Protease-modulating matrix treatments for healing venous leg ulcers

A Comparative Study on Therapeutic Efficacy of Autologous Platelet-rich Plasma, Autologous Platelet-rich Fibrin Matrix, Recombinant Human Epidermal Growth Factor, and Collagen Particles in Nonhealing Leg Ulcers

Background

Nonhealing leg ulcers are challenging to manage and cause significant patient morbidity. To promote healing, newer techniques focus on delivering/enhancing dermal matrix components.

Aim

The aim of this study was to compare the therapeutic efficacy of autologous platelet-rich plasma (PRP), autologous platelet-rich fibrin matrix (PRFM), recombinant human epidermal growth factor (rhEGF), and collagen particles in treating nonhealing leg ulcers.

Materials and Methods

Open, randomized prospective study was conducted in a single tertiary center over 2 years where after fulfilling the criteria, randomization was done into four groups. Group A: Autologous PRP (double spin, manual method, weekly); Group B: Autologous PRFM (weekly); Group C: rhEGF (daily application); and Group D: Collagen particles (weekly) along with cleansing, debris removal, and wound dressing. Treatment endpoints were complete healing/6 months of treatment, whichever was earlier. Follow-up was done two weekly by clinical assessment, photographs, and measurement of the ulcer area. Epi info 7 software was used for statistical analysis.

Results

A total of 48 patients completed the study, 12 in each group, with mean age: 42.37 ± 4.56 years and male-to-female ratio 2.6:1. Underlying etiology was varicosities (43.75%), traumatic (25%), diabetes (22.91%), and leprosy (8.34%). At baseline, all groups were comparable in terms of patient and ulcer characteristics. Complete healing was seen in 79.17% at the end of 12 weeks: 91.67% of patients from Groups A and B each, and 66.67% from Groups C and D each. The mean time to complete healing was 6.9 ± 2.5 weeks, the least in Group B (4.73 ± 2.3 weeks). Differences between excellent (≥75%) ulcer healing across all groups were statistically significant at the end of 8 weeks where Group B showed maximum improvement. No major adverse events were seen.

Conclusion

PRFM resulted in relatively faster ulcer healing compared with other modalities.

Wound Care for Venous Ulceration

Venous leg ulcers (VLUs) affect as many as 20% of patients with advanced chronic venous insufficiency and are associated with significant morbidity and health care costs. VLUs are the most common cause of leg ulcers; however, other etiologies of lower extremity ulcerations should be investigated, most notably arterial insufficiency, to ensure appropriate therapy. Careful clinical examination, standardized documentation, and ultrasound evaluation are needed for diagnosis and treatment success. Reduction of edema and venous hypertension through compression therapy, local wound care, and treatment of venous reflux or obstruction is the foundation of therapy. As key providers in venous disease, interventional radiologists should be aware of current standardized disease classification and scoring systems as well as treatment and wound care guidelines for venous ulcers.

Microneedle arrays for the treatment of chronic wounds

INTRODUCTION

Chronic wounds are seen frequently in diabetic and bedbound patients. Such skin injuries, which do not heal in a timely fashion, can lead to life-threatening conditions. In an effort to resolve the burdens of chronic wounds, numerous investigations have explored the efficacy of various therapeutics on wound healing. Therapeutics can be topically delivered to cutaneous wounds to reduce the complications associated with systemic drug delivery because the compromised skin barrier is not expected to negatively affect drug distribution. However, researchers have recently demonstrated that the complex environment of chronic wounds could lower the localized availability of the applied therapeutics. Microneedle arrays (MNAs) can be exploited to enhance delivery efficiency and consequently improved healing.

AREAS COVERED

In this review, we briefly describe the pathophysiology of chronic wounds and current treatment strategies. We further introduce methods and materials commonly used for the fabrication of MNAs. Subsequently, the studies demonstrating the benefits of MNAs in wound care are highlighted.

EXPERT OPINION

Microneedles have great potential to treat the complicated pathophysiology of chronic wounds. Challenges that will need to be addressed include development of a robust chronic wound model and MNAs that combine complex functionality with simplicity of use.

