Monocyte chemoattractant protein-1 detection in wound tissue fluids for the assisted diagnosis of wound infection

BACKGROUND

Infections are commonly seen in wounds. The overall infection rate is 1.8% to 4.2%. Improper infection management can lead to serious conditions and may progress to life-threatening sepsis. Because there is a need for assistance in predicting wound infection before obvious clinical symptoms, the measurement of cytokines in wound tissue fluids has attracted our attention for determining the overall status of wound infection. Our intent was to assess the potential biomarkers in the diagnosis of wound infection.

METHODS

We collected 146 tissue fluids (acute: 59, chronic: 61, and normal: 26) for analysis of biomarkers using a human cytokine array. Serum C-reactive protein was also measured from 104 patients. The sensitivity and specificity of significant wound cytokines and serum C-reactive protein for the diagnosis of wound infection were evaluated.

RESULTS

Among biomarkers examined, serum C-reactive protein and tissue C-reactive protein were highly expressed in acute infection wounds, whereas monocyte chemoattractant protein-1 was significantly expressed in chronic infection wounds. Because the expression of wound biomarkers varied in different types of wounds, relationships among them were studied. A high correlation between tissue C-reactive protein and interleukin-8 (R2 = 0.7) and a moderate correlation between systemic and local C-reactive protein (R2 = 0.47) were observed. In addition, tissue monocyte chemoattractant protein-1 had better sensitivity (74%) and specificity (65%) in the diagnosis of wound infection. Moreover, combined serum C-reactive protein with monocyte chemoattractant protein-1 examination provided a higher area under the curve in the receiver operator characteristic curve (0.75).

CONCLUSION

We found that tissue monocyte chemoattractant protein-1 is a superior diagnostic marker for assistance with the diagnosis of wound infection.

Wound fluid sampling methods and analysis of cytokine mRNA expression in ulcers from patients with diabetes mellitus

The development of diabetic foot ulcers is a common and severe complication of diabetes that can significantly affect quality of life. The physiological healing cascade does not progress tissue repair in diabetic foot ulcerations in a timely manner. Serum markers from foot ulcers have been used to characterize the healing process of the diabetic foot using various collection techniques. This study aimed to compare the use of cervical brushes and the Levine technique to collect wound fluid from foot ulcers of people with diabetes in order to determine the presence of cytokines. The collected material was used for gene expression analysis of macrophage/monocyte-associated cytokines IL1-β, IL-6, TNF-α, regulatory cytokine IL-10 and growth factor TGFβ, via quantitative polymerase chain reaction (qPCR). Both collection methods produced sufficient amounts of RNA, but significantly more RNA was collected using a cervical brush (brush 224.82 ng/μL vs. Levine 80.90 ng/μL p = 0.0001). Significantly higher levels of expression of the following cytokine genes were detected in samples collected using a cervical brush: IL1-β (p = 0.0001), IL-6 (p = 0.0106), IL-10 (p = 0.0277) and TGFβ (p = 0.0002). Understanding why some wounds are difficult to heal is important for developing more effective treatments, and biomarkers may be useful for predicting the healing trajectory. These results demonstrate that it is possible to collect material from the wound bed for RT-qPCR analysis, and the cervical brush proved to be a simple and rapid method for monitoring cytokine gene expression.

Comparative analysis of electrochemical and optical sensors for detection of chronic wounds biomarkers: A review

Chronic wounds (CW) present a significant healthcare challenge due to their prolonged healing time and associated complications. To effectively treat these wounds and prevent further deterioration, monitoring their healing progress is crucial. Traditional wound assessment methods relying on visual inspection and subjective evaluation are prone to inter-observer variability. Biomarkers play a critical role in objectively evaluating wound status and predicting healing outcomes, providing quantitative measures of wound healing progress, inflammation, infection, and tissue regeneration. Recent attention has been devoted to identifying and validating CW biomarkers. Various studies have investigated potential biomarkers, including growth factors, cytokines, proteases, and extracellular matrix components, shedding light on the complex molecular and cellular processes within CW. This knowledge enables a more targeted and personalized approach to wound management. Accurate and sensitive techniques are necessary for detecting CW biomarkers. Thus, this review compares and discusses the use of electrochemical and optical sensors for biomarker determination. The advantages and disadvantages of these sensors are highlighted. Differences in detection capabilities and characteristics such as non-invasiveness, portability, high sensitivity, specificity, simplicity, cost-effectiveness, compatibility with point-of-care applications, and real-time monitoring of wound biomarkers will be pointed out and compared. In summary, this work provides an overview of CW, explores the emerging field of CW biomarkers, and discusses methods for detecting these biomarkers, with a specific focus on optical and electrochemical sensors. The potential of further research and development in this field for advancing wound care and improving patient outcomes will also be noted.

Chronic Wound Management: From Gauze to Homologous Cellular Matrix

BACKGROUND

Chronic wounds are a significant health problem with devastating consequences for patients' physical, social, and mental health, increasing healthcare systems' costs. Their prolonged healing times, economic burden, diminished quality of life, increased infection risk, and impact on patients' mobility and functionality make them a major concern for healthcare professionals.

PURPOSE

This review offers a multi-perspective analysis of the medical literature focusing on chronic wound management.

METHODS USED

We evaluated 48 articles from the last 21 years registered in the MEDLINE and Global Health databases. The articles included in our study had a minimum of 20 citations, patients > 18 years old, and focused on chronic, complex, and hard-to-heal wounds. Extracted data were summarized into a narrative synthesis using the same health-related quality of life instrument.

RESULTS

We evaluated the efficacy of existing wound care therapies from classical methods to modern concepts, and wound care products to regenerative medicine that uses a patient's pluripotent stem cells and growth factors. Regenerative medicine and stem cell therapies, biologic dressings and scaffolds, negative pressure wound therapy (NPWT), electrical stimulation, topical growth factors and cytokines, hyperbaric oxygen therapy (HBOT), advanced wound dressings, artificial intelligence (AI), and digital wound management are all part of the new arsenal of wound healing.

