Wound healing: potential therapeutic options.

This review highlights the range of therapeutic options available to clinicians treating difficult-to-heal wounds. While certain treatments are established in daily clinical practice, most therapeutic interventions lack robust and rigorous data regarding their efficacy, which would help to determine when, and for whom, they should be used. The purpose of this review is to give a broad overview of the available interventions, with a brief summary of the evidence base for each intervention.

Development and validation of a gene expression test to identify hard-to-heal chronic venous leg ulcers.

BACKGROUND: Chronic venous leg ulcers pose a significant burden to healthcare systems, and predicting wound healing is challenging. The aim of this study was to develop a genetic test to evaluate the propensity of a chronic ulcer to heal. METHODS: Sequential refinement and testing of a gene expression signature was conducted using three distinct cohorts of human wound tissue. The expression of candidate genes was screened using a cohort of acute and chronic wound tissue and normal skin with quantitative transcript analysis. Genes showing significant expression differences were combined and examined, using receiver operating characteristic (ROC) curve analysis, in a controlled prospective study of patients with venous leg ulcers. A refined gene signature was evaluated using a prospective, blinded study of consecutive patients with venous ulcers. RESULTS: The initial gene signature, comprising 25 genes, could identify the outcome (healing versus non-healing) of chronic venous leg ulcers (area under the curve (AUC) 0·84, 95 per cent c.i. 0·73 to 0·94). Subsequent refinement resulted in a final 14-gene signature (WD14), which performed equally well (AUC 0·88, 0·80 to 0·97). When examined in a prospective blinded study, the WD14 signature could also identify wounds likely to demonstrate signs of healing (AUC 0·73, 0·62 to 0·84). CONCLUSION: A gene signature can identify people with chronic venous leg ulcers that are unlikely to heal.

Investigation of standing balance in patients with diabetic neuropathy at different stages of foot complications.

BACKGROUND: Diabetic peripheral neuropathy is known to cause postural instability. This study investigated standing balance in patients with diabetic neuropathy with secondary foot complications: foot ulceration, partial foot amputation and trans-tibial amputation, which are expected to pose further challenge to balance control. METHODS: In this cross-sectional study, 23 patients with diabetic neuropathy alone (controls) were compared with 23 patients with diabetic foot ulceration, 16 patients with partial foot amputation and 22 patients with trans-tibial amputation. Posturography was used to determine the centre of pressure excursion during quiet standing. Differences between the 4 groups were tested using ANOVA and post-hoc comparisons. FINDINGS: The 4 groups varied in neuropathy score (P=0.001) and demonstrated significant decline in balance from neuropathy alone to foot ulceration, to partial foot amputation and trans-tibial amputation based on total excursion of centre of pressure (P<0.001) and centre of pressure excursion in antero-posterior direction (P<0.001). The excursion of centre of pressure in medio-lateral direction varied between 4 groups (P<0.05) however, there was no significant trend. The distance between ankles increased significantly from neuropathy to trans-tibial amputee group (P=0.001). Post-hoc comparison with controls revealed that each of three study groups demonstrated decreased balance (diabetic neuropathy vs. foot ulceration, P=0.001, diabetic neuropathy vs. partial foot amputation, P=0.002 and diabetic neuropathy vs. trans-tibial amputation, P=0.009). INTERPRETATION: Balance deterioration among patient groups from diabetic neuropathy alone to trans-tibial amputation appears to result from bio-mechanical impairment caused by progression of foot complications in addition to postural instability caused by diabetic neuropathy.

Environmental analysis of plastic production processes: comparing petroleum-based polypropylene and polyethylene with biologically-based poly-beta-hydroxybutyric acid using life cycle analysis.

