Randomized, double-blind, placebo-controlled, dose- ranging study of granulocyte-macrophage colony stimulating factor in patients with chronic venous leg ulcers

Effects of Recombinant Human Granulocyte/Macrophage Colony-Stimulating Factor on Diabetic Lower Extremity Ulcers: Case Series of Nine Patients

Background

Diabetic lower extremity ulcer, including diabetic foot ulcer (DFU) and leg ulcer, is one of the refractory complications of diabetes, the treatment of which is challenging, expensive, and lengthy. Recombinant Human Granulocyte/Macrophage Colony-stimulating Factor (rhGM-CSF) is an immunomodulatory cytokine that has been mainly applied in the treatment of hematological diseases. Clinical evidence regarding GM-CSF in the treatment of diabetic lower extremity ulcers is limited. This study is the first case series that investigates the repurpose effects of rhGM-CSF on diabetic ulcer healing in real clinical practice.

Methods

Nine patients diagnosed with diabetes and refractory lower extremity ulcer (ulcer duration ≥2 weeks) were included from September 2021 to February 2023 in the Division of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. Patients with Wagner grade ≥4 and SINDAD ≥5 were excluded. The included subjects were treated with rhGM-CSF plus standard of care (SOC) including glycemic control, foot care education, debridement of necrotic tissues, topical wound dressings, offloading, and infection control when necessary. The observation endpoint was complete epithelialization. Their clinical manifestations, laboratory tests, and therapeutic effects were extracted and analyzed.

Results

The case series included 9 cases aged from 29 to 80 years and all the patients were male. Seven of 9 patients presented neuropathic ulcer. Only one case showed non-infected ulcer from tissue samples and one case presented ankle brachial index (ABI) <0.9. It was observed that the ulcer areas among these 9 patients gradually declined throughout the whole treatment period with the average healing velocity 0.32 ± 013 cm2/day and the mean time to complete healing 16.0 ± 3.7 days. The relative area (percentage of initial ulcer area) decreased to 66.7 ± 13.0% on average after the first treatment. Ulcers in all the 9 patients achieved complete epithelialization after 4-8 times treatments.

Conclusion

The case series suggests rhGM-CSF as a promising therapeutic strategy for the treatment of diabetic ulceration. More robust data from randomized controlled trials are required to further evaluate its clinical efficacy.

Why Are There So Few FDA-Approved Therapeutics for Wound Healing?

Since the only and the milestone FDA approval of becaplermin gel (RegranexTM, 0.01% human recombinant PDGF-BB) as a (diabetic) wound healing therapeutic more than 25 years ago, no new therapeutic (excluding physical therapies, devices, dressings, anti-microbial agents, or other preventive treatments) for any type of wound healing has advanced to clinical applications. During the same period of time, the FDA has approved additional 250 new drugs for various human tumors, which were famously described as "wounds that do not heal". Two similar pathological conditions have experienced such a dramatic difference in therapeutics. More surprisingly, few in the wound healing community seem to be alarmed by this mysterious deficit. As it is often said, "damaging is far easier than re-building". In contrast to the primary duty of a cancer drug to damage a single molecule of the signaling network, a wound healing drug must be able to re-build the multi-level damages in the wound. No known single molecule alone is capable of repairing multi-cell-type and multi-pathway damages all at once. We argue that the previous single molecule-based strategy for developing wound healing therapeutics is profoundly flawed in theory. The future success of effective wound healing therapeutics requires a fundamental change in the paradigm.

Acellular collagen-glycosaminoglycan matrix promotes functional recovery in a rat model of volumetric muscle loss

Aim: Volumetric muscle loss (VML) is a composite loss of skeletal muscle, which heals with fibrosis, minimal muscle regeneration, and incomplete functional recovery. This study investigated whether collagen-glycosaminoglycan scaffolds (CGS) improve functional recovery following VML. Methods: 15 Sprague-Dawley rats underwent either sham injury or bilateral tibialis anterior (TA) VML injury, with or without CGS implantation. Results: In rats with VML injuries treated with CGS, the TA exhibited greater in vivo tetanic forces and in situ twitch and tetanic dorsiflexion forces compared with those in the non-CGS group at 4- and 6-weeks following injury, respectively. Histologically, the VML with CGS group demonstrated reduced fibrosis and increased muscle regeneration. Conclusion: Taken together, CGS implantation has potential augment muscle recovery following VML.

Recombinant GM-CSF for diseases of GM-CSF insufficiency: Correcting dysfunctional mononuclear phagocyte disorders

Introduction

Endogenous granulocyte-macrophage colony-stimulating factor (GM-CSF), identified by its ability to support differentiation of hematopoietic cells into several types of myeloid cells, is now known to support maturation and maintain the metabolic capacity of mononuclear phagocytes including monocytes, macrophages, and dendritic cells. These cells sense and attack potential pathogens, present antigens to adaptive immune cells, and recruit other immune cells. Recombinant human (rhu) GM-CSF (e.g., sargramostim [glycosylated, yeast-derived rhu GM-CSF]) has immune modulating properties and can restore the normal function of mononuclear phagocytes rendered dysfunctional by deficient or insufficient endogenous GM-CSF.

Methods

We reviewed the emerging biologic and cellular effects of GM-CSF. Experts in clinical disease areas caused by deficient or insufficient endogenous GM-CSF examined the role of GM-CSF in mononuclear phagocyte disorders including autoimmune pulmonary alveolar proteinosis (aPAP), diverse infections (including COVID-19), wound healing, and anti-cancer immune checkpoint inhibitor therapy.

Results

We discuss emerging data for GM-CSF biology including the positive effects on mitochondrial function and cell metabolism, augmentation of phagocytosis and efferocytosis, and immune cell modulation. We further address how giving exogenous rhu GM-CSF may control or treat mononuclear phagocyte dysfunction disorders caused or exacerbated by GM-CSF deficiency or insufficiency. We discuss how rhu GM-CSF may augment the anti-cancer effects of immune checkpoint inhibitor immunotherapy as well as ameliorate immune-related adverse events.

