E-cadherin expression in wound healing of mouse skin

Topography-Mediated Induction of Epithelial Mesenchymal Transition via Alumina Textiles for Potential Wound Healing Applications

Substrate topography is vital in determining cell growth and fate of cellular behavior. Although current in vitro studies of the underlying cellular signaling pathways mostly rely on their induction by specific growth factors or chemicals, the influence of substrate topography on specific changes in cells has been explored less often. This study explores the impact of substrate topography, specifically the tricot knit microfibrous structure of alumina textiles, on cell behavior, focusing on fibroblasts and keratinocytes for potential wound healing applications. The textiles, studied for the first time as in vitro substrates, demonstrated support for keratinocyte adhesion, leading to alterations in cell morphology and the expression of E-cadherin and fibronectin. These topography-induced changes resembled the epithelial-to-mesenchymal transition (EMT), crucial for wound healing, and were specific to keratinocytes and absent in identically treated fibroblasts. Biochemically induced EMT in keratinocytes cultured on flat alumina substrates mirrored the changes seen with alumina textiles alone, suggesting the tricot knit microfibrous topography could serve as an in vitro model system to induce EMT-like mechanisms. These results enhance our understanding of how substrate topography influences EMT-related processes in wound healing, paving the way for further evaluation of microfibrous alumina textiles as innovative wound dressings.

GRHL2 regulates keratinocyte EMT-MET dynamics and scar formation during cutaneous wound healing

After cutaneous wounds successfully heal, keratinocytes that underwent the epithelial-mesenchymal transition (EMT) regain their epithelial characteristics, while in scar tissue, epidermal cells persist in a mesenchymal state. However, the regulatory mechanisms governing this reversion are poorly understood, and the impact of persistent mesenchymal-like epidermal cells in scar tissue remains unclear. In the present study, we found that during wound healing, the regulatory factor GRHL2 is highly expressed in normal epidermal cells, downregulated in EMT epidermal cells, and upregulated again during the process of mesenchymal-epithelial transition (MET). We further demonstrated that interfering with GRHL2 expression in epidermal cells can effectively induce the EMT. Conversely, the overexpression of GRHL2 in EMT epidermal cells resulted in partial reversion of the EMT to an epithelial state. To investigate the effects of failed MET in epidermal cells on skin wound healing, we interfered with GRHL2 expression in epidermal cells surrounding the cutaneous wound. The results demonstrated that the persistence of epidermal cells in the mesenchymal state promoted fibrosis in scar tissue, manifested by increased thickness of scar tissue, deposition of collagen and fibronectin, as well as the activation of myofibroblasts. Furthermore, the miR-200s/Zeb1 axis was perturbed in GRHL2 knockdown keratinocytes, and transfection with miR-200s analogs promoted the reversion of EMT in epidermal cells, which indicates that they mediate the EMT process in keratinocytes. These results suggest that restoration of the epithelial state in epidermal cells following the EMT is essential to wound healing, providing potential therapeutic targets for preventing scar formation.

Electric fields reverse the differentiation of keratinocyte monolayer by down-regulating E-cadherin through PI3K/AKT/Snail pathway

Re-epithelialization is an important step in skin wound healing, referring to the migration, proliferation, and differentiation of keratinocytes around the wound. During this process, the edges of the wound begin to form new epithelial cells, which migrate from the periphery of the wound towards the center, gradually covering the entire wound area. These newly formed epithelial cells proliferate and differentiate, ultimately forming a protective layer over the exposed dermal surface. Wound endogenous electric fields (EFs) are known as the dominant factor to facilitate the epidermal migration to wound center. However, the precise mechanisms by which EFs promote epidermal migration remains elusive. Here, we found that in a model of cultured keratinocyte monolayer in vitro, EFs application reversed the differentiation of cells, as indicated by the reduction of the early differentiation markers K1 and K10. Genetic manipulation confirmed that EFs reversed keratinocyte differentiation through down-regulating the E-cadherin-mediated adhesion. By RNA-sequencing analysis, we screened out Snail as the transcription suppressor of E-cadherin. Snail knockdown abolished the down-regulation of E-cadherin and the reversal of differentiation induced by EFs. KEGG analysis identified PI3K/AKT signaling for Snail induction under EFs. Inhibition of PI3K by LY294002 diminished the EFs-induced AKT activation and Snail augmentation, largely restoring the level of E-cadherin reduced by EFs. Finally, in model of full-thickness skin wounds in pigs, we found that weakening of the wound endogenous EFs by the direction-reversed exogenous EFs resulted in an up-regulation of E-cadherin and earlier differentiation in newly formed epidermis in vivo. Our research suggests that electric fields (EFs) decrease E-cadherin expression by suppressing the PI3K/AKT/Snail pathway, thereby reversing the differentiation of keratinocytes. This discovery provides us with new insights into the role of electric fields in wound healing. EFs intervene in intracellular signaling pathways, inhibiting the expression of E-cadherin, which results in a lower differentiation state of keratinocytes. In this state, keratinocytes exhibit increased migratory capacity, facilitating the migration of epidermal cells and wound reepithelialization.

The combined effect of epidermal growth factor and keratinocyte growth factor delivered by hyaluronic acid hydrogel on corneal wound healing

This study strategically incorporates epidermal growth factor (EGF) and keratinocyte growth factor (KGF) within a hyaluronic acid (HA) hydrogel to enhance corneal wound healing. The controlled release of EGF and KGF from the HA hydrogel is engineered to promote the regeneration of both the epithelial and stromal layers. Specifically, EGF plays a pivotal role in the regeneration of the epithelial layer, while KGF exhibits efficacy in the regeneration of the stromal layer. The combination of these growth factors facilitates efficient regeneration of each layer and demonstrates the capability to modulate each other's regenerative effects. The interplay between EGF and KGF provides an understanding of their cooperative influence on the dynamics of corneal wound healing. The results of this study contribute to the development of advanced strategies for corneal wound management and offer insights into the complex process of corneal regeneration.

