy. Results are still limited due to small case numbers and short follow-up periods.

Bewährte und aktuelle Verfahren in der Wundheilung

Most chronic wounds are caused by arterial or venous vascular disease. Wound care is an interdisciplinary task and economic challenge. Numerous new wound dressings and treatment methods have been introduced recently. Basic research has enhanced our understanding of stimulation and inhibition of wound healing. Well-constructed clinical studies have shown some traditional approaches to be effective and others, less so. Successful wound healing requires treatment of the underlying disease as well as correction of local factors that may delay healing. The choice of dressings must be based on continuous re-assessment of the wound. Modern approaches for the most common types of chronic wounds, as well as options such as vacuum treatment and tissue-engineered skin are presented along with information on latest rules for reimbursement for wound care in Germany.

Corticosteroid Avoidance Ameliorates Lymphocele Formation and Wound Healing Complications Associated With Sirolimus Therapy

Introduction Sirolimus (RAPA) and corticosteroids (CS) both inhibit wound healing. To evaluate the possibility that RAPA and CS have additive effects on wound healing, we evaluated the effects of corticosteroid avoidance (CSAV) on wound healing complications in patients treated with RAPA. Methods One hundred nine patients treated with a CSAV regimen (no pretransplantation or posttransplantation CS) were compared with a historical control group (n = 72) that received cyclosporine (CsA), mycophenolate mofetil (MMF), and CS. The CSAV group received low-dose CsA, MMF, RAPA, and thymoglobulin induction. Complications were classified as follows: wound healing complications (WHC) or infectious wound complications (IWC). WHC included lymphocele, hernia, dehiscence, diastasis, and skin edge separation. IWC included wound abscess and empiric antibiotic therapy for wound erythema. Results The CSAV group was largely CS-free: 11% of patients received CS for rejection, 12% of patients received CS for recurrent disease, and 85% of patients are currently off CS. The CSAV group had a significantly lower incidence of WHC (13.7% vs 28%; P = .03) and lymphoceles (5.5% vs 16%; P = .02) than the control group. There was no difference in the incidence of IWC between the 2 groups. Patients who received CSAV were 18% less likely ( P = .57) to develop any type of complication, 41% less likely ( P = .20) to develop a WHC, and 71% less likely ( P = .018) to develop a lymphocele. Conclusions CSAV in a RAPA-based regimen results in a marked reduction in WHC and lymphoceles. Therefore, CSAV provides a promising approach for addressing WHC associated with RAPA therapy.

JNK signaling pathway required for wound healing in regenerating Drosophila wing imaginal discs

We have examined wound healing during regeneration of Drosophila wing imaginal discs fragments by confocal microscopy and assessed the role of components of the JNK pathway in this process. After cutting, columnar and peripodial epithelia cells at the wound edge start to close the wound through formation and contraction of an actin cable. This is followed by a zipping process through filopodial protrusions from both epithelia knitting the wound edges from proximal to distal areas of the disc. Activation of the JNK pathway is involved in such process. puckered ( puc) expression is induced in several rows of cells at the edge of the wound, whereas absence of JNK pathway activity brought about by hemipterous, basket, and Dfos mutants impair wound healing. These defects are accompanied by lowered or loss of expression of puc. In support of a role of puc in wound healing, hep mutant phenotypes are rescued by reducing puc function, whereas overexpression of puc inhibits wound healing. Altogether, these results demonstrate a role for the JNK pathway in imaginal disc wound healing, similar to that reported for other healing processes such as embryonic dorsal closure, thoracic closure, and adult epithelial wound healing in Drosophila. Differences with such processes are also highlighted.

Local Activation of Rap1 Contributes to Directional Vascular Endothelial Cell Migration Accompanied by Extension of Microtubules on Which RAPL, a Rap1-associating Molecule, Localizes

Endothelial cell migration is promoted by chemoattractants and is accompanied with microtubule extension toward the leading edge. Cytoskeletal microtubules polarize to function as rails for delivering a variety of molecules by motor proteins during cell migration. It remains, however, unclear how directional migration with polarized extension of microtubules is regulated. Here we report that Rap1 controls the migration of vascular endothelial cells. We found that Rap1-associating molecule, RAPL, which belongs to the Ras association domain family (Rassf), localized on microtubules and that activated Rap1 induced dissociation of RAPL from microtubules. A Rap1 activation-monitoring probe based on the fluorescence resonance energy transfer enabled us to demonstrate that local Rap1 activation occurs at the leading edge of the cells under the two types of cell migration, chemotaxis and wound healing. Time lapse imaging of microtubules marked by enhanced green fluorescent protein-RAPL showed the directional growth of microtubules toward the leading edge of the migrating cells. Using adenovirus, inactivation of Rap1 by expression of rap1GAPII inhibited wound healing. In addition, disconnection of Rap1 and RAPL by expression of a RAPL mutant also perturbed wound healing. Collectively, the locally activated Rap1 and its association with RAPL controls the directional migration of vascular endothelial cells.

