Beta-catenin and transforming growth factor beta have distinct roles regulating fibroblast cell motility and the induction of collagen lattice contraction

Targeting Wnt/β-catenin signaling and its interplay with TGF-β and Notch signaling pathways for the treatment of chronic wounds

Wound healing is a tightly regulated process that ensures tissue repair and normal function following injury. It is modulated by activation of pathways such as the transforming growth factor-beta (TGF-β), Notch, and Wnt/β-catenin signaling pathways. Dysregulation of this process causes poor wound healing, which leads to tissue fibrosis and ulcerative wounds. The Wnt/β-catenin pathway is involved in all phases of wound healing, primarily in the proliferative phase for formation of granulation tissue. This review focuses on the role of the Wnt/β-catenin signaling pathway in wound healing, and its transcriptional regulation of target genes. The crosstalk between Wnt/β-catenin, Notch, and the TGF-β signaling pathways, as well as the deregulation of Wnt/β-catenin signaling in chronic wounds are also considered, with a special focus on diabetic ulcers. Lastly, we discuss current and prospective therapies for chronic wounds, with a primary focus on strategies that target the Wnt/β-catenin signaling pathway such as photobiomodulation for healing diabetic ulcers.

Role of platelet factor 4 in arteriovenous fistula maturation failure: What do we know so far?

The rate of arteriovenous fistula (AVF) maturation failure remains unacceptably high despite continuous efforts on technique improvement and careful pre-surgery planning. In fact, half of all newly created AVFs are unable to be used for hemodialysis (HD) without a salvage procedure. While vascular stenosis in the venous limb of the access is the culprit, the underlying factors leading to vascular narrowing and AVF maturation failure are yet to be determined. We have recently demonstrated that AVF non-maturation is associated with post-operative medial fibrosis and fibrotic stenosis, and post-operative intimal hyperplasia (IH) exacerbates the situation. Multiple pathological processes and signaling pathways are underlying the stenotic remodeling of the AVF. Our group has recently indicated that a pro-inflammatory cytokine platelet factor 4 (PF4/CXCL4) is upregulated in veins that fail to mature after AVF creation. Platelet factor 4 is a fibrosis marker and can be detected in vascular stenosis tissue, suggesting that it may contribute to AVF maturation failure through stimulation of fibrosis and development of fibrotic stenosis. Here, we present an overview of the how PF4-mediated fibrosis determines AVF maturation failure.

Research progress on and molecular mechanism of vacuum sealing drainage in the treatment of diabetic foot ulcers

Diabetic foot ulcers (DFUs) are common chronic wounds and a common complication of diabetes. The foot is the main site of diabetic ulcers, which involve small and medium-sized arteries, peripheral nerves, and microcirculation, among others. DFUs are prone to coinfections and affect many diabetic patients. In recent years, interdisciplinary research combining medicine and material science has been increasing and has achieved significant clinical therapeutic effects, and the application of vacuum sealing drainage (VSD) in the treatment of DFUs is a typical representative of this progress, but the mechanism of action remains unclear. In this review, we integrated bioinformatics and literature and found that ferroptosis is an important signaling pathway through which VSD promotes the healing of DFUs and that System Xc-GSH-GPX4 and NAD(P)H-CoQ10-FSP1 are important axes in this signaling pathway, and we speculate that VSD is most likely to inhibit ferroptosis to promote DFU healing through the above axes. In addition, we found that some classical pathways, such as the TNF, NF-κB, and Wnt/β-catenin pathways, are also involved in the VSD-mediated promotion of DFU healing. We also compiled and reviewed the progress from clinical studies on VSD, and this information provides a reference for the study of VSD in the treatment of DFUs.

Alpinetin Suppresses Effects of TGF-β1 on Stimulating the Production and Organization of Fibrotic Markers in Human Primary Dermal Fibroblasts

Overgrowths of dermal fibroblasts and myofibroblast phenoconversion in response to TGF-β stimulation are the hallmarks of skin fibrosis. Constitutive activation of dermal fibroblasts by TGF-β induces the excessive production of extracellular matrix as well as certain key intracellular proteins which form a complex interaction network. Current therapies include monoclonal anti-bodies against TGF-β and surgery, but these treatments generally elicit a limited effect on certain kinds of skin fibrosis. In the current study, we investigated the effects of alpinetin (AP) on human primary dermal fibroblasts (HPDFs) stimulated with TGF-β1. Results demonstrated that AP exhibited strong inhibitory effects on TGF-β1-induced proliferation and migration of HPDFs. AP also inhibited TGF-β1-induced morphological changes of fibroblasts to myofibroblasts, and these were found to be from its effects on blocking actin stress fiber formation and organization. The expression of major fibrotic molecules including α-SMA and type I collagen upon TGF-β1 stimulation was also inhibited by AP. In addition, AP attenuated TGF-β1-induced production and organization of vimentin, β-catenin, and N-cadherin, important for the pathophysiology of skin fibrosis. In conclusion, we revealed that AP has an ability to reverse the fibrotic effects of TGF-β1 at the cellular level, and this discovery suggests the therapeutic potential of AP for skin fibrosis.

Exosomes Derived From Umbilical Cord Mesenchymal Stem Cells Treat Cutaneous Nerve Damage and Promote Wound Healing

Wound repair is a key step in the treatment of skin injury caused by burn, surgery, and trauma. Various stem cells have been proven to promote wound healing and skin regeneration as candidate seed cells. Therefore, exosomes derived from stem cells are emerging as a promising method for wound repair. However, the mechanism by which exosomes promote wound repair is still unclear. In this study, we reported that exosomes derived from umbilical cord mesenchymal stem cells (UC-MSCs) promote wound healing and skin regeneration by treating cutaneous nerve damage. The results revealed that UC-MSCs exosomes (UC-MSC-Exo) promote the growth and migration of dermal fibroblast cells. In in vitro culture, dermal fibroblasts could promote to nerve cells and secrete nerve growth factors when stimulated by exosomes. During the repair process UC-MSC-Exo accelerated the recruitment of fibroblasts at the site of trauma and significantly enhanced cutaneous nerve regeneration in vivo. Interestingly, it was found that UC-MSC-Exo could promote wound healing and skin regeneration by recruiting fibroblasts, stimulating them to secrete nerve growth factors (NGFs) and promoting skin nerve regeneration. Therefore, we concluded that UC-MSC-Exo promote cutaneous nerve repair, which may play an important role in wound repair and skin regeneration.

