Differential expression of tissue inhibitors of metalloproteinases (TIMP-1, -2, -3, and -4) in normal and aberrant wound healing

Wildfire-relevant woodsmoke and extracellular vesicles (EVs): Alterations in EV proteomic signatures involved in extracellular matrix degradation and tissue injury in airway organotypic models

Wildfires adversely impact air quality and public health worldwide. Exposures to wildfire smoke are linked to adverse health outcomes, including cardiopulmonary diseases. Critical research gaps remain surrounding the underlying biological pathways leading to wildfire-induced health effects. The regulation of intercellular communication and downstream toxicity driven by extracellular vesicles (EVs) is an important, understudied biological mechanism. This study investigated EVs following a wildfire smoke-relevant in vitro exposure. We hypothesized that woodsmoke (WS) would alter the proteomic content of EVs secreted in organotypic in vitro airway models. Exposures were carried out using a tri-culture model of alveolar epithelial cells, fibroblasts, and endothelial cells and a simplified co-culture model of alveolar epithelial cells and fibroblasts to inform responses across different cell populations. Epithelial cells were exposed to WS condensate and EVs were isolated from basolateral conditioned medium following 24 h exposure. WS exposure did not influence EV particle characteristics, and it moderately increased EV count. Exposure caused the differential loading of 25 and 35 proteins within EVs collected from the tri- and co-culture model, respectively. EV proteins involved in extracellular matrix degradation and wound healing were consistently modulated across both models. However, distinct proteins involved in the wound healing pathway were altered between models, suggesting unique but concerted efforts across cell types to communicate in response to injury. These findings demonstrate that a wildfire-relevant exposure alters the EV proteome and suggest an impact on EV-mediated intercellular communication. Overall, results demonstrate the viability of organotypic approaches in evaluating EVs to investigate exposure-induced biomarkers and underlying mechanisms. Findings also highlight the impact of differences in the biological complexity of in vitro models used to evaluate the effects of inhaled toxicants.

Unlocking the Therapeutic Potential of Adipose-Derived Stem Cell Secretome in Oral and Maxillofacial Medicine: A Composition-Based Perspective

The adipose-derived stem cell (ADSC) secretome is widely studied for its immunomodulatory and regenerative properties, yet its potential in maxillofacial medicine remains largely underexplored. This review takes a composition-driven approach, beginning with a list of chemokines, cytokines, receptors, and inflammatory and growth factors quantified in the ADSC secretome to infer its potential applications in this medical field. First, a review of the literature confirmed the presence of 107 bioactive factors in the secretome of ADSCs or other types of mesenchymal stem cells. This list was then analyzed using the Search Tool for Retrieval of Interacting Genes/Proteins (STRING) software, revealing 844 enriched biological processes. From these, key processes were categorized into three major clinical application areas: immunoregulation (73 factors), bone regeneration (13 factors), and wound healing and soft tissue regeneration (27 factors), with several factors relevant to more than one area. The most relevant molecules were discussed in the context of existing literature to explore their therapeutic potential based on available evidence. Among these, TGFB1, IL10, and CSF2 have been shown to modulate immune and inflammatory responses, while OPG, IL6, HGF, and TIMP1 contribute to bone regeneration and tissue repair. Although the ADSC secretome holds great promise in oral and maxillofacial medicine, further research is needed to optimize its application and validate its clinical efficacy.

The Efficacy and Safety of Negative-Pressure Wound Therapy Combined With Platelet-Rich Plasma in Chronic Refractory Wounds: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background and Aims

Chronic refractory wound is a disease that seriously impairs the quality of life of patients. Negative pressure wound therapy and platelet-rich plasma are commonly used to treat various types of wounds. Further research is necessary to explore the efficacy and safety of the combination of negative pressure wound therapy and platelet-rich plasma in treating chronic refractory wounds.

Methods

PubMed, Web of Science, EMBASE, Cochrane, CINAHL, CNKI, Sino Med, and Wanfang Med Online up until March 2024 were searched(PROSPERO No. CRD42024507963). Two investigators screened literature according to inclusion and exclusion criteria, evaluated bias and certainty of evidence using RoB 2.0 and GRADE. Stata 12.0 was used to analyze the data.

Results

A total of 35 randomized controlled trials involving 2495 participants were included. 34 studies were assessed as having some concerns, and 1 study as having high risk in the risk of bias assessment. The results of meta-analysis showed that effective rate (RR1.23, 95% CI [1.17, 1.30], p < 0.001; I2 = 44.7%, p = 0.013), healing time (WMD-9.32, 95% CI [-10.60, -8.03], p < 0.001; I² = 91.00%, p < 0.001), healing rate (RR1.76, 95% CI [1.50, 2.07], p < 0.001; I2 = 62.6%, p < 0.001), positive rate of bacterial(RR0.25, 95% CI [0.15, 0.40], p < 0.001; I² = 0%, p = 0.841), pain score (WMD-1.43, 95% CI [-2.14, -0.72], p < 0.001; I² = 96.5%, p < 0.001), incidence of complications (RR0.45, 95% CI [0.30, 0.68], p < 0.001; I² = 46.3%, p = 0.098), length of hospital stay (WMD-9.88, 95% CI [-13.42, 6.34], p < 0.001; I2 = 98.9%, p < 0.001), number of dressing changes (WMD-2.56, 95% CI [-4.28, -0.83], p = 0.004; I² = 98.9%, p < 0.001), white blood cell level (WMD-1.71, 95% CI [-2.00, -1.41], p < 0.001; I² = 33.9%, p = 0.195), c-reactive protein level (WMD-0.68, 95% CI [-1.04, -0.33], p < 0.001; I² = 88.8%, p < 0.001), erythrocyte sedimentation rate (WMD-6.09, 95% CI [-8.05, -4.13], p < 0.001; I² = 13%, p = 0.32), score of vancouver scar scale (WMD-1.78, 95% CI [-1.89, -1.66], p < 0.001; I² = 38.3%, p = 0.166) and preparation time of secondary repair (WMD-4.95, 95% CI [-7.03, -2.87], p < 0.001; I² = 84.7%, p < 0.001) had statistically significant effects. However, hospitalization costs (WMD1423.56, 95% CI [-4588.93, 7436.06], p = 0.643; I2 = 100%, p < 0.001) had no significant difference.

Conclusions

This study demonstrates that the combination of negative-pressure wound therapy and platelet-rich plasma can improve the efficacy and safety on chronic refractory wounds. Optimal parameter combinations, elucidation of pathogenesis and treatment mechanisms can be explored in the future.