Discussion

We identify research gaps, opportunities, and the concept that rhu GM-CSF, by supporting and restoring the metabolic capacity and function of mononuclear phagocytes, can have significant therapeutic effects. rhu GM-CSF (e.g., sargramostim) might ameliorate multiple diseases of GM-CSF deficiency or insufficiency and address a high unmet medical need.

Circulating endothelial precursor cells are associated with a healed diabetic foot ulcer evaluated in a prospective cohort study

The goal of this multicentre study was to evaluate whether circulating endothelial precursor cells and microparticles can predict diabetic foot ulcer healing by the 16th week of care. We enrolled 207 subjects, and 40.0% (28.4, 41.5) healed by the 16th week of care. Using flow cytometry analysis, several circulating endothelial precursor cells measured at the first week of care were associated with healing after adjustment for wound area and wound duration. For example, CD34+ CD45dim , the univariate odds ratio was 1.19 (95% confidence interval: 0.88, 1.61) and after adjustment for wound area and wound duration, the odds ratio was (1.67 (1.16, 2.42) p = 0.006). A prognostic model using CD34+ CD45dim , wound area, and wound duration had an area under the curve of 0.75 (0.67, 0.82) and CD34+ CD45dim per initial wound area, an area under the curve of 0.72 (0.64, 0.79). Microparticles were not associated with a healed wound. Previous studies have indicated that circulating endothelial precursor cells measured at the first office visit are associated with a healed diabetic foot ulcer. In this multicentred prospective study, we confirm this finding, show the importance of adjusting circulating endothelial precursor cells measurements by wound area, and show circulating endothelial precursor cells per wound area is highly predictive of a healed diabetic foot ulcer by 16th week of care.

[Low-dose topical recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF) therapy for chronic venous leg ulcers, 10-year follow-up]

BACKGROUND

The treatment of leg ulcers is an enormous problem worldwide. Chronic venous ulceration affects 1% of the population and often has a protracted course. Recurrence rate is high, ranging up to 69% in the first year after healing.

OBJECTIVES

To determine whether topical application of low-dose topical recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF) is safe in venous leg ulcer treatment, and whether it accelerates healing rates and reduces recurrence rates.

MATERIALS AND METHODS

Consecutive patients with chronic venous leg ulcers received topical treatment with low-dose rhu GM-CSF (10 µg/mL 0.9% sodium chloride solution; 1.0-2.3 µg rhu GM-CSF/cm²) in combination with treatment of venous insufficiency. All patients were previously treated with other topical wound remedies for several weeks (median 8 weeks) without success.

RESULTS

In 119 of 130 patients, the wounds healed completely (91.5%). No local or systemic adverse reactions were observed. The mean time to healing was 24 weeks (median 14 weeks). Median follow-up of the 119 patients with healed ulcers was 84 months. The recurrence rates were 5.2% after 1 year, 18.9% after 4 years and 32.0% after 10 years.

CONCLUSIONS

Topical low-dose rhu GM-CSF proved to be safe and highly effective. Healing rates were comparable to those reported in the ESCHAR study (Effects of Surgery and Compression on Healing And Recurrence in venous ulceration) and recurrence rates were the lowest reported in the literature. Topical therapy with rhu GM-CSF can be applied in an outpatient setting and does not require hospitalization.

Topical Aspirin Administration Improves Cutaneous Wound Healing in Diabetic Mice Through a Phenotypic Switch of Wound Macrophages Toward an Anti-inflammatory and Proresolutive Profile Characterized by LXA4 Release

Patients with diabetes present a persistent inflammatory process, leading to impaired wound healing. Since nonhealing diabetic wound management shows limited results, the introduction of advanced therapies targeting and correcting the inflammatory status of macrophages in chronic wounds could be an effective therapeutic strategy to stop the sustained inflammation and to return to a healing state. In an excisional skin injury in a diet-induced diabetic murine model, we demonstrate that topical administration of low-dose aspirin (36 μg/wound/day) improves cutaneous wound healing by increasing wound closure through the promotion of the inflammation resolution program of macrophages. This treatment increased efferocytosis of wound macrophages from aspirin-treated diabetic mice compared with untreated diabetic mice. We also show that aspirin treatment of high-fat-fed mice oriented the phenotype of wound macrophages toward an anti-inflammatory and proresolutive profile characterized by a decrease of LTB4 production. The use of diabetic mice deficient for 5-LOX or 12/15-LOX demonstrated that these two enzymes of acid arachidonic metabolism are essential for the beneficial effect of aspirin on wound healing. Thus, aspirin treatment modified the balance between pro- and anti-inflammatory eicosanoids by promoting the synthesis of proresolving LXA4 through 5-LOX, LTA4, 12/15-LOX signaling. In conclusion, the restoration of an anti-inflammatory and proresolutive phenotype of wound macrophages by the topical administration of low-dose aspirin represents a promising therapeutic approach in chronic wounds.

Growth Factor and Cytokine Delivery Systems for Wound Healing

Skin wound healing is a highly coordinated process involving multiple tissue-resident and recruited cell types. Cells within the wound microenvironment respond to key secreted factors such as pro-proliferative growth factors and immunomodulatory cytokines to repair the skin and promptly restore its essential barrier role. Therefore, recombinant growth factors and cytokines are promising therapeutics for skin wounds, in particular for large acute wounds such as burns, or wounds associated with underlying pathologies such as nonhealing chronic and diabetic wounds. However, translation of growth factors and cytokines into clinically effective treatments has been limited. Short half-life, poor stability, rapid diffusion, uncontrolled signaling, and systemic side effects are currently the key challenges to developing efficient growth factor- and cytokine-based therapies. To overcome these limitations, novel delivery systems have been developed to improve the regenerative potential of recombinant growth factors and cytokines. In this review, we discuss biomaterial and protein engineering strategies used to optimize the delivery of growth factor and cytokine therapeutics for skin wound treatment.