Surgical wound healing complications in metastatic colorectal cancer patients treated with bevacizumab

Bevacizumab (Avastin; rhuMab VEGF), a humanized monoclonal antibody against vascular endothelial growth factor (VEGF), significantly prolongs survival when added to intravenous 5-fluorouracil-based chemotherapy in first-line metastatic colorectal cancer (CRC) treatment. Because antiangiogenic agents might inhibit wound healing, we assessed postoperative wound healing complications in two randomized trials of 5 mg/kg bevacizumab in CRC treatment. We assessed the wound healing complications in patients who: (1) underwent cancer surgery 28-60 days before study treatment and (2) underwent major surgery during study treatment. Cases were reviewed for wound healing complications occurring < or = 60 days after surgery. With cancer surgery 28-60 days before study treatment, wound healing complications occurred in 3/230 (1.3%) bevacizumab-treated patients and 1/194 (0.5%) control patients. With major surgery during study treatment, 10/75 bevacizumab-treated patients (13%) and 1/29 control patients (3.4%) had wound healing complications. Bevacizumab-treated patients experienced complications with surgery < or = 30 and 31-60 days after the last dose. Bevacizumab administered in combination with 5-fluorouracil/leucovorin-based chemotherapy 28-60 days after primary cancer surgery caused no increased risk of wound healing complications compared with chemotherapy alone. While wound healing complications were increased in patients who had major surgery during bevacizumab therapy, the majority of bevacizumab-treated patients experienced no complications.

From an Enhanceosome to a Repressosome: Molecular Antagonism between Glucocorticoids and EGF Leads to Inhibition of Wound Healing

Wound healing in its complexity depends on the concerted activity of many signaling pathways. Here, we analyzed how the simultaneous presence of glucocorticoids (GC), retinoic acid (RA) and epidermal growth factor (EGF) affect wound healing at the molecular, cellular and tissue levels. We found that GC inhibit wound healing by inhibiting keratinocyte migration, whereas RA does not. Furthermore, GC block EGF-mediated migration, whereas RA does not. On the molecular level, these compounds target expression of one of the earliest markers of wound healing, cytoskeletal components, keratins K6 and K16. Both GC and RA repress their transcription, whereas EGF induces it. Interestingly, the GC inhibition is mediated by a repressosome complex consisting of four monomers of the GC receptor, beta-catenin and coactivator-associated-arginine-methyltransferase-1. GC are dominant, EGF cannot rescue GC-mediated inhibition. Pre-treatment of keratinocytes with GC shifts the balance towards the repressosome, allowing for dominant inhibition of K6 even in the presence of EGF or c-fos/c-jun. Although RA receptor gamma and glucocorticoid receptor bind to the same response element repressing transcription of keratins K6/K16, RA receptor interacts with the components of the EGF-enhanceosome (co-activators: glucocorticoid-receptor-interactive protein-1(GRIP-1)/steroid-receptors coactivator-1 (SRC-1)) without breaking it. Consequently, RA has a co-dominant effect with EGF: when present simultaneously, their effects balance each other. When keratinocytes are pre-treated with mitogen-activated protein kinase (MAPK) inhibitor, thus blocking EGF, the balance is shifted towards the RA repression. Similar to clinical findings, pre-treatment of keratinocytes with RA blocks GC-mediated inhibition. In summary, our results identify complex molecular mechanisms through which RA alleviates GC-mediated inhibition of wound healing.