Evaluation of Full Thickness Wounds Following Application of a Visco-Liquid Hemostat in a Swine Model

Wound healing is a complex dynamic biomechanical process as the body attempts to restore the integrity of traumatized or devitalized tissues. There are four stages of wound of healing that begins with hemostasis followed by inflammation, proliferation and finally weeks later wound remodeling. Full thickness wounds usually are covered with a dressing material after hemostasis, which allows for controlled hydration. We investigated the potential of a visco-liquid hemostat, polyhedral oligomeric silsesquioxane (POSS), for providing hemostasis and to maintain a microenvironment in the wound bed that would maintain moisture content and promote early re-epithelialization. We hypothesized that the hemostatic agent POSS if left in the wound bed would maintain a protective barrier and accelerate wound healing similar to using saline to irrigate the wound to keep the wound moist. We compared the early phase of wound repair (3-7 days) in a porcine full thickness wound model to evaluate the efficacy of the material. Biopsies were taken after 3 and 7 days to determine the acute response of the POSS hemostat or saline on inflammation, cell migration, concentrations of metalloproteinase (MMPs), and tissue inhibitors of metalloproteinase (TIMPs). Accelerated healing was observed in POSS treated wounds by changes in wound contraction, keratinocyte migration, and development of granulation tissue in comparison to saline treated wounds. Increased concentrations at day 3 of MMP-2, MMP-3, and in MMP-1 at day 7 in POSS treated wounds compared to saline coincide with keratinocyte migration observed in the tissue histology and changes in wound contraction. Tissue concentrations of TIMP-1 and TIMP-2 in POSS treated wounds appear to coordinate the sequence of MMP events in the healing tissue. Matrix metalloproteinase-13, a marker for tissue remodeling, was not upregulated in the early wound healing cascade in either POSS or saline treated wounds at 3 or 7 days. Overall, the data suggests POSS treatment contributed to enhanced early cell migration and wound closure compared to saline treatment.

Combined analysis of single-cell sequencing and bulk transcriptome sequencing reveals new mechanisms for non-healing diabetic foot ulcers

Diabetic foot ulcers (DFUs) pose a significant challenge in diabetes care. Yet, a comprehensive understanding of the underlying biological disparities between healing and non-healing DFUs remains elusive. We conducted bioinformatics analysis of publicly available transcriptome sequencing data in an attempt to elucidate these differences. Our analysis encompassed differential analysis to unveil shifts in cell composition and gene expression profiles between non-healing and healing DFUs. Cell communication alterations were explored employing the Cellchat R package. Pseudotime analysis and cytoTRACE allowed us to dissect the heterogeneity within fibroblast subpopulations. Our findings unveiled disruptions in various cell types, localized low-grade inflammation, compromised systemic antigen processing and presentation, and extensive extracellular matrix signaling disarray in non-healing DFU patients. Some of these anomalies partially reverted in healing DFUs, particularly within the abnormal ECM-receptor signaling pathway. Furthermore, we distinguished distinct fibroblast subpopulations in non-healing and healing DFUs, each with unique biological functions. Healing-associated fibroblasts exhibited heightened extracellular matrix (ECM) remodeling and a robust wound healing response, while non-healing-associated fibroblasts showed signs of cellular senescence and complement activation, among other characteristics. This analysis offers profound insights into the wound healing microenvironment, identifies pivotal cell types for DFU healing promotion, and reveals potential therapeutic targets for DFU management.

Serum levels of matrix metalloproteinases 1, 2, and 7, and their tissue inhibitors 1, 2, 3, and 4 in polytraumatized patients: Time trajectories, correlations, and their ability to predict mortality

There has been limited research on assessing metalloproteinases (MMPs) 1, 2, and 7, as well as their tissue inhibitors (TIMPs) 1, 2, 3, and 4 in the context of polytrauma. These proteins play crucial roles in various physiological and pathological processes and could be a reliable tool in polytrauma care. We aimed to determine their clinical relevance. We assessed 24 blunt polytrauma survivors and 12 fatalities (mean age, 44.2 years, mean ISS, 45) who were directly admitted to our Level I trauma center and spent at least one night in the intensive care unit. We measured serum levels of the selected proteins on admission (day 0) and days 1, 3, 5, 7, and 10. The serum levels of the seven proteins varied considerably among individuals, resulting in similar median trend curves for TIMP1 and TIMP4 and for MMP1, MMP2, TIMP2, and TIMP3. We also found a significant interrelationship between the MMP2, TIMP2, and TIMP3 levels at the same measurement points. Furthermore, we calculated significant cross-correlations between MMP7 and MMP1, TIMP1 and MMP7, TIMP3 and MMP1, TIMP3 and MMP2, and TIMP4 and TIMP3 and an almost significant correlation between MMP7 and TIMP1 for a two-day-lag. The autocorrelation coefficient reached statistical significance for MMP1 and TIMP3. Finally, lower TIMP1 serum levels were associated with in-hospital mortality upon admission. The causal effects and interrelationships between selected proteins might provide new insights into the interactions of MMPs and TIMPs. Identifying the underlying causes might help develop personalized therapies for patients with multiple injuries. Administering recombinant TIMP1 or increasing endogenous production could improve outcomes for those with multiple injuries. However, before justifying further investigations into basic research and clinical relevance, our findings must be validated in a multicenter study using independent cohorts to account for clinical and biological variability.

Increased Levels of BAMBI Inhibit Canonical TGF-β Signaling in Chronic Wound Tissues

Chronic wounds affect more than 2% of the population worldwide, with a significant burden on affected individuals, healthcare systems, and societies. A key regulator of the entire wound healing cascade is transforming growth factor beta (TGF-β), which regulates not only inflammation and extracellular matrix formation but also revascularization. This present work aimed at characterizing wound tissues obtained from acute and chronic wounds regarding angiogenesis, inflammation, as well as ECM formation and degradation, to identify common disturbances in the healing process. Serum and wound tissues from 38 patients (N = 20 acute and N = 18 chronic wounds) were analyzed. The patients' sera suggested a shift from VEGF/VEGFR to ANGPT/TIE2 signaling in the chronic wounds. However, this shift was not confirmed in the wound tissues. Instead, the chronic wound tissues showed increased levels of MMP9, a known activator of TGF-β. However, regulation of TGF-β target genes, such as CTGF, COL1A1, or IL-6, was absent in the chronic wounds. In wound tissues, all three TGF-β isoforms were expressed with increased levels of TGF-β1 and TGF-β3 and a reporter assay confirmed that the expressed TGF-β was activated. However, Western blots and immunostaining showed decreased canonical TGF-β signaling in the respective chronic wound tissues, suggesting the presence of a TGF-β inhibitor. As a potential regulatory mechanism, the TGF-β proteome profiler array suggested elevated levels of the TGF-β pseudo-receptor BAMBI. Also, tissue expression of BAMBI was significantly increased not only in chronic wounds (10.6-fold) but also in acute wounds that had become chronic (9.5-fold). In summary, our data indicate a possible regulatory role of BAMBI in the development of chronic wounds. The available few in vivo studies support our findings by postulating a therapeutic potential of BAMBI for controlling scar formation.