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.

Advancements in the Delivery of Growth Factors and Cytokines for the Treatment of Cutaneous Wound Indications

Significance: Wound healing involves the phasic production of growth factors (GFs) and cytokines to progress an acute wound to a resolved scar. Dysregulation of these proteins contributes to both wound chronicity and excessive scarring. Direct supplementation of GFs and cytokines for treatment of healing and scarring complications has, however, been disappointing. Failings likely relate to an inability to deliver recombinant proteins at physiologically relevant levels to an environment conducive to healing. Recent Advances: Inspired by the extracellular matrix, natural biomaterials have been developed that resemble human skin, and are capable of delivering bioactives. Hybrid biomaterials made using multiple polymers, fabrication methods, and proteins are proving efficacious in animal models of acute and impaired wound healing. Critical Issues: For clinical translation, these delivery systems must be tailored for specific wound indications and the correct phase of healing. GFs and cytokines must be delivered in a controlled manner that will target specific healing or scarring impairments. Preclinical assessment in clinically relevant animal models of impaired or excessive healing is critical. Future Directions: Clinical success will likely depend on the GF or cytokine selected, their compatibility with the chosen biomaterial(s), degradation rate of the fabricated system, and the degree of control over release kinetics. Further testing is essential to assess which wound indications are most suited to specific delivery systems and to prove whether they provide superior efficacy over direct protein therapies.

Wound Healing Driver Gene and Therapeutic Development: Political and Scientific Hurdles

Significance: Since the last Food and Drug Administration (FDA) approval of a wound healing therapeutic in 1997, no new therapeutic candidate (excluding physical therapies, devices, dressings, and antimicrobial agents) has advanced to clinical applications. During this period, the FDA drug approvals for tumors, which have been referred to as "wounds that do not heal," have reached a total of 284 (by end of 2018). Both political and scientific factors may explain this large discrepancy in drug approvals for the two seemingly related and equally complex pathophysiological conditions. Recent Advances: Using the current research funding ratio of 1:150 for wound healing to cancer and the 5% FDA drug approval rate for oncology, we reach a crude estimate of a 0.03% success rate for wound healing therapeutics. Unless a drastic improvement of the current situation, we express a pessimistic outlook toward new and effective wound healing drugs. Critical Issues: We argue that successful development of wound healing therapeutics will rely on identification of wound healing driver genes (WDGs), and the focus should be on WDGs for the wound closure phase of wound healing. Therefore, WDGs must be both necessary and sufficient for wound closure; the absence of a WDG disrupts wound closure, while its supplementation alone is sufficient to restore full wound closure. Successful translation of a WDG into therapeutics requires availability of well-defined animal models with a high degree of relevance to humans. This review discusses the main hurdles faced by the wound healing research community behind the development of so-called "rescuing drugs" for wound healing. Future Directions: Given the lack of new wound healing drugs for the past 23 years, there is a need for a wide range of fresh, innovative, and thorough debates on wound healing drug development, including an organized movement to raise public support for wound healing research.

The Role of MSC in Wound Healing, Scarring and Regeneration

Tissue repair and regeneration after damage is not completely understood, and current therapies to support this process are limited. The wound healing process is associated with cell migration and proliferation, extracellular matrix remodeling, angiogenesis and re-epithelialization. In normal conditions, a wound will lead to healing, resulting in reparation of the tissue. Several risk factors, chronic inflammation, and some diseases lead to a deficient wound closure, producing a scar that can finish with a pathological fibrosis. Mesenchymal stem/stromal cells (MSCs) are widely used for their regenerative capacity and their possible therapeutically potential. Derived products of MSCs, such as exosomes or extravesicles, have shown a therapeutic potential similar to MSCs, and these cell-free products may be interesting in clinics. MSCs or their derivative products have shown paracrine beneficial effects, regulating inflammation, modifying the fibroblast activation and production of collagen and promoting neovascularization and re-epithelialization. This review describes the effects of MSCs and their derived products in each step of the wound repair process. As well, it reviews the pre-clinical and clinical use of MSCs to benefit in skin wound healing in diabetic associated wounds and in pathophysiological fibrosis.

Review of the Current Evidence for Topical Treatment for Venous Leg Ulcers

OBJECTIVE

The development of a venous leg ulcer (VLU) represents the most severe clinical manifestation of a chronic venous disease. Despite major progress, there is a limited understanding of VLU pathogenesis and wound healing biology. Treatment of VLUs remains a serious challenge for physicians of different specialties. This communication focuses on describing the rationale and scientific basis for topical wound care in the management of VLUs.

METHODS

A literature review was performed to summarize methods with proven efficacy in VLU management. A systematic literature search was also performed to identify new evidence from the randomized controlled trials published within 2014-2021. The scientific challenges, clinical practice concerns, economic obstacles, and possible directions for further research have been discussed.

RESULTS

Hundreds of topical products have been advertised for the treatment of VLUs. Published data on topical treatment of venous ulcers is insufficient, scattered, weak, and has significant methodological flaws. Forty-three randomized controlled trials on topical treatment of VLUs have been published within 2014-2021. Clinical practice guidelines need to be updated. Major gaps in knowledge have been identified, and suggestions for future research directions have been provided.

CONCLUSIONS

The American Venous Forum Research Committee would like to bring attention to topical wound care for VLUs as a critical gap in knowledge, and encourage scientists, practitioners, and industry to collaborate to fill this gap.

