Recent advances and emerging treatments

Antimicrobial clay-based materials for wound care

The historical use of clay minerals for the treatment of wounds and other skin ailments is well documented and continues within numerous human cultures the world over. However, a more scientific inquiry into the chemistry and properties of clay minerals emerged in the 19th century with work investigating their role within health gathering pace since the second half of the 20th century. This review gives an overview of clay minerals and how their properties can be manipulated to facilitate the treatment of infected wounds. Evidence of the antimicrobial and healing effects of some natural clay minerals is presented alongside a range of chemical modifications including metal-ion exchange, the formation of clay–drug composites and the development of various polymer–clay systems. While the evidence for applying these materials to infected wounds is limited, we contextualize and discuss the future of this research.

Effectiveness of an acellular synthetic matrix in the treatment of hard-to-heal leg ulcers

Hard-to-heal leg ulcers are a major cause of morbidity in the elderly population. Despite improvements in wound care, some wounds will not heal and they present a significant challenge for patients and health care providers. A multi-centre cohort study was conducted to evaluate the effectiveness and safety of a synthetic, extracellular matrix protein as an adjunct to standard care in the treatment of hard-to-heal venous or mixed leg ulcers. Primary effectiveness criteria were (i) reduction in wound size evaluated by percentage change in wound area and (ii) healing assessed by number of patients healed by end of the 12 week study. Pain reduction was assessed as a secondary effectiveness criteria using VAS. A total of 45 patients completed the study and no difference was observed between cohorts for treatment frequency. Healing was achieved in 35·6% and wound size decreased in 93·3% of patients. Median wound area percentage reduction was 70·8%. Over 50% of patients reported pain on first visit and 87·0% of these reported no pain at the end of the study. Median time to first reporting of no pain was 14 days after treatment initiation. The authors consider the extracellular synthetic matrix protein an effective and safe adjunct to standard care in the treatment of hard-to-heal leg ulcers.

Dressings for chronic wounds

Covering wounds, acute and chronic, is one of the most fundamental activities of any medical practitioner. Although wound dressings primarily serve to contain the "good" and keep out the "bad," research has characterized more specifically the sophisticated interaction between the human wound bed and its dressing counterpart. Wound dressings for today's chronic wounds come in many flavors, ranging from the classic types of moisture-retentive dressings to silver-coated varieties to biologic dressings serving as skin substitutes. Moisture-retentive dressing types include foams, films, hydrogels, hydrocolloids, and alginates. Appropriate use of these dressings can help to keep the wound bed moist, which allows for epithelial migration, angiogenesis, retention of growth factors, autolytic debridement, and maintenance of electrical gradients.

In vivo effects of tailored laminin-332 α3 conjugated scaffolds enhances wound healing: a histomorphometric analysis

Surface modification techniques have been used to develop biomimetic scaffolds by incorporating cell adhesion peptides. In our previous work, we have shown the tethering of laminin-332 α3 chain to type I collagen scaffold using microbial transglutaminase (mTGase), promotes cell adhesion, migration, and proliferation. In this study, we evaluated the wound healing properties of tailored laminin-332 α3 chain (peptide A: PPFLMLLKGSTR) tethered to a type I collagen scaffold using mTGase by incorporating transglutaminase substrate peptide sequences containing either glutamine (peptide B: PPFLMLLKGSTREAQQIVM) or lysine (peptide C: PPFLMLLKGSTRKKKKG) in rat full-thickness wound model at two different time points (7 and 21 days). Histological evaluations were assessed for wound closure, epithelialization, angiogenesis, inflammatory, fibroblastic cellular infiltrations, and quantified using stereological methods (p < 0.05). Peptide A and B tethered to collagen scaffold using mTGase stimulated neovascularization, decreased the inflammatory cell infiltration and prominently enhanced the fibroblast proliferation which significantly accelerated the wound healing process. We conclude that surface modification by incorporating motif of laminin-332 α3 chain (peptide A: PPFLMLLK GSTR) domain and transglutaminase substrate to the laminin-332 α3 chain (peptide B: PPFLMLLKGSTREAQQIVM) using mTGase may be a potential candidate for tissue engineering applications and skin regeneration.