Quercetin promotes cutaneous wound healing in mice through Wnt/β-catenin signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Oxytropis falcata Bunge is a legume distributed in Northwest China, which is mainly used to treat knife wounds and inflammation. Quercetin is a bioactive flavonoid in O. falcata and becomes a promising healing compound for its angiogenic and anti-inflammatory activities. However, the healing mechanism of quercetin in cutaneous wound remains elusive.

AIM OF THE STUDY

The purpose of this study was to evaluate the healing effect of quercetin on cutaneous wound models in vivo and in vitro, and to reveal the Wnt/β-catenin pathway and Telomerase reverse transcriptase (TERT) involved mechanisms.

MATERIALS AND METHODS

The effects of quercetin on the proliferation and migration of 4 kinds of skin cells were determined by CCK-8 and scratch assay. The wound-healing capacity of quercetin was evaluated in cutaneous wound model of C57BL/6 mice and the wound healing degree was observed by histological staining. The expressions of inflammatory factors, growth factors and the related proteins were detected via Western blot and RT-qPCR analyses. The molecular docking was adopted to evaluate the binding ability of quercetin and TERT.

RESULTS

Quercetin could promote both proliferation and migration of fibroblasts, and enhance cutaneous wound healing capacity in mice. Compared to the control group, the wound healing rates in low (1.5 mg/mL), medium (3.0 mg/mL) and high dose (6.0 mg/mL) quercetin groups reached 94.67%, 97.31% and 98.42%, respectively. Moreover, the dermal structure in quercetin treated mice restored normal and the content of collagen fiber became abundant after administration. The levels of inflammatory factors, including tumor necrosis factor-α, interleukin-1β and interleukin-6 were significantly reduced after quercetin administration. Among which, the level of IL-1β in cutaneous wound was 0.007 times higher than that of the control group when treated with quercetin of high dose (6.0 mg/mL). The improved level of GSH in quercetin treated cutaneous wounds also indicated its higher antioxidant ability. In addition, dose-dependent positive associations were found in the expression levels of vascular endothelial growth factor, fibroblast growth factor and alpha smooth muscle actin in quercetin treated cutaneous wounds. The significantly upregulated protein levels of Wnt and β-catenin further indicated the important role of quercetin in promoting wound healing in mice. According to molecular docking analysis, the formed hydrogen bonds between quercetin and Ala195, Gln308, Asn369 and Lys372 residues of TERT also indicated the indispensable role of TERT in improving wound healing capacity.

CONCLUSION

Quercetin effectively promoted cutaneous wound healing by enhancing the proliferation and migration of fibroblasts, as well as inhibiting inflammation and increasing the expression of growth factors in mice via Wnt/β-catenin signaling pathway and TERT. It provides a basis for a more thorough understanding of mechanism of action of O. falcata Bunge in the treatment of knife wounds and burns.

Approaches for Regenerative Healing of Cutaneous Wound with an Emphasis on Strategies Activating the Wnt/β-Catenin Pathway

Significance: In adult mammals, spontaneous repair of a cutaneous wound occurs slowly and leaves a scar with skin adnexa deficiencies. To accelerate cutaneous wound-healing rates and avoid scar formation, current studies have focused on regenerative therapies. Recent Advances: Emerging therapeutics for regenerative wound healing often focus on the use of growth factors and stem cells. However, these therapeutic approaches have limited routine clinical use due to high costs and technical requirements. Critical Issue: Understanding the molecular mechanisms involved in the signaling pathways for cutaneous wound healing and neogenic synthesis of the skin components is important for identification of novel targets for the development of regenerative wound-healing agents. Future Directions: The Wnt/β-catenin pathway is a well-known key player for enhancement of the overall healing process involving tissue regeneration via crosstalk with other signaling pathways. Strategies that activate the Wnt/β-catenin pathway via modulation of the pathway-controlling regulatory factors could provide effective therapeutic approaches for regenerative wound healing.

Tartrate-resistant acid phosphatase 5 promotes pulmonary fibrosis by modulating β-catenin signaling

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease with limited therapeutic options. Tartrate-resistant acid phosphatase 5 (ACP5) performs a variety of functions. However, its role in IPF remains unclear. Here, we demonstrate that the levels of ACP5 are increased in IPF patient samples and mice with bleomycin (BLM)-induced pulmonary fibrosis. In particular, higher levels of ACP5 are present in the sera of IPF patients with a diffusing capacity of the lungs for carbonmonoxide (DLCO) less than 40% of the predicted value. Additionally, Acp5 deficiency protects mice from BLM-induced lung injury and fibrosis coupled with a significant reduction of fibroblast differentiation and proliferation. Mechanistic studies reveal that Acp5 is upregulated by transforming growth factor-β1 (TGF-β1) in a TGF-β receptor 1 (TGFβR1)/Smad family member 3 (Smad3)-dependent manner, after which Acp5 dephosphorylates p-β-catenin at serine 33 and threonine 41, inhibiting the degradation of β-catenin and subsequently enhancing β-catenin signaling in the nucleus, which promotes the differentiation, proliferation and migration of fibroblast. More importantly, the treatment of mice with Acp5 siRNA-loaded liposomes or Acp5 inhibitor reverses established lung fibrosis. In conclusions, Acp5 is involved in the initiation and progression of pulmonary fibrosis and strategies aimed at silencing or suppressing Acp5 could be considered as potential therapeutic approaches against pulmonary fibrosis.

Idiopathic pulmonary fibrosis is a fatal lung disease with limited treatment options. Here the authors show that tartrate-resistant acid phosphatase 5 (Acp5) promotes lung fibrosis by enhancing beta-catenin signaling and that inhibition of Acp5 can reverse stablished pulmonary fibrosis.

In vitro stimulation with radiofrequency currents promotes proliferation and migration in human keratinocytes and fibroblasts

Capacitive-resistive electric transfer (CRET) therapies have been proposed as strategies for regeneration of cutaneous tissue lesions. Previous studies by our group have shown that intermittent stimulation with 448 kHz CRET currents at subthermal densities promotes in vitro proliferation of human stem cells involved in tissue regeneration. The present study investigates the effects of the in vitro exposure to these radiofrequency (RF) currents on the proliferation and migration of keratinocytes and fibroblasts, the main cell types involved in skin regeneration. The effects of the electric stimulation on cell proliferation and migration were studied through XTT and wound closure assays, respectively. The CRET effects on the expression and location of proteins involved in proliferation and migration were assessed by immunoblot and immunofluorescence. The obtained results reveal that electrostimulation promotes proliferation and/or migration in keratinocytes and fibroblasts. These effects would be mediated by changes observed in the expression and location of intercellular adhesion proteins such as β-catenin and E-cadherin, of proteins involved in cell-to-substrate adhesion such as vinculin, p-FAK and the metalloproteinase MMP-9, and of other proteins that control both processes: MAP kinases p-p38, p-JUNK and p-ERK1/2. These responses could represent a mechanism underlying the promotion of normotrophic wound regeneration induced by CRET. Indeed, electric stimulation would favor completion of granulation tissue formation prior to the closure of the outer tissue layers, thus preventing abnormal wound cicatrization or chronification.