CONCLUSION

Periodic medical evaluation and proper use of modern wound care therapies, including the use of plasma-derived products [such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF)] combined with proper systemic support (adequate protein levels, blood sugar, vitamins involved in tissue regeneration, etc.) are the key to a faster wound healing, and, with the help of AI, can reach the fastest healing rate possible.

A method for harvesting viable cells from wound dressings

Wound fluid has been well studied for exploring protein biomarkers contained in it. However, cells in wound fluid have not received much attention due to the difficulty in their collection. Our study aimed to establish a method for collecting viable cells from discarded wound dressings. A protocol was designed to wash out nonadherent cells and detach adherent cells from silicone-faced foam wound dressings using trypsin-EDTA. The optimal concentration and incubation time of trypsin-EDTA for collecting equivalent proportions of different cell types to the original cell population were determined in vitro. Cell composition and gene expression changes in monocytes, lymphocytes, neutrophils, fibroblasts and keratinocytes were confirmed using immunocytochemistry and RNA-sequencing ex vivo. Full-thickness wounds were created on 9-week-old male C57BL/6J mice. Wound fluid was collected, and half of it was applied to the wound dressings. The original cell population in the wound fluid and the cell population collected from wound dressings were compared. In the in vitro study, 0.25% trypsin-EDTA and 2.5-min incubation time were considered optimal for collecting adherent cells from wound dressings. In the ex vivo study, among all cell types, only CD3+ lymphocytes showed a significantly higher cell proportion in the collected group. The relative gene expression of the five selected cells showed no significant changes (p-value >0.05, |log2 fold change| < 1.5, differential gene expression analysis). Viable nonadherent and adherent cells were collected from wound dressings without altering gene expression and could be used in future studies for cellular analysis of wound fluid.

Effect of mesenchymal stromal cells-derived extracellular vesicles as a treatment to heal diabetic wounds: A meta-analysis

A meta-analysis study to assess the influence of mesenchymal stromal cells-derived extracellular vesicles (MSC-EVs) as a treatment to heal the diabetic wound (DW). A comprehensive literature examination till February 2023 was implemented and 2975 linked studies were appraised. The picked studies contained 381 animals with diabetes mellitus in the picked studies' baseline, 217 of them were using MSC-EVs, and 173 were using control. Odds ratio in addition to 95% confidence intervals (CIs) were used to calculate the consequence of MSC-EVs as a therapy to heal DWs by the dichotomous and continuous styles and a fixed or random model. MSCs-EVs had a significantly higher rate of wound closure of DWs (Mean deviation [MD], 22.20; 95% CI, 19.16-25.24, P < .001), lower width of the scar (MD, -2.57; 95% CI, -3.35 to -1.79, P < .001), higher collagen deposition (MD, 30.82; 95% CI, 20.77-40.86, P < .001), and a higher rate of re-epithelialisation (MD, 34.36; 95% CI, 20.13-48.58, P < .001) compared with the control. MSCs-EVs had a significantly higher rate of wound closure of DWs, lower width of the scar, higher collagen deposition, and higher rate of re- epithelialisation compared with the control. Although precautions should be taken when commerce with the consequences because all of the picked studies for this meta-analysis was with low sample sizes.

NETworking with cancer: The bidirectional interplay between cancer and neutrophil extracellular traps

Neutrophils are major effectors and regulators of the immune system. They play critical roles not only in the eradication of pathogens but also in cancer initiation and progression. Conversely, the presence of cancer affects neutrophil activity, maturation, and lifespan. By promoting or repressing key neutrophil functions, cancer cells co-opt neutrophil biology to their advantage. This co-opting includes hijacking one of neutrophils' most striking pathogen defense mechanisms: the formation of neutrophil extracellular traps (NETs). NETs are web-like filamentous extracellular structures of DNA, histones, and cytotoxic granule-derived proteins. Here, we discuss the bidirectional interplay by which cancer stimulates NET formation, and NETs in turn support disease progression. We review how vascular dysfunction and thrombosis caused by neutrophils and NETs underlie an elevated risk of death from cardiovascular events in cancer patients. Finally, we propose therapeutic strategies that may be effective in targeting NETs in the clinical setting.

A simplified method for monitoring cytokines in wound fluid

Cytokines in wound fluid are used as surrogates for wound healing in clinical research. The current methods used to collect and process wound fluid are noninvasive but not optimal. The aim of this prospective study was to evaluate a method (NovaSwab) by which wound fluid is collected by a surface swab and eluted in a physiological buffer for subsequent cytokine analysis. Wound fluid from 12 patients with leg ulcers was assessed by NovaSwab at the start (Day 0) and at the end of a 23-h collection period of wound fluid retained by foam oblates beneath an occlusive film dressing (Day 1). GM-CSF, IL-1α, IL-1β, IL-6, IL-8, PDGF-AA, TNF-α and VEGF levels were measured by multiplex and electrochemiluminescence assays. IL-1α (2.4×), IL-1β (2.0×) and IL-8 (1.8×) levels increased from Day 0 to Day 1 as detected by NovaSwab, indicating local production of these polypeptides in the wounds. On Day 1, the NovaSwab method yielded higher levels of IL-1α (4.0×), IL-1β (2.7×) and IL-6 (2.7×), and 35% lower levels of VEGF than those in wound fluid accumulated for 23 h in foam oblates (on average, 5 ml of wound fluid). In vitro experiments showed that the investigated cytokines in cell-free wound fluid were recovered in a quantitative manner by the NovaSwab method. We conclude that the method presented here is a promising research tool to study the kinetics of soluble cytokines over the course of wound healing. More studies are needed to determine the interobserver variation and reproducibility of the NovaSwab method.