Granulocyte-colony stimulating factors as adjunctive therapy for diabetic foot infections

BACKGROUND

Granulocyte-colony stimulating factor (G-CSF) increases the release of neutrophil endothelial progenitor cells from the bone marrow and improves neutrophil functions, which are often impaired in people with diabetes.

OBJECTIVES

To examine the effects of adjunctive G-CSF compared with placebo or no growth factor added to usual care on rates of infection, cure and wound healing in people with diabetes who have a foot infection.

SEARCH METHODS

In March 2013, for this second update, we searched the Cochrane Wounds Group Specialised Register (searched 14 March 2013); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 2); Ovid MEDLINE (1948 to March Week 1 2013); Ovid EMBASE (1974 to 2013 March 13); Ovid MEDLINE (In-Process march 13,2013); and EBSCO CINAHL (1982 to 28 February 2013).

SELECTION CRITERIA

Randomised controlled trials (RCTs) that evaluated the effect of adding G-CSF to usual care in people with a diabetic foot infection.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trial eligibility, methodological quality and extracted data. We reported risk ratio (RR) or, for continuous outcomes, mean differences (MD), with 95% confidence intervals (CI). In the case of low or no heterogeneity we pooled studies using a fixed-effect model.

MAIN RESULTS

We identified and included five eligible trials with a total of 167 patients. The investigators administered various G-CSF preparations, at different doses and for different durations of time. Adding G-CSF did not significantly affect the likelihood of resolution of infection or wound healing, but it was associated with a significantly reduced likelihood of lower extremity surgical interventions (RR 0.38; 95 % CI 0.21 to 0.70), including amputation (RR 0.41; 95 % CI 0.18 to 0.95). Moreover, providing G-CSF reduced the duration of hospital stay (MD -1.40 days; 95% CI -2.27 to -0.53 days), but did not significantly affect the duration of systemic antibiotic therapy (MD -0.27 days; 95% CI -1.30 to 0.77 days).

AUTHORS' CONCLUSIONS

The available evidence is limited, but suggests that adjunctive G-CSF treatment in people with a diabetic foot infection, including infected ulcers, does not appear to increase the likelihood of resolution of infection or healing of the foot ulcer. However, it does appear to reduce the need for surgical interventions, especially amputations, and the duration of hospitalisation. Clinicians might consider adding G-CSF to the usual treatment of diabetic foot infections, especially in patients with a limb-threatening infection, but it is not clear which patients might benefit.

Wound healing in mammals and amphibians: toward limb regeneration in mammals

Mammalian fetal skin regenerates perfectly, but adult skin repairs by the formation of scar tissue. The cause of this imperfect repair by adult skin is not understood. In contrast, wounded adult amphibian (urodeles and anurans) skin is like mammalian fetal skin in that it repairs by regeneration, not scarring. Scar-free wound repair in adult Xenopus is associated with expression of the paired homeobox transcription factor Prx1 by mesenchymal cells of the wound, a feature shared by mesenchymal cells of the regeneration blastema of the axolotl limb. Furthermore, mesenchymal cells of Xenopus skin wounds that harbor the mouse Prx1-limb-enhancer as a transgene exhibit activation of the enhancer despite the fact that they are Xenopus cells, suggesting that the mouse Prx1 enhancer possesses all elements required for its activation in skin wound healing, even though activation of the same enhancer in the mouse is not seen in the wounded skin of an adult mouse. Elucidation of the role of the Prx1 gene in amphibian skin wound healing will help to clarify the molecular mechanisms of scarless wound healing. Shifting the molecular mechanism of wound repair in mammals to that of amphibians, including reactivation of the Prx1-limb-enhancer, will be an important clue to stimulate scarless wound repair in mammalian adult skin. Finding or creating Prx1-positive stem cells in adult mammal skin by activating the Prx1-limb-enhancer may be a fast and reliable way to provide for scarless skin wound repair, and even directly lead to limb regeneration in mammals.