Bioactive nanomaterials kickstart early repair processes and potentiate temporally modulated healing of healthy and diabetic wounds

Slow-healing and chronic wounds represent a major global economic and medical burden, and there is significant unmet need for novel therapies which act to both accelerate wound closure and enhance biomechanical recovery of the skin. Here, we report a new approach in which bioactives that augment early stages of wound healing can kickstart and engender effective wound closure in healthy and diabetic, obese animals, and set the stage for subsequent tissue repair processes. We demonstrate that a nanomaterial dressing made of silk fibroin and gold nanorods (GNR) stimulates a pro-neutrophilic, innate immune, and controlled inflammatory wound transcriptomic response. Further, Silk-GNR, lasered into the wound bed, in combination with exogeneous histamine, accelerates early-stage processes in tissue repair leading to effective wound closure. Silk-GNR and histamine enhanced biomechanical recovery of skin, increased transient neoangiogenesis, myofibroblast activation, epithelial-to-mesenchymal transition (EMT) of keratinocytes and a pro-resolving neutrophilic immune response, which are hitherto unknown activities for these bioactives. Predictive and temporally coordinated delivery of growth factor nanoparticles that modulate later stages of tissue repair further accelerated wound closure in healthy and diabetic, obese animals. Our approach of kickstarting healing by delivering the "right bioactive at the right time" stimulates a multifactorial, pro-reparative response by augmenting endogenous healing and immunoregulatory mechanisms and highlights new targets to promote tissue repair.

Wnt4 increases the thickness of the epidermis in burn wounds by activating canonical Wnt signalling and decreasing the cell junctions between epidermal cells

BACKGROUND

Burn wound healing is a complex process and the role of Wnt ligands varies in this process. Whether and how Wnt4 functions in burn wound healing is not well understood. In this study, we aim to reveal the effects and potential mechanisms of Wnt4 in burn wound healing.

METHODS

First, the expression of Wnt4 during burn wound healing was determined by immunofluorescence, Western blotting and qPCR. Then, Wnt4 was overexpressed in burn wounds. The healing rate and healing quality were analysed by gross photography and haematoxyline and eosin staining. Collagen secretion was observed by Masson staining. Vessel formation and fibroblast distribution were observed by immunostaining. Next, Wnt4 was knocked down in HaCaT cells. The migration of HaCaT cells was analysed by scratch healing and transwell assays. Next, the expression of β-catenin was detected by Western blotting and immunofluorescence. The binding of Frizzled2 and Wnt4 was detected by coimmunoprecipitation and immunofluorescence. Finally, the molecular changes induced by Wnt4 were analysed by RNA sequencing, immunofluorescence, Western blotting and qPCR in HaCaT cells and burn wound healing tissues.

RESULTS

The expression of Wnt4 was enhanced in burn wound skin. Overexpression of Wnt4 in burn wound skin increased the thickness of epidermis. Collagen secretion, vessel formation and fibroblast distribution were not significantly impacted by Wnt4 overexpression. When Wnt4 was knocked down in HaCaT cells, the ratio of proliferating cells decreased, the ratio of apoptotic cells increased and the ratio of the healing area in the scratch healing assay to the number of migrated cells in the transwell assay decreased. The nuclear translocation of β-catenin decreased in shRNA of Wnt4 mediated by lentivirus-treated HaCaT cells and increased in Wnt4-overexpressing epidermal cells. RNA-sequencing analysis revealed that cell junction-related signalling pathways were significantly impacted by Wnt4 knockdown. The expression of the cell junction proteins was decreased by the overexpression of Wnt4.

CONCLUSIONS

Wnt4 promoted the migration of epidermal cells. Overexpression of Wnt4 increased the thickness of the burn wound. A potential mechanism for this effect is that Wnt4 binds with Frizzled2 and increases the nuclear translocation of β-catenin, thus activating the canonical Wnt signalling pathway and decreasing the cell junction between epidermal cells.

The unfolded protein response gene Ire1α is required for tissue renewal and normal differentiation in the mouse tongue and esophagus

The IRE1α-XBP1s signaling branch of the unfolded protein response is a well-characterized survival pathway that allows cells to adapt to and resolve endoplasmic reticulum stress. Recent data has broadened our understanding of IRE1α-XBP1s signaling beyond a stress response and revealed a physiological mechanism required for the differentiation and maturation of a wide variety of cell types. Here we provide evidence that the IRE1α-XBP1s signaling pathway is required for the proliferation and maturation of basal keratinocytes in the mouse tongue and esophageal epithelium. Mice with conditional targeted deletion of either Ire1α or Xbp1 in keratin 14 expressing basal keratinocytes displayed severe thinning of the lingual and esophageal mucosa that rendered them unable to eat. In IRE1α null epithelium harvested at an earlier timepoint, genes regulating cell proliferation, cell-cell adhesion, and keratinization were significantly downregulated; indirect immunofluorescence revealed fewer proliferating basal keratinocytes, downregulation of E-cadherin, and thinning of the loricrin-positive granular and cornified layers. The number of Tp63-positive basal keratinocytes was reduced in the absence of IRE1α, and expression of the Wnt pathway transcription factor LEF1, which is required for the proliferation of lingual transit amplifying cells, was also significantly downregulated at the transcript and protein level. Together these results reveal an essential role for IRE1α-XBP1s in the maintenance of the stratified squamous epithelial tissue of the tongue and esophagus.

Role of MMP3 and fibroblast-MMP14 in skin homeostasis and repair

Early lethality of mice with complete deletion of the matrix metalloproteinase MMP14 emphasized the proteases' pleiotropic functions. MMP14 deletion in adult dermal fibroblasts (MMP14^Sf-/-) caused collagen type I accumulation and upregulation of MMP3 expression. To identify the compensatory role of MMP3, mice were generated with MMP3 deletion in addition to MMP14 loss in fibroblasts. These double deficient mice displayed a fibrotic phenotype in skin and tendons as detected in MMP14^Sf-/- mice, but no additional obvious defects were detected. However, challenging the mice with full thickness excision wounds resulted in delayed closure of early wounds in the double deficient mice compared to wildtype and MMP14 single knockout controls. Over time wounds closed and epidermal integrity was restored. Interestingly, on day seven, post-wounding myofibroblast density was lower in the wounds of all knockout than in controls, they were higher on day 14. The delayed resolution of myofibroblasts from the granulation tissue is paralleled by reduced apoptosis of these cells, although proliferation of myofibroblasts is induced in the double deficient mice. Further analysis showed comparable TGFβ1 and TGFβR1 expression among all genotypes. In addition, in vitro, fibroblasts lacking MMP3 and MMP14 retained their ability to differentiate into myofibroblasts in response to TGFβ1 treatment and mechanical stress. However, in vivo, p-Smad2 was reduced in myofibroblasts at day 5 post-wounding, in double, but most significant in single knockout, indicating their involvement in TGFβ1 activation. Thus, although MMP3 does not compensate for the lack of fibroblast-MMP14 in tissue homeostasis, simultaneous deletion of both proteases in fibroblasts delays wound closure during skin repair. Notably, single and double deficiency of these proteases modulates myofibroblast formation and resolution in wounds.

