Factors affecting wound healing

Inflammation and wound repair

Wound repair requires the integration of complex cellular networks to restore tissue homeostasis. Defects in wound repair are associated with human disease including pyoderma gangrenosum, a heterogeneous disorder that is characterized by unhealed wounds and chronic inflammation of unclear etiology. Despite its clinical importance, there remain significant gaps in understanding how different types of cells communicate to integrate inflammation and wound repair. Recent progress in wound and regenerative biology has been gained by studying genetically tractable model organisms, like zebrafish, that retain the ability to regenerate. The optical transparency and ease of genetic manipulation make zebrafish an ideal model system to dissect multi-cellular and tissue level interactions during wound repair. The focus of this review is on recent advances in understanding how inflammation and wound repair are orchestrated and integrated to achieve wound resolution and tissue regeneration using zebrafish.

Association of heme oxygenase 1 with the restoration of liver function after damage in murine malaria by Plasmodium yoelii

The liver efficiently restores function after damage induced during malarial infection once the parasites are cleared from the blood. However, the molecular events leading to the restoration of liver function after malaria are still obscure. To study this, we developed a suitable model wherein mice infected with Plasmodium yoelii (45% parasitemia) were treated with the antimalarial α/β-arteether to clear parasites from the blood and, subsequently, restoration of liver function was monitored. Liver function tests clearly indicated that complete recovery of liver function occurred after 25 days of parasite clearance. Analyses of proinflammatory gene expression and neutrophil infiltration further indicated that hepatic inflammation, which was induced immediately after parasite clearance from the blood, was gradually reduced. Moreover, the inflammation in the liver after parasite clearance was found to be correlated positively with oxidative stress and hepatocyte apoptosis. We investigated the role of heme oxygenase 1 (HO-1) in the restoration of liver function after malaria because HO-1 normally renders protection against inflammation, oxidative stress, and apoptosis under various pathological conditions. The expression and activity of HO-1 were found to be increased significantly after parasite clearance. We even found that chemical silencing of HO-1 by use of zinc protoporphyrin enhanced inflammation, oxidative stress, hepatocyte apoptosis, and liver injury. In contrast, stimulation of HO-1 by cobalt protoporphyrin alleviated liver inflammation and reduced oxidative stress, hepatocyte apoptosis, and associated tissue injury. Therefore, we propose that selective induction of HO-1 in the liver would be beneficial for the restoration of liver function after parasite clearance.

bFGF-grafted electrospun fibrous scaffolds via poly(dopamine) for skin wound healing

Electrospun fibrous membranes coated with basic fibroblast growth factor (bFGF) are effective medical devices to promote wound healing. However, the current strategies of adding bFGF generally cause degradation of electrospun materials or damage to the bioactivity of the biomolecules. Here, we have developed a simple strategy for surface bFGF-functionalization of electrospun fibers in an aqueous solution, which maintained original fiber properties and growth factor bioactivity. Polydopamine (PDA) forming the mussel foot protein was chosen as an adhesive polymeric bridge-layer between substrate poly(lactide-co-glycolide) (PLGA) fibers and bFGF. The bFGF-grafted PDA was analyzed using scanning electron microscopy, water contact angle measurements, and X-ray photoelectron spectroscopy. Improved hydrophilicity together with a stable fibrous structure and biodegradable fibrous matrix suggested that the PLGA/PDA-bFGF electrospun fibrous scaffolds have great potential for promoting wound healing. In vitro experiments showed that the bFGF-grafted PLGA electrospun fibrous scaffolds have highly enhanced adhesion, viability, and proliferation of human dermal fibroblasts. In vivo results showed that such scaffolds shortened wound healing time, accelerated epithelialization and promoted skin remodeling. Therefore, this PDA modification method can be a useful tool to graft biomolecules onto polymeric electrospun fibrous scaffolds which are potential scaffold candidates for repairing skin tissue.

Contrasting mechanisms by which social isolation and restraint impair healing in male mice

Stress modulates vital aspects of immune functioning in both human and non-human animals, including tissue repair. For example, dermal wounds heal more slowly and are associated with prolonged inflammation and increased bacterial load in mice that experience chronic physical restraint. Social stressors also negatively affect healing; however, previous studies suggest that the affected healing mechanisms may be stress model-specific. Here, the effects of either social isolation or physical restraint on dermal wound healing (3.5 mm wounds on the dorsum) were compared in hairless male mice. Social isolation beginning 3 weeks prior to wounding delayed healing comparably to physical restraint (12 h/day for eight days), in spite of marked differences in metabolic and hormonal consequences (i.e. body mass) between the two stress models. Additionally, isolated mice exhibited reductions in wound bacterial load and inflammatory gene expression (interleukin-1beta [IL-1β], monocyte chemoattractant protein [MCP]), whereas restraint significantly increased both of these parameters relative to controls. Experimentally augmenting bacterial concentrations in wounds of isolated mice did not ameliorate healing, whereas this treatment accelerated healing in controls. This work indicates that social isolation and restraint stressors comparably impair healing, but do so through disparate mechanisms and at different phases of healing.

Critical size defects for bone regeneration experiments in rabbit calvariae: systematic review and quality evaluation using ARRIVE guidelines

OBJECTIVES

To perform a systematic review of studies that report the healing of critical size defects (CSDs) in rabbit calvaria and to determine the quality of the studies according to ARRIVE guidelines.

MATERIALS AND METHODS

An Internet search was made in duplicate between December 2011 and August 2013 using MEDLINE, PubMed and Google Scholar (without restrictions on date of publication) for rabbit studies reporting the healing of CSD in the calvaria. Animal Research Reporting in Vivo Experiment (ARRIVE) guidelines (a list of 20 aspects to score and to ensure comparison between different experimental studies in animals) were used to evaluate the quality of the selected works.