Electrical monitoring of infection biomarkers in chronic wounds using nanochannels

Chronic wounds represent an important healthcare challenge in developed countries, being wound infection a serious complication with significant impact on patients' life conditions. However, there is a lack of methods allowing an early diagnosis of infection and a right decision making for a correct treatment. In this context, we propose a novel methodology for the electrical monitoring of infection biomarkers in chronic wound exudates, using nanoporous alumina membranes. Lysozyme, an enzyme produced by the human immune system indicating wound infection, is selected as a model compound to prove the concept. Peptidoglycan, a component of the bacterial layer and the native substrate of lysozyme, is immobilized on the inner walls of the nanochannels, blocking them both sterically and electrostatically. The steric blocking is dependent on the pore size (20-100 nm) and the peptidoglycan concentration, whereas the electrostatic blocking depends on the pH. The proposed analytical method is based on the electrical monitoring of the steric/electrostatic nanochannels unblocking upon the specific degradation of peptidoglycan by lysozyme, allowing to detect the infection biomarker at 280 ng/mL levels, which are below those expected in wounds. The low protein adsorption rate and thus outstanding filtering properties of the nanoporous alumina membranes allowed us to discriminate wound exudates from patients with both sterile and infected ulcers without any sample pre-treatment usually indispensable in most diagnostic devices for analysis of physiological fluids. Although size and charge effects in nanochannels have been previously approached for biosensing purposes, as far as we know, the use of nanoporous membranes for monitoring enzymatic cleavage processes, leading to analytical systems for the specific detection of the enzymes has not been deeply explored so far. Compared with previously reported methods, our methodology presents the advantages of no need of neither bioreceptors (antibodies or aptamers) nor competitive assays, low matrix effects and quantitative and rapid analysis at the point-of-care, being also of potential application for the determination of other protease biomarkers.

MSC-Derived Extracellular Vesicles to Heal Diabetic Wounds: a Systematic Review and Meta-Analysis of Preclinical Animal Studies

Introduction

Extracellular vesicles from mesenchymal stromal cells (MSC-EVs) have shown promise in wound healing. Their use in diabetic wounds specifically, however, remains pre-clinical and their efficacy remains uncertain less clear. A systematic review of preclinical studies is needed to determine the efficacy of MSC-EVs in the treatment of diabetic wounds to accelerate the clinical translation of this cell-based therapy.

Methods

PubMed and Embase were searched (to June 23, 2020). All English-language, full-text, controlled interventional studies comparing MSC-EVs to placebo or a “no treatment” arm in animal models of diabetic wounds were included. Study outcomes, including wound closure (primary outcome), scar width, blood vessel number and density, and re-epithelialisation were pooled using a random effects meta-analysis. Risk of bias (ROB) was assessed using the SYRCLE tool for pre-clinical animal studies.

Results

A total of 313 unique records were identified from our search, with 10 full text articles satisfying inclusion criteria (n = 136 animals). The administration of MSC-EVs improved closure of diabetic wounds compared to controls with a large observed effect (Standardized Mean Difference (SMD) 5.48, 95% Confidence Interval (CI) 3.55–8.13). Healing was further enhanced using MSC-EVs enriched in non-coding RNAs or microRNAs compared to controls (SMD 9.89, 95%CI 7.32–12.46). Other outcomes, such as blood vessel density and number, scar width, and re-epithelialisation were improved with the administration of MSC-EVs, with a large effect. ROB across studies was unclear.

Conclusion

MSC-EVs, particularly following enrichment for specific RNAs, are a promising treatment for diabetic wounds in pre-clinical studies and translation to the clinical domain appears warranted.

Registration

PROSPERO #CRD42020199327 [248].

Graphical abstract

Biofilm-Innate Immune Interface: Contribution to Chronic Wound Formation

Delayed wound healing can cause significant issues for immobile and ageing individuals as well as those living with co-morbid conditions such as diabetes, cardiovascular disease, and cancer. These delays increase a patient’s risk for infection and, in severe cases, can result in the formation of chronic, non-healing ulcers (e.g., diabetic foot ulcers, surgical site infections, pressure ulcers and venous leg ulcers). Chronic wounds are very difficult and expensive to treat and there is an urgent need to develop more effective therapeutics that restore healing processes. Sustained innate immune activation and inflammation are common features observed across most chronic wound types. However, the factors driving this activation remain incompletely understood. Emerging evidence suggests that the composition and structure of the wound microbiome may play a central role in driving this dysregulated activation but the cellular and molecular mechanisms underlying these processes require further investigation. In this review, we will discuss the current literature on: 1) how bacterial populations and biofilms contribute to chronic wound formation, 2) the role of bacteria and biofilms in driving dysfunctional innate immune responses in chronic wounds, and 3) therapeutics currently available (or underdevelopment) that target bacteria-innate immune interactions to improve healing. We will also discuss potential issues in studying the complexity of immune-biofilm interactions in chronic wounds and explore future areas of investigation for the field.

Differential Therapeutic Effect of Extracellular Vesicles Derived by Bone Marrow and Adipose Mesenchymal Stem Cells on Wound Healing of Diabetic Ulcers and Correlation to Their Cargoes

Extracellular vesicles (EVs) derived from mesenchymal stem cells isolated from both bone marrow (BMSCs) and adipose tissue (ADSCs) show potential therapeutic effects. These vesicles often show a similar beneficial effect on tissue regeneration, but in some contexts, they exert different biological properties. To date, a comparison of their molecular cargo that could explain the different biological effect is not available. Here, we demonstrated that ADSC-EVs, and not BMSC-EVs, promote wound healing on a murine model of diabetic wounds. Besides a general similarity, the bioinformatic analysis of their protein and miRNA cargo highlighted important differences between these two types of EVs. Molecules present exclusively in ADSC-EVs were highly correlated to angiogenesis, whereas those expressed in BMSC-EVs were preferentially involved in cellular proliferation. Finally, in vitro analysis confirmed that both ADSC and BMSC-EVs exploited beneficial effect on cells involved in skin wound healing such as fibroblasts, keratinocytes and endothelial cells, but through different cellular processes. Consistent with the bioinformatic analyses, BMSC-EVs were shown to mainly promote proliferation, whereas ADSC-EVs demonstrated a major effect on angiogenesis. Taken together, these results provide deeper comparative information on the cargo of ADSC-EVs and BMSC-EVs and the impact on regenerative processes essential for diabetic wound healing.