Stress exposure modulates peptidergic innervation and degranulates mast cells in murine skin

Stress is said to induce itchiness of the skin, exacerbate inflammatory skin diseases, and inhibit wound healing. Neuropeptides such as substance P (SP) may play a role in these processes. Recently, we were able to show that both stress or SP are associated with neurogenic inflammation and increased apoptosis in the murine hair follicle. Moreover, peptidergic cutaneous innervation is subject to lifelong plasticity due to its association with the cyclic growth of hair follicles. However, peripheral neuronal plasticity has never been reported in altered interactions between the nervous and immune systems under perceived stress. Here, we show for the first time plasticity of the cutaneous peptidergic innervation in response to stress. After exposure to sonic stress, the number of SP+ nerve fibers in the back skin of C57BL/6 mice with their hair follicles in the resting phase of the hair cycle (telogen—low numbers of nerve fibers) increased significantly. Such nerve fibers contacted mast cells more frequently. At the same time, the percentage of degranulated mast cells increased significantly associated with a rise in apoptotic cells in the skin. Increased numbers of peptidergic nerve fibers correlated with increased numbers of growth-associated protein 43 (Gap-43)+ nerve fibers, which is a marker for growing nerves. Thus, neuronal plasticity and increased neuro-immune interaction occur under stress and may alter inflammatory skin diseases and trophic functions in the skin where neurogenic inflammation plays a part.

ADAM-15 inhibits wound healing in human intestinal epithelial cell monolayers.

The disintegrin metalloproteases (or ADAMs) are membrane-anchored glycoproteins that have been implicated in cell-cell or cell-matrix interactions and in proteolysis of molecules on the cell surface. The expression and/or the pathophysiological implications of ADAMs are not known in intestinal epithelial cells. Therefore, our aim was to investigate the expression and the role of ADAMs in intestinal epithelial cells. Expression of ADAMs was assessed by RT-PCR, Western blot analysis, and immunufluorescence experiments. Wound-healing experiments were performed by using the electric cell substrate impedence sensing technology. Our results showed that ADAMs-10, -12, and -15 mRNA are expressed in the colonic human cell lines Caco2-BBE and HT29-Cl.19A. An ADAM-15 complementary DNA cloned from Caco2-BBE poly(A)+ RNA, and encompassing the entire coding region, was found to be shorter and to present a different region encoding the cytoplasmic tail compared with ADAM-15 sequence deposited in the database. In Caco2-BBE cells and colonic epithelial cells, ADAM-15 protein was found in the apical, basolateral, and intracellular compartments. We also showed that the overexpression of ADAM-15 reduced cell migration in a wound-healing assay in Caco2-BBE monolayers. Our data show that 1) ADAM-15 is expressed in human intestinal epithelia, 2) a new variant of ADAM-15 is expressed in a human intestinal epithelial cell line, and 3) ADAM-15 is involved in intestinal epithelial cells wound-healing processes. Together, these results suggest that ADAM-15 may have important pathophysiological roles in intestinal cells.

RhoA and Rac1 are both required for efficient wound closure of airway epithelial cells.

Repair of the airway epithelium after injury is critical for restoring normal lung. The reepithelialization process involves spreading and migration followed later by cell proliferation. Rho-GTPases are key components of the wound healing process in many different types of tissues, but the specific roles for RhoA and Rac1 vary and have not been identified in lung epithelial cells. We investigated whether RhoA and Rac1 regulate wound closure of bronchial epithelial cells. RhoA and Rac1 proteins were efficiently expressed in a cell line of human bronchial epithelial cells (16HBE) by adenovirus-based gene transfer. We found that both constitutively active RhoA and dominant negative RhoA inhibited wound healing, suggesting that both activation and inhibition of RhoA interfere with normal wound healing. Overexpression of wild-type Rac1 induced upregulation of RhoA, disrupted intercellular junctions, and inhibited wound closure. Dominant negative Rac1 also inhibited wound closure. Inhibition of the downstream effector of RhoA, Rho-kinase, with Y-27632 suppressed actin stress fibers and focal adhesion formation, increased Rac1 activity, and stimulated wound closure. The activity of both RhoA and Rac1 are influenced by the polymerization state of microtubules, and cell migration involves coordinated action of actin and microtubules. Microtubule depolymerization upon nocodazole treatment led to an increase in focal adhesions and decreased wound closure. We conclude that coordination of both RhoA and Rac1 activity contributes to bronchial epithelial wound repair mechanisms in vitro, that inhibition of Rho-kinase accelerates wound closure, and that efficient repair involves intact microtubules.