Piper crocatum Ruiz & Pav. ameliorates wound healing through p53, E-cadherin and SOD1 pathways on wounded hyperglycemia fibroblasts

INTRODUCTION

Piper crocatum Ruiz & Pav (P. crocatum) has been reported to accelerate the diabetic wound healing process empirically. Some studies showed the benefits of P. crocatum in treating various diseases but its mechanisms in diabetic wound healing have never been reported. In the present study we investigated the diabetic wound healing activity of the active fraction of P. crocatum on wounded hyperglycemia fibroblasts (wHFs).

METHODS

Bioassay-guided fractionation was performed to get the most active fraction. The selected active fraction was applied to wHFs within 72 h incubation. Mimicking a diabetic condition was done using basal glucose media containing an additional 17 mMol/L D-glucose. A wound was simulated via the scratch assay. The collagen deposition was measured using Picro-Sirius Red and wound closure was measured using scratch wound assay. Underlying mechanisms through p53, αSMA, SOD1 and E-cadherin were measured using western blotting.

RESULTS

We reported that FIV is the most active fraction of P. crocatum. We confirmed that FIV \(7.81 µg/ml, 15.62 µg/ml, 31.25 µg/ml, 62.5 µg/ml, and 125 µg/ml) induced the collagen deposition and wound closure of wHFs. Furthermore, FIV treatment (7.81 µg/ml, 15.62 µg/ml, 31.25 µg/ml) down-regulated the protein expression level of p53 and up-regulated the protein expression levels of αSMA, E-cadherin, and SOD1.

DISCUSSION/CONCLUSIONS

Our findings suggest that ameliorating collagen deposition and wound closure through protein regulation of p53, αSMA, E-cadherin, and SOD1 are some of the mechanisms by which FIV of P. crocatum is involved in diabetic wound healing therapy.

GRHL3 activates FSCN1 to relax cell-cell adhesions between migrating keratinocytes during wound reepithelialization

The migrating keratinocyte wound front is required for skin wound closure. Despite significant advances in wound healing research, we do not fully understand the molecular mechanisms that orchestrate collective keratinocyte migration. Here, we show that, in the wound front, the epidermal transcription factor Grainyhead like-3 (GRHL3) mediates decreased expression of the adherens junction protein E-cadherin; this results in relaxed adhesions between suprabasal keratinocytes, thus promoting collective cell migration and wound closure. Wound fronts from mice lacking GRHL3 in epithelial cells (Grhl3-cKO) have lower expression of Fascin-1 (FSCN1), a known negative regulator of E-cadherin. Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) on wounded keratinocytes shows decreased wound-induced chromatin accessibility near the Fscn1 gene in Grhl3-cKO mice, a region enriched for GRHL3 motifs. These data reveal a wound-induced GRHL3/FSCN1/E-cadherin pathway that regulates keratinocyte-keratinocyte adhesion during wound-front migration; this pathway is activated in acute human wounds and is altered in diabetic wounds in mice, suggesting translational relevance.

Distinct contributions of meprins to skin regeneration after injury - Meprin α a physiological processer of pro-collagen VII

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Meprins subtly support epidermal and dermal skin wound healing.

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Loss of both meprins reduces re-epithelialization and wound macrophage abundance.

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Meprin α is a physiological maturing proteinase of collagen VII.

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Meprins are reduced in recessive dystrophic epidermolysis bullosa skin.

Astacin-like proteinases (ALPs) are regulators of tissue and extracellular matrix (ECM) homeostasis. They convey this property through their ability to convert ECM protein pro-forms to functional mature proteins and by regulating the bioavailability of growth factors that stimulate ECM synthesis. The most studied ALPs in this context are the BMP-1/tolloid-like proteinases. The other subclass of ALPs in vertebrates – the meprins, comprised of meprin α and meprin β – are emerging as regulators of tissue and ECM homeostasis but have so far been only limitedly investigated. Here, we functionally assessed the roles of meprins in skin wound healing using mice genetically deficient in one or both meprins. Meprin deficiency did not change the course of macroscopic wound closure. However, subtle but distinct contributions of meprins to the healing process and dermal homeostasis were observed. Loss of both meprins delayed re-epithelialization and reduced macrophage infiltration. Abnormal dermal healing and ECM regeneration was observed in meprin deficient wounds. Our analyses also revealed meprin α as one proteinase responsible for maturation of pro-collagen VII to anchoring fibril-forming-competent collagen VII in vivo. Collectively, our study identifies meprins as subtle players in skin wound healing.

Skin Wound-Healing Potential of Polysaccharides from Medicinal Mushroom Auricularia auricula-judae (Bull.)

Auricularia auricula-judae, a nutrient-rich mushroom used in traditional medicine, is a macrofungi that exhibits various biological properties. In this study, we have reported on the mechanisms that promote the wound-healing effects of a water-soluble polysaccharide-rich extract obtained from A. auricula-judae (AAP). AAP contained high amounts of polysaccharides (349.83 ± 5.00 mg/g extract) with a molecular weight of 158 kDa. The main sugar composition of AAP includes mannose, galactose, and glucose. AAP displayed antioxidant activity in vitro and was able to abort UVB-induced intracellular ROS production in human fibroblasts in cellulo. AAP significantly promoted both fibroblast and keratinocyte proliferation, migration, and invasion, along with augmentation of the wound-healing process by increasing collagen synthesis and decreasing E-cadherin expression (All p < 0.05). Specifically, the AAP significantly accelerated the wound closure in a mice skin wound-healing model on day 9 (2.5%AAP, p = 0.031 vs. control) and day 12 (1% and 2.5%AAP with p = 0.009 and p < 0.001 vs. control, respectively). Overall, our results indicate that the wound-healing activities of AAP can be applied in an AAP-based product for wound management.