Adhesive protein-based angiogenesis-mimicking spatiotemporal sequential release of angiogenic factors for functional regenerative medicine

Damaged vascular structures after critical diseases are difficult to completely restore to their original conditions without specific treatments. Thus, therapeutic angiogenesis has been spotlighted as an attractive strategy. However, effective strategies for mimicking angiogenic processes in the body have not yet been developed. In the present work, we developed a bioengineered mussel adhesive protein (MAP)-based novel therapeutic angiogenesis platform capable of spatiotemporally releasing angiogenic growth factors to target disease sites with high viscosity and strong adhesiveness in a mucus-containing environment with curvature. Polycationic MAP formed complex coacervate liquid microdroplets with polyanionic hyaluronic acid and subsequently gelated into microparticles. Platelet-derived growth factor (PDGF), which is a late-phase angiogenic factor, was efficiently encapsulated during the process of coacervate microparticle formation. These PDGF-loaded microparticles were blended with vascular endothelial growth factor (VEGF), which is the initial-phase angiogenic factor, in MAP-based pregel solution and finally crosslinked in situ into a hydrogel at the desired site. The microparticle-based angiogenic-molecule spatiotemporal sequential (MASS) release platform showed good adhesion and underwater durability, and its elasticity was close to that of target tissue. Using two in vivo critical models, i.e., full-thickness excisional wound and myocardial infarction models, the MASS release platform was evaluated for its in vivo feasibility as an angiogenesis-inducing platform and demonstrated effective angiogenesis as well as functional regenerative efficacy. Based on these superior physicochemical characteristics, the developed MASS release platform could be successfully applied in many biomedical practices as a waterproof bioadhesive with the capability for the spatiotemporal delivery of angiogenic molecules in the treatment of ischemic diseases.

Effects of Carnosine, Ankaferd, and Silver Sulfadiazine on an Experimental Burn Model: Roles of Irisin and HSP70

In this study, the effects of carnosine, ankaferd, and 1% silver sulfadiazine applied topically on second-degree burns were investigated and the roles of irisin and Heat shock protein 70 (HSP70) in this healing process were evaluated. Ninety male albino rats were used and divided into five groups. The groups were classified as control, burn, burn + carnosine (CAR), burn + ankaferd (ABS), and burn + silver sulfadiazine (SS). It was found that level of irisin increased in the first week and decreased in the second week in the burn and CAR groups. In the ABS and SS groups, the level of irisin was determined that started to increase in the first week and continued to increase in the second week. The level of HSP70 was found to increased in the first week in burn and CAR groups and decreased in the second week, but started to increase in the second week in ABS and SS groups. Both levels of irisin and HSP70 were observed to decreased in all treatment groups in the third week. In this study, it was shown that ankaferd and silver sülfadiazine treatments cause an increase in the irisin levels in the early period and a gradually increase in HSP70 levels in the later period in burns. The inflammatory response was observed to be limited in the early period in the ankaferd and sulfadiazin groups. It was concluded that these findings were effective in early wound healing in burns.

Cells from discarded dressings differentiate chronic from acute wounds in patients with Epidermolysis Bullosa

Impaired wound healing complicates a wide range of diseases and represents a major cost to healthcare systems. Here we describe the use of discarded wound dressings as a novel, cost effective, accessible, and non-invasive method of isolating viable human cells present at the site of skin wounds. By analyzing 133 discarded wound dressings from 51 patients with the inherited skin-blistering disease epidermolysis bullosa (EB), we show that large numbers of cells, often in excess of 100 million per day, continually infiltrate wound dressings. We show, that the method is able to differentiate chronic from acute wounds, identifying significant increases in granulocytes in chronic wounds, and we show that patients with the junctional form of EB have significantly more cells infiltrating their wounds compared with patients with recessive dystrophic EB. Finally, we identify subsets of granulocytes and T lymphocytes present in all wounds paving the way for single cell profiling of innate and adaptive immune cells with relevance to wound pathologies. In summary, our study delineates findings in EB that have potential relevance for all chronic wounds, and presents a method of cellular isolation that has wide reaching clinical application.

Quercetin associated with dimethylsulfoxide has a curative effect on experimental colon anastomosis injury

Purpose

To examine the effects of quercetin on healing of experimental colon anastomosis injury in early and late period.

Methods

Eighty male Wistar-Albino rats were divided into 8 groups. For all groups, left colons of the rats were resected and for the rest end-to-end anastomosis was performed. Two of the groups for which the experiment protocol was ended on the 3rd and 7th day following the anastomosis were not administered with either quercetin or dimethylsulfoxide DMSO, whereas two other groups were administered with DMSO only, and four other groups were administered with quercetin dissolved in DMSO in doses of 20 and 100 mg/kg during the protocol. At the end of the study, anastomosis line was resected, histopathological evaluation was performed and bursting pressure, malondialdehyde, superoxide dismutase, catalase, and hydroxyproline levels were measured.

Results

Quercetin significantly increased hydroxyproline, superoxide dismutase, catalase levels, histopathological healing score, bursting pressure values and decreased malondialdehyde level in early period. It also significantly increased superoxide dismutase, catalase, and hydroxyproline levels and decreased malondialdehyde level in late period.

Conclusion

It was seen that quercetin speeds up the injury healing process and reveals an antioxidant effect, specifically in early period.

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.

Evaluation of the Biological Effects of Lyophilized Hydrophilic Extract of Rhus coriaria on Myeloperoxidase (MPO) Activity, Wound Healing, and Microbial Infections of Skin Wound Tissues