RESULTS

Twenty-five manuscripts were evaluated. Case-control studies predominated (92.59%). Animal age was not stated in 70.37% of the studies; weight was not reported in 29.62%; most animals weighed 3.5 kg (26.31%). A CSD dimension of 15 mm was common (51.61%), generally located centrally (51.85%), followed by bilateral locations (48.14%). Circular (66.66%), rectangular (14.81%), square (14.81%) and ovoid (1.48%) geometries were used. Histomorphometric data showed incomplete healing in all CSDs and higher percentages of healing in smaller defects (<10 mm). The longer the healing time allowed, the more bone healing took place, for both smaller and larger defects (>15 mm). Minimum quality grades were assigned to ARRIVE items study design (6), experimental animals (8), housing and husbandry (9), sample size (10), allocation (11), statistics (13), results-baseline data (14), numbers analyzed (15), adverse events (17) and funding (20).

CONCLUSIONS

Data on CSDs in rabbit calvariae lack homogeneity. Smaller defects can be considered critical depending on the time of sacrifice. When new diagnostic technologies are used in addition to histomorphometry, these should be applied with caution to facilitate future comparison with other research. The ARRIVE guidelines should be followed in any animal research protocol to improve the homogeneity, comparison and reproducibility between studies.

Immunohistochemical monitoring of wound healing in antibiotic treated Buruli ulcer patients

Background

While traditionally surgery has dominated the clinical management of Buruli ulcer (BU), the introduction of the combination chemotherapy with oral rifampicin and intramuscular streptomycin greatly improved treatment and reduced recurrence rates. However management of the often extensive lesions after successful specific therapy has remained a challenge, in particular in rural areas of the African countries which carry the highest burden of disease. For reasons not fully understood, wound healing is delayed in a proportion of antibiotic treated BU patients. Therefore, we have performed immunohistochemical investigations to identify markers which may be suitable to monitor wound healing progression.

Methodology/Principal findings

Tissue specimens from eight BU patients with plaque lesions collected before, during and after chemotherapy were analyzed by immunohistochemistry for the presence of a set of markers associated with connective tissue neo-formation, tissue remodeling and epidermal activation. Several target proteins turned out to be suitable to monitor wound healing. While α-smooth muscle actin positive myofibroblasts were not found in untreated lesions, they emerged during the healing process. These cells produced abundant extracellular matrix proteins, such as pro-collagen 1 and tenascin and were found in fibronectin rich areas. After antibiotic treatment many cells, including myofibroblasts, revealed an activated phenotype as they showed ribosomal protein S6 phosphorylation, a marker for translation initiation. In addition, healing wounds revealed dermal tissue remodeling by apoptosis, and showed increased cytokeratin 16 expression in the epidermis.

Conclusion/Significance

We have identified a set of markers that allow monitoring wound healing in antibiotic treated BU lesions by immunohistochemistry. Studies with this marker panel may help to better understand disturbances responsible for wound healing delays observed in some BU patients.

Coagulative tissue necrosis and local immunosuppression caused by the M. ulcerans macrolide toxin mycolactone are typical features of Buruli ulcer disease (BU). In particular in BU endemic remote rural areas of West Africa, patients often report with large ulcerated lesions. Despite the availability of an effective dual antimycobacterial antibiotic therapy, some ulcerative lesions may take long time to healing and represent a major burden for the patients as well as for the health system. Proper wound healing is a well-orchestrated process involving numerous cellular and acellular components. Here we have performed immunohistochemical studies with tissue from BU lesions collected before, during and after antibiotic treatment. We identified a set of markers which are appropriate to evaluate formation of granulation tissue (alpha-smooth muscle positive fibroblasts), matrix deposition (pro-collagen 1, fibronectin and tenascin C), cell activation (phosphorylated S6), hyper proliferation of the epidermis (cytokeratin 16) and apoptosis (cleaved caspase 3) during wound healing. These markers may become suitable for assessing progression of tissue repair and for investigating the functional basis of impaired wound healing.

Gram negative wound infection in hospitalised adult burn patients--systematic review and metanalysis-

BACKGROUND

Gram negative infection is a major determinant of morbidity and survival. Traditional teaching suggests that burn wound infections in different centres are caused by differing sets of causative organisms. This study established whether Gram-negative burn wound isolates associated to clinical wound infection differ between burn centres.

METHODS

Studies investigating adult hospitalised patients (2000-2010) were critically appraised and qualified to a levels of evidence hierarchy. The contribution of bacterial pathogen type, and burn centre to the variance in standardised incidence of Gram-negative burn wound infection was analysed using two-way analysis of variance.

PRIMARY FINDINGS

Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanni, Enterobacter spp., Proteus spp. and Escherichia coli emerged as the commonest Gram-negative burn wound pathogens. Individual pathogens' incidence did not differ significantly between burn centres (F (4, 20) = 1.1, p = 0.3797; r2 = 9.84).

INTERPRETATION

Gram-negative infections predominate in burn surgery. This study is the first to establish that burn wound infections do not differ significantly between burn centres. It is the first study to report the pathogens responsible for the majority of Gram-negative infections in these patients. Whilst burn wound infection is not exclusive to these bacteria, it is hoped that reporting the presence of this group of common Gram-negative "target organisms" facilitate clinical practice and target research towards a defined clinical demand.