LncRNA COL1A2-AS1 promotes skin fibroblast apoptosis by repressing p-Smad3 and promoting β-catenin expression

LncRNA COL1A2-AS1 has been demonstrated to inhibit fibroblast proliferation of hypertrophic scars. However, the function of COL1A2-AS1 in normal skin fibroblasts remains poorly studied. Here, we report that overexpression of COL1A2-AS1 promoted normal skin fibroblast apoptosis. On the basis of mRNA-seq data and gene set enrichment analysis plus Kyoto encyclopedia of genes and genomes pathway analysis, 16 upregulated and 125 downregulated mRNAs were found; TGF-β, Wnt, and MAPK pathways were potentially involved. Western blot assay confirmed that overexpression of COL1A2-AS1 repressed p-Smad3 expression and promoted β-catenin expression. Furthermore, COL1A2-AS1 overexpression combined with either TGF-β1 or siRNA against β-catenin reversed the upregulation of apoptosis in the COL1A2-AS1 overexpression group. In conclusion, our study revealed the roles of COL1A2-AS1 in normal skin fibroblast apoptosis, with COL1A2-AS1 functioning by repressing p-Smad3 expression and promoting β-catenin expression.

Protective Effects of Melatonin on the Skin: Future Perspectives

When exposed to hostile environments such as radiation, physical injuries, chemicals, pollution, and microorganisms, the skin requires protective chemical molecules and pathways. Melatonin, a highly conserved ancient molecule, plays a crucial role in the maintenance of skin. As human skin has functional melatonin receptors and also acts as a complete system that is capable of producing and regulating melatonin synthesis, melatonin is a promising candidate for its maintenance and protection. Below, we review the studies of new metabolic pathways involved in the protective functions of melatonin in dermal cells. We also discuss the advantages of the topical use of melatonin for therapeutic purposes and skin protection. In our view, endogenous intracutaneous melatonin production, together with topically-applied exogenous melatonin and its metabolites, represent two of the most potent defense systems against external damage to the skin.

Bromfenac Inhibits TGF-β1-Induced Fibrotic Effects in Human Pterygium and Conjunctival Fibroblasts

Purpose

Nonsteroidal anti-inflammatory drugs (NSAIDs) have shown antifibrotic effects on several diseases. The aims of the present in vitro study were to investigate the antifibrotic effects of bromfenac (a kind of NSAID) on primary human pterygium fibroblasts (HPFs) and primary human conjunctival fibroblasts (HConFs), as well as to explore the possible mechanisms of these effects.

Methods

The cells used in this study were primary HPFs and HConFs, and profibrotic activation was induced by transforming growth factor-beta1 (TGF-β1). Western blot, quantitative real-time PCR, and immunofluorescence (IF) assays were used to detect the effects of TGF-β1 and bromfenac on the synthesis of fibronectin (FN), type III collagen (COL3), and alpha-smooth muscle actin (α-SMA) in HPFs and HConFs; the changes of signaling pathways were detected by Western blot; cell migration ability was detected by wound healing assay; cell proliferation ability was detected by CCK-8 assay; and pharmaceutical inhibitions of the downstream signaling pathways of TGF-β1 were used to assess their possible associations with the effects of bromfenac.

Results

Bromfenac suppressed the TGF-β1-induced protein expression of FN (0.59 ± 0.07 folds, P = 0.008), COL3 (0.48 ± 0.08 folds, P = 0.001), and α-SMA (0.61 ± 0.03 folds, P = 0.008) in HPFs. Bromfenac also attenuated TGF-β1-induced cell migration (0.30 ± 0.07 folds, P < 0.001), cell proliferation (0.64 ± 0.03 folds, P = 0.002) and the expression levels of p-AKT (0.66 ± 0.08 folds, P = 0.032), p-ERK1/2 (0.69 ± 0.11 folds, P = 0.003), and p-GSK-3β-S9 (0.65 ± 0.10 folds, P = 0.002) in HPFs. PI3K/AKT inhibitor (wortmannin) and MEK/ERK inhibitor (U0126) reduced the TGF-β1-induced synthesis of FN, COL3, and α-SMA in HPFs. All the results were similar in HConFs.

Conclusions

Bromfenac protects against TGF-β1-induced synthesis of FN, α-SMA, and COL3 in HPFs and HConFs at least in part by inactivating the AKT and ERK pathways.

Examining the contribution of surrounding intact skin during cutaneous healing

Severe cutaneous wounds expose the body to the external environment, which may lead to impairments in bodily functions and increased risk of infection. There is a need to develop skin substitutes which could effectively promote complete skin regeneration following an injury. Murine models are used to test such skin substitutes, but their healing involves contraction of the dermis not found in human wounds. We have previously described a device called a dome, which comes in two models, that is used to prevent skin contraction in mice. One model provides a physical barrier to minimize contraction, and the other model has additional perforations in the barrier to allow cellular contribution from the surrounding intact skin. Taking advantage of an enhanced version of these two models, we compared granulation tissue formation, the extent of vascularization, and the transition to myofibroblastic phenotype between the models. We enhanced the dome by developing a twist open cap dome and applied the two models of the dome into the excisional wound biopsy in mice. We demonstrate that the dome can be used to prevent skin contraction in mice. The control model prevented skin contraction while barricading the contribution of surrounding intact skin. When not barricaded, the intact skin enhances wound healing by increasing the number of myofibroblasts and neovascularization. Using a novel model of inhibition of skin contraction in rodents, we examined the contribution from the surrounding intact skin to granulation tissue formation, myofibroblastic differentiation, and neovascularization during the course of skin healing in mice.

Lithium interacts with cardiac remodeling: the fundamental value in the pharmacotherapy of bipolar disorder

Patients with bipolar disorder (BD) have an increased risk of cardiovascular morbidity and mortality during the course of their illness. For over half a century, lithium has been the gold-standard medication used to treat the mood burdens of BD. In addition, lithium possesses several biological effects that may modulate cardiovascular risk in patients with BD. In this review, we update the current knowledge of cellular and molecular mechanisms underlying the possible cardiac actions of lithium. The mechanistic insights suggest that lithium at therapeutic levels potentially exerts cardioprotective effects on ischemic hearts by modulating structural and electrical remodeling. The possible cardioprotective actions of lithium may involve an extensive range of signaling pathways, including the Wnt/glycogen synthase kinase-3β, phosphatidylinositol-3-kinase/protein kinase B, phosphoinositide/protein kinase C, and mitogen-activated protein kinase/extracellular signal-regulated kinase cascades. Accordingly, understanding the cardioprotective effects of lithium may lead to the development of a potential strategy for reducing cardiovascular morbidity in patients with BD.