Polymers based on olefins have wide commercial applicability. However, they are made from non-renewable resources and are characterised by difficulty in disposal where recycle and re-use is not feasible. Poly-beta-hydroxybutyric acid (PHB) provides one example of a polymer made from renewable resources. Before motivating its widespread use, the advantages of a renewable polymer must be weighed against the environmental aspects of its production. Previous studies relating the environmental impacts of petroleum-based and bio-plastics have centred on the impact categories of global warming and fossil fuel depletion. Cradle-to-grave studies report equivalent or reduced global warming impacts, in comparison to equivalent polyolefin processes. This stems from a perceived CO(2) neutral status of the renewable resource. Indeed, no previous work has reported the results of a life cycle assessment (LCA) giving the environmental impacts in all major categories. This study investigates a cradle-to-gate LCA of PHB production taking into account net CO(2) generation and all major impact categories. It compares the findings with similar studies of polypropylene (PP) and polyethylene (PE). It is found that, in all of the life cycle categories, PHB is superior to PP. Energy requirements are slightly lower than previously observed and significantly lower than those for polyolefin production. PE impacts are lower than PHB values in acidification and eutrophication.

A pilot study on the effect of topical negative pressure on quality of life.

OBJECTIVE: To discover the impact of topical negative pressure (TNP) on quality of life. METHOD: An exploratory prospective cohort study was conducted on 26 patients undergoing TNP. The Cardiff Wound Impact Schedule (CWIS), a wound-specific tool, was used to investigate quality-of-life scores before therapy and four weeks after therapy or at wound closure. Wound dimensions were measured at both assessments, and the values for the CWIS domains (physical symptoms, social functioning, well-being and overall quality of life) were investigated using parametric and non-parametric tests. RESULTS: The mean duration of TNP therapy was 3.3 +/- 1.7 weeks. Topical negative pressure therapy helped to achieve complete wound closure in 14 patients (54%), and there was a mean reduction in wound surface area from 52.2 cm2 (range 4-150) to 26.8 cm2 (0-120). While there was no significant change in quality of life in patients whose wounds healed (1 +/- 11.9), the physical-functioning domain improved in obese patients (20 +/- 21, p < 0.05) and worsened in ambulatory patients (-3 +/- 13, p < 0.05). The portableTNP system had no significant impact on quality of life (-3 +/- 16), while the global quality-of-life score worsened with surgical intervention (-0.5 +/- 2, p < 0.05). CONCLUSION: Although TNP aids wound closure in patients with complex wounds, in selected cases their quality of life can worsen. This is the first exploratory cohort study of its kind, and has identified an urgent need to validate the use of patient-based outcome measures in TNP therapy. Such data can be useful in allocating resources and justifying funding in wound care.

The clinical significance and impact of interleukin 15 on keratinocyte cell growth and migration.

Chronic wounds represent a significant burden to health services and are associated with patient morbidity. Novel methods to diagnose and/or treat problematic wounds are needed. Interleukin (IL)-15 is a cytokine involved in a number of biological processes and disease states such as inflammation, healing and cancer progression. The current study explores the expression profile of IL-15 and IL-15 receptor α (IL-15Rα) in chronic wounds and its impact on keratinocytes. IL-15 and IL-15Rα expression were examined in healing and non-healing chronic wounds using qPCR and immunohistochemical analysis. The impact of recombinant IL-15 (rhIL-15) on human adult low calcium temperature (HaCaT) keratinocyte growth and migratory potential was further examined. IL-15 transcript expression was slightly, though non-significantly elevated in healing chronic wounds compared with non-healing chronic wounds. IL-15 protein staining was minimal in both subtypes of chronic wounds. By contrast, IL-15Rα transcript and protein expression were both observed to be enhanced in non-healing chronic wounds compared with healing chronic wounds. The treatment of HaCaT cells with rhIL-15 generally enhanced cell growth and promoted migration. Analysis with small molecule inhibitors suggested that the pro-migratory effect of rhIL-15 may be associated with ERK, AKT, PLCγ and FAK signalling. IL-15 may promote healing traits in keratinocytes and the differential expression of IL-15Rα is observed in chronic wounds. Together, this may imply a complex role for this interleukin in wound healing.

Use of a hydrocapillary dressing in the management of highly exuding ulcers: a comparative study.

