Venous leg ulcers - the search for a prognostic indicator

Utility of routine laboratory tests in the assessment of chronic venous disease progression in female patients

Chronic venous disease (CVD) is a frequently encountered disease that progresses with age. Although the principal method of evaluation and diagnosis is Doppler ultrasound, routine laboratory tests may be an easier and more accessible way to evaluate CVD progression. The present retrospective study evaluated the laboratory results of 256 patients diagnosed with CVD. According to the Clinical, Etiological, Anatomical and Pathophysiological classification, depending on the CVD stage, patients were stratified into three groups: Group 1 (C2-C3; mild disease), Group 2 (C4; moderate to severe disease) and Group 3 (C5-C6; severe disease). The considered parameters were age, red blood cell count (RBC), white blood cell count (WBC) and platelet count (PLT), percentage of neutrophils and lymphocytes, neutrophil-to-lymphocyte ratio (NLR), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), fibrinogen, prothrombin time (in percentages and seconds), internal normalized ratio, activated partial thromboplastin time, creatine kinase (CK), CK myocardial band, alanine transaminase, aspartate transaminase, total bilirubin and urea. No significant differences among the groups were noted in RBC, WBC, PLT and coagulation factors; on the other hand, inflammatory markers exhibited differences among the groups. Several differences were observed in hepatic, metabolic and muscle tissue markers. Intraluminal thrombus formation in the case of varicose veins (thrombophlebitis) may be due to conditions of turbulent flow, stasis and endothelial inflammation, rather than hypercoagulability. The results of the present study confirmed the implication of inflammatory factors in pathophysiological modifications, including thickening of venous walls and valvular modification, as well as the appearance of intraluminal thrombi and trophic lesions. NLR, ESR, CRP and fibrinogen were increased with CVD progression and may be considered useful markers in evaluating CVD progression. Simple blood tests may provide phlebologists with additional insight for the management of those patients.

Sensitivity of the Wound Edge Gene Signature "WD14" in Responding to Clinical Change: A Longitudinal Cohort Study

Introduction: WounD14 (WD14) gene signature is a recently developed tool derived from genetic interrogation of wound edge biopsies of chronic venous leg ulcers to identify heard-to-heal wounds and enable clinicians to target aggressive therapies to promote wound healing. This study aimed to evaluate if changes in wound clinical healing status were detected by the WD14 gene signature over time as this is currently poorly understood. Material and methods: WD14 was developed through gene screening and subsequent validation in 3 patient cohorts involving 85 consecutive patients with chronic venous leg ulcers referred to a tertiary wound healing unit. Patients underwent a wound edge biopsy to interrogate for a "healing" or "non-healing" genotype. A smaller cohort (18%) underwent a second biopsy, which comprised this pilot cohort reported herein. Twelve weeks following biopsy, wounds were clinically assessed for healing status based on reduction in size and compared to WD14 genotype. Results: Sequential biopsies and WD14 scores were derived from 16 patients. WD14 signature predicted wound healing status among this cohort at either visit (32 wound edge biopsies) with a positive predictive value (PPV) of 85.2% (95% CI 74.1%-92.0%) and negative predictive value (NPV) of 80.0% (95% CI 34.2%-96.9%). A total of 6 wounds underwent altered clinical status between the 2 visits. In this cohort, WD14 has a PPV of 66.7% (95% CI 47.3%-81.7%) and NPV of 100%. Conclusion: Although the WD14 gene signature did change with wound healing status, larger studies are required to precisely clarify its role and ability to prognosticate wounds of differing clinical status over time.

Growth factors for treating chronic venous leg ulcers: A systematic review and meta-analysis

Chronic venous leg ulcers (VLU) are wounds that commonly occur due to venous insufficiency. Many growth factors have been introduced over the past two decades to treat VLU. This systematic review and meta-analysis evaluates the impact of growth factor treatments of VLU in comparison to control for complete wound healing, percent reduction in wound area, time to wound healing, and adverse events. A systematic review and meta-analysis of randomised trials was conducted. MEDLINE and EMBASE were searched up to December 2020. Studies were included if they compared a growth factor versus placebo or standard care in patients with VLU. From 1645 articles, 13 trials were included (n = 991). There was a significant difference between any growth factor and placebo in complete wound healing (P = 0.04). Any growth factor compared to placebo significantly increased the likelihood of percent wound reduction by 48.80% (P = <0.00001). There was no difference in overall adverse event rate. Most comparisons have low certainty of evidence according to Grading of Recommendations, Assessment, Development, and Evaluation. This meta-analysis suggests that growth factors have a beneficial effect in complete wound healing of VLU. Growth factors may also increase percent reduction in wound area. The suggestion of benefit for growth factors identified in this review is not a strong one based on the low quality of evidence.