Optimizing Wound Bed Preparation With Collagenase Enzymatic Debridement

Difficult-to-heal and chronic wounds affect tens of millions of people worldwide. In the U.S. alone, the direct cost for their treatment exceeds $25 billion. Yet despite advances in wound research and treatment that have markedly improved patient care, wound healing is often delayed for weeks or months. For venous and diabetic ulcers, complete wound closure is achieved in as few as 25%-50% of chronic or hard-to-heal wounds. Wound bed preparation and the consistent application of appropriate and effective debridement techniques are recommended for the optimized treatment of chronic wounds. The TIME paradigm (Tissue, Inflammation/infection, Moisture balance and Edge of wound) provides a model to remove barriers to healing and optimize the healing process. While we often think of debridement as an episodic event that occurs in specific care giver/patient interface. There is the possibility of a maintenance debridement in which the chronic application of a medication can assist in both the macroscopic and microscopic debridement of a wound. We review the various debridement therapies available to clinicians in the United States, and explore the characteristics and capabilities of clostridial collagenase ointment (CCO), a type of enzymatic debridement, that potentially allows for epithelialization while debriding. It appears that in the case of CCO it may exert this influences by removal of the necrotic plug while promoting granulation and sustaining epithelialization. It is also easily combined with other methods of debridement, is selective to necrotic tissue, and has been safely used in various populations. We review the body of evidence has indicated that this concept of maintenance debridement, especially when combined episodic debridement may add a cost an efficacious, safe and cost-effective choice for debridement of cutaneous ulcers and burn wounds and it will likely play an expanding role in all phases of wound bed preparation.

uPARAP function in cutaneous wound repair

Optimal skin wound healing relies on tight balance between collagen synthesis and degradation in new tissue formation and remodeling phases. The endocytic receptor uPARAP regulates collagen uptake and intracellular degradation. In this study we examined cutaneous wound repair response of uPARAP null (uPARAP-/-) mice. Full thickness wounds were created on dorsal surface of uPARAP-/- or their wildtype littermates. Wound healing evaluation was done by macroscopic observation, histology, gene transcription and biochemical analysis at specific intervals. We found that absence of uPARAP delayed re-epithelialization during wound closure, and altered stiffness of the scar tissue. Despite the absence of the uPARAP-mediated intracellular pathway for collagen degradation, there was no difference in total collagen content of the wounds in uPARAP-/- compared to wildtype mice. This suggests in the absence of uPARAP, a compensatory feedback mechanism functions to keep net collagen in balance.

The role of the extracellular matrix components in cutaneous wound healing

Wound healing is the physiologic response to tissue trauma proceeding as a complex pathway of biochemical reactions and cellular events, secreted growth factors, and cytokines. Extracellular matrix constituents are essential components of the wound repair phenomenon. Firstly, they create a provisional matrix, providing a structural integrity of matrix during each stage of healing process. Secondly, matrix molecules regulate cellular functions, mediate the cell-cell and cell-matrix interactions, and serve as a reservoir and modulator of cytokines and growth factors' action. Currently known mechanisms, by which extracellular matrix components modulate each stage of the process of soft tissue remodeling after injury, have been discussed.

Propolis modulates fibronectin expression in the matrix of thermal injury

The aim of the study was to assess the propolis effect on fibronectin metabolism in the course of burn wounds healing process. A model of burn wound healing of pig skin was applied. The amount of the released glycoprotein was assessed by a surface plasmon resonance. The profile of extracted fibronectin components was also assessed by an electrophoresis in polyacrylamide gel, with a subsequent immunodetection by Western Blotting. Propolis burn treatment decreased the release of fibronectin components from healing wounds in relation to damages treated with silver sulfadiazine. The main reason of decreased extraction of fibronectin components from wounds treated with propolis was a substantial decrease of degradation product release of the mentioned glycoprotein, which was observed particularly from the 3rd to 5th day of the repair. Wounds treatment with propolis demonstrated, especially in relation to damages treated with silver sulfadiazine, the decreased release of synthesized fibronectin molecules. The obtained results suggest that propolis modifies fibronectin metabolism in the course of wound healing process. The influence of propolis is reflected in prevention of fibronectin biosynthesis as well as its degradation in the wound area. The above-mentioned metabolic changes may decrease the risk of complications in the repair wounds process.

Nonwoven-based gelatin/polycaprolactone membrane proves suitability in a preclinical assessment for treatment of soft tissue defects

Standard preclinical assessments in vitro often have limitations regarding their transferability to human beings, mainly evoked by their nonhuman and tissue-different/nontissue-specific source. Here, we aimed at employing tissue-authentic simple and complex interactive fibroblast-epithelial cell systems and their in vivo-relevant biomarkers for preclinical in vitro assessment of nonwoven-based gelatin/polycaprolactone membranes (NBMs) for treatment of soft tissue defects. NBMs were composed of electrospun gelatin and polycaprolactone nanofiber nonwovens. Scanning electron microscopy in conjunction with actin/focal contact integrin fluorescence revealed successful adhesion and proper morphogenesis of keratinocytes and fibroblasts, along with cells' derived extracellular matrix deposits. The "feel-good factor" of cells under study on the NBM was substantiated by forming a confluent connective tissue entity, which was concomitant with a stratified epithelial equivalent. Immunohistochemistry proved tissue authenticity over time by abundance of the biomarker vimentin in the connective tissue entity, and chronological increase of keratins KRT1/10 and involucrin expression in epithelial equivalents. Suitability of the novel NBM as wound dressing was evidenced by an almost completion of epithelial wound closure in a pilot mini-pig study, after a surgical intervention-caused gingival dehiscence. In summary, preclinical assessment by tissue-authentic cell systems and the animal pilot study revealed the NBM as an encouraging therapeutic medical device for prospective clinical applications.