Human Keratinocytes and Fibroblasts Co-Cultured on Silk Fibroin Scaffolds Exosomally Overrelease Angiogenic and Growth Factors

Objectives: The optimal healing of skin wounds, deep burns, and chronic ulcers is an important clinical problem. Attempts to solve it have been driving the search for skin equivalents based on synthetic or natural polymers. Methods: Consistent with this endeavor, we used regenerated silk fibroin (SF) from Bombyx mori to produce a novel compound scaffold by welding a 3D carded/hydroentangled SF-microfiber-based nonwoven layer (C/H-3D-SFnw; to support dermis engineering) to an electrospun 2D SF nanofiber layer (ESFN; a basal lamina surrogate). Next, we assessed-via scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry, mono- and co-cultures of HaCaT keratinocytes and adult human dermal fibroblasts (HDFs), dsDNA assays, exosome isolation, double-antibody arrays, and angiogenesis assays-whether the C/H-3D-SFnws/ESFNs would allow the reconstitution of a functional human skin analog in vitro. Results: Physical analyses proved that the C/H-3D-SFnws/ESFNs met the requirements for human soft-tissue-like implants. dsDNA assays revealed that co-cultures of HaCaTs (on the 2D ESFN surface) and HDFs (inside the 3D C/H-3D-SFnws) grew more intensely than did the respective monocultures. Double-antibody arrays showed that the CD9⁺/CD81⁺ exosomes isolated from the 14-day pooled growth media of HDF and/or HaCaT mono- or co-cultures conveyed 35 distinct angiogenic/growth factors (AGFs). However, versus monocultures' exosomes, HaCaT/HDF co-cultures' exosomes (i) transported larger amounts of 15 AGFs, i.e., PIGF, ANGPT-1, bFGF, Tie-2, Angiogenin, VEGF-A, VEGF-D, TIMP-1/-2, GRO-α/-β/-γ, IL-1β, IL-6, IL-8, MMP-9, and MCP-1, and (ii) significantly more strongly stimulated human dermal microvascular endothelial cells to migrate and assemble tubes/nodes in vitro. Conclusions: Our results showed that both cell-cell and cell-SF interactions boosted the exosomal release of AGFs from HaCaTs/HDFs co-cultured on C/H-3D-SFnws/ESFNs. Hence, such exosomes are an asset for prospective clinical applications as they advance cell growth and neoangiogenesis and consequently graft take and skin healing. Moreover, this new integument analog could be instrumental in preclinical and translational studies on human skin pathophysiology and regeneration.

Microcurrent Reverses Cigarette Smoke-Induced Angiogenesis Impairment in Human Keratinocytes In Vitro

Cigarette smoking (CS) leads to several adverse health effects, including diseases, disabilities, and even death. Post-operative and trauma patients who smoke have an increased risk for complications, such as delayed bone or wound healing. In clinical trials, microcurrent (MC) has been shown to be a safe, non-invasive, and effective way to accelerate wound healing. Our study aimed to investigate if MC with the strength of 100 μA may be beneficial in treating CS-related healing impairment, especially in regard to angiogenesis. In this study, we investigated the effect of human keratinocyte cells (HaCaT) on angiogenesis after 72 h of cigarette smoke extract (CSE) exposure in the presence or absence of 100 μA MC. Cell viability and proliferation were evaluated by resazurin conversion, Sulforhodamine B, and Calcein-AM/Hoechst 33342 staining; the pro-angiogenic potential of HaCaT cells was evaluated by tube formation assay and angiogenesis array assay; signaling pathway alterations were investigated using Western blot. Constant exposure for 72 h to a 100 μA MC enhanced the angiogenic ability of HaCaT cells, which was mediated through the PI3K-Akt signaling pathway. In conclusion, the current data indicate that 100 μA MC may support wound healing in smoking patients by enhancing angiogenesis.

Establishment of an In Vitro Scab Model for Investigating Different Phases of Wound Healing

Chronic wounds are a serious problem in clinical work and a heavy burden for individuals and society. In order to develop novel therapies, adequate model systems for the investigation of wound healing are required. Although in past years different in vitro and in vitro wound healing models have been established, a true human-like model does still not exist. Animal models are limited in their use due to species-specific differences in the skin, a lengthy manufacturing process, experimental costs, and ethical concerns. Both 2D and 3D in vitro models are usually comprised of only one or two skin cell types and fail to capture the reaction between blood cells and skin cells. Thus, our aim was to develop an in vitro scab model to investigate early reactions in the wound healing process. The here established scab model is comprised of HaCaT cells and freshly collected blood from healthy volunteers. The generated scabs were stably cultured for more than 2 weeks. TGF-β signaling is well known to regulate the early phases of wound healing. All three TGF-β isoforms and target genes involved in extracellular matrix composition and degradation were expressed in the in vitro scabs. To validate the in vitro scab model, the effects of either additional stimulation or the inhibition of the TGF-β signaling pathway were investigated. Exogenous application of TGF-β1 stimulated matrix remodeling, which loosened the structure of the in vitro scabs with time, also induced expression of the inhibitory Smad7. Inhibition of the endogenous TGF-β signaling, on the contrary, resulted in a rapid condensation and degranulation of the in vitro scabs. In summary, the here established in vitro scab model can be used to analyze the first phases of wound healing where blood and skin cells interact, as it is viable and responsive for more than 2 weeks.

Reactive oxygen species-degradable polythioketal urethane foam dressings to promote porcine skin wound repair

Porous, resorbable biomaterials can serve as temporary scaffolds that support cell infiltration, tissue formation, and remodeling of nonhealing skin wounds. Synthetic biomaterials are less expensive to manufacture than biologic dressings and can achieve a broader range of physiochemical properties, but opportunities remain to tailor these materials for ideal host immune and regenerative responses. Polyesters are a well-established class of synthetic biomaterials; however, acidic degradation products released by their hydrolysis can cause poorly controlled autocatalytic degradation. Here, we systemically explored reactive oxygen species (ROS)-degradable polythioketal (PTK) urethane (UR) foams with varied hydrophilicity for skin wound healing. The most hydrophilic PTK-UR variant, with seven ethylene glycol (EG7) repeats flanking each side of a thioketal bond, exhibited the highest ROS reactivity and promoted optimal tissue infiltration, extracellular matrix (ECM) deposition, and reepithelialization in porcine skin wounds. EG7 induced lower foreign body response, greater recruitment of regenerative immune cell populations, and resolution of type 1 inflammation compared to more hydrophobic PTK-UR scaffolds. Porcine wounds treated with EG7 PTK-UR foams had greater ECM production, vascularization, and resolution of proinflammatory immune cells compared to polyester UR foam-based NovoSorb Biodegradable Temporizing Matrix (BTM)-treated wounds and greater early vascular perfusion and similar wound resurfacing relative to clinical gold standard Integra Bilayer Wound Matrix (BWM). In a porcine ischemic flap excisional wound model, EG7 PTK-UR treatment led to higher wound healing scores driven by lower inflammation and higher reepithelialization compared to NovoSorb BTM. PTK-UR foams warrant further investigation as synthetic biomaterials for wound healing applications.

Design, in vitro bioactivity and in vivo influence on oxidative stress and matrix metalloproteinases of bioglasses in experimental skin wound

BACKGROUND

The bioactive glasses (BGs) are very attractive materials increasingly used in healing skin lesions due to their antibacterial effect and stimulation of collagen deposition and angiogenesis. In this study, three specimens of bioactive glasses (BG1, BG2 and BG3) have been synthesized and characterized.

METHODS

In order to evaluate their in vitro bioactivity, the pH measurements, zeta potential and the concentration of Ca²⁺ and fluor ions released after immersion in phosphate buffered saline (PBS) followed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, inductively coupled plasma optical emission spectrometry (ICP-OES) and for BG1 and BG3, X-ray powder diffraction analysis, were performed. X-ray photoelectron spectroscopy (XPS) was also used for detection of different ions in the solid bioglasses before immersion in PBS. The impact of BG1 and BG3 on skin healing mechanisms was evaluated by oxidative stress and matrix metalloproteases (MMP)-2 and -9 and by histopathological analysis.