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.

Varicose Veins and Chronic Venous Disease

Chronic venous disease is a worldwide problem associated with significant morbidity and is expected to increase in prevalence as the current population ages. This is a comprehensive review of the anatomy, pathophysiology, genomics, clinical classification, and treatment modalities of chronic venous disease.

Why Venous Leg Ulcers Have Difficulty Healing: Overview on Pathophysiology, Clinical Consequences, and Treatment

Venous leg ulcers (VLUs) are one of the most common ulcers of the lower extremity. VLU affects many individuals worldwide, could pose a significant socioeconomic burden to the healthcare system, and has major psychological and physical impacts on the affected individual. VLU often occurs in association with post-thrombotic syndrome, advanced chronic venous disease, varicose veins, and venous hypertension. Several demographic, genetic, and environmental factors could trigger chronic venous disease with venous dilation, incompetent valves, venous reflux, and venous hypertension. Endothelial cell injury and changes in the glycocalyx, venous shear-stress, and adhesion molecules could be initiating events in VLU. Increased endothelial cell permeability and leukocyte infiltration, and increases in inflammatory cytokines, matrix metalloproteinases (MMPs), reactive oxygen and nitrogen species, iron deposition, and tissue metabolites also contribute to the pathogenesis of VLU. Treatment of VLU includes compression therapy and endovenous ablation to occlude the axial reflux. Other interventional approaches such as subfascial endoscopic perforator surgery and iliac venous stent have shown mixed results. With good wound care and compression therapy, VLU usually heals within 6 months. VLU healing involves orchestrated processes including hemostasis, inflammation, proliferation, and remodeling and the contribution of different cells including leukocytes, platelets, fibroblasts, vascular smooth muscle cells, endothelial cells, and keratinocytes as well as the release of various biomolecules including transforming growth factor-β, cytokines, chemokines, MMPs, tissue inhibitors of MMPs (TIMPs), elastase, urokinase plasminogen activator, fibrin, collagen, and albumin. Alterations in any of these physiological wound closure processes could delay VLU healing. Also, these histological and soluble biomarkers can be used for VLU diagnosis and assessment of its progression, responsiveness to healing, and prognosis. If not treated adequately, VLU could progress to non-healed or granulating VLU, causing physical immobility, reduced quality of life, cellulitis, severe infections, osteomyelitis, and neoplastic transformation. Recalcitrant VLU shows prolonged healing time with advanced age, obesity, nutritional deficiencies, colder temperature, preexisting venous disease, deep venous thrombosis, and larger wound area. VLU also has a high, 50-70% recurrence rate, likely due to noncompliance with compression therapy, failure of surgical procedures, incorrect ulcer diagnosis, progression of venous disease, and poorly understood pathophysiology. Understanding the molecular pathways underlying VLU has led to new lines of therapy with significant promise including biologics such as bilayer living skin construct, fibroblast derivatives, and extracellular matrices and non-biologic products such as poly-N-acetyl glucosamine, human placental membranes amnion/chorion allografts, ACT1 peptide inhibitor of connexin 43, sulodexide, growth factors, silver dressings, MMP inhibitors, and modulators of reactive oxygen and nitrogen species, the immune response and tissue metabolites. Preventive measures including compression therapy and venotonics could also reduce the risk of progression to chronic venous insufficiency and VLU in susceptible individuals.