Crustacean Proteases and Their Application in Debridement

Digestive proteases from marine organisms have been poorly applied to biomedicine. Exceptions are trypsin and other digestive proteases from a few cold-adapted or temperate fish and crustacean species. These enzymes are more efficient than enzymes from microorganism and higher vertebrates that have been used traditionally. However, the biomedical potential of digestive proteases from warm environment species has received less research attention. This review aims to provide an overview of this unrealised biomedical potential, using the debridement application as a paradigm. Debridement is intended to remove nonviable, necrotic and contaminated tissue, as well as fibrin clots, and is a key step in wound treatment. We discuss the physiological role of enzymes in wound healing, the use of exogenous enzymes in debridement, and the limitations of cold-adapted enzymes such as their poor thermal stability. We show that digestive proteases from tropical crustaceans may have advantages over their cold-adapted counterparts for this and similar uses. Differences in thermal stability, auto-proteolytic stability, and susceptibility to proteinase inhibitors are discussed. Furthermore, it is proposed that the feeding behaviour of the source organism may direct the evaluation of enzymes for particular applications, as digestive proteases have evolved to fill a wide variety of feeding habitats, natural substrates, and environmental conditions. We encourage more research on the biomedical application of digestive enzymes from tropical marine crustaceans.

Why is the Sensory Response of Organic Probes within a Polymer Film Different in Solution and in the Solid-State? Evidence and Application to the Detection of Amino Acids in Human Chronic Wounds

We anchored a colourimetric probe, comprising a complex containing copper (Cu(II)) and a dye, to a polymer matrix obtaining film-shaped chemosensors with induced selectivity toward glycine. This sensory material is exploited in the selectivity detection of glycine in complex mixtures of amino acids mimicking elastin, collagen and epidermis, and also in following the protease activity in a beefsteak and chronic human wounds. We use the term inducing because the probe in solution is not selective toward any amino acid and we get selectivity toward glycine using the solid-state. Overall, we found that the chemical behaviour of a chemical probe can be entirely changed by changing its chemical environment. Regarding its behaviour in solution, this change has been achieved by isolating the probe by anchoring the motifs in a polymer matrix, in an amorphous state, avoiding the interaction of one sensory motif with another. Moreover, this selectivity change can be further tuned because of the effectiveness of the transport of targets both by the physical nature of the interface of the polymer matrix/solution, where the target chemicals are dissolved, for instance, and inside the matrix where the recognition takes place. The interest in chronic human wounds is related to the fact that our methods are rapid and inexpensive, and also considering that the protease activity can correlate with the evolution of chronic wounds.

Impact of omega-3 fatty acid oral therapy on healing of chronic venous leg ulcers in older adults: Study protocol for a randomized controlled single-center trial

Background

This trial addresses the global problem of chronic venous leg ulcers (CVLUs), wounds that cause significant infirmity for an estimated 9.7 million people annually, mainly older adults with comorbidities. Advanced therapies are needed because standard topical therapies are often ineffective or yield only short-term wound healing. Thus, we are testing a new oral therapy containing the bioactive elements of fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), for targeting and reducing the high numbers of activated polymorphonuclear leukocytes (PMN) in wound microenvironments that keep CVLUs “trapped” in a chronic inflammatory state.

Methods

This double-blind RCT will include 248 eligible adults ≥ 55 years of age with CVLUs receiving standard care at a large Midwest outpatient wound clinic. Participants are randomized to two groups: 12 weeks of daily oral therapy with EPA + DHA (1.87 g/day of EPA + 1.0 g/day of DHA) or daily oral therapy with placebo. At 0, 4, 8, and 12 weeks, across the two groups, we are pursuing three specific aims: Aim 1. Compare levels of EPA + DHA-derived lipid mediators, and inflammatory cytokines in blood and wound fluid; Subaim 1a. Compare inflammatory cytokine gene expression by PMNs in blood; Aim 2. Compare PMN activation in blood and wound fluid, and PMN-derived protease levels in wound fluid; Aim 3. Compare reduction in wound area, controlling for factors known to impact healing, and determine relationships with lipid mediators, cytokines, and PMN activation. Subaim 3a. Compare frequency of CVLU recurrence and levels of study variables in blood between the randomly assigned two subgroups (continuing EPA + DHA therapy versus placebo therapy beyond week 12) within the EPA + DHA group with healed CVLUs after 3 months of therapy. Subaim 3b. Compare symptoms of pain at all time points and quality of life at first and last time points across the two groups and two subgroups.