Development of an easy-to-handle murine model for the characterization of radiation-induced gross and molecular changes in skin

BACKGROUND

Radiation-induced skin injury is a dose-limiting complication of radiotherapy. To investigate this problem and to develop a framework for making decisions on treatment and dose prescription, a murine model of radiation-induced skin injury was developed.

METHODS

The dorsal skin of the mice was isolated, and irradiation was applied at single doses of 15, 30, and 50 Gy. The mice were followed for 12 weeks with serial photography and laser Doppler analysis. Sequential skin biopsy samples were obtained and subjected to a histological analysis, immunostaining against transforming growth factor beta (TGF-β), and Western blotting with Wnt-3 and β-catenin. Increases in the levels of TGF-β, Wnt, and β-catenin were detected after irradiation.

RESULTS

All tested radiation doses caused progressive dermal thickening and fibrosis. The cause of this process, however, may not be radiation alone, as the natural course of wound healing may elicit a similar response. The latent appearance of molecular and histological markers that induce fibrosis in the 15 Gy group without causing apparent gross skin injuries indicates that 15 Gy is an appropriate dose for characterizing the effects of chronic irradiation alone. Thus, this model best mimics the patterns of injury that occur in human subjects.

CONCLUSIONS

This animal model can be used to elucidate the gross and molecular changes that occur in radiation-induced skin injury and provides an effective platform for studying this adverse effect without complicating the process of wound healing.

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.

FK506-binding protein 10 (FKBP10) regulates lung fibroblast migration via collagen VI synthesis

Background

In idiopathic pulmonary fibrosis (IPF), fibroblasts gain a more migratory phenotype and excessively secrete extracellular matrix (ECM), ultimately leading to alveolar scarring and progressive dyspnea. Here, we analyzed the effects of deficiency of FK506-binding protein 10 (FKBP10), a potential IPF drug target, on primary human lung fibroblast (phLF) adhesion and migration.

Methods

Using siRNA, FKBP10 expression was inhibited in phLF in absence or presence of 2ng/ml transforming growth factor-β1 (TGF-β1) and 0.1mM 2-phosphoascorbate. Effects on cell adhesion and migration were monitored by an immunofluorescence (IF)-based attachment assay, a conventional scratch assay, and single cell tracking by time-lapse microscopy. Effects on expression of key players in adhesion dynamics and migration were analyzed by qPCR and Western Blot. Colocalization was evaluated by IF microscopy and by proximity ligation assays.

Results

FKBP10 knockdown significantly attenuated adhesion and migration of phLF. Expression of collagen VI was decreased, while expression of key components of the focal adhesion complex was mostly upregulated. The effects on migration were 2-phosphoascorbate-dependent, suggesting collagen synthesis as the underlying mechanism. FKBP10 colocalized with collagen VI and coating culture dishes with collagen VI, and to a lesser extent with collagen I, abolished the effect of FKBP10 deficiency on migration.

Conclusions

These findings show, to our knowledge for the first time, that FKBP10 interacts with collagen VI and that deficiency of FKBP10 reduces phLF migration mainly by downregulation of collagen VI synthesis. The results strengthen FKBP10 as an important intracellular regulator of ECM remodeling and support the concept of FKBP10 as drug target in IPF.

Scar management in burn injuries using drug delivery and molecular signaling: Current treatments and future directions

In recent decades, there have been tremendous improvements in burn care that have allowed patients to survive severe burn injuries that were once fatal. However, a major limitation of burn care currently is the development of hypertrophic scars in approximately 70% of patients. This significantly decreases the quality of life for patients due to the physical and psychosocial symptoms associated with scarring. Current approaches to manage scarring include surgical techniques and non-surgical methods such as laser therapy, steroid injections, and compression therapy. These treatments are limited in their effectiveness and regularly fail to manage symptoms. As a result, the development of novel treatments that aim to improve outcomes and quality of life is imperative. Drug delivery that targets the molecular cascades of wound healing to attenuate or prevent hypertrophic scarring is a promising approach that has therapeutic potential. In this review, we discuss current treatments for scar management after burn injury, and how drug delivery targeting molecular signaling can lead to new therapeutic strategies.

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.

Acellular Gelatinous Material of Human Umbilical Cord Enhances Wound Healing: A Candidate Remedy for Deficient Wound Healing

Impaired wound healing is a severe clinical challenge and research into finding effective wound healing strategies is underway as there is no ideal treatment. Gelatinous material from the umbilical cord called Wharton's jelly is a valuable source of mesenchymal stem cells which have been shown to aid wound healing. While the cellular component of Wharton's jelly has been the subject of extensive research during the last few years, little is known about the de-cellularized jelly material of the umbilical cord. This is important as they are native niche of stem cells. We have isolated Wharton's jelly from umbilical cords and then fractionated acellular gelatinous Wharton's jelly (AGWJ). Here, we show for the first time that AGWJ enhances wound healing in vitro as well as in vivo for wounds in a murine model. In vivo staining of the wounds revealed a smaller wound length in the AGWJ treated wounds in comparison to control treatment by enhancing cell migration and differentiation. AGWJ significantly enhanced fibroblast cell migration in vitro. Aside from cell migration, AGWJ changed the cell morphology of fibroblasts to a more elongated phenotype, characteristic of myofibroblasts, confirmed by upregulation of alpha smooth muscle actin using immunoblotting. AGWJ treatment of wounds led to accelerated differentiation of cells into myofibroblasts, shortening the proliferation phase of wound healing. This data provides support for a novel wound healing remedy using AGWJ. AGWJ being native biological, cost effective and abundantly available globally, makes it a highly promising treatment option for wound dressing and skin regeneration.