The Detection of Wound Infection by Ion Mobility Chemical Analysis

Surgical site infection represents a large burden of care in the National Health Service. Current methods for diagnosis include a subjective clinical assessment and wound swab culture that may take several days to return a result. Both techniques are potentially unreliable and result in delays in using targeted antibiotics. Volatile organic compounds (VOCs) are produced by micro-organisms such as those present in an infected wound. This study describes the use of a device to differentiate VOCs produced by an infected wound vs. colonised wound. Malodourous wound dressings were collected from patients, these were a mix of post-operative wounds and vascular leg ulcers. Wound microbiology swabs were taken and antibiotics commenced as clinically appropriate. A control group of soiled, but not malodorous wound dressings were collected from patients who had a split skin graft (SSG) donor site. The analyser used was a G.A.S. GC-IMS. The results from the samples had a sensitivity of 100% and a specificity of 88%, with a positive predictive value of 90%. An area under the curve (AUC) of 91% demonstrates an excellent ability to discriminate those with an infected wound from those without. VOC detection using GC-IMS has the potential to serve as a diagnostic tool for the differentiation of infected and non-infected wounds and facilitate the treatment of wound infections that is cost effective, non-invasive, acceptable to patients, portable, and reliable.

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.

Use of voltammetric analysis for fast and objective discrimination of the etiology, evolution, and bacterial infection of lower limb ulcers

The timely recognition of leg ulcers (LU) etiology and infection is pivotal to optimize management and accelerate healing. The objective of this proof-of-concept study was to test the diagnostic performance of voltammetric analysis (VA) on ulcer exudate to identify LU etiology, infection, and predict clinical course. We enrolled 25 patients aged ≥60 years, affected by 42 venous/arterial LU. Clinical examination (Leg Ulcer Measurement Tool score, LUMT), swab culture, and VA were performed at baseline and 30 days. The ability of VA to predict outcomes was tested using partial least square-discrimination analysis. Mean age was 75 years (SD 11.1), 9/25 were male. The accuracy, sensitivity, and specificity vs. etiology were 97.4, 100%, and 94.1%, respectively; the corresponding figures were 95.2%, 100%, 88.9%, for infection and 94%, 84.6%, 100% for predicted objective LUMT worsening. VA is a promising diagnostic/prognostic tool for management of LU that may allow a more timely targeted therapy.

Protease activity as a prognostic factor for wound healing in venous leg ulcers

BACKGROUND

Venous leg ulcers (VLUs) are a common type of complex wound that have a negative impact on people's lives and incur high costs for health services and society. It has been suggested that prolonged high levels of protease activity in the later stages of the healing of chronic wounds may be associated with delayed healing. Protease modulating treatments have been developed which seek to modulate protease activity and thereby promote healing in chronic wounds.

OBJECTIVES

To determine whether protease activity is an independent prognostic factor for the healing of venous leg ulcers.

SEARCH METHODS

In February 2018, we searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Ovid Embase and CINAHL.

SELECTION CRITERIA

We included prospective and retrospective longitudinal studies with any follow-up period that recruited people with VLUs and investigated whether protease activity in wound fluid was associated with future healing of VLUs. We included randomised controlled trials (RCTs) analysed as cohort studies, provided interventions were taken into account in the analysis, and case-control studies if there were no available cohort studies. We also included prediction model studies provided they reported separately associations of individual prognostic factors (protease activity) with healing. Studies of any type of protease or combination of proteases were eligible, including proteases from bacteria, and the prognostic factor could be examined as a continuous or categorical variable; any cut-off point was permitted. The primary outcomes were time to healing (survival analysis) and the proportion of people with ulcers completely healed; the secondary outcome was change in ulcer size/rate of wound closure. We extracted unadjusted (simple) and adjusted (multivariable) associations between the prognostic factor and healing.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion at each stage, and undertook data extraction, assessment of risk of bias and GRADE assessment. We collected association statistics where available. No study reported adjusted analyses: instead we collected unadjusted results or calculated association measures from raw data. We calculated risk ratios when both outcome and prognostic factor were dichotomous variables. When the prognostic factor was reported as continuous data and healing outcomes were dichotomous, we either performed regression analysis or analysed the impact of healing on protease levels, analysing as the standardised mean difference. When both prognostic factor and outcome were continuous data, we reported correlation coefficients or calculated them from individual participant data.We displayed all results on forest plots to give an overall visual representation. We planned to conduct meta-analyses where this was appropriate, otherwise we summarised narratively.