Synergistic effect of immunomodulatory S100A8/A9 and ciprofloxacin against Pseudomonas aeruginosa biofilm in a murine chronic wound model

The majority of chronic wounds are associated with bacterial biofilms recalcitrant to antibiotics and host responses. Immunomodulatory S100A8/A9 is suppressed in Pseudomonas aeruginosa biofilm infected wounds. We aimed at investigating a possible additive effect between S100A8/A9 and ciprofloxacin against biofilms.

MATERIALS/METHODS

Thirty-two mice were injected with alginate-embedded P. aeruginosa following a third-degree burn. The mice were randomized into four groups receiving combination ciprofloxacin and S100A8/A9 or monotherapy ciprofloxacin, S100A8/A9 or a placebo and evaluated by host responses and quantitative bacteriology in wounds. In addition, in vitro checkerboard analysis was performed, with P. aeruginosa and ascending S100A8/A9 and ciprofloxacin concentrations.

RESULTS

S100A8/A9 augmented the effect of ciprofloxacin in vivo by lowering the bacterial quantity compared to the placebo arm and the two monointervention groups (P < 0.0001). S100A8 and 100A9 were increased in the double-treated group as compared to the monointervention groups (P = 0.032, P = 0.0023). Tissue inhibitor of metalloproteinases-1 and keratinocyte\chemokine chemoattractant-1 were increased in the double-intervention group compared to the S100A8/A9 group (P = 0.050, P = 0.050). No in vitro synergism was detected.

CONCLUSION

The observed ciprofloxacin-augmenting effect of S100A8/A9 in vivo was not confirmed by checkerboard analysis, indicating dependence on host cells for the S100A8/A9 effect. S100A8/A9 and ciprofloxacin is a promising therapy for optimizing chronic wound treatment.

Mesenchymal Stem Cells as a Cornerstone in a Galaxy of Intercellular Signals: Basis for a New Era of Medicine

Around 40% of the population will suffer at some point in their life a disease involving tissue loss or an inflammatory or autoimmune process that cannot be satisfactorily controlled with current therapies. An alternative for these processes is represented by stem cells and, especially, mesenchymal stem cells (MSC). Numerous preclinical studies have shown MSC to have therapeutic effects in different clinical conditions, probably due to their mesodermal origin. Thereby, MSC appear to play a central role in the control of a galaxy of intercellular signals of anti-inflammatory, regenerative, angiogenic, anti-fibrotic, anti-oxidative stress effects of anti-apoptotic, anti-tumor, or anti-microbial type. This concept forces us to return to the origin of natural physiological processes as a starting point to understand the evolution of MSC therapy in the field of regenerative medicine. These biological effects, demonstrated in countless preclinical studies, justify their first clinical applications, and draw a horizon of new therapeutic strategies. However, several limitations of MSC as cell therapy are recognized, such as safety issues, handling difficulties for therapeutic purposes, and high economic cost. For these reasons, there is an ongoing tendency to consider the use of MSC-derived secretome products as a therapeutic tool, since they reproduce the effects of their parent cells. However, it will be necessary to resolve key aspects, such as the choice of the ideal type of MSC according to their origin for each therapeutic indication and the implementation of new standardized production strategies. Therefore, stem cell science based on an intelligently designed production of MSC and or their derivative products will be able to advance towards an innovative and more personalized medical biotechnology.

Skin well-being in diabetes: Role of macrophages

Macrophages are key players in wound healing- along with mediating the acute inflammatory response, macrophages activate cutaneous epithelial cells and promote tissue repair. Diabetes complications, including diabetic chronic wounds, are accompanied by persistent inflammation and macrophage malfunction. Several studies indicate that hyperglycemia induces various alterations that affect macrophage function in wound healing including epigenetic changes, imbalance between pro- and anti-inflammatory modulators, and insensitivity to proliferative stimuli. In this review, we briefly summarize recent studies regarding those alterations and their implications on skin well-being in diabetes.

A porous collagen-GAG scaffold promotes muscle regeneration following volumetric muscle loss injury

Volumetric muscle loss (VML) is a segmental loss of skeletal muscle which commonly heals with fibrosis, minimal muscle regeneration, and loss of muscle strength. Treatment options for these wounds which promote functional recovery are currently lacking. This study was designed to investigate whether the collagen-GAG scaffold (CGS) promotes functional muscle recovery following VML. A total of 66 C57/Bl6 mice were used in a three-stage experiment. First, 24 animals were split into three groups which underwent sham injury or unilateral quadriceps VML injury with or without CGS implantation. Two weeks post-surgery, muscle was harvested for histological and gene expression analysis. In the second stage, 18 mice underwent bilateral quadriceps VML injury, followed by weekly functional testing using a treadmill. In the third stage, 24 mice underwent sham or bilateral quadriceps VML injury with or without CGS implantation, with tissue harvested six weeks post-surgery for histological and gene expression analysis. VML mice treated with CGS demonstrated increased remnant fiber hypertrophy versus both the VML with no CGS and uninjured groups. Both VML groups showed greater muscle fiber hypertrophy than non-injured muscle. This phenomenon was still evident in the longer-term experiment. The gene array indicated that the CGS promoted upregulation of factors involved in promoting wound healing and regeneration. In terms of functional improvement, the VML mice treated with CGS ran at higher maximum speeds than VML without CGS. A CGS was shown to enhance muscle hypertrophy in response to VML injury with a resultant improvement in functional performance. A gene array highlighted increased gene expression of multiple growth factors following CGS implantation. This suggests that implantation of a CGS could be a promising treatment for VML wounds.