OBJECTIVE: To evaluate the safety and performance of Alione Hydrocapillary dressing (Coloplast A/S) in the management of highly exuding chronic venous leg ulcers and compare it with two hydropolymer dressings,Tielle and Tielle Plus (Johnson & Johnson). METHOD: A comparative clinical trial was conducted on 97 patients with an ankle brachial pressure index > or = 0.8 and a highly exuding leg ulcer. Ulcer duration was at least four weeks. Treatment continued until healing or for a maximum of 12 months. RESULTS: There was no statistically significant difference in healing time or wound area reduction between the two treatment protocols. The test dressing (Alione Hydrocapillary) had better absorption capacity and was more comfortable for the patients than the comparator dressings (Tielle/Tielle Plus) and adhered less to the wound bed.Also, more patients preferred the test dressing to their previous treatment. Although severe leakage and maceration were observed more frequently in the comparator group compared with the test group, this was not statistically significant. CONCLUSION: Both treatment protocols were safe and effective in treating highly exuding chronic venous leg ulcers. The test dressing performed as well as or better than the comparator dressings for all study parameters and more patients preferred the test dressing to their previous dressing compared with the comparator dressings.

Sustained silver-releasing dressing in the treatment of diabetic foot ulcers.

This study investigated the clinical performance and safety of a sustained silver-releasing foam dressing, Contreet Foam, in the treatment of diabetic foot ulcers. Twenty-seven patients with diabetic foot ulcers of grade I or II (Wagner's classification) were followed for six weeks: one week run-in using Biatain dressings, four weeks' treatment with Contreet dressings. Four ulcers healed during the four-week treatment with Contreet 56% in average. Contreet Foam showed good exudate management properties and was considered easy to use. Only two infections occurred showed that all six of the non-study ulcers developed an infection during the study. All ulcers (study ulcers as well as non-study ulcers) were treated according to good practice of diabetic wound care. There were no directions for the treatment of secondary wounds. No device-related adverse events were observed. This study demonstrated that Contreet Foam is safe and easy to use and effectively supports healing and good wound progress of diabetic foot ulcers.

Defective extracellular matrix reorganization by chronic wound fibroblasts is associated with alterations in TIMP-1, TIMP-2, and MMP-2 activity.

Chronic leg wounds are characterized by defective remodeling of the extracellular matrix, failure of reepithelialization, and prolonged inflammation. The hypothesis that this defective extracellular matrix remodeling is associated with phenotypic differences in the activity of the matrix metalloproteinases and tissue inhibitors of metalloproteinases was studied in chronic wound and patient-matched normal fibroblasts in three-dimensional collagen lattice systems. Chronic wound fibroblasts exhibited no differences in morphology or proliferation (p > 0.1) compared with patient-matched uninvolved dermal fibroblasts. The ability of chronic wound fibroblasts to reorganize extracellular matrix was significantly impaired, however, in comparison to the uninvolved dermal fibroblasts (p < 0.01). This difference in extracellular matrix reorganization was not related to differences in proliferation within the collagen lattices (p > 0.05) or attachment to type I collagen (p > 0.1). Marked differences were evident in matrix metalloproteinase-2 activity between chronic wound and patient-matched normal fibroblasts. Whereas levels of pro-matrix metalloproteinase-2 were similar between the two fibroblast populations (p > 0.1), the chronic wound fibroblasts exhibited significantly decreased levels of the 62 kDa active form of matrix metalloproteinase-2 (p < 0.01). Reverse zymography and enzyme-linked immunosorbent assay demonstrated that the decreased matrix metalloproteinase-2 activity was associated with increased production of tissue inhibitors of metalloproteinase-1 and -2 by the chronic wound fibroblasts (p < 0.05). Increased production of tissue inhibitors of metalloproteinases in chronic wound fibroblasts was also reflected in decreased levels of matrix metalloproteinase-1 (p < 0.005). These data suggest that the impaired ability of chronic wound fibroblasts to reorganize extracellular matrix in vitro is related to decreased levels of active matrix metalloproteinase-2 and matrix metalloproteinase-1 resulting from increased production of tissue inhibitors of metalloproteinase-1 and -2 by chronic wound fibroblasts. These findings provide a mechanism to explain the impaired cellular responses and extracellular matrix reorganization observed in chronic leg wounds in vivo.