Changes of Mineralogical Properties and Biological Activities of Gypsum and Its Calcined Products with Different Phase Structures

Raw gypsum (RG) and calcined gypsum (CG) are widely used in traditional Chinese medicine (TCM). RG is usually taken orally to resolve heat and diminish inflammation, while CG is only used externally to treat ulcerations and empyrosis. Calcination at different temperatures, three phase CG structures, namely, bassanite, anhydrite III, and anhydrite II, may be generated. We herein investigated the relationship between the phase structure and the efficacy of CG and the optimum phase structure for CG. RG has a compact structure, small pore size, weak anti-inflammatory effect, but no antibacterial effect, and has almost no effect on the repair of scalds. CG150 (bassanite) has a loose texture, large pore size and specific surface area, and certain antibacterial and anti-inflammatory effects, but it has a poor repair effect on scalds. CG750 (anhydrite II) has a compact structure, small pore size and specific surface area, and low antibacterial and anti-inflammatory effects, but it has a certain repair effect on scalds. Only CG350 (anhydrite III) has good performance in texture, pore size, specific surface area, antibacterial, anti-inflammatory, and scald repair. Our research has proved that the mineral properties and biological activities of CG are different due to different phase structures. CG350, namely, anhydrite III, is considered by our research to be the optimal phase structure as CG.

Gene expression profiles of oral soft tissue-derived fibroblast from healing wounds: correlation with clinical outcome, autophagy activation and fibrotic markers expression

AIM

Our aim was to evaluate gene expression profiling of fibroblasts from human alveolar mucosa (M), buccal attached gingiva (G) and palatal (P) tissues during early wound healing, correlating it with clinical response.

MATERIALS AND METHODS

M, G and P biopsies were harvested from six patients at baseline and 24 hr after surgery. Clinical response was evaluated through Early wound Healing Score (EHS). Fibrotic markers expression and autophagy were assessed on fibroblasts isolated from those tissues by Western blot and qRT-PCR. Fibroblasts from two patients were subjected to RT² profiler array, followed by network analysis of the differentially expressed genes. The expression of key genes was validated with qRT-PCR on all patients.

RESULTS

At 24 hr after surgery, EHS was higher in P and G than in M. In line with our clinical results, no autophagy and myofibroblast differentiation were observed in G and P. We observed significant variations in mRNA expression of key genes: RAC1, SERPINE1 and TIMP1, involved in scar formation; CDH1, ITGA4 and ITGB5, contributing to myofibroblast differentiation; and IL6 and CXCL1, involved in inflammation.

CONCLUSIONS

We identified some genes involved in periodontal soft tissue clinical outcome, providing novel insights into the molecular mechanisms of oral repair (ClinicalTrial.gov-NCT04202822).

Regulatory T Cells Conditioned Media Stimulates Migration in HaCaT Keratinocytes: Involvement of Wound Healing

Purpose

Regulatory T (Treg) cells, a type of immune cell, play a very important role in the immune response as a subpopulation of T cells. In this study, we investigated the effects of Treg cells conditioned media (CM) on cell migration. Various cytokines and growth factors of Treg cells CM can effect on re-epithelialization stage during the wound healing.

Methods

Isolated CD4+CD25+ Treg cells from Peripheral Blood Mononuclear Cells (PBMCs) were cultured and CM obtained. HaCaT keratinocytes were treated with various concentration of Treg cells CM. Cell migration, proliferation and expression of proteins that are related to the Epithelial-Mesenchymal Transition (EMT) process, matrix metalloproteinase-1 (MMP-1) were analyzed.

Results

Above 90% CD4+CD25+ Treg cells were obtained from CD8+ depleted PBMCs and the CM have various cytokines and growth factors.One percent and 5% concentration of Treg cells CM increased HaCaT keratinocytes migration. The Treg cells CM stimulated EMT, which led to the down-regulation of E-cadherin in the HaCaT keratinocytes at the wound edge. The Treg cells CM increased MMP-1, which is involved in tissue remodeling.

Conclusion

Our results suggest that Treg cells CM which has various cytokines and growth factors promote wound healing by stimulating HaCaT keratinocytes migration.

Skin remodeling and wound healing in the Gottingen minipig following exposure to sulfur mustard

Sulfur mustard (SM), a dermal vesicant that has been used in chemical warfare, causes inflammation, edema and epidermal erosions depending on the dose and time following exposure. Herein, a minipig model was used to characterize wound healing following dermal exposure to SM. Saturated SM vapor caps were placed on the dorsal flanks of 3-month-old male Gottingen minipigs for 30 min. After 48 h the control and SM wounded sites were debrided daily for 7 days with wet to wet saline gauze soaks. Animals were then euthanized, and full thickness skin biopsies prepared for histology and immunohistochemistry. Control skin contained a well differentiated epidermis with a prominent stratum corneum. A well-developed eschar covered the skin of SM treated animals, however, the epidermis beneath the eschar displayed significant wound healing with a hyperplastic epidermis. Stratum corneum shedding and a multilayered basal epithelium consisting of cuboidal and columnar cells were also evident in the neoepidermis. Nuclear expression of proliferating cell nuclear antigen (PCNA) was contiguous in cells along the basal epidermal layer of control and SM exposed skin; SM caused a significant increase in PCNA expression in basal and suprabasal cells. SM exposure was also associated with marked changes in expression of markers of wound healing including increases in keratin 10, keratin 17 and loricrin and decreases in E-cadherin. Trichrome staining of control skin showed a well-developed collagen network with no delineation between the papillary and reticular dermis. Conversely, a major delineation was observed in SM-exposed skin including a web-like papillary dermis composed of filamentous extracellular matrix, and compact collagen fibrils in the lower reticular dermis. Although the dermis below the wound site was disrupted, there was substantive epidermal regeneration following SM-induced injury. Further studies analyzing the wound healing process in minipig skin will be important to provide a model to evaluate potential vesicant countermeasures.