Reduced Expression of YAP in Dermal Fibroblasts is Associated with Impaired Wound Healing in Type 2 Diabetic Mice

Dermal fibroblasts play essential roles in wound healing and their dysfunction has been shown to be associated with impaired wound healing in diabetes. In the present study, we aimed at investigating whether Yes-associated protein (YAP), a mediator of mechanotransduction in dermal fibroblasts, is associated with impaired wound healing in diabetic mice. Compared with that in the control, the rate of wound contraction was decreased twofold in db/db type 2 diabetic mice (db/db mice). To mimic diabetic pathological condition, dermal fibroblasts were cultured under high glucose conditions (25.5 mM glucose). Further, dermal fibroblast-mediated contraction of wound was evaluated by in vitro collagen gel contraction assay. Dermal fibroblasts cultured under hyperglycemic condition showed impaired gel contraction and mitochondrial dysfunction, compared to the cells cultured under normoglycemic conditions (5.5 mM glucose). Importantly, compared with the normal dermal fibroblasts, diabetic db/db dermal fibroblasts expressed lower levels of growth factors and cytokines that enhance wound healing, such as insulin-like growth factor-1, stromal cell-derived factor-1, connective tissue growth factor, and transforming growth factor-β (TGF-β). The quantity of YAP mRNA was also lower in diabetic db/db dermal fibroblasts, compared with that in the control fibroblasts. These results indicate that impaired wound healing in diabetics is associated with the dysfunction of dermal fibroblasts, including downregulation of YAP, which plays essential roles in extracellular matrix remodeling and TGF-β-mediated wound healing.

Adenosine A2A receptor promotes collagen type III synthesis via β-catenin activation in human dermal fibroblasts

BACKGROUND AND PURPOSE

Adenosine A_2A receptor stimulation promotes the synthesis of collagen type I and type III (Col1 and Col3), mediators of fibrosis and scarring. The A_2A receptor modulates collagen balance via cAMP/PKA/p38-MAPK/Akt pathways. Wnt signalling is important in fibrosis and the cAMP and Wnt pathways converge. Because the A_2A receptor is Gs-linked and increases cAMP, we determined whether A_2A receptors and Wnt signalling interact.

EXPERIMENTAL APPROACH

Total β-catenin, de-phosphorylated β-catenin (canonical activation, de-phospho β-catenin) and phosphorylated β-catenin at Ser⁵⁵² (non-canonical activation, p-Ser⁵⁵² β-catenin) levels were determined in primary human dermal fibroblasts, cytosol and nucleus, by western blot analysis and fluorescence microscopy, before and after stimulation by A_2A receptor-selective agonist CGS21680, with/without A_2A receptor-selective antagonist (SCH56261) pretreatment. β-Catenin was knocked down by transfection with scrambled-siRNA or specific-siRNA, and Col1 and Col3 levels determined by western blots.

KEY RESULTS

CGS21680 stimulation rapidly (15 min) increased cellular β-catenin levels. Both de-phospho β-catenin and p-Ser⁵⁵² β-catenin levels were also increased. CGS21680 stimulated the translocation of total de-phospho and p-Ser⁵⁵² β-catenin to the nucleus. A_2A receptor-stimulation increased Col1 synthesis similarly in β-catenin knockeddown and scrambled cells. However, β-catenin knockdown abolished the increase in Col3 synthesis induced in A_2A receptor-stimulated fibroblasts.

CONCLUSIONS AND IMPLICATIONS

A_2A receptor stimulation promotes Col3 synthesis via the activation of canonical and non-canonical β-catenin, consistent with a role for A_2A receptors in dermal fibrosis and scarring.

Methodologies in creating skin substitutes

The creation of skin substitutes has significantly decreased morbidity and mortality of skin wounds. Although there are still a number of disadvantages of currently available skin substitutes, there has been a significant decline in research advances over the past several years in improving these skin substitutes. Clinically most skin substitutes used are acellular and do not use growth factors to assist wound healing, key areas of potential in this field of research. This article discusses the five necessary attributes of an ideal skin substitute. It comprehensively discusses the three major basic components of currently available skin substitutes: scaffold materials, growth factors, and cells, comparing and contrasting what has been used so far. It then examines a variety of techniques in how to incorporate these basic components together to act as a guide for further research in the field to create cellular skin substitutes with better clinical results.

Wnt signaling induces epithelial differentiation during cutaneous wound healing

Cutaneous wound repair in adult mammals typically does not regenerate original dermal architecture. Skin that has undergone repair following injury is not identical to intact uninjured skin. This disparity may be caused by differences in the mechanisms that regulate postnatal cutaneous wound repair compared to embryonic skin development and thus we seek a deeper understanding of the role that Wnt signaling plays in the mechanisms of skin repair in both fetal and adult wounds. The influence of secreted Wnt signaling proteins in tissue homeostasis has galvanized efforts to identify small molecules that target Wnt-mediated cellular responses. Wnt signaling is activated by wounding and participates in every subsequent stage of the healing process from the control of inflammation and programmed cell death, to the mobilization of stem cell reservoirs within the wound site. Endogenous Wnt signaling augmentation represents an attractive option to aid in the restoration of cutaneous wounds, as the complex mechanisms of the Wnt pathway have been increasingly investigated over the years. In this review, we summarize recent data elucidating the roles that Wnt signaling plays in cutaneous wound healing process.

Dermal fibroblasts induce cell cycle arrest and block epithelial-mesenchymal transition to inhibit the early stage melanoma development

Stromal fibroblasts are an integral part of the tumor stroma and constantly interact with cancer cells to promote their initiation and progression. However, the role and function of dermal fibroblasts during the early stage of melanoma development remain poorly understood. We, therefore, designed a novel genetic approach to deactivate stromal fibroblasts at the onset of melanoma formation by targeted ablation of β-catenin. To our surprise, melanoma tumors formed from β-catenin-deficient group (B16F10 mixed with β-catenin-deficient fibroblasts) appeared earlier than tumors formed from control group (B16F10 mixed with normal dermal fibroblasts). At the end point when tumors were collected, mutant tumors were bigger and heavier than control tumors. Further analysis showed that there were fewer amounts of stromal fibroblasts and myofibroblasts inside mutant tumor stroma. Melanoma tumors from control group showed reduced proliferation, down-regulated expression of cyclin D1 and increased expression of cyclin-dependent kinase inhibitor p16, suggesting dermal fibroblasts blocked the onset of melanoma tumor formation by inducing a cell cycle arrest in B16F10 melanoma cells. Furthermore, we discovered that dermal fibroblasts prevented epithelial-mesenchymal transition in melanoma cells. Overall, our findings demonstrated that dermal fibroblasts crosstalk with melanoma cells to regulate in vivo tumor development via multiple mechanisms, and the outcomes of their reciprocal interactions depend on activation states of stromal fibroblasts and stages of melanoma development.