Iodine released from the wound dressing Iodosorb modulates the secretion of cytokines by human macrophages responding to bacterial lipopolysaccharide.

Clinical data suggests that iodine released into the wound environment by Iodosorb may enhance the healing of chronic leg ulcers by a mechanism additional to its anti-bacterial activity. The macrophage is considered to play a central role in controlling wound healing and this study was designed to determine whether interaction with iodine could modulate macrophage cytokine output. The human macrophage cell line U937 was co-cultured with Iodosorb, Iodosorb conditioned medium or elemental iodine in the presence of optimal and sub-optimal stimulatory concentrations of bacterial lipopolysaccharide (LPS). The concentration of tumour necrosis factor-alpha (TNF alpha) and interleukin-6 (IL-6) were assayed in the culture medium after 24 hr culture. Co-culture with 0.25% Iodosorb, Iodosorb conditioned medium or 20 micrograms/ml iodine enhanced TNF alpha secretion (48 +/- 3% cytotoxicity in L929 bioassay to 78 +/- 2% cytotoxicity, +/-SD) by U937 cells stimulated with sub-optimal concentrations of LPS (0.25 ng/ml) and inhibited secretion of IL-6 from cells stimulated with 10 ng/ml LPS (> 750 pg/ml to 267 +/- 52 pg/ml, +/-SD, n = 4). Immunohistological staining of sections prepared from biopsies of chronic leg ulcers indicated that the majority of macrophages present were negative for TNF alpha. Thus one potential mechanism of action of iodine released from Iodosorb used as a wound dressing is to provide a pro-inflammatory stimulus in the wound tissue by activation of the resident macrophage population. This would result in a localized production of pro-inflammatory cytokines and generate an influx of monocytes and T-lymphocytes into the wound that may trigger the wound into a healing phase.

Diagnosing foot infection in diabetes.

Infection represents the presence of an inflammatory response and tissue injury due to the interaction of the host with multiplying bacteria. The disease spectrum is a consequence of the variability in these interactions. Diabetes, because of its effects on the vascular, neurological, and immune systems, can compromise the local and systemic response to infection, potentially masking the typical clinical features and hindering diagnosis. The early recognition of infection, particularly osteomyelitis, is paramount in the management of diabetic foot disease. Careful clinical appraisal remains the cornerstone of the assessment. Hematologic, biochemical, and radiological investigations are important aids in assessing the severity of infection. Microbiological assessment, particularly in more severe infection, requires good-quality samples, combined with rapid transport in an appropriate medium and effective communication with the laboratory. A focused, systematic approach to the accurate diagnosis and treatment of infection, combined with careful monitoring, ensures the maintenance of optimal management.

Wound dressings in diabetic foot disease.

Wound dressings represent a part of the management of diabetic foot ulceration. Ideally, dressings should alleviate symptoms, provide wound protection, and encourage healing. No single dressing fulfills all the requirements of a diabetic patient with an infected foot ulcer. Dressings research in this area is generally poor. However, each category of dressings has particular characteristics that aid selection. Nonadhesive dressings are simple, inexpensive, and well tolerated. Foam and alginate dressings are highly absorbent and effective for heavily exuding wounds. Hydrogels facilitate autolysis and may be beneficial in managing ulcers containing necrotic tissue. Dressings containing inidine and silver may aid in managing wound infection. Occlusive dressings should be avoided for infected wounds. All dressings require frequent change for wound inspection. Heavily exudating ulcers require frequent change to reduce maceration of surrounding skin. Dressing choice should be guided by the characteristics of the ulcer, the requirements of the patient, and costs.

Alginates from wound dressings activate human macrophages to secrete tumour necrosis factor-alpha.