The discovery and development of topical medicines for wound healing

INTRODUCTION

Chronic, nonhealing skin wounds claim >3% of the health-care budget in industrialized countries, and the incidence is rising. Currently, two parallel trends influence innovations within the field of wound healing: the need to reduce spread of antibiotic resistance and the emerging use of health economy and value-based models. Areas covered: This review focuses on the discovery of drug candidates and development of treatments aiming to enhance wound healing in the heterogeneous group of patients with nonhealing wounds. Expert opinion: Nonhealing wounds are multifaceted and recognized as difficult indications. The majority of products currently in use are medical device dressings, or concepts of negative pressure or hyperbaric oxygen treatment. Global best practice guidelines for the treatment of diabetic foot ulcers recommend debridement, redressing, as well as infection control, and are critical to the lack of coherent clinical evidence for many approved products in active wound care. To accelerate wound healing, there is an emerging trend toward biologics, gene therapy, and novel concepts for drug delivery in research and in the pipeline for clinical trials. Scientific delineation of the therapeutic mechanism of action is, in our opinion, vital for clinical trial success and for an increased fraction of medical products in the pharmaceutical pipeline.

Deregulated AUF1 Assists BMP-EZH2-Mediated Delayed Wound Healing during Candida albicans Infection

Tissue repair is a complex process that necessitates an interplay of cellular processes, now known to be dictated by epigenetics. Intriguingly, macrophages are testimony to a large repertoire of evolving functions in this process. We identified a role for BMP signaling in regulating macrophage responses to Candida albicans infection during wound repair in a murine model. In this study, the RNA binding protein, AU-rich element-binding factor 1, was posttranslationally destabilized to bring about ubiquitin ligase, NEDD4-directed activation of BMP signaling. Concomitantly, PI3K/PKCδ mobilized the rapid phosphorylation of BMP-responsive Smad1/5/8. Activated BMP pathway orchestrated the elevated recruitment of EZH2 at promoters of genes assisting timely wound closure. In vivo, the repressive H3K27 trimethylation was observed to persist, accompanied by a robust upregulation of BMP pathway upon infection with C. albicans, culminating in delayed wound healing. Altogether, we uncovered the signaling networks coordinated by fungal colonies that are now increasingly associated with the infected wound microbiome, resulting in altered wound fate.

AVURT: aspirin versus placebo for the treatment of venous leg ulcers - a Phase II pilot randomised controlled trial

BACKGROUND

Venous leg ulcers (VLUs) are the most common cause of leg ulceration, affecting 1 in 100 adults. VLUs may take many months to heal (25% fail to heal). Estimated prevalence is between 1% and 3% of the elderly population. Compression is the mainstay of treatment and few additional therapies exist to improve healing. Two previous trials have indicated that low-dose aspirin, as an adjunct to standard care, may improve healing time, but these trials were insufficiently robust. Aspirin is an inexpensive, widely used medication but its safety and efficacy in the treatment of VLUs remains to be established.

OBJECTIVES

Primary objective - to assess the effects of 300 mg of aspirin (daily) versus placebo on the time to healing of the reference VLU. Secondary objectives - to assess the feasibility of leading into a larger pragmatic Phase III trial and the safety of aspirin in this population.

DESIGN

A multicentred, pilot, Phase II randomised double-blind, parallel-group, placebo-controlled efficacy trial.

SETTING

Community leg ulcer clinics or services, hospital outpatient clinics, leg ulcer clinics, tissue viability clinics and wound clinics in England, Wales and Scotland.

PARTICIPANTS

Patients aged ≥ 18 years with a chronic VLU (i.e. the VLU is > 6 weeks in duration or the patient has a history of VLU) and who are not regularly taking aspirin.

INTERVENTIONS

300 mg of daily oral aspirin versus placebo. All patients were offered care in accordance with Scottish Intercollegiate Guidelines Network (SIGN) guidance with multicomponent compression therapy aiming to deliver 40 mmHg at the ankle when possible.

RANDOMISATION

Participants were allocated in a 1 : 1 (aspirin : placebo) ratio by the Research Pharmacy, St George's University Hospitals NHS Foundation Trust, using a randomisation schedule generated in advance by the investigational medicinal product manufacturer. Randomisation was stratified according to ulcer size (≤ 5cm² or > 5cm²).

MAIN OUTCOME MEASURE

The primary outcome was time to healing of the largest eligible ulcer (reference ulcer).

FEASIBILITY RESULTS – RECRUITMENT

27 patients were recruited from eight sites over a period of 8 months. The target of 100 patients was not achieved and two sites did not recruit. Barriers to recruitment included a short recruitment window and a large proportion of participants failing to meet the eligibility criteria.

RESULTS

The average age of the 27 randomised participants (placebo, n = 13; aspirin, n = 14) was 62 years (standard deviation 13 years), and two-thirds were male (n = 18). Participants had their reference ulcer for a median of 15 months, and the median size of ulcer was 17.1 cm². There was no evidence of a difference in time to healing of the reference ulcer between groups in an adjusted analysis for log-ulcer area and duration (hazard ratio 0.58, 95% confidence interval 0.18 to 1.85; p = 0.357). One expected, related serious adverse event was recorded for a participant in the aspirin group.

LIMITATIONS

The trial under-recruited because many patients did not meet the eligibility criteria.

CONCLUSIONS

There was no evidence that aspirin was efficacious in hastening the healing of chronic VLUs. It can be concluded that a larger Phase III (effectiveness) trial would not be feasible.

TRIAL REGISTRATION

Clinical Trials.gov NCT02333123; European Clinical Trials Database (EudraCT) 2014-003979-39.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 55. See the NIHR Journals Library website for further project information.