A novel exopolysaccharide from marine bacterium Pantoea sp. YU16-S3 accelerates cutaneous wound healing through Wnt/β-catenin pathway

Natural polysaccharides with versatile properties are the potential candidates for wound healing applications. In this study, an exopolysaccharide, EPS-S3, isolated from a marine bacteria Pantoea sp. YU16-S3 was evaluated for its wound-healing abilities by studying the key molecular mechanisms in vitro and in vivo. Basic characterisation showed EPS-S3 as a heteropolysaccharide with glucose, galactose, N-acetyl galactosamine and glucosamine. The molecular weight of EPS-S3 was estimated to be 1.75 × 10⁵ Da. It showed thermal stability up to 200 °C and shear-thickening non-Newtonian behaviour. It was biocompatible with dermal fibroblasts and keratinocytes and showed cell adhesion and cell proliferation properties. EPS-S3 facilitated cell migration in fibroblasts, induced rapid transition of cell cycle phases and also activated macrophages. In vivo experiments in rats showed the re-epithelialization of injured tissue with increased expression of HB-EGF, FGF, E-cadherin and β-catenin in EPS-S3 treatment. The results indicate that EPS-S3 modulates healing process through Wnt/β-catenin pathway due to its unique characteristics. In conclusion, EPS-S3 biosynthesized by the marine bacterium is a potential biomolecule for cutaneous wound healing applications.

Kallikreins: Essential epidermal messengers for regulation of the skin microenvironment during homeostasis, repair and disease

As the outermost layer of the skin, the epidermis is playing a major role in organism homeostasis providing the first barrier against external aggressions. Although considered as an extracellular matrix (ECM)-poor subtissue, the epidermal microenvironment is a key regulator of skin homeostasis and functionality. Among the proteins essential for upholding the epidermal microenvironment are the members of the kallikrein (KLK) family composed of 15 secreted serine proteases. Most of the members of these epithelial-specific proteins are present in skin and regulate skin desquamation and inflammation. However, although epidermal products, the consequences of KLK activities are not confined to the epidermis but widespread in the skin. In this review starting with the location and proteolytic activation cascade of KLKs, we present KLKs involvement in skin homeostasis, regeneration and pathology. KLKs have a large variety of substrates including ECM proteins, and evidence suggests that they are involved in the different steps of skin wound healing as discussed here. KLKs are also used as prognosis/diagnosis markers for many cancer types and we are focusing later on KLKs in cutaneous cancers, although their pathogenicity remains to be fully elucidated. Dysregulation of the KLK cascade is directly responsible for skin diseases with heavy inflammatory aspects, highlighting their involvement in skin immune homeostasis. Future studies will be needed to support the therapeutic potential of adjusting KLK activities for treatment of inflammatory skin diseases and wound healing pathologies.

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Regulation of the microenvironment even in an extracellular matrix-poor tissue can heavily impact organ function.

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Extracellular activities of kallikreins maintain skin homeostasis by regulating desquamation and inflammation.

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The activation of skin epidermal-specific kallikrein family of proteases is regulated by an intricate proteolytic cascade.

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Kallikreins are emerging as players during skin wound healing.

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Dysregulated kallikrein expression and activity occur in cancers and inflammatory skin diseases.

Epithelial-to-mesenchymal transition and keratinocyte differentiation in equine experimental body and limb wounds healing by second intention

BACKGROUND

The re-epithelialization process in equine wound healing is incompletely described. For epithelial cells to migrate during embryogenesis they undergo epithelial-to-mesenchymal transition (EMT); this phenotypic transition occurs during wound healing in humans and rodents, but it has not been investigated in horses.

HYPOTHESIS/OBJECTIVES

To investigate keratinocyte differentiation and EMT in equine experimental excisional limb and body wounds healing by second intention.

ANIMALS

Six adult research horses.

METHODS AND MATERIALS

Immunohistochemical analysis was used to detect expression of the differentiation markers cytokeratin (CK)10, CK14, loricrin and peroxisome proliferator-activated receptor alpha (PPAR-α), and of the EMT markers E-cadherin and N-cadherin in normal limb and body skin, and biopsies from limb and body wounds.

RESULTS

Loricrin and CK10 were expressed in normal skin and periwound skin but not in migrating epithelium of body and limb wounds. However, they reappeared at the migrating epithelial tip of body wounds only. CK14 and PPAR-α had uniform distribution throughout the migrating epithelium. N-cadherin was not expressed in normal unwounded skin but was detected in periwound skin adjacent to the wound margin. E-cadherin expression decreased at the wound margin.

CONCLUSIONS AND CLINICAL IMPORTANCE

Presence of N-cadherin suggests that cadherin switching occurred during wound healing, this may be an indication that EMT occurs in horses. To the best of the authors' knowledge, this has never been described in horses before and warrants further investigation to assess the clinical implications. The tip of the migrating epithelium in body wounds appeared more differentiated than limb wounds, which could be part of the explanation for the superior healing of body wounds.

Sustainable Graphene Aerogel as an Ecofriendly Cell Growth Promoter and Highly Efficient Adsorbent for Histamine from Red Wine

The utilization of a sustainable and lightweight graphene aerogel (GA), synthesized from crude biomass, as a cell growth promoter and an adsorbent for the efficient removal of histamine (HIS), a food toxicant, from the real food matrix has been explored. Due to the self-supported three-dimensional nanoporous honeycomb-like structure of the graphene framework and the high surface area, the synthesized GA achieved an 80.69 ± 0.89% removal of HIS from red wine (spiked with HIS) after just 60 min under both acidic (3.0) and neutral (7.4) pH conditions. Furthermore, simple cleaning with 50% ethanol and deionized water, without any change in weight, allowed them to be reused more than 10 times with a still significant HIS removal ability (more than 71.6 ± 2.57%). In vitro cell culture experiments demonstrated that the synthesized GA had nontoxic effects on the cell viability (up to 80.35%) even at higher concentrations (10 mg mL^-1), as determined via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays using human lung bronchial epithelial cells. Interestingly, GA promotes the wound-healing ability on the scratched epithelial cell surfaces via enhancing the cell migrations as also validated by the western blot analysis via expression levels of epithelial β-catenin and E-cadherin proteins. The distinct structural advantage along with the nontoxicity of the green synthesized GA will not only facilitate the economic feasibility of the synthesized GA for its practical real-life applications in liquid toxin and pollutant removal from the food and environment but also broaden its applicability as a promising biomaterial of choice for biomedical applications.