Discussion

This trial will provide new evidence about the effectiveness of EPA + DHA oral therapy to target and reduce excessive PMN activation systemically and locally in patients with CVLUs. If effective, this therapy may facilitate healing and thus be a new adjunct treatment for CVLUs in the aging population.

Trial registration

ClinicalTrials.gov, NCT03576989; Registered on 13 June 2018.

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.

Dressings and topical agents for treating venous leg ulcers

BACKGROUND

Venous leg ulcers are open skin wounds on the lower leg which can be slow to heal, and are both painful and costly. The point prevalence of open venous leg ulcers in the UK is about 3 cases per 10,000 people, and many people experience recurrent episodes of prolonged ulceration. First-line treatment for venous leg ulcers is compression therapy, but a wide range of dressings and topical treatments are also used. This diversity of treatments makes evidence-based decision-making challenging, and a clear and current overview of all the evidence is required. This review is a network meta-analysis (NMA) which assesses the probability of complete ulcer healing associated with alternative dressings and topical agents.

OBJECTIVES

To assess the effects of (1) dressings and (2) topical agents for healing venous leg ulcers in any care setting and to rank treatments in order of effectiveness, with assessment of uncertainty and evidence quality.

SEARCH METHODS

In March 2017 we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also scanned reference lists of relevant included studies as well as reviews, meta-analyses, guidelines and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting. We updated this search in March 2018; as a result several studies are awaiting classification.

SELECTION CRITERIA

We included published or unpublished randomised controlled trials (RCTs) that enrolled adults with venous leg ulcers and compared the effects of at least one of the following interventions with any other intervention in the treatment of venous leg ulcers: any dressing, or any topical agent applied directly to an open venous leg ulcer and left in situ. We excluded from this review dressings attached to external devices such as negative pressure wound therapies, skin grafts, growth factors and other biological agents, larval therapy and treatments such as laser, heat or ultrasound. Studies were required to report complete wound healing to be eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, 'Risk of bias' assessment and data extraction. We conducted this NMA using frequentist meta-regression methods for the efficacy outcome; the probability of complete healing. We assumed that treatment effects were similar within dressings classes (e.g. hydrocolloid, foam). We present estimates of effect with their 95% confidence intervals (CIs) for individual treatments focusing on comparisons with widely used dressing classes, and we report ranking probabilities for each intervention (probability of being the best, second best, etc treatment). We assessed the certainty (quality) of the body of evidence using GRADE for each network comparison and for the network as whole.

MAIN RESULTS

We included 78 RCTs (7014 participants) in this review. Of these, 59 studies (5156 participants, 25 different interventions) were included in the NMA; resulting in 40 direct contrasts which informed 300 mixed-treatment contrasts.The evidence for the network as a whole was of low certainty. This judgement was based on the sparsity of the network leading to imprecision and the general high risk of bias in the included studies. Sensitivity analyses also demonstrated instability in key aspects of the network and results are reported for the extended sensitivity analysis. Evidence for individual contrasts was mainly judged to be low or very low certainty.The uncertainty was perpetuated when the results were considered by ranking the treatments in terms of the probability that they were the most effective for ulcer healing, with many treatments having similar, low, probabilities of being the best treatment. The two most highly-ranked treatments both had more than 50% probability of being the best (sucralfate and silver dressings). However, the data for sucralfate was from one small study, which means that this finding should be interpreted with caution. When exploring the data for silver and sucralfate compared with widely-used dressing classes, there was some evidence that silver dressings may increase the probability of venous leg ulcer healing, compared with nonadherent dressings: RR 2.43, 95% CI 1.58 to 3.74 (moderate-certainty evidence in the context of a low-certainty network). For all other combinations of these five interventions it was unclear whether the intervention increased the probability of healing; in each case this was low- or very low-certainty evidence as a consequence of one or more of imprecision, risk of bias and inconsistency.