Alginates are used to manufacture a number of wound dressings. Clinical observations indicate that they may initiate or accelerate healing of chronic wounds after treatment of underlying pathology. Wound granulation tissue contains large numbers of macrophages and they are thought to regulate the healing process. As purified alginates have been demonstrated to activate macrophages this study was initiated to determine whether alginates present within wound dressings may interact with wound macrophages. Alginate fibres taken from four commercially available dressings were co-cultured with the human histiocytic lymphoma cell line U937 following its differentiation with PMA. Activation was assessed by measurement of TNFalpha production. Two of the dressings, Seasorb and Tegagen, had a minimal effect whilst Sorbsan at 1 mg/ml induced 302 + 19 pg/ml TNFalpha. This effect was inhibited by polymyxin B indicating that activation was due to endotoxin contamination. Kaltostat induced production of 839 + 36 pg/ml TNFalpha. This effect was induced both by polymyxin inhibitable endotoxin and a direct interaction with the alginate fibres. These data indicate that some alginate containing dressings have the potential to activate macrophages within the chronic wound bed and generate a pro-inflammatory signal which may initiate a resolving inflammation characteristic of healing wounds.

Molecular analysis of the microflora in chronic venous leg ulceration.

There is growing evidence to suggest that the resident microflora of chronic venous leg ulcers impairs cellular wound-healing responses, thereby playing an important role in maintaining the non-healing phenotype of many of these wounds. The significance of individual species of bacteria will remain unclear until it is possible to characterize fully the microflora of such lesions. The limitations and biases of culture-based microbiology are being realized and the subsequent application of molecular methods is revealing greater diversity within mixed bacterial populations than that demonstrated by culture alone. To date, this approach has been limited to a small number of systems, including the oral microflora. Here, for the first time, the comprehensive characterization of the microflora present in the tissue of a chronic venous leg ulcer is described by the comparison of 16S rDNA sequences amplified directly from the wound tissue with sequences obtained from bacteria that were isolated by culture. The molecular approach demonstrated significantly greater bacterial diversity than that revealed by culture. Furthermore, sequences were retrieved that may possibly represent novel species of bacteria. It is only by the comprehensive analysis of the wound microflora by both molecular and cultural methods that it will be possible to further our understanding of the role of bacteria in this important condition.

Continuing education for general practice and the role of the pharmaceutical industry.

A survey of the involvement in and attitudes towards continuing medical education of 101 general practitioners achieved a 95% response rate. Ninety per cent of the 96 doctors worked in practices which held meetings the content of which was organized by representatives of pharmaceutical companies but only 46% worked in practices which organized their own educational meetings. Seventy six per cent attended meetings away from their practice which were organized by drug companies and 75% had attended at some time continuing medical education activities organized by a local postgraduate centre. The promotional aspects of the drug company organized meetings were disliked by a majority of respondents (58%); more of the trainers (62%) and more of those who had entered general practice within the last seven years (71%) disliked this aspect. Nonetheless the educational content of both meetings held in the practice and those held elsewhere was the aspect most liked by over half of the respondents (59% and 53% respectively). Only 16% of all respondents thought that visits by representatives from pharmaceutical companies were educationally valuable and 37% thought that educational events organized by these companies were of value. Surprisingly 60% of those who worked in practices which held meetings organized by drug company representatives thought them to be of little or no educational value. There is clearly a need for practice based continuing medical education but the current level of dependence on drug companies for organizing these meetings must be questioned. Alternative strategies for the provision of independent non-sponsored educational activities should be sought.

Healing of an MRSA-colonized, hydroxyurea-induced leg ulcer with honey.

BACKGROUND: With the everincreasing emergence of antibiotic-resistant pathogens, in particular methicillin-resistant Staphylococcus aureus (MRSA) in leg ulcers, a means of reducing the bacterial bioburden of such ulcers, other than by the use of either topical or systemic antibiotics, is urgently required. METHODS: We report the case of an immunosuppressed patient who developed a hydroxyurea-induced leg ulcer with subclinical MRSA infection which was subsequently treated with topical application of manuka honey, without cessation of hydroxyurea or cyclosporin. RESULTS: MRSA was eradicated from the ulcer and rapid healing was successfully achieved. CONCLUSION: Honey is recognized to have antibacterial properties, and can also promote effective wound healing. A traditional therapy, therefore, appears to have enormous potential in solving new problems.