In vivo healing potential of Aegle marmelos in excision, incision, and dead space wound models

The study incorporates the wound healing potential of Aegle marmelos fruit pulp extract (AME) on excision, incision, and dead space wound models in rats. AME (200 mg/kg) was administered orally once daily for variable days depending on the type of wound ulcer study. AME was studied for its wound breaking strength (incision wound), rate of contraction, period of epithelization and histology of skin (excision model), and granulation tissue free radicals, antioxidants, acute inflammatory marker, and connective tissue markers and deep connective tissue histology (dead space wound). Complete wound contraction and epithelization were observed at the 20th day after treatment with AME as compared to the 24th day in control rats. Mean epithelization period and scar area were decreased while wound breaking strength was increased with AME compared with control. Granulation tissue showed increased levels of collagen determinants (33.7 to 64.4%, P < 0.001) and antioxidants (13.0 to 38.8%, P < 0.05 to P < 0.001), whereas markers of oxidative stress (55.0 to 55.6%, P < 0.001) and myeloperoxidase (21.3%, P < 0.001) were decreased in AME treated group. A. marmelos seems to promote wound healing by enhancing connective tissue formation and antioxidants status with decrease in free radicals and myeloperoxidase having tissue damaging effects.

Enhancing spontaneous stem cell healing (Review)

Adult stem cells are distributed throughout the human body and are responsible to a great extent for the body's ability to maintain and heal itself. Accumulating data since the 1990s regarding stem cells have demonstrated that the beneficial effects of stem cells are not restricted to their ability to differentiate and are more likely due to their ability to release a multitude of molecules. Recent studies indicated that ≤80% of the therapeutic benefit of adult stem cells is manifested by the stem cell released molecules (SRM) rather than the differentiation of the stem cells into mature tissue. Stem cells may release potent combinations of factors that modulate the molecular composition of the cellular milieu to evoke a multitude of responses from neighboring cells. A multitude of pathways are involved in cellular and tissue function and, when the body is in a state of disease or trauma, a multitude of pathways are involved in the underlying mechanisms of that disease or trauma. Therefore, stem cells represent a natural systems-based biological factory for the production and release of a multitude of molecules that interact with the system of biomolecular circuits underlying disease or tissue damage. Currently, efforts are aimed at defining, stimulating, enhancing and harnessing SRM mechanisms, in order to develop systems-based methods for tissue regeneration, develop drugs/biologics or other therapeutics and enhance the release of SRM into the body for natural healing through proper dietary, exercise and other lifestyle strategies.

Retention of insulin-like growth factor I bioactivity during the fabrication of sintered polymeric scaffolds

The use of growth factors in tissue engineering offers an added benefit to cartilage regeneration. Growth factors, such as insulin-like growth factor I (IGF-I), increase cell proliferation and can therefore decrease the time it takes for cartilage tissue to regrow. In this study, IGF-I was released from poly(lactic-co-glycolic acid) (PLGA) scaffolds that were designed to have a decreased burst release often associated with tissue engineering scaffolds. The scaffolds were fabricated from IGF-I-loaded PLGA microspheres prepared by a double emulsion (W1/O/W2) technique. The microspheres were then compressed, sintered at 49 °C and salt leached. The bioactivity of soluble IGF-I was verified after being heat treated at 37, 43, 45, 49 and 60 °C. Additionally, the bioactivity of IGF-I was confirmed after being released from the sintered scaffolds. The triphasic release lasted 120 days resulting in 20%, 55% and 25% of the IGF-I being released during days 1-3, 4-58 and 59-120, respectively. Seeding bone marrow cells directly onto the IGF-I-loaded scaffolds showed an increase in cell proliferation, based on DNA content, leading to increased glycosaminoglycan production. The present results demonstrated that IGF-I remains active after being incorporated into heat-treated scaffolds, further enhancing tissue regeneration possibilities.

Effect of bacteria on the wound healing behavior of oral epithelial cells

Wounded tissue offers opportunity to microflora to adhere, colonize, invade and infect surrounding healthy tissue. The bacteria of the oral cavity have the potential to alter the wound healing process by interacting with keratinocytes. The aim of this study was to investigate mechanisms through which oral bacteria may influence re-epithelialization by interacting with gingival keratinocytes. By an in vitro scratch assay we demonstrate that primary gingival keratinocytes have impaired closure when exposed to two well characterized oral bacteria, P. gingivalis, and to a lesser extent, F. nucleatum. P. gingivalis reduced wound closure by ∼40%, which was partially dependent on proteolytic activity, and bacteria was still present within infected cells 9 days later despite exposure to bacteria for only 24 h. Both oral bacteria caused keratinocyte apoptosis at the wound site with cell death being greatest at the wound edge. P. gingivalis and F. nucleatum adversely affected cell proliferation and the effect also had a spatial component being most striking at the edge. The impact of the bacteria was long lasting even when exposure was brief. Cell migration was compromised in bacteria challenged keratinocytes with P. gingivalis having more severe effect (p<0.05) than F. nucleatum. Quantitative real time PCR of bacteria challenged cells showed that P. gingivalis and to a lesser extent F. nucleatum significantly downregulated cell cycle genes cyclin1, CDK1, and CDK4 (p<0.05) that are critical for GI/S transition. Further, genes associated with cell migration such as integrin beta-3 and -6 were significantly downregulated by P. gingivalis (p<0.05).

Continuous versus interrupted skin sutures for non-obstetric surgery

BACKGROUND

Most surgical procedures involve a cut in the skin, allowing the surgeon to gain access to the surgical site. Most surgical wounds are closed fully at the end of the procedure; this review focuses on these closed wounds. There are many ways to close the surgical incision, for example, using sutures (stitches), staples, tissue adhesives or tapes. Skin sutures can be continuous or interrupted. In general, continuous sutures are usually subcuticular and can be absorbable or non-absorbable, while interrupted sutures are usually non-absorbable and involve the full thickness of the skin - although some surgeons do use absorbable interrupted sutures.