RESULTS

The results have shown that all the BGs tested are characterized by a very high degradation rate and a very fast Ca²⁺, fluor and boron releases and displayed changed surface morphology at SEM, after 7 and 14 days of immersion in PBS. In addition, BG1 and BG3 reduced in vivo the lipid peroxidation, increased the nitric oxide, especially at 14 days and improved superoxide dismutase activity, mainly in BG1 treated animals. In parallel, both BG1 and BG3, diminished MMP-9 at 14 days and increased the proportion of normal collagen in the bed of the wound, particularly BG3.

CONCLUSION

These results suggested that due to the antioxidant and anti-inflammatory properties of components released from BGs and regulatory properties on MMPs activities, BGs can exert beneficial effects in wound healing.

Approaches to Modulate the Chronic Wound Environment Using Localized Nucleic Acid Delivery

Significance: Nonhealing wounds have been the subject of decades of basic and clinical research. Despite new knowledge about the biology of impaired wound healing, little progress has been made in treating chronic wounds, leaving patients with few therapeutic options. Diabetic ulcers are a particularly common form of nonhealing wound. Recent Advances: Recently, investigation of therapeutic nucleic acids (TNAs), including plasmid DNA, small interfering RNA, microRNA mimics, anti-microRNA oligonucleotides, messenger RNA, and antisense oligonucleotides, has created a new treatment strategy for chronic wounds. TNAs can modulate the wound toward a prohealing environment by targeting gene pathways associated with inflammation, proteases, cell motility, angiogenesis, epithelialization, and oxidative stress. A variety of delivery systems have been investigated for TNAs, including dendrimers, lipid nanoparticles (NPs), polymeric micelles, polyplexes, metal NPs, and hydrogels. This review summarizes recent developments in TNA delivery for therapeutic targets associated with chronic wounds, with an emphasis on diabetic ulcers. Critical Issues: Translational potential of TNAs remains a key challenge; we highlight some drug delivery approaches for TNAs that may hold promise. We also describe current commercial efforts to locally deliver nucleic acids to modulate the wound environment. Future Directions: Localized nucleic acid delivery holds promise for the treatment of nonhealing chronic wounds. Future efforts to improve targeting of these nucleic acid therapies in the wound with both spatial and temporal control through drug delivery systems will be crucial to successful clinical translation.

IL-1β Impaired Diabetic Wound Healing by Regulating MMP-2 and MMP-9 through the p38 Pathway

Diabetes mellitus is one of the most prominent metabolic disorders in the world, and insulin resistance in diabetic patients leads to several complications including increased inflammation and delayed wound healing. Fibroblast migration and reepithelialization play a significant role in wound healing. In this study, we explored the effects of IL-1β signaling on proliferation and migration of human fibroblasts from diabetic wound tissues. We observed elevated levels of IL-1β in samples from diabetic patients when compared to normal wound tissues. At high concentrations, IL-1β inhibited cell proliferation and migration in ex vivo fibroblast cultures. Moreover, expression of matrix metalloproteinases (MMPs) was upregulated, and tissue inhibitor of metalloproteinases (TIMPs) was downregulated in diabetic wound tissues and cells. These effects were regulated by levels of IL-1β. Furthermore, IL-1β induced p38 phosphorylation thereby activating the p38 MAPK pathway that in turn regulated the expression of MMPs and TIMPs. Together, our study identifies a novel mechanism behind delayed wound closure in diabetes mellitus that involves IL-1β-dependent regulation of cell proliferation and migration.

Exosomes of adult human fibroblasts cultured on 3D silk fibroin nonwovens intensely stimulate neoangiogenesis

Background

Bombyx mori silk fibroin is a biomacromolecule that allows the assembly of scaffolds for tissue engineering and regeneration purposes due to its cellular adhesiveness, high biocompatibility and low immunogenicity. Earlier work showed that two types of 3D silk fibroin nonwovens (3D-SFnws) implanted into mouse subcutaneous tissue were promptly vascularized via undefined molecular mechanisms. The present study used nontumorigenic adult human dermal fibroblasts (HDFs) adhering to a third type of 3D-SFnws to assess whether HDFs release exosomes whose contents promote neoangiogenesis.

Methods

Electron microscopy imaging and physical tests defined the features of the novel carded/hydroentangled 3D-SFnws. HDFs were cultured on 3D-SFnws and polystyrene plates in an exosome-depleted medium. DNA amounts and D-glucose consumption revealed the growth and metabolic activities of HDFs on 3D-SFnws. CD9-expressing total exosome fractions were from conditioned media of 3D-SFnws and 2D polystyrene plates HDF cultures. Angiogenic growth factors (AGFs) in equal amounts of the two groups of exosomal proteins were analysed via double-antibody arrays. A tube formation assay using human dermal microvascular endothelial cells (HDMVECs) was used to evaluate the exosomes’ angiogenic power.

Results

The novel features of the 3D-SFnws met the biomechanical requirements typical of human soft tissues. By experimental day 15, 3D-SFnws-adhering HDFs had increased 4.5-fold in numbers and metabolized 5.4-fold more D-glucose than at day 3 in vitro. Compared to polystyrene-stuck HDFs, exosomes from 3D-SFnws-adhering HDFs carried significantly higher amounts of AGFs, such as interleukin (IL)-1α, IL-4 and IL-8; angiopoietin-1 and angiopoietin-2; angiopoietin-1 receptor (or Tie-2); growth-regulated oncogene (GRO)-α, GRO-β and GRO-γ; matrix metalloproteinase-1; tissue inhibitor metalloproteinase-1; and urokinase-type plasminogen activator surface receptor, but lesser amounts of anti-angiogenic tissue inhibitor metalloproteinase-2 and pro-inflammatory monocyte chemoattractant protein-1. At concentrations from 0.62 to 10 μg/ml, the exosomes from 3D-SFnws-cultured HDFs proved their angiogenic power by inducing HDMVECs to form significant amounts of tubes in vitro.

Conclusions

The structural and mechanical properties of carded/hydroentangled 3D-SFnws proved their suitability for tissue engineering and regeneration applications. Consistent with our hypothesis, 3D-SFnws-adhering HDFs released exosomes carrying several AGFs that induced HDMVECs to promptly assemble vascular tubes in vitro. Hence, we posit that once implanted in vivo, the 3D-SFnws/HDFs interactions could promote the vascularization and repair of extended skin wounds due to burns or other noxious agents in human and veterinary clinical settings.