MAIN RESULTS

We included 19 studies comprising 21 cohorts involving 646 participants. Only 11 studies (13 cohorts, 522 participants) had data available for analysis. Of these, five were prospective cohort studies, four were RCTs and two had a type of case-control design. Follow-up time ranged from four to 36 weeks. Studies covered 10 different matrix metalloproteases (MMPs) and two serine proteases (human neutrophil elastase and urokinase-type plasminogen activators). Two studies recorded complete healing as an outcome; other studies recorded partial healing measures. There was clinical and methodological heterogeneity across studies; for example, in the definition of healing, the type of protease and its measurement, the distribution of active and bound protease species, the types of treatment and the reporting of results. Therefore, meta-analysis was not performed. No study had conducted multivariable analyses and all included evidence was of very low certainty because of the lack of adjustment for confounders, the high risk of bias for all studies except one, imprecision around the measures of association and inconsistency in the direction of association. Collectively the research indicated complete uncertainty as to the association between protease activity and VLU healing.

AUTHORS' CONCLUSIONS

This review identified very low validity evidence regarding any association between protease activity and VLU healing and there is complete uncertainty regarding the relationship. The review offers information for both future research and systematic review methodology.

Structure/Function Analysis of Cotton-Based Peptide-Cellulose Conjugates: Spatiotemporal/Kinetic Assessment of Protease Aerogels Compared to Nanocrystalline and Paper Cellulose

Nanocellulose has high specific surface area, hydration properties, and ease of derivatization to prepare protease sensors. A Human Neutrophil Elastase sensor designed with a nanocellulose aerogel transducer surface derived from cotton is compared with cotton filter paper, and nanocrystalline cellulose versions of the sensor. X-ray crystallography was employed along with Michaelis–Menten enzyme kinetics, and circular dichroism to contrast the structure/function relations of the peptide-cellulose conjugate conformation to enzyme/substrate binding and turnover rates. The nanocellulosic aerogel was found to have a cellulose II structure. The spatiotemporal relation of crystallite surface to peptide-cellulose conformation is discussed in light of observed enzyme kinetics. A higher substrate binding affinity (K_m) of elastase was observed with the nanocellulose aerogel and nanocrystalline peptide-cellulose conjugates than with the solution-based elastase substrate. An increased K_m observed for the nanocellulosic aerogel sensor yields a higher enzyme efficiency (k_cat/K_m), attributable to binding of the serine protease to the negatively charged cellulose surface. The effect of crystallite size and β-turn peptide conformation are related to the peptide-cellulose kinetics. Models demonstrating the orientation of cellulose to peptide O6-hydroxymethyl rotamers of the conjugates at the surface of the cellulose crystal suggest the relative accessibility of the peptide-cellulose conjugates for enzyme active site binding.

Designing cellulosic and nanocellulosic sensors for interface with a protease sequestrant wound-dressing prototype: Implications of material selection for dressing and protease sensor design

Interfacing nanocellulosic-based biosensors with chronic wound dressings for protease point of care diagnostics combines functional material properties of high specific surface area, appropriate surface charge, and hydrophilicity with biocompatibility to the wound environment. Combining a protease sensor with a dressing is consistent with the concept of an intelligent dressing, which has been a goal of wound-dressing design for more than a quarter century. We present here biosensors with a nanocellulosic transducer surface (nanocrystals, nanocellulose composites, and nanocellulosic aerogels) immobilized with a fluorescent elastase tripeptide or tetrapeptide biomolecule, which has selectivity and affinity for human neutrophil elastase present in chronic wound fluid. The specific surface area of the materials correlates with a greater loading of the elastase peptide substrate. Nitrogen adsorption and mercury intrusion studies revealed gas permeable systems with different porosities (28–98%) and pore sizes (2–50 nm, 210 µm) respectively, which influence water vapor transmission rates. A correlation between zeta potential values and the degree of protease sequestration imply that the greater the negative surface charge of the nanomaterials, the greater the sequestration of positively charged neutrophil proteases. The biosensors gave detection sensitivities of 0.015–0.13 units/ml, which are at detectable human neutrophil elastase levels present in chronic wound fluid. Thus, the physical and interactive biochemical properties of the nano-based biosensors are suitable for interfacing with protease sequestrant prototype wound dressings. A discussion of the relevance of protease sensors and cellulose nanomaterials to current chronic wound dressing design and technology is included.