Impaired wound healing was mainly associated with severe microbial infections which significantly affect diagnostic and therapeutic strategies. Thus, in this study, the potential wound healing activity, anti-inflammatory, and antimicrobial activity of an aqueous extract of Rhus coriaria extract (AERc) were evaluated by wound contraction, scar formation, period of epithelization, MPO enzyme activity, collagenase-2 (MMP-8), hydroxyproline (HPX), and collagen deposition as markers of wound healing at different days of postwound. Phytoconstituents, microbial activity, and fibrogenic markers were screened by HPLC, disc-diffusion, and colorimetric assays. The animals were treated with Rhus coriaria extract (AERc) concentrations at doses of 5 mg.kg⁻¹and 10 mg.kg⁻¹, respectively. On days 6 and 9, the AERc-treated animals at doses of 5 mg.mL⁻¹ and 10 mg.mL⁻¹ exhibited a significant reduction in the wound area, increased deposition of collagen, HPX, and reduction in MMP-8, and MPO enzyme activity when compared with controls. Scar formation and epithelization were completed in 10 days compared to controls. In addition, in wounds infected separately with Staph. aureus or P. aeruginosa, the AERc extract significantly improved wound contraction, deposition of collagen, and HPx and reduced MMP-8 and MPO concentrations, with complete epithelization of wounds in 10-13 days compared to the saline-treated group. Hydrolyzable tannins, gallic acid, quercetin, and myricetin were the most common active components of AERc. In vitro, the AERc and its components were effective against a set of microbes especially Staph. aureus, P. aeruginosa, and Staph. aureus (MRSA). In conclusion, the results showed that antimicrobial, anti-inflammatory, and antioxidant activity of Rhus coriaria extract suggested its importance as a target for formulation of novel drugs against many microbial infections with minimal side effects and could play a good potential role in accelerating wound healing activity via promoting myofibroblast activity, increase of hydroxyproline and collagen deposition, and regulation of MMP-8 and MPO enzyme activities.

Inflammation Biomarkers and Correlation to Wound Status After Full-Thickness Skin Grafting

Background: A surgical site infection (SSI) is believed to be the result of an exaggerated inflammatory response. Objective: Examine the relationship between clinical status and inflammation biomarkers in full-thickness skin grafting wounds. Methods: Twenty patients planned for facial full-thickness skin grafting were enrolled. A week after surgery, all graft wounds were clinically assessed using a 3-step scale for inflammation (low, moderate, high). All wounds were swabbed for routine microbiological analysis and assessment of numbers of aerobic bacteria. Tie-over dressings from all patients were collected and used for wound fluid extraction and subsequent analysis of MMPs, cytokines, and NF-κB inducing activity. Results: Wounds with a high degree of inflammation contained increased total MMP activity (P ≤ 0.05) in their corresponding fluids. Likewise, the level of the cytokines IL-1ß, IL-8, IL-6, TNF-α was analyzed, and particularly IL-1ß was discriminatory for highly inflamed wounds (P ≤ 0.01). Moreover, bacterial loads were increased in highly inflamed wounds compared to wounds with a low degree of inflammation (P ≤ 0.01). NF-κB activation in the monocytic cell line THP-1 was significantly higher when these cells were stimulated by wound fluids with a high degree of inflammation (P ≤ 0.01). Growth of S. aureus in wounds did not vary between wounds with different degrees of inflammation (chi-square 3.8, P = 0.144). Conclusion: Biomarkers analyzed from tie-over dressings correlated to clinical wound healing in full-thickness skin grafting.

Nanocarrier-based systems for wound healing

In general, the systems intended for the treatment and recovery of wounds, seek to act as a coating for the damaged area, maintaining an adequate level of humidity, reducing pain, and preventing the invasion and proliferation of microorganisms. Although many of the systems that are currently on the market meet the purposes mentioned above, with the arrival of nanotechnology, it has sought to improve the performance of these coatings. The variety of nano-systems that have been proposed is very extensive, including the use of very different materials (natural or synthetic) ranging from polymers or lipids to systems derived from microorganisms. With the objective of improving the performance of the systems, seeking to combat several of the problems that arise in a wound, especially when it is chronic, these materials have been combined, giving rise to nanocomposites or scaffolds. In recent years, the interest in the development of systems for the treatment of wounds is notable, which is reflected in the increase in publications related to the subject. Therefore, this document presents generalities of systems involving nanocarriers, mentioning some examples of representative systems of each case.

Lysozyme-Responsive Spray-Dried Chitosan Particles for Early Detection of Wound Infection

Infections are a severe health issue, and the need for an early point-of-care diagnostic approach for wound infections is continuously growing. Lysozyme has shown a great potential as a biomarker for rapid detection of wound infection. In this study, spray-drying of labeled and derivatized chitosans was investigated for the production of small particles responsive to lysozyme. Therefore, various chitosans, differing in their origin (snow crab, Chionoecetes sp., with medium and low molecular weight or shrimp) were N-acetylated, labeled with reactive black 5, and tested for solubility and spray-drying suitability. Reactive black-5-stained N-acetylated chitosan (low molecular weight, origin crab) was successfully spray-dried, and the obtained particles were characterized regarding size, ζ potential, and morphology. The particles showed an average hydrodynamic radius of 612.5 ± 132.8 nm. ζ potential was measured in the context of a later application as an infection detection system for wound infections in artificial wound fluid (-6.14 ± 0.16 mV) and infected wound fluid (-7.93 ± 1.35 mV). Furthermore, the aggregation behavior and surface structure were analyzed by using scanning electron microscopy and confocal laser scanning microscopy revealing spherical-shaped particles with explicit surface topologies. Spray-dried N-acetylated chitosan particles showed a 5-fold increase in lysozyme-responsive release of dyed chitosan fragments due to the enhanced surface area to volume ratio when compared to non-spray-dried N-acetylated chitosan flakes. On the basis of these results, the study showed the improved properties of N-acetylated spray-dried chitosan particles for future applications for early and rapid infection detection.

Use of platelet-rich plasma to facilitate wound healing

Platelet-rich plasma (PRP) is widely used nowadays in different fields of medicine, affecting physiological processes including tissue regeneration. The use of PRP in maxillofacial surgical interventions and its efficiency in the improvement of postoperative wound healing were analysed. Patients undergoing plastic and reconstructive surgeries in the maxillofacial region were recruited: 50 patients were enrolled into a control group (received no PPRP injection) and 50 patients were enrolled into a treatment group, where PRP was applied during the surgical procedure. Evaluation of treatment outcomes was carried out by determination of IL-1β, TNFα, and IL-6 cytokines levels in the wound-drain fluid. The stages of wound healing were assessed by cytological analyses and ultrasound within a month period. The use of the PRP has substantially positive effects, contributing to the improvement of the healing process. In the treatment group, fibroblasts, macrophages, and collagen fibres appeared and their quantities increased earlier than when compared with control group patients. The concentration of IL-1β and TNFα in wound fluid on day 1 and day 5 after operation was higher for the treatment group as opposed to the control group, which was linked to the influence of PRP on inflammatory and granulation phases of the healing process. An ultrasound examination showed less oedema and infiltration in the tissues around the wound of the treatment group.