SDF-1α Gene-Activated Collagen Scaffold Restores Pro-Angiogenic Wound Healing Features in Human Diabetic Adipose-Derived Stem Cells

Non-healing diabetic foot ulcers (DFUs) can lead to leg amputation in diabetic patients. Autologous stem cell therapy holds some potential to solve this problem; however, diabetic stem cells are relatively dysfunctional and restrictive in their wound healing abilities. This study sought to explore if a novel collagen-chondroitin sulfate (coll-CS) scaffold, functionalized with polyplex nanoparticles carrying the gene encoding for stromal-derived factor-1 alpha (SDF-1α gene-activated scaffold), can enhance the regenerative functionality of human diabetic adipose-derived stem cells (ADSCs). We assessed the impact of the gene-activated scaffold on diabetic ADSCs by comparing their response against healthy ADSCs cultured on a gene-free scaffold over two weeks. Overall, we found that the gene-activated scaffold could restore the pro-angiogenic regenerative response in the human diabetic ADSCs similar to the healthy ADSCs on the gene-free scaffold. Gene and protein expression analysis revealed that the gene-activated scaffold induced the overexpression of SDF-1α in diabetic ADSCs and engaged the receptor CXCR7, causing downstream β-arrestin signaling, as effectively as the transfected healthy ADSCs. The transfected diabetic ADSCs also exhibited pro-wound healing features characterized by active matrix remodeling of the provisional fibronectin matrix and basement membrane protein collagen IV. The gene-activated scaffold also induced a controlled pro-healing response in the healthy ADSCs by disabling early developmental factors signaling while promoting the expression of tissue remodeling components. Conclusively, we show that the SDF-1α gene-activated scaffold can overcome the deficiencies associated with diabetic ADSCs, paving the way for autologous stem cell therapies combined with novel biomaterials to treat DFUs.

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

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

What Makes Wounds Chronic

Chronic wounds present a unique therapeutic challenge to heal. Chronic wounds are colonized with bacteria and the presence of a biofilm that further inhibits the normal wound healing processes, and are locked into a very damaging proinflammatory response. The treatment of chronic wounds requires a coordinated approach, including debridement of devitalized tissue, minimizing bacteria and biofilm, control of inflammation, and the use of specialized dressings to address the specific aspects of the particular nonhealing ulcer.

The Association of Matrix Metalloproteinases with Chronic Kidney Disease and Peripheral Vascular Disease: A Light at the End of the Tunnel?

: Chronic Kidney Disease (CKD) represents a risk factor for fatal and nonfatal cardiovascular (CV) events, including peripheral vascular disease (PVD). This occurs because CKD encompasses several factors that lead to poor prognoses, mainly due to a reduction of the estimated glomerular filtration rate (eGFR), the presence of proteinuria, and the uremic inflammatory milieu. The matrix metalloproteinases (MMPs) are a group of zinc-containing endopeptidases implicated in extracellular matrix (ECM) remodeling, a systemic process in tissue homeostasis. MMPs play an important role in cell differentiation, angiogenesis, inflammation, and vascular damage. Our aim was to review the published evidence regarding the association between MMPs, PVD, and CKD to find possible common pathophysiological mechanisms. MMPs favor ECM deposition through the glomeruli, and start the shedding of cellular junctions and epithelial-mesenchymal transition in the renal tubules. MMP-2 and -9 have also been associated with the presence of systemic vascular damage, since they exert a pro-inflammatory and proatherosclerotic actions. An imbalance of MMPs was found in the context of PVD, where MMPs are predictors of poor prognoses in patients who underwent lower extremity revascularization. MMP circulating levels are increased in both conditions, i.e., that of CKD and PVD. A possible pathogenic link between these conditions is represented by the enhanced production of transforming growth factor-β that worsens vascular calcifications and atherosclerosis and the development of proteinuria in patients with increased levels of MMPs. Proteinuria has been recognized as a marker of systemic vascular damage, and this may explain in part the increase in CV risk that is manifest in patients with CKD and PVD. In conclusion, MMPs can be considered a useful tool by which to stratify CV risk in patients with CKD and PVD. Further studies are needed to investigate the causal-relationships between MMPs, CKD, and PVD, and to optimize their prognostic and predictive (in response to treatments) roles.

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.

Impact of Elastin-Derived Peptide VGVAPG on Matrix Metalloprotease-2 and -9 and the Tissue Inhibitor of Metalloproteinase-1, -2, -3 and -4 mRNA Expression in Mouse Cortical Glial Cells In Vitro

Degradation products of elastin, i.e. elastin-derived peptides (EDPs), are involved in various physiological and pathological processes. EDPs are detectable in cerebrospinal fluid in healthy people and in patients after ischemic stroke. However, to date, no studies concerning the role of EDP in the nervous system were conducted. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) play important roles during the repair phases of cerebral ischemia, particularly during angiogenesis and reestablishment of cerebral blood flow. Therefore, the aim of this study was to investigate the impact of the specific elastin-derived peptide VGVAPG on Mmp-2, -9 and Timp-1, -2, -3 and -4 mRNA expression in mouse cortical glial cells in vitro. Primary glial cells were maintained in DMEM/F12 without phenol red supplemented with 10% fetal bovine serum and the cells were exposed to 50 nM, 1 and 50 μM of the VGVAPG peptide. After 3 and 6 h of exposition to the peptide, expression of Mmp-2, -9 and Timp-1, -2, -3 and -4 mRNA was measured. Moreover, siRNA gene knockdown, cytotoxicity and apoptosis measurement were included in our experiments, which showed that VGVAPG in a wide range of concentrations exhibited neither proapoptotic nor cytotoxic properties in mouse glial cells in vitro. The peptides enhanced mRNA expression of Timp-2 and Timp-3 genes in an elastin-binding protein (EBP)-dependent manner. However, changes in mRNA expression of Mmp-2, Mmp-9 and Timp-4 were partially EBP-dependent. The decrease in mRNA expression of Timp-1 was EBP-independent. However, further studies underlying the VGVAPG peptide’s mechanism of action in the nervous system are necessary.

Xanthine Oxidoreductase: A Novel Therapeutic Target for the Treatment of Chronic Wounds?

Significance: Chronic wounds are a major burden to patients and to healthcare systems worldwide. These wounds are difficult to heal and treatment is often lengthy and expensive. This has led to research efforts focussed on the wound environment attempting to understand the underlying pathological mechanisms of impaired wound healing. While some of this research has translated to advancements in wound therapies and implementation of new treatment options, chronic wounds remain a significant challenge to treat. Thus, identification of effective, low-cost, advanced wound therapies that enhance healing rates of these problematic wounds is still essential. Recent Advances and Critical Issues: Xanthine oxidoreductase (XOR), a molybdoflavin enzyme, is emerging as an important source of reactive oxygen species (ROS) in various pathologies, including diabetes and chronic wounds. XOR has recently been shown to be upregulated in chronic wounds, stimulating the overproduction of ROS during dysfunctional wound healing. XOR-induced ROS can amplify and potentiate inflammation in the wound environment further delaying wound closure. Future Directions: The detrimental role of XOR in impaired healing indicates it may be a therapeutic target. Targeted inhibition of XOR has been shown to reduce the expression and activity of this enzyme in diabetic wound models. In turn, this resulted in a significant decrease in ROS levels in the wound environment and improved wound healing. Therefore, repurposing existing XOR inhibitors that are approved for human use may be able to restore homeostasis at the wound site and enable damaged tissue to return to normal healing.