A Pilot Randomized, Controlled Study of Nanocrystalline Silver, Manuka Honey, and Conventional Dressing in Healing Diabetic Foot Ulcer

Nanocrystalline silver (nAg) and Manuka honey (MH) dressing have increasing popularity for treating diabetic foot ulcer (DFU). This study was an open-label randomized controlled trial with three parallel groups' design in examining the preliminary effectiveness of nAg against MH and conventional dressing in healing DFU in terms of ulcer healing, ulcer infection, and inflammation. 31 participants (11 in the nAg group, 10 in the MH group, and 10 in the convention group) diagnosed with type 2 diabetes were enrolled. Wound cleaning, debridement, and topical dressing application were performed according to the group allocation in each visit at weeks 1, 2, 3, 4, 6, 8, 10, and 12. The results found that the proportions of complete ulcer healing were 81.8%, 50%, and 40% in the nAg, MH, and conventional groups, respectively. The ulcer size reduction rate was potentially higher in the nAg group (97.45%) than the MH group (86.21%) and the conventional group (75.17%). In bacteriology, nAg showed a greater rate of microorganism reduction although it was not significant. To conclude, nAg alginate was potentially superior to MH and conventional dressing in healing diabetic foot ulcer in terms of ulcer size reduction rate.

Preparation, Characterization and Activity of a Peptide-Cellulosic Aerogel Protease Sensor from Cotton

Nanocellulosic aerogels (NA) provide a lightweight biocompatible material with structural properties, like interconnected high porosity and specific surface area, suitable for biosensor design. We report here the preparation, characterization and activity of peptide-nanocellulose aerogels (PepNA) made from unprocessed cotton and designed with protease detection activity. Low-density cellulosic aerogels were prepared from greige cotton by employing calcium thiocyanate octahydrate/lithium chloride as a direct cellulose dissolving medium. Subsequent casting, coagulation, solvent exchange and supercritical carbon dioxide drying afforded homogeneous cellulose II aerogels of fibrous morphology. The cotton-based aerogel had a porosity of 99% largely dominated by mesopores (2-50 nm) and an internal surface of 163 m²·g-1. A fluorescent tripeptide-substrate (succinyl-alanine-proline-alanine-4-amino-7-methyl-coumarin) was tethered to NA by (1) esterification of cellulose C6 surface hydroxyl groups with glycidyl-fluorenylmethyloxycarbonyl (FMOC), (2) deprotection and (3) coupling of the immobilized glycine with the tripeptide. Characterization of the NA and PepNA included techniques, such as elemental analysis, mass spectral analysis, attenuated total reflectance infrared imaging, nitrogen adsorption, scanning electron microscopy and bioactivity studies. The degree of substitution of the peptide analog attached to the anhydroglucose units of PepNA was 0.015. The findings from mass spectral analysis and attenuated total reflectance infrared imaging indicated that the peptide substrate was immobilized on to the surface of the NA. Nitrogen adsorption revealed a high specific surface area and a highly porous system, which supports the open porous structure observed from scanning electron microscopy images. Bioactivity studies of PepNA revealed a detection sensitivity of 0.13 units/milliliter for human neutrophil elastase, a diagnostic biomarker for inflammatory diseases. The physical properties of the aerogel are suitable for interfacing with an intelligent protease sequestrant wound dressing.

Chronic venous disease - Part II: Proteolytic biomarkers in wound healing

Venous leg ulcers (VLU) are characterized by sustained proteolytic microenvironment impairing the healing process. Wound fluid (WF) reflect the biomolecular activities occurring within the wound area; however, it is unclear if WF from different healing phases have different proteolytic profiles and how VLU microenvironment affects the wound healing mechanisms. We investigated the proteolytic network of WF from distinct VLU phases, and in WF- and LPS-stimulated THP-1 monocytes treated with glycosaminoglycan sulodexide, a well known therapeutic approach for VLU healing. WF were collected from patients with VLU during inflammatory (Infl) and granulating (Gran) phases. WF and THP-1 supernatants were analyzed for nine matrix metalloproteinases (MMP) and four tissue inhibitors of metalloproteinases (TIMP) by multiplex immunoassays. Our results demonstrated that: 1) WF from Infl VLU contained significantly increased concentrations of MMP-2, MMP-9, MMP-12, TIMP-1, and TIMP-2 compared to Gran WF; 2) WF from Gran VLU showed significantly increased levels of MMP-1, MMP-7, MMP-13, and TIMP-4 compared to Infl WF; 3) LPS- and WF-stimulation of THP-1 cells significantly increased the expression of several MMP compared to untreated cells; 4) Sulodexide treatment of both LPS- and WF-stimulated THP-1 significantly down-regulated the release of several MMPs. Our study provides evidence-based medicine during treatment of patients with VLU. WF from Infl and Gran VLU have different MMP and TIMP signatures, consistent with their clinical state. The modulation of proteolytic pathways in wound microenvironment by glycosaminoglycan sulodexide, provide insights for translating research into clinical practice during VLU therapy.