OBJECTIVES

To compare the benefits and harms of continuous compared with interrupted skin closure techniques in participants undergoing non-obstetric surgery.

SEARCH METHODS

In August 2013 we searched the following databases: Cochrane Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid Embase; and EBSCO CINAHL.

SELECTION CRITERIA

We included only randomised controlled trials (RCTs) that compared skin closure using continuous sutures with skin closure using interrupted sutures, irrespective of whether there were differences in the nature of the suture materials used in the two groups. We included all relevant RCTs in the analysis, irrespective of language of publication, publication status, publication year or sample size.

DATA COLLECTION AND ANALYSIS

Two review authors independently identified the trials and extracted data. We calculated the risk ratio (RR) with 95% confidence intervals (CI) for comparing binary outcomes between the groups, and calculated the mean difference (MD) with 95% CI for comparing continuous outcomes. We performed meta-analysis using a fixed-effect model and a random-effects model. We performed intention-to-treat analysis whenever possible.

MAIN RESULTS

We included five RCTs with a total of 827 participants. Outcomes were available for 730 participants (384 participants randomised to continuous sutures and 346 participants to interrupted sutures). All the trials were of unclear or high risk of bias. The participants underwent abdominal or groin operations. The only outcomes reported in the trials were superficial surgical site infection, superficial wound dehiscence (breakdown) and length of hospital stay. Other important outcomes such as quality of life, long-term patient outcomes and use of healthcare resources were not reported in these trials.Overall, 6.5% (39/602 participants, four trials) developed superficial surgical site infections. There was no significant difference between the groups in the proportion of participants who developed superficial surgical site infections (RR 0.73; 95% CI 0.40 to 1.33). A total of 23 participants (23/625 (3.7%), four trials) developed superficial wound dehiscence. Twenty-two of the 23 participants belonged to the interrupted suture group.The proportion of participants who developed superficial wound dehiscence was statistically significantly lower in the continuous suture group compared to the interrupted suture group (RR 0.08; 95% CI 0.02 to 0.35). Most of these wound dehiscences were reported in two recent trials in which the continuous skin suture groups received absorbable subcuticular sutures while the interrupted skin suture groups received non-absorbable transcutaneous sutures. The non-absorbable sutures were removed seven to nine days after surgery in the interrupted sutures groups whilst sutures in the comparator groups were not removed, being absorbable. The continuous suture technique with absorbable suture does not require suture removal and provides support for the wound for a longer period of time. This may have contributed to the difference between the two groups in the proportion of participants who developed superficial wound dehiscence. There was no significant difference in the length of the hospital stay between the two groups (MD -1.40 days; 95% CI -7.14 to 4.34).

AUTHORS' CONCLUSIONS

Superficial wound dehiscence may be reduced by using continuous subcuticular sutures. However, there is uncertainty about this because of the quality of the evidence. Besides, the nature of the suture material used may have led to this observation, as the continuous suturing technique used suture material that did not need to be removed, whereas the comparator used interrupted (non-absorbable) sutures that did need to be removed. Differences in the methods of skin closure have the potential to affect patient outcomes and use of healthcare resources. Further well-designed trials at low risk of bias are necessary to determine which type of suturing is better.

Treating the whole not the hole: necessary coupling of technologies for diabetic foot ulcer treatment

Type 2 diabetes is the epidemic of our generation, and diabetic foot ulcers (DFUs) are a major complication. Although DFU formation itself can indicate disease progression, the failure to effectively treat ulcers contributes further to a decay in patient quality of life and increased mortality. Herein we discuss the development of next-generation DFU therapies including: (i) topical growth factors, (ii) scaffolds, and (iii) cellular therapies. Individually these therapies have yielded measurable but modest improvements in DFU repair. Because DFUs arise as a result of multiple biochemical deficiencies, a singular treatment modality is unlikely to be effective. Next-generation DFU technologies must be combined to address effectively the complex underlying pathology and enable reliable DFU repair.

The effects of social isolation on wound healing mechanisms in female mice

Various stressors impair wound healing in humans and rodents. For example, social isolation delays wound closure in rodents, but the healing mechanisms that underlie this delay have yet to be identified. Here, the effects of three weeks of social isolation on hypothalamic-pituitary-adrenal axis responses and healing factors involved in the inflammatory and proliferative phases of wound healing were assessed in adult female hairless mice. Social isolation reduced basal circulating corticosterone concentrations and increased body and thymus weights compared with group-housed controls. Isolation impaired dermal wound closure by up to 30% and reduced initial total wound bacterial load relative to controls. Inflammatory gene expression in the wounds was not affected by the observed differences in wound bacterial load. However, isolation reduced wound gene expression of keratinocyte growth factor and vascular endothelial growth factor, which are involved in keratinocyte proliferation/migration and angiogenesis during the proliferative phase of healing. These data indicate that social isolation induces healing impairments that may be attributed to reductions in growth factors necessary for proper skin cell proliferation and blood vessel growth during healing. This healing impairment occurred in the absence of both high wound bacterial load and elevated circulating glucocorticoids, which have previously been hypothesized to be required for stress-impaired healing in mice.