Immune Regulation of Skin Wound Healing: Mechanisms and Novel Therapeutic Targets

Significance: The immune system plays a central role in orchestrating the tissue healing process. Hence, controlling the immune system to promote tissue repair and regeneration is an attractive approach when designing regenerative strategies. This review discusses the pathophysiology of both acute and chronic wounds and possible strategies to control the immune system to accelerate chronic wound closure and promote skin regeneration (scar-less healing) of acute wounds. Recent Advances: Recent studies have revealed the key roles of various immune cells and immune mediators in skin repair. Thus, immune components have been targeted to promote chronic wound repair or skin regeneration and several growth factors, cytokines, and biomaterials have shown promising results in animal models. However, these novel strategies are often struggling to meet efficacy standards in clinical trials, partly due to inadequate drug delivery systems and safety concerns. Critical Issues: Excess inflammation is a major culprit in the dysregulation of normal wound healing, and further limiting inflammation effectively reduces scarring. However, current knowledge is insufficient to efficiently control inflammation and specific immune cells. This is further complicated by inadequate drug delivery methods. Future Directions: Improving our understanding of the molecular pathways through which the immune system controls the wound healing process could facilitate the design of novel regenerative therapies. Additionally, better delivery systems may make current and future therapies more effective. To promote the entry of current regenerative strategies into clinical trials, more evidence on their safety, efficacy, and cost-effectiveness is also needed.

The Role of Macrophages in Acute and Chronic Wound Healing and Interventions to Promote Pro-wound Healing Phenotypes

Macrophages play key roles in all phases of adult wound healing, which are inflammation, proliferation, and remodeling. As wounds heal, the local macrophage population transitions from predominantly pro-inflammatory (M1-like phenotypes) to anti-inflammatory (M2-like phenotypes). Non-healing chronic wounds, such as pressure, arterial, venous, and diabetic ulcers indefinitely remain in inflammation—the first stage of wound healing. Thus, local macrophages retain pro-inflammatory characteristics. This review discusses the physiology of monocytes and macrophages in acute wound healing and the different phenotypes described in the literature for both in vitro and in vivo models. We also discuss aberrations that occur in macrophage populations in chronic wounds, and attempts to restore macrophage function by therapeutic approaches. These include endogenous M1 attenuation, exogenous M2 supplementation and endogenous macrophage modulation/M2 promotion via mesenchymal stem cells, growth factors, biomaterials, heme oxygenase-1 (HO-1) expression, and oxygen therapy. We recognize the challenges and controversies that exist in this field, such as standardization of macrophage phenotype nomenclature, definition of their distinct roles and understanding which phenotype is optimal in order to promote healing in chronic wounds.

Delivery systems of current biologicals for the treatment of chronic cutaneous wounds and severe burns

While wound therapy remains a clinical challenge in current medical practice, much effort has focused on developing biological therapeutic approaches. This paper presents a comprehensive review of delivery systems for current biologicals for the treatment of chronic wounds and severe burns. The biologicals discussed here include proteins such as growth factors and gene modifying molecules, which may be delivered to wounds free, encapsulated, or released from living systems (cells, skin grafts or skin equivalents) or biomaterials. Advances in biomaterial science and technologies have enabled the synthesis of delivery systems such as scaffolds, hydrogels and nanoparticles, designed to not only allow spatially and temporally controlled release of biologicals, but to also emulate the natural extracellular matrix microenvironment. These technologies represent an attractive field for regenerative wound therapy, by offering more personalised and effective treatments.

Topically administered rhGM-CSF affects PPARβ expression in the stasis zone

Using a rat comb thermal damage model, we investigated the effects of topically administered recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on peroxisome proliferator-activated receptor PPARβ expression. We created bilateral comb scald models on the backs of fifty Sprague-Dawley rats. The left sides of the backs served as the experimental group and the right sides served as the control group. The experimental group received topically applied rhGM-CSF hydrogel and the control group did not. The survival situations of the stasis zones were compared between the experimental and control groups on the 1st, 3rd, 7th, 14th and 21st post-burn days. Tissues from the surviving stasis zones of both groups were collected at different time-points. Reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting were used to detect the PPARβ mRNA and protein expression levels. Immunohistochemical methods were applied to detect the localization of PPARβ protein expression. The results showed that, first, the tissue viability numbers for the stasis zones of the experimental group were significantly increased compared with those of the control group. Second, RT-PCR revealed that the PPARβ mRNA expression first increased and then gradually declined in both groups. At all time-points, the expression level in the experimental group was increased compared with that in the control group and the highest expression levels were observed in both groups on the 3rd post-burn day. Third, western blot analysis revealed that the PPARβ protein expression in both groups increased after thermal damage and then gradually decreased. PPARβ protein expression in the experimental group was greater than that in the control group, and the highest expression quantities in both groups were observed on the 3rd post-burn day. In conclusion, rhGM-CSF hydrogel effectively promotes the expression of PPARβ, and the hydrogel had a specific protective effect for the stasis zone.

Mesenchymal stem cell in venous leg ulcer: An intoxicating therapy

Venous leg ulcers (VLU) are a prevalent and reoccurring type of complicated wound, turning as a considerable public healthcare issue, with critical social and economic concern. There are both medical and surgical therapies to treat venous leg ulcers; however, a cure does not yet exist. Mesenchymal stem cells (MSC) are capable and proved of accelerating wound healing in vivo and their study with human chronic wounds is currently awaited. MSCs are a promising source of adult progenitor cells for cellular therapy and have been demonstrated to differentiate into various mesenchymal cell lineages. They have a crucial and integral role in native wound healing by regulating immune response and inflammation. Improved understanding of the cellular and molecular mechanisms at work in delayed wound healing compels to the development of cellular therapy in VLU. This review focuses on the current treatment option of VLU and further emphasizing the role of MSCs in accelerating the healing process. With further understanding of the mechanism of action of these cells in wound improvement and, the involvement of cytokines can also be revealed that could be used for the therapeutic purpose for VLU healing. Clinical uses of MSCs have been started already, and induced MSCs are surely a promising tool or compelling therapy for VLU.