Back to basics: histological, microbiological and biochemical sampling in wound care

Despite the advances in our understanding of normal and abnormal wound healing over the past decade, a specific biomarker which can be used clinically to identify 'hard-to-heal' wounds still remains elusive. Tissue and exudate samples extracted from the site of the wound are traditionally analysed using histological, microbiological and biochemical laboratory techniques. The aim of this paper is to review the advantages of these techniques, their limitations and the rapid developments in the fields of microbiology and proteomics, which are offering new insights into the differences between healing and non-healing wounds.

A systematic review of circulating markers in primary chronic venous insufficiency

OBJECTIVES

The etiology of primary chronic venous insufficiency is poorly understood. This systematic review aimed to summarize published evidence assessing the association of circulating markers with primary chronic venous insufficiency.

METHODS

A search was undertaken through the PubMed database using the terms "venous insufficiency" and "biological marker" or "plasma" or "serum". Search limits included English language, human subjects and studies with publication dates from 1994. Studies which classified patients using the Clinical-Etiology-Anatomy-Pathophysiology system of venous disease were analyzed.

RESULTS

Seventeen studies were included, which have examined > 60 different biomarkers. A total of 13 markers were assessed in >1 study with the number of primary chronic venous insufficiency cases ranging from 41 to 244 and the number of controls ranging from 30 to 144 in these studies. Circulating estradiol, homocysteine and vascular endothelial growth factor were the most consistently associated with primary chronic venous insufficiency.

CONCLUSIONS

Whilst a number of studies have examined biomarkers associated with primary chronic venous insufficiency, further studies are required using improved and standardized approaches on larger populations. Biomarker research may increase pathogenic knowledge and result in opportunities to decrease chronic venous insufficiency burden.

Neutrophil activity in chronic venous leg ulcers--a target for therapy?

Chronic venous leg ulcers (CVLUs) affect approximately 600,000 people annually in the United States and accrue yearly treatment costs of US $2.5-5 billion. As the population ages, demands on health care resources for CVLU treatments are predicted to drastically increase because the incidence of CVLUs is highest in those ≥65 years of age. Furthermore, regardless of current standards of care, healing complications and high recurrence rates prevail. Thus, it is critical that factors leading to or exacerbating CVLUs be discerned and more effective, adjuvant, evidence-based treatment strategies be utilized. Previous studies have suggested that CVLUs' pathogenesis is related to the prolonged presence of high numbers of activated neutrophils secreting proteases in the wound bed that destroy growth factors, receptors, and the extracellular matrix that are essential for healing. These events are believed to contribute to a chronically inflamed wound that fails to heal. Therefore, the purpose of this project was to review studies from the past 15 years (1996-2011) that characterized neutrophil activity in the microenvironment of human CVLUs for new evidence that could explicate the proposed relationship between excessive, sustained neutrophil activity and CVLUs. We also appraised the strength of evidence for current and potential therapeutics that target excessive neutrophil activity.

Panbacterial real-time PCR to evaluate bacterial burden in chronic wounds treated with Cutimed™ Sorbact™

The impact of polymicrobial bacterial infection on chronic wounds has been studied extensively, but standard bacteriological analysis is not always sensitive enough. Molecular approaches represent a promising alternative to the standard bacteriological analysis. This work aimed to assess the usefulness of a panbacterial quantitative real-time PCR reaction to quantitate the total bacterial load in chronic wounds treated with Cutimed™ Sorbact™, a novel therapeutic approach based on hydrophobic binding of bacteria to a membrane. The results obtained by panbacterial real-time PCR on conserved sequences of the bacterial 16S gene show that the bacterial burden significantly decreased in 10 out of 15 healing chronic wounds, and did not change in 5 out of 5 non-healing chronic wounds. On the contrary, classical culture for S. aureus and P. aeruginosa, and real-time PCR for Bacteroides and Fusobacterium did not show any correlation with the clinical outcome. Our study also shows that quantification of chronic wounds by panbacterial real-time PCR is to be performed on biopsies and not on swabs. These results show that panbacterial real-time PCR is a promising and quick method of determining the total bacterial load in chronic wounds, and suggest that it might be an important biomarker for the prognosis of chronic wounds under treatment.