Antioxidant Preconditioning Improves the Paracrine Responsiveness of Mouse Bone Marrow Mesenchymal Stem Cells to Diabetic Wound Fluid

Mesenchymal stem cells (MSCs) are a promising therapeutic tool for the treatment of nonhealing diabetic wounds. The pathological nature of the niche microenvironment limits the use of autologous cell therapy in diabetic patients. Prolonged exposure of endogenous MSCs to a pathological microenvironment in vivo reduces their ability to respond to environmental cues. This study investigated the effectiveness of ex vivo antioxidant treatment [N-acetylcysteine (7.5 mM NAC) and Ascorbic acid 2-phosphate (0.6 mM AAP)] to restore the paracrine function of diabetic MSCs. Healthy control [bone marrow stem cells derived from wild-type mice (SC^WT)] (source: wild-type C57BL/6J mice) (n = 12) and impaired/dysfunctional [bone marrow stem cells derived from ob/ob mice (SC^ob)] (source: obese diabetic, B6.Cg-Lep^ob/J mice) (n = 12) MSCs were isolated. Ex vivo treatment groups (SC^WT vs. SC^ob) were as follows: (1) no treatment (baseline phenotype), (2) stimulated with diabetic wound fluid (DWF) (baseline response), (3) antioxidant preconditioning (preconditioned phenotype), and (4) antioxidant preconditioned with subsequent stimulation with DWF (preconditioned response). The paracrine responsiveness on both the molecular (mRNA expression of 80 cytokines and receptors, quantitative polymerase chain reaction microarray) and protein (23-plex bead-array Luminex assay) level was assessed. At baseline, 31 genes were overexpressed (> × 2-fold) and 39 genes were underexpressed (> × 2-fold) in SC^ob versus SC^WT. In conditioned media, significant differences (P < 0.05) were detected at baseline for two proinflammatory cytokines [tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ)], four chemokines [keratinocyte chemoattractant (KC), granulocyte colony-stimulating factor (GCSF), Eotaxin, and macrophage chemoattractant protein (MCP1)], and one anti-inflammatory cytokine [interleukin 10 (IL10)]. Following stimulation with DWF, significant differences (P < 0.05) were detected in the secretion of two chemokines [granulocyte macrophage colony-stimulating factor (GMCSF) and Eotaxin], three proinflammatory cytokines (TNFα, IFNγ, and IL9), and four anti-inflammatory cytokines (IL10, IL4, IL13, and IL3). Antioxidant preconditioning significantly dampened the excessive TNFα response observed in SC^ob and improved the secretion of IL10. Taken together these data suggest that the combined ex vivo treatment of autologous stem cells with NAC and AAP could potentially be an effective strategy to restore the paracrine function of impaired diabetic MSCs before transplantation.

Immunology of Wound Healing

Purpose of Review

Chronic wounds are a tremendous burden on the healthcare system and lead to significant patient morbidity and mortality. Normal cutaneous wound healing occurs through an intricate and delicate interplay between the immune system, keratinocytes, and dermal cells. Each cell type contributes signals that drive the normal phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This paper reviews how various immunological cell types and signaling molecules influence the way wounds develop, persist, and heal.

Recent Findings

Concurrent with the achievement of hemostasis, neutrophils are the first cells to migrate to the wound bed, brought in by pro-inflammatory signals including IL-8. Their apoptosis and engulfment by macrophages (efferocytosis) provides a key signal to the local immune milieu, including macrophages, to transition to an anti-inflammatory, pro-repair state, where angiogenesis occurs and granulation tissue is laid down. Myofibroblasts, activated through contractile forces and signaling molecules, then drive remodeling, where granulation tissue becomes scar. Unchecked inflammation at this stage can result in abnormal scar formation.

Summary

Although the derangement of immune signals at any stage can result in impaired wound healing, recent research has shown that the key transition point lies between the inflammatory and the proliferative phases. This review summarizes the events that facilitate this transition and discusses how this process can be disrupted, leading to chronic, non-healing wounds.

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.

Increased extracellular ubiquitin in surgical wound fluid provides a chemotactic signal for myeloid dendritic cells

PURPOSE

Myeloid dendritic cells (MDC) decline significantly after multiple traumas which might be due to an increased migration into injured regions. Ubiquitin is released from dying cells and is increased in serum after trauma. Ubiquitin can bind to the chemokine receptor CXCR4. Thus, we hypothesized that elevated ubiquitin provides a chemotactic signal for MDC to injured regions.

METHODS

Surgical wound fluid (SWF) and serum from patients with mono-trauma (n = 20) were used to simulate the humoral situation in injured tissue. MDC were identified by flow cytometry. Chemotaxis was measured using transwell migration assays. Ubiquitin and CXCL12 (natural CXCR4 ligand) were determined by ELISA.

RESULTS

MDC express CXCR4 and fluorescence-labeled ubiquitin binds to MDC. Ubiquitin exerts a dose-dependent chemotactic effect (fourfold at 100 ng/mL, p < 0.05). Ubiquitin concentration was sixfold higher in SWF (p < 0.05), whereas CXCL12 was increased in serum. MDC migration towards SWF was significantly reduced (- 40%, p < 0.05), if ubiquitin was neutralized by specific antibodies.

CONCLUSIONS

Ubiquitin is increased in SWF and exerts a significant chemotactic effect on MDC. This mechanism might play a role in attraction of immune cells to injured regions and might contribute to the decline of circulating MDC in multiple traumas.

Descriptive vs mechanistic scientific approach to study wound healing and its inhibition: Is there a value of translational research involving human subjects?