Cancer: the dark side of wound healing

Complex multicellular organisms have evolved sophisticated mechanisms to rapidly resolve epithelial injuries. Epithelial integrity is critical to maintaining internal homeostasis. An epithelial breach represents the potential for pathogen ingress and fluid loss, both of which may have severe consequences if not limited. The mammalian wound healing response involves a finely tuned, self-limiting series of cellular and molecular events orchestrated by the transient activation of specific signalling pathways. Accurate regulation of these events is essential; failure to initiate key steps at the right time delays healing and leads to chronic wounds, while aberrant initiation of wound healing processes may produce cell behaviours that promote cancer progression. In this review, we discuss how wound healing pathways co-opted in cancer lose their stringent regulation and become compromised in their reversibility. We hypothesize on how the commandeering of wound healing 'master regulators' is involved in this process, and also highlight the implications of these findings in the treatment of both chronic wounds and cancer.

Cell-Cell Junctions Organize Structural and Signaling Networks

Cell-cell junctions link cells to each other in tissues, and regulate tissue homeostasis in critical cell processes that include tissue barrier function, cell proliferation, and migration. Defects in cell-cell junctions give rise to a wide range of tissue abnormalities that disrupt homeostasis and are common in genetic abnormalities and cancers. Here, we discuss the organization and function of cell-cell junctions primarily involved in adhesion (tight junction, adherens junction, and desmosomes) in two different epithelial tissues: a simple epithelium (intestine) and a stratified epithelium (epidermis). Studies in these tissues reveal similarities and differences in the organization and functions of different cell-cell junctions that meet the requirements for the specialized functions of each tissue. We discuss cell-cell junction responses to genetic and environmental perturbations that provide further insights into their roles in maintaining tissue homeostasis.

Repigmentation in vitiligo: position paper of the Vitiligo Global Issues Consensus Conference

The Vitiligo Global Issues Consensus Conference (VGICC), through an international e-Delphi consensus, concluded that 'repigmentation' and 'maintenance of gained repigmentation' are essential core outcome measures in future vitiligo trials. This VGICC position paper addresses these core topics in two sections and includes an atlas depicting vitiligo repigmentation patterns and color match. The first section delineates mechanisms and characteristics of vitiligo repigmentation, and the second section summarizes the outcomes of international meeting discussions and two e-surveys on vitiligo repigmentation, which had been carried out over 3 yr. Treatment is defined as successful if repigmentation exceeds 80% and at least 80% of the gained repigmentation is maintained for over 6 months. No agreement was found on the best outcome measure for assessing target or global repigmentation, therefore highlighting the limitations of e-surveys in addressing clinical measurements. Until there is a clear consensus, existing tools should be selected according to the specific needs of each study. A workshop will be conducted to address the remaining issues so as to achieve a consensus.

Epithelial-to-mesenchymal transition in cutaneous wound healing: Where we are and where we are heading

Cutaneous wound healing occurs in distinct yet overlapping steps with the end goal of reforming a stratified epithelium to restore epidermal barrier function. A key component of this process is re-epithelialization, which involves the proliferation and migration of epidermal keratinocytes surrounding the wound. This spatiotemporally controlled process resembles aspects of the epithelial-to-mesenchymal transition (EMT) process and is thus proposed to involve a partial EMT. Here, we review current literature on the cellular and molecular changes that occur during, and the known or potential regulatory factors of cutaneous wound re-epithelialization and EMT to highlight their similarities and differences. We also discuss possible future directions toward a better understanding of the underlying regulatory mechanisms with implications for developing new therapeutics to improve wound repair in humans. Developmental Dynamics 247:473-480, 2018. © 2017 Wiley Periodicals, Inc.

Vitiligo: characterization of melanocytes in repigmented skin after punch grafting

BACKGROUND

Punch grafting is a surgical technique mainly applied in therapy-resistant, stable and circumscribed vitiligo.

OBJECTIVE

(i) To characterize in detail the features of the repigmented skin among punch grafts; and (ii) to correlate the ex vivo results with clinical data and punch grafting outcome.

METHODS

We evaluated by immunohistochemistry and image analysis the expression of a panel of specific melanocyte markers including HMB45, MITF, c-kit, MART-1 and TRP1, the proliferation marker Ki67 and the cell-cell adhesion molecule E-cadherin in tissue samples collected from nine patients after punch grafting.

RESULTS

Cells positive for MITF, c-kit, MART-1 and TRP1 were detected in the repigmented skin of all biopsies, whereas no reactivity was observed for HMB45. Melanocytes were identified along the entire length of the sections, and their mature state was assessed by the immuno-reactivity for the differentiation marker MART-1, the absence of cells positively stained for Ki67 and by the co-expression of c-kit and TRP1, a marker of a differentiated and pigmented state. Clinically, smaller punch grafts aimed at repigmenting lesional areas on the face gave the faster clinical results with no side-effects. Patients subjected to bigger punch grafts on the knee exhibited a longer repigmentation time and presented cobble stoning.

CONCLUSION

Our results suggest that the repigmentation observed in the areas between the grafts is due to the activation of the melanocytes located in the donor sites. These cells start to horizontally migrate towards the lesional skin thanks to successively the enlargement of intercellular spaces in relation to a decrease of E-cadherin reactivity and the up-modulation of pro-melanogenic mediators. Production and transfer of melanin in the surrounding keratinocytes and their persistence were assessed by the reactivity for MITF, c-kit, MART-1 and TRP1 but not for the pre-melanosome marker (HMB45).