Human wound contraction: collagen organization, fibroblasts, and myofibroblasts.

The closure of ungrafted sacrococcygeal pilonidal sinus excisional wounds was studied in 15 patients. Wound punch biopsies were taken on a regular basis, and histologic sections were made. To document changes, computer-assisted morphometric image analysis was employed. Initial average wound depth was 37.8 +/- 4.6 mm, and complete closure (0 wound depth) was reached by 68 days. Wound contraction contributed 88 percent to wound closure, whereas the deposition of scar only contributed 12 percent. Maximum cells density within granulation tissue was reached by day 18. Myofibroblasts, identified by alpha-smooth muscle actin immunostaining, first appeared on day 11. Unlike those observed in laboratory animals, myofibroblasts were a minor cell population of granulation tissue, never exceeding 10 percent of the cells. The pattern of collagen fiber organization was documented by polarized light microscopy of Sirius red-stained sections. Early granulation tissue collagen fibers demonstrated a fine greenish birefringence, whereas more mature granulation tissue collagen fibers were thicker, displaying orange-yellowish birefringence. Myofibroblasts were associated exclusively with thicker collagen fibers, whereas fibroblasts were associated with both fine and thick collagen fibers. It is proposed that human wound contraction involves a volume change whereby normal dermal and adipose tissues are pulled into the defect by forces generated within fibroblasts.

The pathogenesis of hypertrophic/keloid scarring.

The formation of hypertrophic and keloid scars after cutaneous wounding is of particular relevance to the practice of maxillofacial surgery. This paper reviews current knowledge of the local and systemic factors underlying the formation of these scars and outlines the current and potential treatment modalities for these lesions.

Causes and effects of the chronic inflammation in venous leg ulcers.

The pathogenesis of venous leg ulcers is multifactorial. In this review article new physiological, molecular and cellular abnormalities in venous ulcers related to the chronic inflammation are presented and discussed. Venous hypertension causes disturbed microcirculation and pathological changes of the capillaries, which eventually locks the condition in a self-amplifying, detrimental cascade with persistent elevated levels and activities of pro-inflammatory cytokines and proteases preventing progress into a healing phase. As a consequence fibroblasts senescence and become less responsive to growth factors the older the ulcers become. Current data imply there is no deficiency but rather an unfavorable distribution of growth factors in venous ulcers. An imbalance in proteolytic enzymes and their endogenous inhibitors is a common finding in chronic venous leg ulcers. Variation in disease severity and concomitant ailments in this heterogeneous patient group may explain the contradictory results in the literature. Thus, to advance the areas of research further, longitudinal studies involving larger number of patients are required to identify the major pathogenic factors.

Measurement of the skin microcirculation through intact bandages using laser Doppler flowmetry.

The microcirculation under compression bandages has been assessed by numerous methods; however, the measurement techniques can disrupt the bandage-skin interface, affecting the measurement. In this study, a non-invasive method for measuring cutaneous blood flow using laser Doppler flowmetry (LDF) is presented. Ten volunteers had their microcirculation assessed by a laser Doppler probe being placed on their upper forearm with and without a light-transmissive gel and with a compression bandage plus light-transmissive gel. A circulatory challenge to the bandaged forearm in two of the volunteers was also undertaken. The median (95% confidence interval) perfusion (p.u.) for the skin surface was 24 (15-33) perfusion units (p.u.), and the skin plus light-transmissive gel demonstrated a higher perfusion: 66 (50-82) p.u., (p < 0.012). The addition of the compression bandage, with additional gel allowed to permeate through to the underlying skin, decreased the perfusion to 27 (20-34) p.u. (p < 0.007). In both volunteers, the microcirculatory flow responded to the vascular challenge, resulting in flow changes related to the cuff pressure (45-27 and 14-8 p.u.). This method demonstrated that it may be possible to assess the microcirculation through intact bandages, without the need to place any sensors at the skin-bandage interface.