Acceleration of Wound Healing by Multiple Growth Factors and Cytokines Secreted from Multipotential Stromal Cells/Mesenchymal Stem Cells

BACKGROUND

Although multipotential stromal cells/mesenchymal stem cell (MSCs) initially gained attention because of their ability to differentiate into multiple cell lineages, it is their capacity to produce and secrete growth factors and cytokines that makes them particularly valuable as potential cell therapeutics.

THE PROBLEM

Wound healing is an intricate process consisting of several integrated stages, including angiogenesis, collagen production, and cell migration and proliferation. Coordinating these processes to ensure rapid and thorough wound healing is necessary when developing therapeutics. This coordination, however, is disrupted in chronic nonhealing wounds, wherein the impaired blood supply and resulting ischemia compromise cellular functions and make it difficult to deliver the necessary signaling molecules.

BASIC/CLINICAL SCIENCE ADVANCES

MSCs secrete a combination of growth factors and cytokines, which have been shown to promote wound repair. This combination of growth factors and cytokines successfully induces angiogenesis, reduces inflammation, and promotes fibroblast migration and collagen production.

CLINICAL CARE RELEVANCE

The growth factors and cytokines secreted by MSCs can be administered to wounds by either transplanting cells or, as a safer alternative, using the conditioned medium of MSCs, which contains these secreted bioactive molecules. For their success in reducing wound closure time, MSCs offer a promising option for treating chronic wounds. Still, possible undesirable effects of MSC-based therapeutics, such as keloid formation, need to be carefully studied.

CONCLUSION

With its strong ability to secrete diverse growth factors and cytokines, MSC-based therapeutics, either with cell transplantation or the conditioned medium, offers a novel approach toward chronic nonhealing wounds.

Levels of macrophage migration inhibitory factor and glucocorticoids in chronic wound patients and their potential interactions with impaired wound endothelial progenitor cell migration

Macrophage migration inhibitory factor (MIF), a structurally and functionally unique pleiotropic mediator in inflammation and immune processes, was identified decades ago. There is now strong evidence that MIF promotes revascularization and is involved in wound healing processes. However, its exact role in wound healing is still a matter of debate. A cohort of 33 patients was recruited, including 14 patients with acute and 19 patients with chronic wounds. Both serum and wound fluid samples were collected from each patient, and MIF and cortisol concentrations were determined. To functionally underscore MIF's potential role in wound revascularization, a chemotaxis assay was adapted to test whether and to what extent serum samples and wound fluids of each group promote the chemotactic migration of endothelial progenitor cells (EPCs). MIF serum levels were significantly higher in chronic wound patients than in acute wound patients. Wound exudates of chronic wounds, however, contained a significantly lower concentration of MIF. In chronic wound patients, EPC migration might be delayed, as suggested by in vitro chemotaxis experiments. Despite the overall descriptive nature of this study, we conclude that MIF is correlated with occurrence of chronic wound. The increased MIF levels in the serum of chronic wound patients might be due to MIF's systemic effect of its proinflammatory activities, while its locally decreased levels in chronic wound exudates might be responsible for impaired recruitment of EPCs. Additional prospective data and detailed in vivo models are needed for a more comprehensive understanding of the role of MIF in chronic wound healing.