Lin28 enhances tissue repair by reprogramming cellular metabolism

Regeneration capacity declines with age, but why juvenile organisms show enhanced tissue repair remains unexplained. Lin28a, a highly conserved RNA-binding protein expressed during embryogenesis, plays roles in development, pluripotency, and metabolism. To determine whether Lin28a might influence tissue repair in adults, we engineered the reactivation of Lin28a expression in several models of tissue injury. Lin28a reactivation improved hair regrowth by promoting anagen in hair follicles and accelerated regrowth of cartilage, bone, and mesenchyme after ear and digit injuries. Lin28a inhibits let-7 microRNA biogenesis; however, let-7 repression was necessary but insufficient to enhance repair. Lin28a bound to and enhanced the translation of mRNAs for several metabolic enzymes, thereby increasing glycolysis and oxidative phosphorylation (OxPhos). Lin28a-mediated enhancement of tissue repair was negated by OxPhos inhibition, whereas a pharmacologically induced increase in OxPhos enhanced repair. Thus, Lin28a enhances tissue repair in some adult tissues by reprogramming cellular bioenergetics. PAPERCLIP:

Subcutaneous closure versus no subcutaneous closure after non-caesarean surgical procedures

BACKGROUND

Most surgical procedures involve a cut in the skin that allows the surgeon to gain access to the surgical site. Most surgical wounds are closed fully at the end of the procedure, and this review focuses on these. The human body has multiple layers of tissues, and the skin is the outermost of these layers. The loose connective tissue just beneath the skin is called subcutaneous tissue, and this generally contains fat. There is uncertainty about closure of subcutaneous tissue after surgery: some surgeons advocate closure of subcutaneous tissue, as they consider this closes dead space and leads to a decrease in wound complications; others consider closure of subcutaneous tissue to be an unnecessary step that increases operating time and involves the use of additional suture material without offering any benefit.

OBJECTIVES

To compare the benefits (such as decreased wound-related complications) and consequences (such as increased operating time) of subcutaneous closure compared with no subcutaneous closure in participants undergoing non-caesarean surgical procedures.

SEARCH METHODS

In August 2013 we searched the following databases: Cochrane Wounds Group Specialised Register (searched 29 August, 2013); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 7); Ovid MEDLINE (1946 to August Week 3 2013); Ovid MEDLINE (In-Process & Other Non-Indexed Citations August 28, 2013); Ovid EMBASE (1974 to 2013 Week 34); and EBSCO CINAHL (1982 to 23 August 2013). We did not restrict studies with respect to language, date of publication or study setting.

SELECTION CRITERIA

We included only randomised controlled trials (RCTs) comparing subcutaneous closure with no subcutaneous closure irrespective of the nature of the suture material(s) or whether continuous or interrupted sutures were used. We included all RCTs in the analysis, regardless of language, publication status, publication year, or sample size.

DATA COLLECTION AND ANALYSIS

Two review authors independently identified the trials and extracted data. We calculated the risk ratio (RR) with 95% confidence intervals (CI) for comparing binary (dichotomous) outcomes between the groups and calculated the mean difference (MD) with 95% CI for continuous outcomes. We performed meta-analysis using the fixed-effect model and random-effects model. We performed intention-to-treat analysis whenever possible.

MAIN RESULTS

Eight RCTs met the inclusion criteria. Six of the trials provided data for this review and all of these were at high risk of bias. Six trials randomised a total of 815 participants to subcutaneous closure (410 participants) or no subcutaneous closure (405 participants). Overall, 7.7% of participants (63/815 of participants) developed superficial surgical site infections and there was no clear evidence of a difference between the two intervention groups (RR 0.84; 95% CI 0.53 to 1.33; very low quality evidence). Only two trials reported superficial wound dehiscence, with 7.9% (17/215) of participants developing the problem. It is not clear whether the lack of reporting of this outcome in other trials was because it did not occur, or was not measured. There was no clear evidence of a between-group difference in the proportion of participants who developed superficial wound dehiscence in the trials that reported this outcome (RR 0.56; 95% CI 0.22 to 1.41; very low quality evidence). Only one trial reported deep wound dehiscence, which occurred in 8.3% (5/60) of participants. There was no clear evidence of a difference in the proportion of participants who developed deep wound dehiscence between the two groups (RR 0.25; 95% CI 0.03 to 2.11; very low quality evidence). Three trials reported the length of hospital stay and found no significant difference between groups (MD 0.10 days; 95% CI -0.45 to 0.64; very low quality evidence). We do not know whether this review reveals a lack of effect or lack of evidence of effect. The confidence intervals for these outcomes were wide, and significant benefits or harms from subcutaneous closure cannot be ruled out. In addition, none of the trials assessed the impact of subcutaneous closure on quality of life, long-term patient outcomes (the follow-up period in the trials varied between one week and two months after surgery) or financial implications to the healthcare provider.

AUTHORS' CONCLUSIONS

There is currently evidence of very low quality which is insufficient to support or refute subcutaneous closure after non-caesarean operations. The use of subcutaneous closure has the potential to affect patient outcomes and utilisation of healthcare resources. Further well-designed trials at low risk of bias are necessary.

Shedding light on a new treatment for diabetic wound healing: a review on phototherapy

Impaired wound healing is a common complication associated with diabetes with complex pathophysiological underlying mechanisms and often necessitates amputation. With the advancement in laser technology, irradiation of these wounds with low-intensity laser irradiation (LILI) or phototherapy, has shown a vast improvement in wound healing. At the correct laser parameters, LILI has shown to increase migration, viability, and proliferation of diabetic cells in vitro; there is a stimulatory effect on the mitochondria with a resulting increase in adenosine triphosphate (ATP). In addition, LILI also has an anti-inflammatory and protective effect on these cells. In light of the ever present threat of diabetic foot ulcers, infection, and amputation, new improved therapies and the fortification of wound healing research deserves better prioritization. In this review we look at the complications associated with diabetic wound healing and the effect of laser irradiation both in vitro and in vivo in diabetic wound healing.