Study on the role of Hsa-miR-31-5p in hypertrophic scar formation and the mechanism

Hypertrophic scar (HS) formation is associated with the fibrosis of fibrocytes caused by excessive extracellular matrix (ECM) synthesis and deposition, the initial event of HS formation. Our high throughput screen of miRNA expression profiles identified hsa-miR31-5p, whose transcription level was most differentially in normal skin fibroblasts (NS) and HS among other miRNAs. The level of hsa-miR31-5p in HS was significantly higher than in NS. In-vitro functional experiments showed hsa-miR31-5p knockdown remarkably suppressed the proliferation of hypertrophic scar fibroblasts (HSFBs) under hypoxia, promoted cell invasion, and inhibited the expression of Collagen I and III and Fibronectin (FN), suggesting that hsa-miR31-5p knockdown effectively reduces HS formation caused by excessive ECM synthesis and deposition in HSFBs under hypoxia. Mechanism study showed that the regulation of HS formation by hsa-miR31-5p was mediated by its target gene, factor-inhibiting HIF-1 (FIH): under hypoxia, hsa-miR31-5p down-regulated FIH and thus increased the level of hypoxia inducible factor-1α (HIF-1α), which subsequently activated the HIF-1α fibrosis regulation pathway in HSFBs, and stimulated the proliferation and ECM synthesis in HSFBs, eventually resulting in fibrosis and scar formation. The data also show that knockdown of hsa-miR31-5p in HSFBs impaired the trend of increased proliferation, reduced invasion and excessive ECM synthesis and deposition caused by HIF-1a activation under hypoxia through upregulating FIH, indicating that knockdown of hsa-miR31-5p effectively inhibits the formation of HS. In conclusion, hsa-miR31 -5p plays an important role in HS formation by inhibiting FIH and regulating the HIF-1α pathway. Therefore, hsa-miR31 -5p may be a novel therapeutic target for HS.

Optimization of Storage Temperature for Retention of Undifferentiated Cell Character of Cultured Human Epidermal Cell Sheets

Cultured epidermal cell sheets (CES) containing undifferentiated cells are useful for treating skin burns and have potential for regenerative treatment of other types of epithelial injuries. The undifferentiated phenotype is therefore important for success in both applications. This study aimed to optimize a method for one-week storage of CES for their widespread distribution and use in regenerative medicine. The effect of storage temperatures 4 °C, 8 °C, 12 °C, 16 °C, and 24 °C on CES was evaluated. Analyses included assessment of viability, mitochondrial reactive oxygen species (ROS), membrane damage, mitochondrial DNA (mtDNA) integrity, morphology, phenotype and cytokine secretion into storage buffer. Lowest cell viability was seen at 4 °C. Compared to non-stored cells, ABCG2 expression increased between temperatures 8–16 °C. At 24 °C, reduced ABCG2 expression coincided with increased mitochondrial ROS, as well as increased differentiation, cell death and mtDNA damage. P63, C/EBPδ, CK10 and involucrin fluorescence combined with morphology observations supported retention of undifferentiated cell phenotype at 12 °C, transition to differentiation at 16 °C, and increased differentiation at 24 °C. Several cytokines relevant to healing were upregulated during storage. Importantly, cells stored at 12 °C showed similar viability and undifferentiated phenotype as the non-stored control suggesting that this temperature may be ideal for storage of CES.

Molecular and cellular impact of Psoriasin (S100A7) on the healing of human wounds

Psoriasin, which is also known as S100A7, is a member of the S100 protein family, a group of calcium-responsive signalling proteins. Psoriasin expression remains high in patients with psoriasis, whereas it is downregulated in patients with invasive breast carcinoma. This observation suggests that this protein may be a notable marker of keratinocyte function and differentiation during wound healing. The aim of the present study was to determine the cellular impact of Psoriasin in keratinocytes, which are the primary cell type associated with wound healing. Psoriasin expression in wound tissues was examined using reverse transcription-quantitative polymerase chain reaction and immunochemical staining. Knockdown of Psoriasin in HaCaT cells was performed using anti-Psoriasin ribozyme transgenes and the effect on growth, adhesion and migration of keratinocytes was subsequently determined using in vitro cellular functional assays. Psoriasin expression is upregulated in wounds, particularly at the wound edges. The present study demonstrated that Psoriasin is expressed in keratinocytes and is a fundamental regulator of keratinocyte migration. Significant increases in the rate of keratinocyte adhesion, migration and growth were observed in Psoriasin-deficient cells (P<0.01 vs. control). Application of small inhibitors identified the potential association of neural Wiskott-Aldrich syndrome protein, focal adhesion primase and rho-associated protein kinase signalling pathways with Psoriasin-regulated cell adhesion and motility. In conclusion, Psoriasin serves an important role in the wound healing process, suggesting that it may be utilized as a potential wound healing biomarker.

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.

Tobacco toxins deposited on surfaces (third hand smoke) impair wound healing

Third hand smoke (THS) is the accumulation of second hand smoke (SHS) toxins on surfaces in homes, cars, clothing and hair of smokers. It is known that 88M US nonsmokers ≥3 years old living in homes of smokers are exposed to THS toxicants and show blood cotinine levels of ≥0.05 ng/ml, indicating that the toxins are circulating in their circulatory systems. The goal of the present study is to investigate the mechanisms by which THS causes impaired wound healing. We show that mice living under conditions that mimic THS exposure in humans display delayed wound closure, impaired collagen deposition, altered inflammatory response, decreased angiogenesis, microvessels with fibrin cuffs and a highly proteolytic wound environment. Moreover, THS-exposed mouse wounds have high levels of oxidative stress and significantly lower levels of antioxidant activity leading to molecular damage, including protein nitration, lipid peroxidation and DNA damage that contribute to tissue dysfunction. Furthermore, we show that elastase is elevated, suggesting that elastin is degraded and the plasticity of the wound tissue is decreased. Taken together, our results lead us to conclude that THS toxicants delay and impair wound healing by disrupting the sequential processes that lead to normal healing. In addition, the lack of elastin results in loss of wound plasticity, which may be responsible for reopening of wounds.

Efficacy of glutathione mesotherapy in burns: an experimental study

BACKGROUND

Thermal burns are the leading cause of trauma worldwide. Currently, no consensus on optimal treatment of deep partial-thickness (second-degree) burns has emerged, as reflected by the wide variability in available wound-care materials. The relative efficacies of products used for treatment of partial-thickness thermal burns remain unclear. Mesotherapy features intradermal administration of various agents, depending on burn location. In the present experimental study, we explored the efficacy of mesotherapy used to treat partial-thickness thermal burns in 50 male Wistar rats divided into five groups of equal number. No procedure was performed after infliction of thermal burns in control group (Group 1). Mesotherapy was applied with physiological saline in sham group (Group 2), glutathione, taurine, and L-carnitine were separately applied in Group 3, Group 4, and Group 5, respectively.

MATERIALS AND METHODS

Mesotherapeutic agents were injected intradermally into the reticular layer of the dermis using the point technique. The first course of mesotherapy was given within the first 2 h after infliction of thermal burns, and therapy was continued to day 10. On day 22, unhealed thermal burn areas were measured prior to sacrifice, and biopsies covering the total areas of burns were performed to allow of pathological evaluation.

RESULTS

Group 3 (the glutathione group) showed the best extent of healing, followed by Group 4 (the taurine group) and Group 5 (the L-carnitine group). The healed thermal burn areas in these groups were significantly greater than those in the control and sham groups (P = 0.001). All of healing, acute and chronic inflammation, the amount of granulation tissue, the level of fibroblast maturation, the amount of collagen, the extent of re-epithelization and neovascularization, and ulcer depth were scored upon pathological examination of tissue cross-sections. The best outcomes were evident in the glutathione group, with statistical significance. Although wound healing in the L-carnitine and taurine groups was better than in the control and sham groups, the differences were not statistically significant.