Circulating fibrocytes--biology and mechanisms in wound healing and scar formation

Fibrocytes were first described in 1994 as fibroblast-like, peripheral blood cells. These bone marrow-derived mesenchymal progenitor cells migrate into regions of tissue injury. They are unique in their expression of hematopoietic and monocyte lineage markers and extracellular matrix proteins. Several studies have focused on the specific role of fibrocytes in the process of wound repair and tissue regeneration. We discuss herein the biology and mechanistic action of fibrocytes in wound healing, scar formation, and maintenance of tissue integrity. Fibrocytes synthesize and secrete different cytokines, chemokines, and growth factors, providing a wound milieu that supports tissue repair. They further promote angiogenesis and contribute to wound closure via pathways involving specific cytokines, leukocyte-specific protein-1, serum amyloid P, and adenosine A(2A) receptors. Fibrocytes are involved in inflammatory fibrotic processes in such diseases as systemic fibrosis, atherosclerosis, asthma, hypertrophic scarring, and keloid formation. Accumulating literature has emphasized the important role of fibrocytes in wound healing and fibrosis. Detailed mechanisms nevertheless remain to be investigated to elucidate the full therapeutic potential of fibrocytes in the treatment of fibrosing disorders and the enhancement of tissue repair.

High thrombin concentrations in fibrin sealants induce apoptosis in human keratinocytes

Over the last century many studies have been performed to assess the impact of fibrin sealant (FS) components on cells. Because of the noncovalent bonding of thrombin to fibrin during fibrin clot formation, we wanted to further evaluate the impact of fibrin bound thrombin on cell viability. Initially, we quantified the activity of thrombin in three different, commercially available FS. This information was used to prepare fibrin clots covering a range of thrombin concentrations from 4 to 820 IU mL(-1), but which were identical with respect to all other constituents. Although these fibrin clots did not differ in their three-dimensional structure, clots prepared with highly concentrated thrombin (820 IU mL(-1)) failed to support adhesion and spreading of primary human keratinocytes (NHEK). The number of attached cells was also significantly reduced on high thrombin activity clots. We hypothesized that these observations are not only the consequence of decreased proliferation but of apoptotic mechanisms, since the expression of cleaved caspase 3 and 7 was strongly enhanced on fibrin clots with high thrombin activity. This was accompanied by an induction of expression of Trail-R2 which is a receptor known to mediate apoptosis signals. Blocking of thrombin activity by hirudin led to an improvement of cell morphology and to an increase in number of attached cells. In addition, the induction of caspase 3 and 7 was also reduced. Thus, here we report for the first time that fibrin bound thrombin does not only decrease proliferation (as already published by others), it also does induce NHEK apoptosis when present at high concentrations.

Venous leg ulcerations: a treatment update

OPINION STATEMENT

Selecting the appropriate treatment for venous leg ulcerations is essential for optimal wound healing and patient quality of life. Compression therapy remains the mainstay of treatment for these wounds. Compression methods should be carefully selected and tailored for compatibility with patients' daily life. Pain management should not be neglected. When response to compression therapy is limited, adjuvant therapy such as medication, débridement, or surgical procedures should be considered on an individual basis.

CONSORT 2010 statement: updated guidelines can improve wound care

There is a growing need to add to the evidence base in wound care. Randomised controlled trials (RCTs) are one methodological approach for this. The CONSORT statement, which provides guidance on how to conduct a rigorous RCT, was updated earlier this year. Implementation of the Consort statement will clarify to the reader what exactly was done in the RCT, to whom and when. In this way, practitioners and health-care providers can determine its validity. The Consort statement has the potential to play a crucial role in influencing the quality of research and clinical practice, and so to improve wound care. The benefits of Consort 2010 are clear; the challenge is for clinicians and researchers to use it.

Improving venous ulcer healing: designing and reporting randomised controlled trials

The randomised controlled trial (RCT) is often considered the gold standard for judging the benefits of treatments. The application of randomised controlled clinical trials to treatments of venous ulcer healing has lagged behind that of other areas of medicine. To interpret the results of an RCT, readers must understand a variety of aspects of their design, analysis and interpretation. Venous ulcer disease has a high prevalence and has a significant socioeconomic impact in most parts of the world. The management of venous ulcers causes a considerable strain on the health system and is likely to worsen in future. The multi-layer high compression system is described as the current gold standard for treating venous ulcers. A recent meta-analysis of bandaging systems found that multi-layer compression bandages appeared to be superior to single-layer bandages in promoting venous ulcer healing. However, it was noted that many of the studies had small sample sizes and the quality of research in the area was poor. The consolidating standards of reporting trials (CONSORT) statement can help clinicians to discern high-quality studies from ones of poorer quality. This paper discusses how CONSORT can help clinicians and researchers to design and report quality studies to contribute to evidence-based venous ulcer healing.