TGF-β: the master regulator of fibrosis

Transforming growth factor-β (TGF-β) is the primary factor that drives fibrosis in most, if not all, forms of chronic kidney disease (CKD). Inhibition of the TGF-β isoform, TGF-β1, or its downstream signalling pathways substantially limits renal fibrosis in a wide range of disease models whereas overexpression of TGF-β1 induces renal fibrosis. TGF-β1 can induce renal fibrosis via activation of both canonical (Smad-based) and non-canonical (non-Smad-based) signalling pathways, which result in activation of myofibroblasts, excessive production of extracellular matrix (ECM) and inhibition of ECM degradation. The role of Smad proteins in the regulation of fibrosis is complex, with competing profibrotic and antifibrotic actions (including in the regulation of mesenchymal transitioning), and with complex interplay between TGF-β/Smads and other signalling pathways. Studies over the past 5 years have identified additional mechanisms that regulate the action of TGF-β1/Smad signalling in fibrosis, including short and long noncoding RNA molecules and epigenetic modifications of DNA and histone proteins. Although direct targeting of TGF-β1 is unlikely to yield a viable antifibrotic therapy due to the involvement of TGF-β1 in other processes, greater understanding of the various pathways by which TGF-β1 controls fibrosis has identified alternative targets for the development of novel therapeutics to halt this most damaging process in CKD.

The emerging roles of β-arrestins in fibrotic diseases

β-Arrestins and β-arrestin2 are important adaptor proteins and signal transduction proteins that are mainly involved in the desensitization and internalization of G-protein-coupled receptors. Fibrosis is characterized by accumulation of excess extracellular matrix (ECM) molecules caused by chronic tissue injury. If highly progressive, the fibrotic process leads to organ malfunction and, eventually, death. The incurable lung fibrosis, renal fibrosis and liver fibrosis are among the most common fibrotic diseases. Recent studies show that β-arrestins can activate signaling cascades independent of G-protein activation and scaffold many intracellular signaling networks by diverse types of signaling pathways, including the Hedgehog, Wnt, Notch and transforming growth factor-β pathways, as well as downstream kinases such as MAPK and PI3K. These signaling pathways are involved in the pathological process of fibrosis and fibrotic diseases. This β-arrestin-mediated regulation not only affects cell growth and apoptosis, but also the deposition of ECM, activation of inflammatory response and development of fibrotic diseases. In this review, we survey the involvement of β-arrestins in various signaling pathways and highlight different aspects of their regulation of fibrosis. We also discuss the important roles of β-arrestins in the process of fibrotic diseases by regulating the inflammation and deposit of ECM. It is becoming more evident that targeting β-arrestins may offer therapeutic potential for the treatment of fibrotic diseases.

Pathophysiologic Response to Burns in the Elderly

Over the last decades advancements have improved survival and outcomes of severely burned patients except one population, elderly. The Lethal Dose 50 (LD50) burn size in elderly has remained the same over the past three decades, and so has morbidity and mortality, despite the increased demand for elderly burn care. The objective of this study is to gain insights on why elderly burn patients have had such a poor outcome when compared to adult burn patients. The significance of this project is that to this date, burn care providers recognize the extreme poor outcome of elderly, but the reason remains unclear. In this prospective translational trial, we have determined clinical, metabolic, inflammatory, immune, and skin healing aspects. We found that elderly have a profound increased mortality, more premorbid conditions, and stay at the hospital for longer, p < 0.05. Interestingly, we could not find a higher incidence of infection or sepsis in elderly, p > 0.05, but a significant increased incidence of multi organ failure, p < 0.05. These clinical outcomes were associated with a delayed hypermetabolic response, increased hyperglycemic and hyperlipidemic responses, inversed inflammatory response, immune-compromisation and substantial delay in wound healing predominantly due to alteration in characteristics of progenitor cells, p < 0.05. In summary, elderly have substantially different responses to burns when compared to adults associated with increased morbidity and mortality. This study indicates that these responses are complex and not linear, requiring a multi-modal approach to improve the outcome of severely burned elderly.

•

The outcome of elderly burn management is low with reasons that remain unclear.

•

Elderly have a higher mortality, more premorbid conditions and a higher incidence of multi organ failure.

•

Elderly stay at the hospital for longer time.

•

The incidence of infection or sepsis is not higher than young adult.

•

Elderly show delayed hyper-metabolic response, increased hyperglycemic and hyperlipidemic responses.

•

Elderly present inversed inflammatory response.

•

Elderly show substantial delay in wound healing, predominantly due to alteration in characteristics of progenitor cells.

Despite advancements in treatment of severely burned patients, the death rate is still high in elderly. In this project, we investigate the reason behind this poor outcome. Our report highlights some of the deficiencies that we have observed in elderly patients and compare them to the young adults. Elderly have late immune responses which are necessary to fight the disease. Their body lacks some of the essential stem cells which are essential for skin healing. By learning the major deficiencies that come with this age group, we will be able to help elderly who have been subjected to burn injury.

Wnt and Notch signaling pathway involved in wound healing by targeting c-Myc and Hes1 separately

Introduction

Wnt and Notch signaling pathways are critically involved in relative cell fate decisions within the development of cutaneous tissues. Moreover, several studies identified the above two pathways as having a significant role during wound healing. However, their biological effects during cutaneous tissues repair are unclear.

Methods

We employed a self-controlled model (Sprague–Dawley rats with full-thickness skin wounds) to observe the action and effect of Wnt/β-catenin and Notch signalings in vivo. The quality of wound repair relevant to the gain/loss-of-function Wnt/β-catenin and Notch activation was estimated by hematoxylin-and-eosin and Masson staining. Immunofluorescence analysis and Western blot analysis were used to elucidate the underlying mechanism of the regulation of Wnt and Notch signaling pathways in wound healing. Meanwhile, epidermal stem cells (ESCs) were cultured in keratinocyte serum-free medium with Jaggedl or in DAPT (N-[(3,5-difluorophenyl)acetyl]-L-alanyl-2-phenyl]glycine-1,1-dimethylethyl) to investigate whether the interruption of Notch signaling contributes to the expression of Wnt/β-catenin signaling.

Results

The results showed that in vivo the gain-of-function Wnt/β-catenin and Notch activation extended the ability to promote wound closure. We further determined that activation or inhibition of Wnt signaling and Notch signaling can affect the proliferation of ESCs, the differentiation and migration of keratinocytes, and follicle regeneration by targeting c-Myc and Hes1, which ultimately lead to enhanced or delayed wound healing. Furthermore, Western blot analysis suggested that the two pathways might interact in vivo and in vitro.

Conclusion

These results suggest that Wnt and Notch signalings play important roles in cutaneous repair by targeting c-Myc and Hes1 separately. What’s more, interaction between the above two pathways might act as a vital role in regulation of wound healing.