AUTHORS' CONCLUSIONS

More research is needed to determine whether particular dressings or topical agents improve the probability of healing of venous leg ulcers. However, the NMA is uninformative regarding which interventions might best be included in a large trial, largely because of the low certainty of the whole network and of individual comparisons.The results of this NMA focus exclusively on complete healing; whilst this is of key importance to people living with venous leg ulcers, clinicians may wish to take into account other patient-important outcomes and factors such as patient preference and cost.

Drug delivery systems and materials for wound healing applications

Chronic, non-healing wounds place a significant burden on patients and healthcare systems, resulting in impaired mobility, limb amputation, or even death. Chronic wounds result from a disruption in the highly orchestrated cascade of events involved in wound closure. Significant advances in our understanding of the pathophysiology of chronic wounds have resulted in the development of drugs designed to target different aspects of the impaired processes. However, the hostility of the wound environment rich in degradative enzymes and its elevated pH, combined with differences in the time scales of different physiological processes involved in tissue regeneration require the use of effective drug delivery systems. In this review, we will first discuss the pathophysiology of chronic wounds and then the materials used for engineering drug delivery systems. Different passive and active drug delivery systems used in wound care will be reviewed. In addition, the architecture of the delivery platform and its ability to modulate drug delivery are discussed. Emerging technologies and the opportunities for engineering more effective wound care devices are also highlighted.

Evidence-Based Clinical Practice Points for the Management of Venous Ulcers

Venous ulcer is an extremely common aetiology of lower extremity ulceration, which affects approximately 1% population in most of the countries, and the incidence rate increases with age and female gender. Proper assessment and diagnosis of both the patient and ulcer are inevitable in order to differentiate venous ulcers from other lower extremity ulceration and to frame an adequate and individualised management plan. Venous ulcers generally persist for weeks to many years and are typically recurrent in nature. This consensus aims to present an evidence-based management approach for the patients with venous ulcers. Various management options for venous ulcers include compression therapy, minimally invasive procedures like sclerotherapy and ablation techniques, surgical procedures, debridement and medical management with micronised purified flavonoid fraction (MPFF). Compression therapy is the mainstay treatment for venous ulcer. However, in failure cases, surgery can be preferred. Medical management with MPFF as an adjuvant therapy to standard treatment has been reported to be effective and safe in patients with venous ulcer. In addition to standard therapy, diet and lifestyle modification including progressive resistance exercise, patient education, leg elevation, weight reduction, maintaining a healthy cardiac status and strong psychosocial support reduces the risk of recurrence and improves the quality of life in patients with venous ulcer.

Oxidized Regenerated Cellulose/Collagen Dressings: Review of Evidence and Recommendations

OBJECTIVE

Healthcare systems are being challenged to manage increasing numbers of nonhealing wounds. Wound dressings are one of the first lines of defense in wound management, and numerous options exist. The oxidized regenerated cellulose (ORC)/collagen dressing may offer healthcare providers a robust and cost-effective tool for use in a variety of wounds.

DESIGN

A multidisciplinary panel meeting was convened to discuss the use of ORC/collagen dressings in wound care and provide practice recommendations. A literature search was conducted to provide a brief review of the peer-reviewed studies published between January 2000 and March 2016 to inform the meeting.

SETTING

A 2-day panel meeting convened in February 2017.

PARTICIPANTS

Healthcare providers with experience using ORC/collagen dressings. This multidisciplinary panel of 15 experts in wound healing included podiatrists, wound care specialists (doctors, certified wound care nurses, and research scientists), and an orthopedist.

RESULTS

The literature search identified 58 articles, a majority of which were low levels of evidence (69.3% were level 3 or lower). Panel members identified wound types, such as abrasions, burns, stalled wounds, diabetic foot ulcers, and pressure injuries, where ORC/collagen dressing use could be beneficial. Panel members then provided recommendations and technical pearls for the use of ORC/collagen dressings in practice. Barriers to ORC/collagen dressing use were discussed, and potential resolutions were offered.

CONCLUSIONS

An ORC/collagen dressing can be a critical tool for clinicians to help manage a variety of wounds. Clinical and economic studies comparing standard-of-care dressings and plain collagen dressings to ORC/collagen dressings are needed.