Granulocyte-colony stimulating factors as adjunctive therapy for diabetic foot infections

BACKGROUND

G-CSF increases the release of neutrophil endothelial progenitor cells from the bone marrow, and improves neutrophil functions, which are often impaired in people with diabetes.

OBJECTIVES

To examine the effects of adjunctive G-CSF compared with placebo or no growth factor added to usual care on rates of infection, cure and wound healing in people with diabetes who have a foot infection.

SEARCH STRATEGY

We searched the Cochrane Wounds Group Specialised Register (Searched 16/3/09); the Cochrane Central Register of Controlled Trials (The Cochrane Library, issue 1 2009); Ovid MEDLINE (1950 to March Week 1 2009); Ovid EMBASE (1980 to 2009 Week 11); EBSCO CINAHL (1982 to March Week 2 2009); LookSmart's Find Articles (January 1990 to January 2008); conference proceedings and references lists in the included studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that evaluated the effect of adding G-CSF to usual care in people with a diabetic foot infection.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trial eligibility, methodological quality and extracted data. Relative risk (RR), or for continuous outcomes, mean differences (MD), with 95% confidence intervals (CI) were reported. In the case of low or no heterogeneity studies were pooled using a fixed-effect model.

MAIN RESULTS

We identified and included five eligible trials with a total of 167 patients. The investigators administered various G-CSF preparations, at different doses and for different durations of time. Adding G-CSF did not significantly affect the likelihood of resolution of infection or wound healing, but it was associated with a significantly reduced likelihood of lower extremity surgical interventions (RR 0.37; 95 % CI 0.20 to 0.68), including amputation (RR 0.41; 95 % CI 0.18 to 0.95). Moreover, providing G-CSF reduced the duration of hospital stay (MD, -1.40 days; 95 % CI, -2.27 to -0.53 days), but did not significantly affect the duration of systemic antibiotic therapy (MD, -0.27 days; 95 % CI, -1.30 to 0.77 days).

AUTHORS' CONCLUSIONS

The available evidence is limited, but suggests that adjunctive G-CSF treatment in people with a diabetic foot infection, including infected ulcers, does not appear to increase the likelihood of resolution of infection or healing of the foot ulcer. However, it does appear to reduce the need for surgical interventions, especially amputations, and the duration of hospitalisation. Clinicians might consider adding G-CSF to the usual treatment of diabetic foot infections, especially in patients with a limb-threatening infection, but it is not clear which patients might benefit.

A three species model to simulate application of Hyperbaric Oxygen Therapy to chronic wounds

Chronic wounds are a significant socioeconomic problem for governments worldwide. Approximately 15% of people who suffer from diabetes will experience a lower-limb ulcer at some stage of their lives, and 24% of these wounds will ultimately result in amputation of the lower limb. Hyperbaric Oxygen Therapy (HBOT) has been shown to aid the healing of chronic wounds; however, the causal reasons for the improved healing remain unclear and hence current HBOT protocols remain empirical. Here we develop a three-species mathematical model of wound healing that is used to simulate the application of hyperbaric oxygen therapy in the treatment of wounds. Based on our modelling, we predict that intermittent HBOT will assist chronic wound healing while normobaric oxygen is ineffective in treating such wounds. Furthermore, treatment should continue until healing is complete, and HBOT will not stimulate healing under all circumstances, leading us to conclude that finding the right protocol for an individual patient is crucial if HBOT is to be effective. We provide constraints that depend on the model parameters for the range of HBOT protocols that will stimulate healing. More specifically, we predict that patients with a poor arterial supply of oxygen, high consumption of oxygen by the wound tissue, chronically hypoxic wounds, and/or a dysfunctional endothelial cell response to oxygen are at risk of nonresponsiveness to HBOT. The work of this paper can, in some way, highlight which patients are most likely to respond well to HBOT (for example, those with a good arterial supply), and thus has the potential to assist in improving both the success rate and hence the cost-effectiveness of this therapy.