CONCLUSION

Thus, glutathione mesotherapy was effective when used to treat partial-thickness thermal burns and may be a useful treatment option for various human burns.

Metalloproteinases and Wound Healing

Significance: Matrix metalloproteinases (MMPs) are present in both acute and chronic wounds. They play a pivotal role, with their inhibitors, in regulating extracellular matrix degradation and deposition that is essential for wound reepithelialization. The excess protease activity can lead to a chronic nonhealing wound. The timed expression and activation of MMPs in response to wounding are vital for successful wound healing. MMPs are grouped into eight families and display extensive homology within these families. This homology leads in part to the initial failure of MMP inhibitors in clinical trials and the development of alternative methods for modulating the MMP activity. MMP-knockout mouse models display altered wound healing responses, but these are often subtle phenotypic changes indicating the overlapping MMP substrate specificity and inter-MMP compensation. Recent Advances: Recent research has identified several new MMP modulators, including photodynamic therapy, protease-absorbing dressing, microRNA regulation, signaling molecules, and peptides. Critical Issues: Wound healing requires the controlled activity of MMPs at all stages of the wound healing process. The loss of MMP regulation is a characteristic of chronic wounds and contributes to the failure to heal. Future Directions: Further research into how MMPs are regulated should allow the development of novel treatments for wound healing.

Extracellular Matrix Reorganization During Wound Healing and Its Impact on Abnormal Scarring

Significance: When a cutaneous injury occurs, the wound heals via a dynamic series of physiological events, including coagulation, granulation tissue formation, re-epithelialization, and extracellular matrix (ECM) remodeling. The final stage can take many months, yet the new ECM forms a scar that never achieves the flexibility or strength of the original tissue. In certain circumstances, the normal scar is replaced by pathological fibrotic tissue, which results in hypertrophic or keloid scars. These scars cause significant morbidity through physical dysfunction and psychological stress. Recent Advances and Critical Issues: The cutaneous ECM comprises a complex assortment of proteins that was traditionally thought to simply provide structural integrity and scaffolding characteristics. However, recent findings show that the ECM has multiple functions, including, storage and delivery of growth factors and cytokines, tissue repair and various physiological functions. Abnormal ECM reconstruction during wound healing contributes to the formation of hypertrophic and keloid scars. Whereas adult wounds heal with scarring, the developing foetus has the ability to heal wounds in a scarless fashion by regenerating skin and restoring the normal ECM architecture, strength, and function. Recent studies show that the lack of inflammation in fetal wounds contributes to this perfect healing. Future Directions: Better understanding of the exact roles of ECM components in scarring will allow us to produce therapeutic agents to prevent hypertrophic and keloid scars. This review will focus on the components of the ECM and their role in both physiological and pathological (hypertrophic and keloid) cutaneous scar formation.

An integrated omics analysis: impact of microgravity on host response to lipopolysaccharide in vitro

BACKGROUND

Microgravity facilitates the opportunistic infections by augmenting the pathogenic virulence and suppressing the host resistance. Hence the extraterrestrial infections may activate potentially novel bionetworks different from the terrestrial equivalent, which could only be probed by investigating the host-pathogen relationship with a minimum of terrestrial bias.

RESULTS

We customized a cell culture module to expose human endothelial cells to lipopolysaccharide (LPS). The assay was carried out onboard the STS-135 spaceflight, and a concurrent ground study constituted the baseline. Transcriptomic investigation revealed a possible immune blunting in microgravity suppressing in particular Lbp, MyD88 and MD-2, which encode proteins responsible for early LPS uptake. Certain cytokines, such as IL-6 and IL-8, surged in response to LPS insult in microgravity, as suggested by the proteomics study. Contrasting proteomic expressions of B2M, TIMP-1 and VEGRs suggested impaired pro-survival adaptation and healing mechanisms. Differential expression of miR-200a and miR-146b suggested the susceptibility of hosts in spaceflight to oxidative stress and further underscored the influence of microgravity on the immunity.

CONCLUSIONS

A molecular interpretation explaining the etiology of the microgravitational impact on the host-pathogen relationship elucidated comprehensive immune blunting of the host cells responding to LPS challenges. Longer LPS exposure prompted a delayed host response, potentially ineffectual in preventing pathogens from opportunistic invasion. Significant consequences include the subsequent failure in recruiting the growth factors and a debilitated apoptosis. Follow up studies with larger sample size are warranted.

Extracellular matrix assessment of infected chronic venous leg ulcers: role of metalloproteinases and inflammatory cytokines

Chronic venous ulcer (CVU) represents a dreaded complication of chronic venous disease (CVD). The onset of infection may further delay the already precarious healing process in such lesions. Some evidences have shown that matrix metalloproteinases (MMPs) are involved and play a central role in both CVUs and infectious diseases. Two groups of patients were enrolled to evaluate the expression of MMPs in infected ulcers and the levels of inflammatory cytokines as well as their prevalence. Group I comprised 63 patients (36 females and 27 males with a median age of 68·7 years) with infected CVUs, and group II (control group) comprised 66 patients (38 females and 28 males with a median age of 61·2 years) with non-infected venous ulcers. MMP evaluation and dosage of inflammatory cytokines in plasma and wound fluid was performed by means of enzyme-linked immunosorbent assay test; protein extraction and immunoblot analysis were performed on biopsied wounds. The first three most common agents involved in CVUs were Staphylococcus aureus (38·09%), Corynebacterium striatum (19·05%) and Pseudomonas aeruginosa (12·7%). In this study, we documented overall higher levels of MMP-1 and MMP-8 in patients with infected ulcers compared to those with uninfected ulcers that showed higher levels of MMP-2 and MMP-9. We also documented higher levels of interleukin (IL)-1, IL-6, IL-8, vascular endothelial growth factor and tumour necrosis factor-alpha in patients with infected ulcers with respect to those with uninfected ulcers, documenting a possible association between infection, MMP activation, cytokine secretions and symptoms. The present results could represent the basis for further studies on drug use that mimic the action of tissue inhibitors of metalloproteinases in order to make infected CVU more manageable.

Polysaccharides of Aloe vera induce MMP-3 and TIMP-2 gene expression during the skin wound repair of rat

Polysaccharides are the main macromolecules of Aloe vera gel but no data about their effect on extracellular matrix (ECM) elements are available. Here, mannose rich Aloe vera polysaccharides (AVP) with molecular weight between 50 and 250 kDa were isolated and characterized. Open cutaneous wounds on the back of 45 rats (control and treated) were daily treated with 25mg (n=15) and 50 mg (n=15) AVP for 30 days. The levels of MMP-3 and TIMP-2 gene expression were analyzed using real time PCR. The levels of n-acetyl glucosamine (NAGA), n-acetyl galactosamine (NAGLA) and collagen contents were also measured using standard biochemical methods. Faster wound closure was observed at day 15 post wounding in AVP treated animals in comparison with untreated group. At day 10 post wounding, AVP inhibited MMP-3 gene expression, while afterwards MMP-3 gene expression was upregulated. AVP enhanced TIMP-2 gene expression, collagen, NAGLA and NAGA synthesis in relation to untreated wounds. Our results suggest that AVP has positive effects on the regulation of ECM factor synthesis, which open up new perspectives for the wound repair activity of Aloe vera polysaccharide at molecular level.