The clinical field of wound healing is challenged by numerous hurdles. Not only are wound-healing disorders complex and multifactorial, but the corresponding patient population is diverse, often elderly and burdened by multiple comorbidities such as diabetes and cardiovascular disease. The care of such patients requires a dedicated, multidisciplinary team of physicians, surgeons, nurses and scientists. In spite of the critical clinical need, it has been over 15 years since a treatment received approval for efficacy by the FDA in the United States. Among the reasons contributing to this lack of effective new treatment modalities is poor understanding of mechanisms that inhibit healing in patients. Additionally, preclinical models do not fully reflect the disease complexity of the human condition, which brings us to a paradox: if we are to use a "mechanistic" approach that favours animal models, we can dissect specific mechanisms using advanced genetic, molecular and cellular technologies, with the caveat that it may not be directly applicable to patients. Traditionally, scientific review panels, for either grant funding or manuscript publication purposes, favour such "mechanistic" approaches whereby human tissue analyses, deemed "descriptive" science, are characterized as a "fishing expedition" and are considered "fatally flawed." However, more emerging evidence supports the notion that the use of human samples provides significant new knowledge regarding the molecular and cellular mechanisms that control wound healing and contribute to inhibition of the process in patients. Here, we discuss the advances, benefits and challenges of translational research in wound healing focusing on human subject research.

A Neutrophil Proteomic Signature in Surgical Trauma Wounds

Non-healing wounds continue to be a clinical challenge for patients and medical staff. These wounds have a heterogeneous etiology, including diabetes and surgical trauma wounds. It is therefore important to decipher molecular signatures that reflect the macroscopic process of wound healing. To this end, we collected wound sponge dressings routinely used in vacuum assisted therapy after surgical trauma to generate wound-derived protein profiles via global mass spectrometry. We confidently identified 311 proteins in exudates. Among them were expected targets belonging to the immunoglobulin superfamily, complement, and skin-derived proteins, such as keratins. Next to several S100 proteins, chaperones, heat shock proteins, and immune modulators, the exudates presented a number of redox proteins as well as a discrete neutrophil proteomic signature, including for example cathepsin G, elastase, myeloperoxidase, CD66c, and lipocalin 2. We mapped over 200 post-translational modifications (PTMs; cysteine/methionine oxidation, tyrosine nitration, cysteine trioxidation) to the proteomic profile, for example, in peroxiredoxin 1. Investigating manually collected exudates, we confirmed presence of neutrophils and their products, such as microparticles and fragments containing myeloperoxidase and DNA. These data confirmed known and identified less known wound proteins and their PTMs, which may serve as resource for future studies on human wound healing.

Perceived Stress and Surgical Wound Cytokine Patterns

This was a pilot study to examine pre- and postoperative stress experienced by women who were undergoing autologous breast reconstruction and how stress might impact wound healing, specifically examining cytokines and other chemical mediators in the wound environment. A nonexperimental descriptive design over time was utilized. Participants were women who were undergoing autologous abdominal breast reconstruction for breast cancer (N = 20). Data were collected preoperatively and at 24, 48, 72, and 96 hr postsurgery. Complications were monitored intraoperatively and up to 30 days postsurgery. Psychological stress was measured with the 10-item Perceived Stress Scale (PSS), the Impact of Events Scale-Revised (IES-R), and a 100-mm Visual Analog Scale (VAS). Cytokines were assayed using the 27-plex kit with a Bio-Plex Plus. Although breast cancer is considered a stressor, in this sample of women, scores of the PSS, IES-R, and VAS showed that in fact these participants experienced low levels of psychological stress. All measured biochemical mediators in serum and wound fluid were detected and trends were identified. IL-1ra, IL-6, IL-8, G-CSF, IP-10, MCP-1, MIP-1β, RANTES, and VEGF were present in the highest concentrations. Significant changes in levels of cytokines in wound fluid were observed in IL-1β, IL-2, IL-5, IL-6, IL-8, IL-9, IL-10, IL-17, FGF-basic, G-CSF, MIP-1α, PDGF-bb, MIP-1β, RANTES, and TNF-α. The remaining cytokine concentrations stayed stable over time. These findings suggest that although these women were not experiencing high levels of stress, meaningful cytokine patterns were detected.

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.

Biology and Biomarkers for Wound Healing

BACKGROUND

As the population grows older, the incidence and prevalence of conditions that lead to a predisposition for poor wound healing also increase. Ultimately, this increase in nonhealing wounds has led to significant morbidity and mortality with subsequent huge economic ramifications. Therefore, understanding specific molecular mechanisms underlying aberrant wound healing is of great importance. It has and will continue to be the leading pathway to the discovery of therapeutic targets, as well as diagnostic molecular biomarkers. Biomarkers may help identify and stratify subsets of nonhealing patients for whom biomarker-guided approaches may aid in healing.

METHODS

A series of literature searches were performed using Medline, PubMed, Cochrane Library, and Internet searches.

RESULTS

Currently, biomarkers are being identified using biomaterials sourced locally from human wounds and/or systemically using high-throughput "omics" modalities (genomic, proteomic, lipidomic, and metabolomic analysis). In this review, we highlight the current status of clinically applicable biomarkers and propose multiple steps in validation and implementation spectrum, including those measured in tissue specimens, for example, β-catenin and c-myc, wound fluid, matrix metalloproteinases and interleukins, swabs, wound microbiota, and serum, for example, procalcitonin and matrix metalloproteinases.

CONCLUSIONS

Identification of numerous potential biomarkers using different avenues of sample collection and molecular approaches is currently underway. A focus on simplicity and consistent implementation of these biomarkers, as well as an emphasis on efficacious follow-up therapeutics, is necessary for transition of this technology to clinically feasible point-of-care applications.

Role of biomarkers in predicting diabetes complications with special reference to diabetic foot ulcers

Diabetic foot ulcer (DFU) is one of the major complications of diabetes and about 1% of people with diabetes have to go for lower limb amputation. With better understanding of the pathological basis of DFU, number of biomarkers like atrial natriuretic peptides, galectin-3, and cardiac troponins for diabetic cardiomyopathy, cystatin C for diabetics nephropathy and C-reactive protein for infection and procalcitonin could aid in early and noninvasive diagnosis especially when clinical signs are misleading. Predictive role of novel biomarkers in primary prevention however, requires additional studies considering sex, age and multiple complications in DFU. The current review provides an insight about the novel and emerging biomarkers of diabetes and its complications with special reference to DFUs.