Key Fibrogenic Signaling

Fibrosis is defined as an excessive accumulation of extracellular matrix components that lead to the destruction of organ architecture and impairment of organ function. Moreover, fibrosis is an intricate process attributable to a variety of interlaced fibrogenic signals and intrinsic mechanisms of activation of myofibroblasts. Being the dominant matrix-producing cells in organ fibrosis, myofibroblasts may be differentiated from various types of precursor cells. Identification of the signal pathways that play a key role in the pathogenesis of fibrotic diseases may suggest potential therapeutic targets. Here, we emphasize several intracellular signaling pathways that control the activation of myofibroblasts and matrix production.

Reduced granulation tissue and wound strength in the absence of α11β1 integrin

Previous wound healing studies have failed to define a role for either α1β1 or α2β1 integrin in fibroblast-mediated wound contraction, suggesting the involvement of another collagen receptor in this process. Our previous work demonstrated that the integrin subunit α11 is highly induced during wound healing both at the mRNA and protein level, prompting us to investigate and dissect the role of the integrin α11β1 during this process. Therefore, we used mice with a global ablation of either α2 or α11 or both integrin subunits and investigated the repair of excisional wounds. Analyses of wounds demonstrated that α11β1 deficiency results in reduced granulation tissue formation and impaired wound contraction, independently of the presence of α2β1. Our combined in vivo and in vitro data further demonstrate that dermal fibroblasts lacking α11β1 are unable to efficiently convert to myofibroblasts, resulting in scar tissue with compromised tensile strength. Moreover, we suggest that the reduced stability of the scar is a consequence of poor collagen remodeling in α11^−/− wounds associated with defective transforming growth factor-β–dependent JNK signaling.

β-Catenin-regulated myeloid cell adhesion and migration determine wound healing

A β-catenin/T cell factor-dependent transcriptional program is critical during cutaneous wound repair for the regulation of scar size; however, the relative contribution of β-catenin activity and function in specific cell types in the granulation tissue during the healing process is unknown. Here, cell lineage tracing revealed that cells in which β-catenin is transcriptionally active express a gene profile that is characteristic of the myeloid lineage. Mice harboring a macrophage-specific deletion of the gene encoding β-catenin exhibited insufficient skin wound healing due to macrophage-specific defects in migration, adhesion to fibroblasts, and ability to produce TGF-β1. In irradiated mice, only macrophages expressing β-catenin were able to rescue wound-healing deficiency. Evaluation of scar tissue collected from patients with hypertrophic and normal scars revealed a correlation between the number of macrophages within the wound, β-catenin levels, and cellularity. Our data indicate that β-catenin regulates myeloid cell motility and adhesion and that β-catenin-mediated macrophage motility contributes to the number of mesenchymal cells and ultimate scar size following cutaneous injury.

Effects of human epidermal growth factor gene-transfected mesenchymal stem cells on fibroblast migration and proliferation

OBJECTIVES

We were interested in determining whether epidermal growth factor gene-transfected mesenchymal stem cells (EGF-MSC) would accelerate fibroblast migration and proliferation.

MATERIALS AND METHODS

Fibroblasts were cultured in serum-free conditioned media from EGF-MSC; RT-PCR was performed to detect expression of EGF gene in EGF-MSCs. EGF protein levels in cell culture supernatants from EGF-MSC were assayed by ELISA and proliferation of EGF-MSC-treated fibroblasts was performed using MTT assay. Effects of EGF-MSC on fibroblast migration were evaluated using scratch wound and transmigration assays. Cell adhesion molecules, cell dynamics molecules and phospho-(Ser) kinase substrate expressions of EGF-MSC-treated fibroblasts were evaluated by western blotting.

RESULTS

EGF gene expression increased in EGF-MSCs and viability of EGF-MSC-treated fibroblasts was elevated. EGF-MSC-treated fibroblasts showed increased migration compared to controls. Expressions of cell adhesion molecules (β-catenin, N-cadherin), cell dynamics molecules (cofilin, ezrin) and phospho-(Ser) kinase substrates (phospho-MAPK/CDK substrate, phospho-Arg-(Ser)-X-Tyr/Phe-X-pSer motif) increased in EGF-MSC-treated fibroblasts. These results imply that EGF-MSCs contributed to enhancing the wound healing process by increased cell adhesion, dynamic effects, fibroblast migration, and proliferation.

CONCLUSIONS

This study indicates that EGF-MSCs had a positive influence on fibroblast migration and proliferation and EGF-MSC may provide a useful strategy for wound healing.

Cutaneous wound healing: recruiting developmental pathways for regeneration

Following a skin injury, the damaged tissue is repaired through the coordinated biological actions that constitute the cutaneous healing response. In mammals, repaired skin is not identical to intact uninjured skin, however, and this disparity may be caused by differences in the mechanisms that regulate postnatal cutaneous wound repair compared to embryonic skin development. Improving our understanding of the molecular pathways that are involved in these processes is essential to generate new therapies for wound healing complications. Here we focus on the roles of several key developmental signaling pathways (Wnt/β-catenin, TGF-β, Hedgehog, Notch) in mammalian cutaneous wound repair, and compare this to their function in skin development. We discuss the varying responses to cutaneous injury across the taxa, ranging from complete regeneration to scar tissue formation. Finally, we outline how research into the role of developmental pathways during skin repair has contributed to current wound therapies, and holds potential for the development of more effective treatments.

β-catenin signaling: a novel mediator of fibrosis and potential therapeutic target

PURPOSE OF REVIEW

The Wnt/β-catenin signaling pathway plays a critical role in development and adult tissue homeostasis. Recent investigations implicate Wnt/β-catenin signaling in abnormal wound repair and fibrogenesis. The purpose of this review is to highlight recent key studies that support a role for Wnt/β-catenin signaling in fibrosis.

RECENT FINDINGS

Studies of patients with fibrotic diseases have demonstrated changes in components of the Wnt/β-catenin pathway. In animal models, perturbations in Wnt/β-catenin signaling appear to aggravate or ameliorate markers of injury and fibrosis in a variety of different tissues. Studies also suggest that fibroblasts from different tissue sources may have markedly divergent responses to Wnt/β-catenin signaling. Cross-talk between Wnt/β-catenin and transforming growth factor-β pathways is complex and context-dependent, and may promote fibrogenesis through coregulation of fibrogenic gene targets. High throughput screening has identified several novel chemical inhibitors of Wnt/β-catenin signaling that may be of therapeutic potential.