Chronic wound fluid--thinking outside the box

Chronic wounds are associated with an altered wound milieu that results from an imbalance in extracellular matrix (ECM) homeostasis. This alteration is characterized by an increased destruction and degradation of components of the ECM with a concomitant lack of synthesis of these elements. Traditionally wound fluid has been considered a reflection of the internal wound milieu. It has been used to monitor and reflect on the chronic status of a wound or to measure the efficacy of wound treatment. However, on closer inspection of chronic wound fluid, certain components of the fluid, particularly matrix metalloproteinases (MMPs) and their subcomponents (MMP-9) have been found to exist at higher levels in wound fluid than in the corresponding wound. There is mounting evidence that much of the destructive effects observed in chronic wounds may be compounded by components of the wound exudate which are corrosive in nature resulting in a continuum of ECM breakdown. Isolation of these components has identified MMPs, in particular MMP-9 as dominant in this destructive process. Additionally an association has been made between high bacterial levels and elevated MMP9 in chronic wounds. Agents that have efficacy against MMP-9 and significant antibacterial potency thus provide a dual defense against chronic wounds. It is likely that these agents cause a change in the chronic wound fluid components that more closely resemble the balance of proteases and growth factors seen acute wounds, thus triggering a positive wound healing process. Nanocrystalline silver appears to fulfill these criteria. A strategy is suggested whereby wound fluid is directly targeted to diminish the corrosive wound fluid elements in an attempt to break the ongoing destructive inflammatory cycle. This presents a relatively new treatment paradigm attempting to influence wound healing by working from without to initiate changes within.

The role of biofilms: are we hitting the right target?

BACKGROUND

Chronic infections affect 17 million people yearly, and approximately 550,000 people die each year from, or with, their chronic infections. Acute and chornic infection differences are well known to clinicians, but the role of bacteria in producing these clinical differences remains poorly understood.

METHODS

This review relies on basic science, clinical studies, and a general review of the medical biofilm literature. The basic science studies are level A and B quality of evidence. The clinical studies are mainly retrospective cohort (level B) and case studies (level C). The biofilm literature includes reviews with varying levels of evidence. All articles have been peer reviewed and meet the standard of evidence-based medicine.

RESULTS

Acute infections are associated with planktonic bacteria and must be diagnosed rapidly and accurately to prevent tissue damage and/or death. In contrast, biofilm behavior pursues a more parasitic course by producing sustained host hyperinflammation, with the biofilm feeding on plasma exudate. Chronic infections vacillate over long periods of time, responding only partially to antibiotics and reemerging once the antibiotics are withdrawn. Chronic wounds exhibit similar clinical behavior seen in other chronic infections and are associated with biofilm phenotype bacteria on their surface. Biofilm infections, such as chronic wounds, cannot be adequately diagnosed with current clinical cultures; therefore, molecular methods are necessary.

CONCLUSIONS

Biofilm phenotype bacteria require multiple concurrent strategies, including débridement and targeted antibiofilm agents. Biofilm phenotype bacteria predominate on the surface of wounds, and biofilm-based management improves wound healing outcomes, indicating that biofilm is the right target for managing the bioburden barrier of chronic wounds.

Matrix metalloproteinase activity and glycosaminoglycans in chronic venous disease: the linkage among cell biology, pathology and translational research

Primary chronic venous disease (CVD) is an inflammatory pathology involving an erratic structural remodeling in the venous well leading to vascular incompetence and the development of varicose vein, characterized by altered collagen and elastin content. In the early steps of varicose vein formation is crucial the role of MMP/TIMP balance, implicated in both ECM and vascular degradation during inflammation processes in early and late stages of venous diseases. Although several pharmacological and surgical strategies are being utilized in the management of varicose vein and CVD with variable success and recurrence rate, inhibition of MMP through glycosaminoglycans may represent a novel therapeutic intervention to limit the progression of varicose vein to CVD and leg ulceration, suggesting possible opportunity to prevent future morbidity and enhancing clinical benefits and quality of life.