Role of matrix metalloproteinases in non-healing venous ulcers

Chronic venous ulceration (CVU) of the lower limbs is a common condition affecting 1% of the adult population in Western countries, which is burdened with a high complication rate and a marked reduction in the quality of life often due to prolonged healing time. Several metalloproteinases (MMPs) such as MMP-9 together with neutrophil gelatinase-associated lipocalin (NGAL) appear to be involved in the onset and healing phases of venous ulcer, but it is still unclear how many biochemical components are responsible for prolonged healing time in those ulcers. In this study, we evaluate the role of MMP-1 and MMP-8 in long lasting and refractory venous ulcers. In a 2-year period we enroled 45 patients (28 female and 17 male, median age 65) with CVU. The enroled population was divided into two groups: group I were patients with non-healing ulcers (ulcers that had failed to heal for more than 2 months despite appropriate treatments) and group II were patients with healing ulcers (ulcers in healing phases). MMP-1 and MMP-8 were measured in fluids and tissues of healing and non-healing ulcers by means of enzyme-linked immunosorbent assay (ELISA) and Western blot analysis, respectively. In particular the patterns of the collagenases MMP-1 and MMP-8 in healing wounds were distinct, with MMP-8 appearing in significantly greater amounts especially in the non-healing group. Our findings suggest that MMP-1, and MMP-8 are overexpressed in long lasting CVU. Therefore, this dysregulation may represent the main cause of the pathogenesis of non-healing CVU.

Matrix metaloproteinase-2 and -9 serum levels as potential markers of intraperitoneal adhesions

OBJECTIVE

To assess the value of matrix metalloproteinases-2 (MMP-2) and -9 (MMP-9) as prognostic serum markers for intraperitoneal adhesions.

BACKGROUND

Postoperative adhesions are associated with serious complications responsible for increased patient's morbidity.

METHODS

Forty-eight rabbits were used and randomized into groups A, B, C, and D. Abdominal laparotomy and experimental adhesion formation model was carried out. In group A, 60 mL of N/S 0.9% were instilled intraperitoneally, in group B 60 mL of icodextrin 4% were instilled intraperitoneally, in group C 0.1 mL/kg of dimetindene maleate were administered intravenously, and in group D both agents were administered. Prior to euthanasia 0.5 mL of blood was obtained. The type, the surface area of adhesions, and serum concentration of MMPs were assessed.

RESULTS

The mean surface area and Zuhlke classification of adhesions of groups B, C, and D has been proved to be significantly lower compared to group A. Serum MMP-2 levels were significantly higher in groups B and D than in group A, while group D was higher when compared to group C. Serum MMP-9 levels were significantly higher in group D compared to groups A, B, and C. Serum MMP-9 was the most accurate test to differentiate between animals with and without adhesions with a sensitivity of 81.8% and a specificity of 100% at a cut-off point of 21.5 (AUC = 0.934).

CONCLUSIONS

The administration of icodextrin 4% and dimetindene maleate seems to prevent postoperative adhesion formation. Serum levels of MMP-2 and MMP-9 may serve as prognostic markers to identify postoperative adhesions.

Current aspects in the pathophysiology and treatment of chronic wounds in diabetes mellitus

Impaired wound healing is a frequent and very severe problem in patients with diabetes mellitus, yet little is known about the underlying pathomechanisms. In this paper we review the biology of wound healing with particular attention to the pathophysiology of chronic wounds in diabetic patients. The standard treatment of diabetic ulcers includes measures to optimize glycemic control as well as extensive debridement, infection elimination by antibiotic therapy based on wound pathogen cultures, the use of moisture dressings, and offloading high pressure from the wound bed. In this paper we discuss novel adjuvant therapies with particular reference to the use of autologous skin transplants for the treatment of diabetic foot ulcers which do not respond to standard care.

The molecular mechanism of hypertrophic scar

Hypertrophic scar (HTS) is a dermal form of fibroproliferative disorder which often develops after thermal or traumatic injury to the deep regions of the skin and is characterized by excessive deposition and alterations in morphology of collagen and other extracellular matrix (ECM) proteins. HTS are cosmetically disfiguring and can cause functional problems that often recur despite surgical attempts to remove or improve the scars. In this review, the roles of various fibrotic and anti-fibrotic molecules are discussed in order to improve our understanding of the molecular mechanism of the pathogenesis of HTS. These molecules include growth factors, cytokines, ECM molecules, and proteolytic enzymes. By exploring the mechanisms of this form of dermal fibrosis, we seek to provide some insight into this form of dermal fibrosis that may allow clinicians to improve treatment and prevention in the future.

MMP-8 overexpression and persistence of neutrophils relate to stress-impaired healing and poor collagen architecture in mice

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase (TIMPs) are critical for tissue remodeling during wound repair. Psychological stress has been found to impair wound healing in humans and animals. The objective of this study was to assess MMP and TIMP gene expression during stress-impaired healing. Female SKH-1 mice (n=299) were divided into control and stress groups (13h restraint/day for 3days prior to and 5days post-wounding). Two 3.5mm cutaneous full-thickness wounds were placed on the dorsum of each mouse and wound measurements were performed daily. RT-PCR for gene expression of MMP-2, MMP-8, MMP-9, TIMP-1 and TIMP-2 was performed at days 1, 3 and 5. Immunohistochemical analyses of the healed wounds were performed at days 15 and 28. As expected, wounds healed more slowly in restraint-stressed mice compared to controls. Stressed mice exhibited MMP-8 overexpression and lower TIMP-1 levels during healing, and poorer collagen organization once healed. MMP-8 overexpression may have stemmed from a higher level of neutrophils, observed in wound tissue on days 3 and 5. These findings implicate higher neutrophil numbers, MMP-8 overexpression, and TIMP-1 under-expression, as mechanisms that may compromise wound outcomes such as scarring under conditions of stress.

The transcriptional effects of the vesicants lewisite and sulfur mustard on human epidermal keratinocytes

Sulfur mustard (SM) injury is a complex process that begins with extensive alkylation of critical cellular components and culminates in cell death and skin vesication. The mechanism of toxicity is not well understood since SM broadly alkylates cellular nucleophiles. However, two events appear integral-the formation of DNA cross-links and the release of proteases into the extracellular matrix. To identify genes directly involved in vesication, the transcriptional profile of SM was compared to the vesicant lewisite (L). Similarly, to identify genes directly involved in DNA damage, the transcriptional profile of SM was compared to the genotoxic agent cisplatin (c-Pt). Microarrays containing 7,075 sequence-verified human cDNAs were screened with mRNA from human epidermal keratinocytes treated with 200 mu M agent for 2 h. A large number of differentially expressed genes were identified, with many similarities observed between agents. Many genes not previously associated with SM and L injury were also identified, including a large percentage of unknown function. A comparison of the differential expression profiles revealed that L had the broadest and most robustly altered expression. Apoptotic transcripts were clearly evident in L but not in SM, suggesting a late stage in L injury.