The use of MelMax in the healing of chronic wounds

Chronic wounds can have detrimental consequences for the quality of life of patients as well as presenting a huge financial burden to the NHS. An imbalance in the level of matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs) in chronic wounds impedes the healing process. In addition, high levels of bacteria in the wound bed are a common feature of chronic wounds and also cited as a major cause of delayed healing. The aim of this article is to look in more detail at the role of MMPs in wound healing as well as the antimicrobial properties of honey when combined with a dressing to combat wound infection. The article also introduces a new dressing, MelMax (distributed by CliniMed), which utilizes protease regulation and the antimicrobial properties of honey when addressing chronic wound infection. Short-term case studies are used to demonstrate how the dressing was successfully incorporated into the author's practice.

Non-healing wounds: the geriatric approach

The most common types of non-healing wounds are four types: pressure ulcers, diabetic ulcers, ischemic ulcers and venous ulcers. Many of those wounds develop among the elderly, becoming non-healing to the extent that the patient may live with them all of his life, or even die because of them. Not enough attention is paid to the underlying contributing problems specific to the elderly patient. Those factors are physiologic (aging skin, immune state and atherosclerosis) and pathologic situation (diabetic disease, ischemia of leg). Therefore, the geriatric approach to a non-healing wound is comprehensive and multidisciplinary. Those including: patient's co-morbidities, functional state as measured by the activities of daily living (ADL) scale, nutritional status, social support, ethical beliefs and quality of life and not only the wound itself. Each discipline (the nursing staff, physician, dietitian, occupational, physical therapists and social worker) has its own task in preventing and treating such wounds. The ultimate goal therefore has been altered from healing of the wounds to symptom control, prevention of complications and to contribute to the patient's overall wellbeing. This review discusses all those items in a geriatric point of view, and how to deal with the non-healing wounds as a geriatric syndrome.

The use of hyperbaric oxygen therapy to treat chronic wounds: A review

Chronic wounds, defined as those wounds which fail to proceed through an orderly process to produce anatomic and functional integrity, are a significant socioeconomic problem. A wound may fail to heal for a variety of reasons including the use of corticosteroids, formation of squamous cell carcinoma, persistent infection, unrelieved pressure, and underlying hypoxia within the wound bed. Hypoxia appears to inhibit the wound healing process by blocking fibroblast proliferation, collagen production, and capillary angiogenesis and to increase the risk of infection. Hyperbaric oxygen therapy (HBOT) has been shown to aid the healing of ulcerated wounds and demonstrated to reduce the risk of amputation in diabetic patients. However, the causal reasons for the response of the underlying biological processes of wound repair to HBOT, such as the up-regulation of angiogenesis and collagen synthesis are unclear and, consequently, current protocols remain empirical. Here we review chronic wound healing and the use of hyperbaric oxygen as an adjunctive treatment for nonhealing wounds. Databases including PubMed, ScienceDirect, Blackwell Synergy, and The Cochrane Library were searched for relevant phrases including HBOT, HBO/HBOT, wound healing, and chronic/nonhealing wounds/ulcers.

Discussion on wound care in the 21st century

In June of this year, Liverpool John Moores University was the venue for the Advancing Wound Care conference. Experts in wound healing from both the university and from the Royal Liverpool and Broadgreen University Hospital NHS Trust gave keynote speeches aimed at informing, improving and advancing healthcare knowledge on such topics as: wound healing in the 21st century; evidence-based practice for superficial burns; infected and complex wounds; and the use of silver in wound care. This paper introduced the conference and considered some of the complex issues involved in clinical decision making for wound management.