Chitosan Wound Dressings Incorporating Exosomes Derived from MicroRNA-126-Overexpressing Synovium Mesenchymal Stem Cells Provide Sustained Release of Exosomes and Heal Full-Thickness Skin Defects in a Diabetic Rat Model

There is a need to find better strategies to promote wound healing, especially of chronic wounds, which remain a challenge. We found that synovium mesenchymal stem cells (SMSCs) have the ability to strongly promote cell proliferation of fibroblasts; however, they are ineffective at promoting angiogenesis. Using gene overexpression technology, we overexpressed microRNA‐126‐3p (miR‐126‐3p) and transferred the angiogenic ability of endothelial progenitor cells to SMSCs, promoting angiogenesis. We tested a therapeutic strategy involving controlled‐release exosomes derived from miR‐126‐3p‐overexpressing SMSCs combined with chitosan. Our in vitro results showed that exosomes derived from miR‐126‐3p‐overexpressing SMSCs (SMSC‐126‐Exos) stimulated the proliferation of human dermal fibroblasts and human dermal microvascular endothelial cells (HMEC‐1) in a dose‐dependent manner. Furthermore, SMSC‐126‐Exos also promoted migration and tube formation of HMEC‐1. Testing this system in a diabetic rat model, we found that this approach resulted in accelerated re‐epithelialization, activated angiogenesis, and promotion of collagen maturity in vivo. These data provide the first evidence of the potential of SMSC‐126‐Exos in treating cutaneous wounds and indicate that modifying the cells—for example, by gene overexpression—and using the exosomes derived from these modified cells provides a potential drug delivery system and could have infinite possibilities for future therapy. Stem Cells Translational Medicine2017;6:736–747

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

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

Microdialysis Sampling from Wound Fluids Enables Quantitative Assessment of Cytokines, Proteins, and Metabolites Reveals Bone Defect-Specific Molecular Profiles

Bone healing involves a variety of different cell types and biological processes. Although certain key molecules have been identified, the molecular interactions of the healing progress are not completely understood. Moreover, a clinical routine for predicting the quality of bone healing after a fracture in an early phase is missing. This is mainly due to a lack of techniques to comprehensively screen for cytokines, growth factors and metabolites at their local site of action. Since all soluble molecules of interest are present in the fracture hematoma, its in-depth assessment could reveal potential markers for the monitoring of bone healing. Here, we describe an approach for sampling and quantification of cytokines and metabolites by using microdialysis, combined with solid phase extractions of proteins from wound fluids. By using a control group with an isolated soft tissue wound, we could reveal several bone defect-specific molecular features. In bone defect dialysates the neutrophil chemoattractants CXCL1, CXCL2 and CXCL3 were quantified with either a higher or earlier response compared to dialysate from soft tissue wound. Moreover, by analyzing downstream adaptions of the cells on protein level and focusing on early immune response, several proteins involved in the immune cell migration and activity could be identified to be specific for the bone defect group, e.g. immune modulators, proteases and their corresponding inhibitors. Additionally, the metabolite screening revealed different profiles between the bone defect group and the control group. In summary, we identified potential biomarkers to indicate imbalanced healing progress on all levels of analysis.

Effect of Photobiomodulation on Transforming Growth Factor-β1, Platelet-Derived Growth Factor-BB, and Interleukin-8 Release in Palatal Wounds After Free Gingival Graft Harvesting: A Randomized Clinical Study

Objective: This study evaluated the impact of photobiomodulation (PBM) on the healing of the donor palatal area following free gingival graft (FGG) harvesting by examining changes in transforming growth factor (TGF)-β₁, platelet-derived growth factor (PDGF)-BB, and interleukin (IL)-8 levels in palatal wound fluid (PWF). Material and methods: Thirty patients were selected and randomly assigned to receive PBM (laser group) or PBM sham (sham group) in the palatine area after FGG harvesting. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm) was applied to the test sites immediately after surgery and every 24 h thereafter for 4 days. PWF was collected on Days 7 and 12, and PWF TGF-β₁, PDGF-BB, and IL-8 levels were analyzed by enzyme-linked immunosorbent assays (ELISA). Results: PWF TGF-β₁, PDGF-BB, and IL-8 levels were significantly lower on Day 12 than on Day 7 for both groups. PWF TGF-β₁, PDGF-BB, and IL-8 levels of the laser group were significantly higher than those of sham group on Day 7 (p < 0.05). PWF TGF-β₁ levels were also significantly higher in laser group than in the sham group on Day 12; however, differences in PDGF-BB and IL-8 levels between groups on Day 12 were statistically nonsignificant. Conclusions: Observed increases in PWF TGF-β₁, PDGF-BB, and IL-8 levels suggest that PBM may accelerate wound healing by stimulating production of selected mediators.

Vitamin C promotes wound healing through novel pleiotropic mechanisms

Vitamin C (VitC) or ascorbic acid (AscA), a cofactor for collagen synthesis and a primary antioxidant, is rapidly consumed post-wounding. Parenteral VitC administration suppresses pro-inflammatory responses while promoting anti-inflammatory and pro-resolution effects in human/murine sepsis. We hypothesised that VitC could promote wound healing by altering the inflammatory, proliferative and remodelling phases of wound healing. Mice unable to synthesise VitC (Gulo(-/-) ) were used in this study. VitC was provided in the water (sufficient), withheld from another group (deficient) and supplemented by daily intra-peritoneal infusion (200 mg/kg, deficient + AscA) in a third group. Full thickness excisional wounds (6 mm) were created and tissue collected on days 7 and 14 for histology, quantitative polymerase chain reaction (qPCR) and Western blotting. Human neonatal dermal fibroblasts (HnDFs) were used to assess effects of In conclusion, VitC favorably on proliferation. Histological analysis showed improved wound matrix deposition and organisation in sufficient and deficient +AscA mice. Wounds from VitC sufficient and deficient + AscA mice had reduced expression of pro-inflammatory mediators and higher expression of wound healing mediators. Supplementation of HnDF with AscA induced the expression of self-renewal genes and promoted fibroblast proliferation. VitC favourably impacts the spatiotemporal expression of transcripts associated with early resolution of inflammation and tissue remodelling.