Concise Review: The Use of Adipose-Derived Stromal Vascular Fraction Cells and Platelet Rich Plasma in Regenerative Plastic Surgery

Tissue engineering has emerged at the intersection of numerous disciplines to meet a global clinical need for technologies to promote the regeneration of tissues. Recently, many authors have focused their attention on mesenchymal stem/stromal cells (MSCs) for their capacity to differentiate into many cell lineages. The most widely studied cell types are bone marrow mesenchymal stem cells and adipose-derived stem cells (ASCs), which display similar results. Biomaterials, cells, and growth factors are needed to design a regenerative plastic surgery approach in the treatment of organ and tissue defects, but not all tissues are created equal. The aim of this article is to describe the advances in tissue engineering through the use of ASCs, platelet rich plasma, and biomaterials to enable regeneration of damaged complex tissue. Stem Cells 2017;35:117-134.

Innovative Therapies in Wound Healing

Background:

Apligraf is a bioengineered skin product composed of neonatal fibroblasts and keratinocytes. The FDA has approved Apligraf for the treatment of chronic venous ulcers and diabetic ulcers.

Objective:

We review the development of bioengineered skin, examine the cellular activities of various growth factors that may facilitate wound healing, and discuss the results of clinical trials with a particular construct, Apligraf, as proof of principle.

Conclusion:

Bioengineered skin acts as a “smart” delivery system for growth factors and other stimulatory substances. Not only does it present a novel treatment for chronic and diabetic ulcers, but it could also be considered for application to other types of acute wounds.

Aspirin for Venous Ulcers: Randomised Trial (AVURT): study protocol for a randomised controlled trial

BACKGROUND

Venous leg ulcers (VLUs) are the commonest cause of leg ulceration, affecting 1 in 100 adults. There is a significant health burden associated with VLUs - it is estimated that the cost of treatment for 1 ulcer is up to £1300 per year in the NHS. The mainstay of treatment is with graduated compression bandaging; however, treatment is often prolonged and up to one quarter of venous leg ulcers do not heal despite standard care. Two previous trials have suggested that low-dose aspirin, as an adjunct to standard care, may hasten healing, but these trials were small and of poor quality. Aspirin is an inexpensive, widely used medication but its safety and efficacy in the treatment of VLUs remains to be established.

METHODS/DESIGN

AVURT is a phase II randomised double blind, parallel-group, placebo-controlled efficacy trial. The primary objective is to examine whether aspirin, in addition to standard care, is effective in patients with chronic VLUs (i.e. over 6 weeks in duration or a history of VLU). Secondary objectives include feasibility and safety of aspirin in this population. A target of 100 participants, identified from community leg ulcer clinics and hospital clinics, will be randomised to receive either 300 mg of aspirin once daily or placebo. All participants will receive standard care with compression therapy. The primary outcome will be time to healing of the reference ulcer. Follow-up will occur for a maximum of 27 weeks. The primary analysis will use a Cox proportional hazards model to compare time to healing using the principles of intention-to-treat. Secondary outcomes will include ulcer size, pain evaluation, compliance and adverse events.

DISCUSSION

The AVURT trial will investigate the efficacy and safety of aspirin as a treatment for VLU and will inform on the feasibility of proceeding to a larger phase III study. This study will address the paucity of information currently available regarding aspirin therapy to treat VLU.

TRIAL REGISTRATION

The study is registered on a public database with clinicaltrials.gov ( NCT02333123 ; registered on 5 November 2014).

Wound repair and regeneration: mechanisms, signaling, and translation

The cellular and molecular mechanisms underpinning tissue repair and its failure to heal are still poorly understood, and current therapies are limited. Poor wound healing after trauma, surgery, acute illness, or chronic disease conditions affects millions of people worldwide each year and is the consequence of poorly regulated elements of the healthy tissue repair response, including inflammation, angiogenesis, matrix deposition, and cell recruitment. Failure of one or several of these cellular processes is generally linked to an underlying clinical condition, such as vascular disease, diabetes, or aging, which are all frequently associated with healing pathologies. The search for clinical strategies that might improve the body's natural repair mechanisms will need to be based on a thorough understanding of the basic biology of repair and regeneration. In this review, we highlight emerging concepts in tissue regeneration and repair, and provide some perspectives on how to translate current knowledge into viable clinical approaches for treating patients with wound-healing pathologies.

Efficacy of a new multifunctional surfactant-based biomaterial dressing with 1% silver sulphadiazine in chronic wounds

Chronic wounds represent a large and growing segment of health care and add considerably to human suffering and economic burden as populations age. More effective materials, especially those promoting ease of use and economy, are needed to treat this increasing number of patients. A case series conducted at a European outpatient tertiary wound centre used a novel surfactant-based biomaterial dressing containing 1% silver sulphadiazine on 226 chronic wound patients with various aetiologies. Eighty-eight patients had been undergoing standard of care treatment at the facility, while the remainder (n = 138) began treatment with the surfactant-based biomaterial dressing on enrollment. A total of 73% of the first group healed or showed improvement, with 60% healing by a median of 17 weeks after beginning treatment, and 86% of the group of new enrollees healed or showed improvement, with 73% healing within a median of 12 weeks of beginning treatment with the new product. Patient and clinician reports showed improved compliance, reduced pain and a favourable side-effect profile. Limited economic analysis showed markedly reduced treatment costs compared with standard of care. Further research is recommended.

Clinical application of growth factors and cytokines in wound healing

Wound healing is a complex and dynamic biological process that involves the coordinated efforts of multiple cell types and is executed and regulated by numerous growth factors and cytokines. There has been a drive in the past two decades to study the therapeutic effects of various growth factors in the clinical management of nonhealing wounds (e.g., pressure ulcers, chronic venous ulcers, diabetic foot ulcers). For this review, we conducted an online search of Medline/PubMed and critically analyzed the literature regarding the role of growth factors and cytokines in the management of these wounds. We focused on currently approved therapies, emerging therapies, and future research possibilities. In this review, we discuss four growth factors and cytokines currently being used on and off label for the healing of wounds. These include granulocyte-macrophage colony-stimulating factor, platelet-derived growth factor, vascular endothelial growth factor, and basic fibroblast growth factor. While the clinical results of using growth factors and cytokines are encouraging, many studies involved a small sample size and are disparate in measured endpoints. Therefore, further research is required to provide definitive evidence of efficacy.