111 HB‐50: A Pre‐Clinical Study of a Prophylactic for Wound Infection

Topical prophylaxis against wound infection by an agent that is active against multi‐resistant bacteria does not generate resistance and is rapidly cidal would be of great clinical benefit. Peptides of the innate immune system have long been known to protect a wide range of organisms from attack by bacterial and fungal pathogens. Helix BioMedix Inc. has developed a short bioactive peptide antimicrobial modeled after these peptides. HB‐50 is an amphipathic cationic alpha‐helical peptide that has broad spectrum activity and is rapidly microbicidal. These attributes make HB‐50 an ideal candidate for wound infection prophylaxis. In vitro studies have demonstrated HB‐50 to be active against both gram‐positive and gram‐negative bacteria killing 5–7 log orders of bacteria within minutes. In addition, this peptide has potent activity against Vancomycin and Mupirocin resistant S. aureus. Preliminary testing of the peptide in a rat abraded skin infection model has shown the peptide’s effectiveness in preventing wound infection while not inhibiting wound healing. Additionally, the HB‐50 sequence has been specifically developed to be cost effective to manufacture and therefore is well suited for use as a topical antimicrobial agent.

138 Molecular Pathogenesis of Chronic Wounds: The Role of β‐Catenin and C‐MYC

The lack of understanding of molecular pathogenesis of impaired healing in chronic ulcers leads to a serious health issue that contributes to excessive limb amputations and mortality. Using biopsies from patients with chronic wounds, skin organ culture and primary keratinocytes in culture we identified that β‐catenin and its downstream target, c‐myc, play important role in development of chronic wounds. In contrast to normal epidermis, we observed significant nuclearization of β‐catenin and elevated c‐myc expression at the non‐healing wound edge of patients with chronic ulcers. In vitro studies indicated that activation and stabilization of nuclear β‐catenin inhibits wound healing and keratinocyte migration by: blocking EGF response and inducing c‐myc. Using Affymetrix large scale microarrays we found that β‐catenin downstream target, c‐myc, is induced in skin by an inhibitor of wound healing (glucocorticoids) and repressed in the initial phase of normal wound healing, 4 to 48 hr, whereas it becomes de‐repressed at 96 hr post wounding. Therefore, the activation of β‐catenin/c‐myc pathway(s) contributes to impaired healing by inhibiting of keratinocyte migration and altering keratinocyte differentiation. The presence of activated β‐catenin and c‐myc in the epidermis of chronic wounds may serve as molecular markers of impaired healing and future targets for therapeutic intervention. While β‐catenin signaling has been implicated in epithelial development and oncogenesis its role in wound healing has never been postulated. This further illustrates the importance of “tissue context” specificity, because β‐catenin in the context of malignant tissue promotes invasion whereas in the context of a wound environment does the opposite.

Healing of Colon Anastomoses Covered With Fibrin Glue After Immediate Postoperative Intraperitoneal Administration of 5-Fluorouracil

The aim of this experimental study was to investigate whether covering the colonic anastomoses with fibrin glue can protect the colonic healing from the adverse effects of 5-fluorouracil (5-FU), when it is injected intraperitoneally immediately after colon resection. Sixty-four rats were randomized to one of four groups. After resection of a 1-cm segment of the transverse colon, an end-to-end sutured anastomosis was performed. Rats of the control group and the fibrin glue group were injected with 6 ml of solution 0.9 percent NaCl intraperitoneally. Rats in the 5-FU and the 5-FU + fibrin glue groups received 5-FU intraperitoneally. The colonic anastomoses of the rats in the fibrin glue group and in the 5-FU + fibrin glue group were covered with fibrin glue. All rats were killed on the 8th postoperative day and the anastomoses were examined macroscopically. The bursting pressure measurements were recorded and the anastomoses were graded histologically. The leakage rate of the anastomoses was significantly higher in the rats of the 5-FU group than in those of the fibrin glue group and those of the 5-FU + fibrin glue group (37.5 percent vs. 0 percent, P = 0.020). The adhesion formation score was significantly higher in rats of the 5-FU group than in the other groups. Bursting pressures were also significantly lower in the 5-FUgroup than in the other groups ( P < 0.001). Rats in the 5-FU + fibrin glue group developed significantly more marked neoagiogenesis than rats in the other groups. Rats in the 5-FU + fibrin glue group also presented significantly more fibroblast activity than those in the 5-FU group. ( P = 0.004) The immediate postoperative, intraperitoneal administration of 5-FU inhibited wound healing. However, when the colonic anastomoses were covered with fibrin glue, the injection of 5-FU had no adverse effects on the healing of the anastomoses.