Protocol for cutaneous wound healing assay in a murine model

Cutaneous wound healing assay is important to address many key questions including (1) migration ability of different cells; (2) communication between the different cell types such as keratinocytes, fibroblasts, and immune cells; (3) understanding the cell-autonomous and non-cell-autonomous function(s) of the different cells; and (4) gene regulation in healing processes. Wound healing studies can be used to test new treatment modalities, function of new drugs/compounds, and stem cell-based therapies on the different stages of healing and for accelerating wound healing in patients with compromised healing. In this chapter, we have described a simple step-by-step protocol to generate full-thickness cutaneous wounds in the dorsal skin of mice, followed by collecting the post-wounding biopsied materials on specific days for histological and immunohistochemical analyses and for RNA and protein extractions.

Ocular inflammation in uveal tract in aged obese type 2 diabetic rats (Spontaneously Diabetic Torii fatty rats)

We report uveitis observed in an obese type 2 diabetes rat model, Spontaneously Diabetic Torii Lepr(fa) (SDT fatty) rats aged over 50 weeks. The eyes of SDT fatty rats (16 animals: 7 males and 9 females with 50 or 60 weeks of age) were examined histopathologically. Infiltration of inflammatory cells in the uveal tract was observed in 13 of 16 animals. One female showed severe inflammation affecting the entire uveal tract including the iris, ciliary body, and choroid with a variety of inflammatory cells (neutrophils, lymphocytes, and macrophages). Those changes clinically mimic the findings of diabetic iridocyclitis in diabetic patients. Uveitis associated with diabetes can occur in diabetic patients but the pathogenesis still remains unknown. Since increased extramedullary hematopoiesis in the spleen and abscess in the genital and lower urinary tracts were observed in some SDT fatty rats, increased susceptibility to infection, prolongation of inflammatory states, and disorders of the immune system were considered to be possible factors of the uveitis in aged SDT fatty rats. There have been few reports on how diabetes has influence on the development of uveitis associated with bacterial infection. The SDT fatty rat can be an animal model to investigate diabetes-associated uveitis.

Exercise, Obesity, and Cutaneous Wound Healing: Evidence from Rodent and Human Studies

Significance: Impaired cutaneous wound healing is a major health concern. Obesity has been shown in a number of studies to impair wound healing, and chronic nonhealing wounds in obesity and diabetes are a major cause of limb amputations in the United States. Recent Advances: Recent evidence indicates that aberrant wound site inflammation may be an underlying cause for delayed healing. Obesity, diabetes, and other conditions such as stress and aging can result in a chronic low-level inflammatory state, thereby potentially affecting wound healing negatively. Critical Issues: Interventions which can speed the healing rate in individuals with slowly healing or nonhealing wounds are of critical importance. Recently, physical exercise training has been shown to speed healing in both aged and obese mice and in older adults. Exercise is a relatively low-cost intervention strategy which may be able to be used clinically to prevent or treat impairments in the wound-healing process. Future Directions: Little is known about the mechanisms by which exercise speeds healing. Future translational studies should address potential mechanisms for these exercise effects. Additionally, clinical studies in obese humans are necessary to determine if findings in obese rodent models translate to the human population.

Expectation-induced placebo responses fail to accelerate wound healing in healthy volunteers: results from a prospective controlled experimental trial

Placebo responses have been shown to affect the symptomatology of skin diseases. However, expectation-induced placebo effects on wound healing processes have not been investigated yet. We analysed whether subjects' expectation of receiving an active drug accelerates the healing process of experimentally induced wounds. In 22 healthy men (experimental group, n = 11; control group, n = 11) wounds were induced by ablative laser on both thighs. Using a deceptive paradigm, participants in the experimental group were informed that an innovative 'wound gel' was applied on one of the two wounds, whereas a 'non-active gel' was applied on the wound of the other thigh. In fact, both gels were identical hydrogels without any active components. A control group was informed to receive a non-active gel on both wounds. Progress in wound healing was documented via planimetry on days 1, 4 and 7 after wound induction. From day 9 onwards wound inspections were performed daily accompanied by a change of the dressing and a new application of the gel. No significant differences could be observed with regard to duration or process of wound healing, either by intraindividual or by interindividual comparisons. These data document no expectation-induced placebo effect on the healing process of experimentally induced wounds in healthy volunteers.

Role of stearoyl-CoA desaturase-1 in skin integrity and whole body energy balance

The skin is the single largest organ in humans, serving as a major barrier to infection, water loss, and abrasion. The functional diversity of skin requires the synthesis of large amounts of lipids, such as triglycerides, wax esters, squalene, ceramides, free cholesterol, free fatty acids, and cholesterol and retinyl esters. Some of these lipids are used as cell membrane components, signaling molecules, and a source of energy. An important class of lipid metabolism enzymes expressed in skin is the Δ(9)-desaturases, which catalyze the synthesis in Δ(9)-monounsaturated lipids, primarily oleoyl-CoA (18:1n-9) and palmitoyl-CoA (16:1n-7), the major monounsaturated fatty acids in cutaneous lipids. Mice with a deletion of the Δ(9)-desaturase-1 isoform (SCD1) either globally (Scd1(-/-)) or specifically in the skin (skin-specific Scd1-knockout; SKO) present with marked changes in cutaneous lipids and skin integrity. Interestingly, these mice also exhibit increased whole body energy expenditure, protection against diet-induced adiposity, hepatic steatosis, and glucose intolerance. The increased energy expenditure in skin-specific Scd1-knockout (SKO) mice is a surprising phenotype, as it links cutaneous lipid homeostasis with whole body energy balance. This minireview summarizes the role of skin SCD1 in regulating skin integrity and whole body energy homeostasis and offers a discussion of potential pathways that may connect these seemingly disparate phenotypes.