Differential downregulation of e-cadherin and desmoglein by epidermal growth factor

Modulation of cell : cell junctions is a key event in cutaneous wound repair. In this study we report that activation of the epidermal growth factor (EGF) receptor disrupts cell : cell adhesion, but with different kinetics and fates for the desmosomal cadherin desmoglein and for E-cadherin. Downregulation of desmoglein preceded that of E-cadherin in vivo and in an EGF-stimulated in vitro wound reepithelialization model. Dual immunofluorescence staining revealed that neither E-cadherin nor desmoglein-2 internalized with the EGF receptor, or with one another. In response to EGF, desmoglein-2 entered a recycling compartment based on predominant colocalization with the recycling marker Rab11. In contrast, E-cadherin downregulation was accompanied by cleavage of the extracellular domain. A broad-spectrum matrix metalloproteinase inhibitor protected E-cadherin but not the desmosomal cadherin, desmoglein-2, from EGF-stimulated disruption. These findings demonstrate that although activation of the EGF receptor regulates adherens junction and desmosomal components, this stimulus downregulates associated cadherins through different mechanisms.

The use of an in vitro 3D melanoma model to predict in vivo plasmid transfection using electroporation

A large-scale in vitro 3D tumor model was generated to evaluate gene delivery procedures in vivo. This 3D tumor model consists of a "tissue-like" spheroid that provides a micro-environment supportive of melanoma proliferation, allowing cells to behave similarly to cells in vivo. This functional spheroid measures approximately 1 cm in diameter and can be used to effectively evaluate plasmid transfection when testing various electroporation (EP) electrode applicators. In this study, we identified EP conditions that efficiently transfect green fluorescent protein (GFP) and interleukin 15 (IL-15) plasmids into tumor cells residing in the 3D construct. We found that plasmids delivered using a 6-plate electrode applying 6 pulses with nominal electric field strength of 500 V/cm and pulse-length of 20 ms produced significant increase of GFP (7.3-fold) and IL-15 (3.0-fold) expression compared to controls. This in vitro 3D model demonstrates the predictability of cellular response toward delivery techniques, limits the numbers of animals employed for transfection studies, and may facilitate future developments of clinical trials for cancer therapies in vivo.

Hypoxia and hypoxia-inducible factor in the burn wound

The importance of hypoxia-inducible factor (HIF) in promoting angiogenesis and vasculogenesis during wound healing has been demonstrated. It is widely accepted that HIF activity can be promoted by many factors, including hypoxia in the wound or cytokines from inflammatory cells infiltrating the wound. However, there has not been a systematic exploration of the relationship between HIF activity and hypoxia in the burn wound. The location of the hypoxic tissue has not been clearly delineated. The time course of the appearance of hypoxia and the increased activity of HIF and appearance of HIF's downstream transcription products has not been described. The aim of this study was to utilize pimonidazole, a specific tissue hypoxia marker, to characterize the spatial and temporal course of hypoxia in a murine burn model and correlate this with the appearance of HIF-1α and its important angiogenic and vasculogenic transcription products vascular endothelial growth factor and SDF-1. Hypoxia was found in the healing margin of burn wounds beginning at 48 hours after burn and peaking at day 3 after burn. On sequential sections of the same tissue block, positive staining of HIF-1α, SDF-1, and vascular endothelial growth factor all occurred at the leading margin of the healing area and peaked at day 3, as did hypoxia. Immunohistochemical analysis was used to explore the characteristics of the hypoxic region of the wound. The localization of hypoxia was found to be related to cell growth and migration, but not to proliferation or inflammatory infiltration.

Immunohistochemical Evaluation of p63, E-Cadherin, Collagen I and III Expression in Lower Limb Wound Healing under Honey

Honey is recognized traditionally for its medicinal properties and also appreciated as a topical healing agent for infected and noninfected wounds. This study evaluates impact of honey-based occlusive dressing on nonhealing (nonresponding to conventional antibiotics) traumatic lower limb wounds (n = 34) through clinicopathological and immunohistochemical (e.g., expression of p63, E-cadherin, and Collagen I and III) evaluations to enrich the scientific validation. Clinical findings noted the nonadherence of honey dressing with remarkable chemical debridement and healing progression within 11–15 days of postintervention. Histopathologically, in comparison to preintervention biopsies, the postintervention tissues of wound peripheries demonstrated gradual normalization of epithelial and connective tissue features with significant changes in p63⁺ epithelial cell population, reappearance of membranous E-cadherin (P < .0001), and optimum deposition of collagen I and III (P < .0001). Thus, the present study for the first time reports the impact of honey on vital protein expressions in epithelial and connective tissues during repair of nonhealing lower limb wounds.

Cutaneous wound reepithelialization is compromised in mice lacking functional Slug (Snai2)

BACKGROUND

Keratinocytes at wound margins undergo partial epithelial to mesenchymal transition (EMT). Based on previous in vitro and ex vivo findings, Slug (Snai2), a transcriptional regulator of EMT in development, may play an important role in this process.

OBJECTIVES

This study was designed to validate an in vivo role for Slug in wound healing.

METHODS

Excisional wounds in Slug null and wild type mice were examined histologically at 6, 24, 48, and 72h after wounding; reepithelialization was measured and immunohistochemistry for keratins 8, 10, 14, and 6 and E-cadherin was performed. In 20 Slug null and 20 wild type mice exposed three times weekly to two minimal erythemal doses of UVR, the development of non-healing cutaneous ulcers was documented. Ulcers were examined histologically and by immunohistochemistry.

RESULTS

The reepithelialization component of excisional wound healing was reduced 1.7-fold and expression of the Slug target genes keratin 8 and E-cadherin was increased at wound margins in Slug null compared to wild type mice. In contrast, no differences in expression of keratins 10 or 14 or in markers of proliferation K6 and Ki-67 were observed. Forty per cent of Slug null mice but no wild type mice developed non-healing cutaneous ulcers in response to chronic UVR. Keratinocytes at ulcer margins expressed high levels of keratin 8 and retained E-cadherin expression, thus resembling excisional wounds.

CONCLUSION

Slug is an important modulator of successful wound repair in adult tissue and may be critical for maintaining epidermal integrity in response to chronic injury.