Which dressings reduce inflammation and improve venous leg ulcer healing

Chronic venous leg ulcers (VLU) affect around 1% of the adult population in the Western world. The impact of VLU is both social and economic, with significant expenditures on active venous ulcers to provide medical treatment and eventual healing. At the core of VLU is venous hypertension which affects the venous macrocirculation. The changes incurred in venous hemodynamics leads to microcirculatory changes affecting the postcapillary venule and surrounding tissues. Inflammation by leukocytes affecting the venous endothelium, promotes a complex cascade and activation of adhesion molecules expression, chemokines and cytokines released, altered growth factor responses, and activation of protease (e.g. tPA) and proteinase (e.g. MMPs) activity that causes dysregulation and compromise of tissue integrity with eventual dermal damage and ulcer development. A critical component to treating VLU is correcting the abnormal venous hemodynamics and compression therapy. Unfortunately, VLU recurrence ranges between 30–70%, and other modalities in therapy along with compression are required. The goal for adjuvant products is to restore the balance from an inflammatory chronic wound to that of a reparative wound that will promote provisional matrix and epithelialization. There are many products on the market that can be used as adjuvant to compression therapy, but it must be recognized that there is a paucity of clinical trials that have evaluated the clinical effectiveness of specific products with clearly defined end points, and most importantly a healed VLU with a low recurrence rate. This review will discuss the fundamentals of VLU inflammation, and evaluate the available literature that may have benefit in reducing inflammation and lead to effective VLU healing.

Combined application of alginate dressing and human granulocyte-macrophage colony stimulating factor promotes healing in refractory chronic skin ulcers

The aim of the present study was to evaluate the clinical therapeutic effect of the combined application of alginate and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on the healing of refractory chronic skin ulcers. A single center, three arm, randomized study was performed at Jinan Central Hospital (Jinan, Shandong, China). A total of 60 patients with refractory chronic skin ulcers, which persisted for >1 month, were enrolled and randomly assigned into one of the following three groups: alginate dressing/rhGM-CSF group (group A), rhGM-CSF only group (group B) and conventional (vaseline dressing) group (group C). The wound area rate was measured, granulation and color were observed and pain was evaluated. The data were summarized and statistical analysis was performed. The results demonstrated that group A exhibited a significantly faster wound healing rate and lower pain score compared with the other groups (P<0.01). In conclusion, the combined application of alginate dressing and rhGM-CSF for the treatment of refractory chronic skin ulcers demonstrated significant advantages. It promoted the growth of granulation tissue, accelerated re-epithelialization and also effectively reduced wound pain, and thus improved the quality of life for the patient. This suggests that the combined application of alginate and rhGM-CSF may be an effective therapeutic strategy for the clinical treatment of refractory chronic skin ulcers.

Wound bed preparation for chronic diabetic foot ulcers

The escalating incidence of diabetic mellitus has given rise to the increasing problems of chronic diabetic ulcers that confront the practice of medicine. Peripheral vascular disease, neuropathy, and infection contribute to the multifactorial pathogenesis of diabetic ulcers. Approaches to the management of diabetic ulcers should start with an assessment and optimization of the patient's general conditions, followed by considerations of the local and regional factors. This paper aims to address the management strategies for wound bed preparation in chronic diabetic foot ulcers and also emphasizes the importance of preventive measures and future directions. The “TIME” framework in wound bed preparation encompasses tissue management, inflammation and infection control, moisture balance, and epithelial (edge) advancement. Tissue management aims to remove the necrotic tissue burden via various methods of debridement. Infection and inflammation control restores bacterial balance with the reduction of bacterial biofilms. Achieving a moist wound healing environment without excessive wound moisture or dryness will result in moisture balance. Epithelial advancement is promoted via removing the physical and biochemical barriers for migration of epithelium from wound edges. These systematic and holistic approaches will potentiate the healing abilities of the chronic diabetic ulcers, including those that are recalcitrant.

Wound bed preparation from a clinical perspective

Wound bed preparation has been performed for over two decades, and the concept is well accepted. The ‘TIME’ acronym, consisting of tissue debridement, infection or inflammation, moisture balance and edge effect, has assisted clinicians systematically in wound assessment and management. While the focus has usually been concentrated around the wound, the evolving concept of wound bed preparation promotes the treatment of the patient as a whole. This article discusses wound bed preparation and its clinical management components along with the principles of advanced wound care management at the present time. Management of tissue necrosis can be tailored according to the wound and local expertise. It ranges from simple to modern techniques like wet to dry dressing, enzymatic, biological and surgical debridement. Restoration of the bacterial balance is also an important element in managing chronic wounds that are critically colonized. Achieving a balance moist wound will hasten healing and correct biochemical imbalance by removing the excessive enzymes and growth factors. This can be achieved will multitude of dressing materials. The negative pressure wound therapy being one of the great breakthroughs. The progress and understanding on scientific basis of the wound bed preparation over the last two decades are discussed further in this article in the clinical perspectives.

Harnessing growth factors to influence wound healing

Cutaneous wound healing is a dynamic process with the ultimate goal of restoring skin integrity. On injury to the skin, inflammatory cells, endothelial cells, fibroblasts, and keratinocytes undergo changes in gene expression and phenotype, leading to cell proliferation, migration, and differentiation. Cytokines and growth factors play an essential role in initiating and directing the phases of wound healing. These signaling peptides are produced by a variety of cells and lead to a concerted effort to restore the skin barrier function.