Wound Healing Activity of the Inflorescence of Typha elephantina (Cattail)

Methanolic extracts of Typha elephantina inflorescence (TE) and its bandage were screened for wound healing by incision and excision wound models in Wistar rats. In the incision wound model, incision wounds were topically treated with TE gel (2.0% [w/w], 3.0% [w/w], and 5.0% [w/w]), Typha elephantina inflorescence bandage, and the reference standard 5.0% w/w povidone iodine for a period of 10 days. When the wounds healed thoroughly, sutures were removed on the 8th postwounding day, and the tensile strength of the skin was measured on the 10th day. In the excision wound model, excision wounds were treated with TE gel (3.0% [w/w] and 5.0% [w/w]), inflorescence bandage, and 5.0% w/w povidone iodine till the wounds completely healed. Epithelization time, wound contraction, hydroxyproline and hexosamine content of the scab, and ascorbic acid and malondialdehyde content of the plasma were determined in this model. In the incision wound model, high tensile strength of the skin of the healed wound was observed in rats treated with the TE gels and the inflorescence bandage when compared with wounded control rats. The increase in tensile strength indicates a promotion of collagen fibers and a firm knitting of the disrupted wound surfaces by collagen. In the excision wound model, higher rate of wound contraction, decreased period of epithelization, elevated hydroxyproline, hexosamine, and ascorbic acid levels, and a significant decrease in malondialdehyde content was observed in treated groups when compared with the wounded control animals. It may be concluded that the inflorescence of Typha elephantina possesses a potent wound healing activity, which may be due to an underlying antioxidant mechanism.

Ganglioside GM3 depletion reverses impaired wound healing in diabetic mice by activating IGF-1 and insulin receptors

Background

Ganglioside GM3 mediates adipocyte insulin resistance, but the role of GM3 in diabetic wound healing, a major cause of morbidity, is unclear.

Purpose

Determine whether GM3 depletion promotes diabetic wound healing and directly activates keratinocyte insulin pathway signaling.

Results

GM3 synthase (GM3S) expression is increased in human diabetic foot skin, ob/ob and diet-induced obese diabetic mouse skin, and mouse keratinocytes exposed to increased glucose. GM3S knockout in diet-induced obese mice prevents the diabetic wound healing defect. Keratinocyte proliferation, migration, and activation of insulin receptor (IR) and insulin growth factor-1 receptor (IGF-1R) are suppressed by excess glucose in wild type cells, but increased in GM3S ^−/− keratinocytes with supplemental glucose. Co-immunoprecipitation of IR, IR substrate-1 (IRS-1), and IGF-1R, and increased IRS-1 and Akt phosphorylation accompany receptor activation. GM3 supplementation or inhibition of IGF-1R or PI3K reverses the increased migration of GM3S^−/− keratinocytes, whereas IR knockdown only partially suppresses migration.

Conclusions

Cutaneous GM3 accumulation may participate in the impaired wound healing of diet-induced diabetes by suppressing keratinocyte insulin/IGF-1 axis signaling. Strategies to deplete GM3S/GM3 may improve diabetic wound healing.

Use of a silver dressing for management of an open abdominal wound complicated by an enterocutaneous fistula-from hospital to community

BACKGROUND

Management of an open abdominal wound complicated by an enterocutaneous fistula poses multiple challenges. The enterocutaneous fistula we discuss opened directly into the abdominal wound, without forming a track through skin.

CASE

We discuss a patient who underwent a Hartmann's procedure for diverticulitis, followed by repeat laparotomies for washout. Due to the edematous bowel and ongoing sepsis, it was not possible to close the abdomen by primary closure. Negative pressure wound therapy (NPWT) has been used successfully in these circumstances. However, the position of an enterocutaneous fistula prevented application of NPWT, and a more conservative approach was used to reduce infection and enable wound closure by secondary intention.

CONCLUSION

Owing to the presence of an enterocutaneous fistula, we applied a silver-based dressing as an alternative to NPWT. The silver-based dressing was initially applied during the patient's hospital course and continued into the community, ultimately resulting in closure of the wound and fistula.

Effect of diets with different fat contents on the development of diabetes in female Zucker diabetic fatty rat with leptin mutation

The aim of the study was to develop a diet which causes stable hyperglycaemia and development of diabetes in female Zucker diabetic fatty (ZDF) rats. We also examined whether worsened wound healing is caused only by hyperglycaemia or whether it is caused by more factors. Four types of special diets with a different content of fat were fed to eight groups of 3–7 (fa/fa or fa/+) rats. The following diets were used: H1 (24.6% fat), H2 (33.2%), C13004 (25.6%), and St1 (3.4%). We detected significant diet-dependent changes of weight and concentration of glucose in animals with leptin mutation (fa/fa). All examined indicators were significantly (P < 0.001) higher in (fa/fa) animals compared to the fa/+ ones no matter what diet they ate. All diets with high-fat content caused increased glycaemia, but only the diet with 24.6% fat caused a significant (P < 0.01) increase of glycaemia. Our results have proved that this diet is the most suitable to invoke and keep hyperglycaemia. The diet with 25.6% fat is suitable to invoke stable slightly increased glycaemia (10 mmol/l) and hyperinsulinaemia. On the other hand, the diet with 33.2% fat is unsuitable. We did not observe a significant influence of diet on wound healing. We developed a new diet more suitable for induction of stable hyperglycaemia in female ZDF rats than commercially available mixtures. Our study is the first to present recommendations for adjusting a high-fat diet to produce stable hyperglycaemia and hyperinsulinaemia in the rat model.