SUMMARY

Wnt/β-catenin signaling appears important in normal wound healing and its sustained activation is associated with fibrogenesis. The mechanism by which Wnt/β-catenin signaling may modify the response to injury is cell-type and context-dependent. Better understanding of this signaling pathway may provide a promising new therapeutic approach for human fibrotic diseases.

β-catenin signaling: a novel mediator of fibrosis and potential therapeutic target

PURPOSE OF REVIEW

The Wnt/β-catenin signaling pathway plays a critical role in development and adult tissue homeostasis. Recent investigations implicate Wnt/β-catenin signaling in abnormal wound repair and fibrogenesis. The purpose of this review is to highlight recent key studies that support a role for Wnt/β-catenin signaling in fibrosis.

RECENT FINDINGS

Studies of patients with fibrotic diseases have demonstrated changes in components of the Wnt/β-catenin pathway. In animal models, perturbations in Wnt/β-catenin signaling appear to aggravate or ameliorate markers of injury and fibrosis in a variety of different tissues. Studies also suggest that fibroblasts from different tissue sources may have markedly divergent responses to Wnt/β-catenin signaling. Cross-talk between Wnt/β-catenin and transforming growth factor-β pathways is complex and context-dependent, and may promote fibrogenesis through coregulation of fibrogenic gene targets. High throughput screening has identified several novel chemical inhibitors of Wnt/β-catenin signaling that may be of therapeutic potential.

SUMMARY

Wnt/β-catenin signaling appears important in normal wound healing and its sustained activation is associated with fibrogenesis. The mechanism by which Wnt/β-catenin signaling may modify the response to injury is cell-type and context-dependent. Better understanding of this signaling pathway may provide a promising new therapeutic approach for human fibrotic diseases.

Wnt/β-catenin pathway forms a negative feedback loop during TGF-β1 induced human normal skin fibroblast-to-myofibroblast transition

BACKGROUND

Fibroblast-to-myofibroblast transition is a key event during wound healing and hypertrophic scar formation. Previous studies suggested Wnt/β-catenin signaling might be involved in the wound healing. However, its specific role in skin fibroblast-to-myofibroblast transition remains unclear.

OBJECTIVE

To investigate the specific role of β-catenin during the transforming growth factor-β1 induced normal skin myofibroblasts transition.

METHODS

By real-time quantitative polymerase chain reaction, Western-blot and immunocytochemistry, the activation of Wnt/β-catenin pathway in cultured human normal skin fibroblasts during TGF-β1 induced fibroblast-to-myofibroblast transition was investigated. The effects of β-catenin on myofibroblasts transition were also investigated when SB-216763, over-expression and siRNA of β-catenin were utilized. In addition, fibroblasts populated collagen lattices contraction assays were conducted to examine the effects of β-catenin on the contractility of the fibroblasts induced by TGF-β1. Furthermore, the effects of β-catenin on the expression of α-smooth muscle actin and collagen types I and III in hypertrophic scar derived fibroblasts were studied.

RESULTS

The expression of Wnts mRNA and β-catenin protein was up-regulated by TGF-β1 stimulation during the myofibroblasts transition. Both of SB-216763 and β-catenin over-expression was paralleled with decreased expression of α-smooth muscle actin, collagen types I and III, while siRNA targeting β-catenin leads to up-regulation of α-smooth muscle actin, collagen types I and III. The increased contractility and α-smooth muscle actin expression of the fibroblasts in the collagen lattices induced by TGF-β1 was inhibited by SB-216763. In addition, the expression levels of α-smooth muscle actin, collagen types I and III in hypertrophic scar derived fibroblasts were also down-regulated by SB-216763.

CONCLUSION

Specifically in normal skin fibroblasts, β-catenin might be involved in the myofibroblasts transition and negatively regulate the TGF-β1-induced myofibroblast transition.

Effects of external application of Chinese medicine on diabetic ulcers and the expressions of β-catenin, c-myc and K6

OBJECTIVE

To observe the clinical efficacy of Chinese medicine (CM) treatment of Hongyou Ointment and Shengji Powder on diabetic ulcers, and to observe the influence of CM treatment on the expressions of proteins associated with the Wnt signaling pathway, such as β-catenin, c-myc and K6.

METHODS

sixty-two patients fitting the registration standards were randomly divided into the CM group (31 patients) and the Western medicine (WM) group (31 patients) by a random number table. The patients in the CM group were treated with Hongyou Ointment and Shengji Powder externally. The patients in the WM group were treated with mupirocin ointment, growth factor (bFGF), and Vaseline gauze for external use and with basic therapies. Wound-healing time and four-week healing rate were recorded. The wounds were measured by digital photography and ImageJ software. Skin biopsies were obtained from 24 patients before CM treatment and 20 patients after CM treatment. Immunohistochemical tests and semi-quantitative imaging with NIH ImageJ 1.42 software were used to analyze the changes in protein expression of β-catenin, c-myc, and K6.

RESULTS

Fifty-three patients completed the trial; four patients in the CM treatment group and five patients in the WM group dropped out. Among them, four were dissatisfied with the treatment process, two could not continue because of their jobs, two failed to complete the course of follow-up appointments, and one was diagnosed with squamous cell carcinoma during treatment. The comparison of ulcer healing rates between the two groups showed insignificant differences (P=0.77). The ulcer healing rates were 33.33% (9/27) in the CM group and 26.92% (7/26) in the WM group. However, the effective rate was significantly higher in the CM group (81.48%, 22/27) than in the WM group (57.69%, 15/26, P=0.04). The mean wound healing time was shorter in the CM group (22.71 ±5.46 days) than in the WM group (26.56 ±7.56 days, P=0.04). CM treatment was well tolerated, and there was no withdrawal due to adverse reactions. Immunohistochemical analysis in the refractory wound indicated higher expressions of β-catenin, c-myc and K6 compared with the normal skin. β-catenin was abnormally expressed in the nuclei of the keratinocytes and fibroblasts at the wound margins, and the expressions of c-myc and K6 were highly expressed in the full hyperplastic epidermis, especially in the granular layer (P<0.05). The expressions of these proteins decreased after CM treatment. The expression levels of β-catenin, c-myc, and K6 proteins before and after the treatment were 101.88 ± 10.76 vs. 140.42 ±8.45; 113.27 ± 16.75 vs. 153.79 ±8.32; 90.39 ±11.07 vs. 151.29 ±7.39, respectively.

CONCLUSIONS

CM treatment using Hongyou Ointment and Shengji Powder was efficient in the management of diabetic skin ulcers. The mechanism of action might be related to the inhibition of the Wnt signaling pathway.