Altered expression of the urokinase receptor homologue, C4.4A, in invasive areas of human esophageal squamous cell carcinoma

C4.4A is a glycolipid-anchored membrane protein with structural homology to the urokinase-type plasminogen activator receptor (uPAR). Although C4.4A was identified as a metastasis-associated protein little is known about its actual expression and possible function in malignant disease. In the present study, we have therefore analyzed the expression of C4.4A in 14 esophageal squamous cell carcinomas (ESCC). Normal squamous esophageal epithelium shows a strong cell surface associated C4.4A expression in the suprabasal layers, whereas basal cells are negative. Upon transition to dysplasia and carcinoma in situ the expression of C4.4A is abruptly and coordinately weakened. Double immunofluorescence staining of normal and dysplastic tissue showed that C4.4A colocalizes with the epithelial cell surface marker E-cadherin in the suprabasal cells and has a complementary expression pattern compared to the proliferation marker Ki-67. A prominent, but frequently intracellular, C4.4A expression reappeared in tumor cells located at the invasive front and local lymph node metastases. Because C4.4A was reported previously to be a putative laminin-5 (LN5) ligand, and both proteins are expressed by invasive tumor cells, we analyzed the possible coexpression of C4.4A and the gamma 2-chain of LN5 (LN5-gamma 2). Although these proteins are indeed expressed by either neighboring cancer cells or in a few cases even coexpressed by the same cells in the tumor front and metastases, we found no evidence for a general colocalization in the extracellular compartment by confocal microscopy. In conclusion, C4.4A is expressed during invasion and metastasis of human ESCC and may thus provide a new histological marker in this disease.

Differential expression and localization of WNTs in an animal model of skin wound healing

Wound healing is a dynamic process, and a variety of growth factors have a significant impact on the process. Although the WNT family has a multitude of effects on the state of various physiological pathways, the expression and role of WNT in wounded tissue have remained an enigma. The aim of this study was to assess the expression and localization of WNTs in a murine model of wound healing. RNA isolated from full-thickness cutaneous wounds from day 1 to day 21 postwounding were subjected to reverse transcription-polymerase chain reaction, and expression of WNT3, 4, 5a, and 10b were observed. Immunohistochemistry localized WNT10b to regenerating epithelial cells on day 1 and 3, and WNT4 on day 3 and 5. WNT4 also reacted with fibroblast-like cells beneath the epithelium. The cytoplasmic staining of beta-catenin, a WNT signaling molecule, in the epithelial cells indicates an activation of the WNT signaling pathway. Among target genes downstream of the pathway, matrix metalloproteinases (MMPs) degrade and remodel the extracellular matrix during wound healing. Gelatin zymography showed that MMP9 was expressed from day 1 to day 5. MMP-2 was continuously expressed, but maximally up-regulated at day 5. Activation of MMP-2 coincided with expression of membrane-type 1 MMP, suggesting an involvement of WNTs in this proteolytic cascade. Therefore, WNTs may contribute to the process of wound healing in a spatiotemporal manner.

Isolation of a putative progenitor subpopulation of alveolar epithelial type 2 cells

Alveolar epithelial type 2 cells (AEC2) isolated from hyperoxia-treated animals exhibit increases in both proliferation and DNA damage in response to culture. AEC2 express the zonula adherens proteins E-cadherin, -, - and -catenin, desmoglein, and pp120, as demonstrated by Western blotting. Immunohistochemical analysis of cultured AEC2 showed expression of E-cadherin on cytoplasmic membranes varying from strongly to weakly staining. When cultured AEC2 placed in suspension were labeled with fluorescent-tagged antibodies to E-cadherin, cells could be sorted into at least two subpopulations, either dim or brightly staining for this marker. With the use of antibody to E-cadherin bound to magnetic beads, cells were physically separated into E-cadherin-positive and -negative subpopulations, which were then analyzed for differences in proliferation and DNA damage. The E-cadherin-positive subpopulation contained the majority of damaged cells, was quiescent, and expressed low levels of telomerase activity, whereas the E-cadherin-negative subpopulation was undamaged, proliferative, and expressed high levels of telomerase activity.

Keratinocyte growth factor 1 inhibits wound edge epithelial cell apoptosis in vitro

The ability of keratinocyte growth factor 1 to modulate apoptosis in the absence of proliferation was studied in vitro. A HaCaT scrape wound model was developed in which dense monolayers prior to wounding were cultured to quiescence in defined media with hydroxyurea at concentrations that blocked proliferation without loss of cell viability. Scrape wounding was then found to induce apoptosis, originating at the wound edge, but subsequently radiating away over a 24 h period to encompass areas not originally damaged. Keratinocyte growth factor 1 inhibited this radial progression of apoptosis in a concentration-dependent manner up to 20 ng per mL with induced migration present at the wound edge. The extent of this rescue was modulated by the concentration of Ca2+ prior to wounding. In control wound cultures apoptotic bodies were found in cells adjacent to the wound interface but were greatly reduced in keratinocyte-growth-factor-1-treated groups. Keratinocyte growth factor 1 receptor expression was significantly induced within two to three cell widths of the scraped wound edge, at levels far exceeding those found at the leading edge of a nonwounded epithelial sheet. Tumor necrosis factor alpha (1-5 ng per mL) or Escherichia coli lipopolysaccharide (10-50 ng per mL) exacerbated scrape-induced early apoptosis (1-4 h), but was largely ameliorated by coculture with keratinocyte growth factor 1. Keratinocyte growth factor 1 protection was associated with a reduction in both caspase-3 activation and cytokeratin-19 loss. Protected wound edges were also associated with the maintenance of e-cadherin expression and induction of beta1 integrin and actin stress fiber organization. These results suggest that keratinocyte growth factor 1 may play a role in limiting mechanically induced apoptotic processes at the epithelial wound edge in a manner that is distinct from its proliferative function.

Fibronectin and adhesion molecules on canine scarred vocal folds

OBJECTIVE

To examine the expressions of fibronectin and other adhesion molecules on the scarred vocal folds in a short- and long-term animal model.

STUDY DESIGN

Animal model.

METHODS

Six beagles' vocal folds were stripped unilaterally and left untreated. After wounding the vocal folds were harvested from three dogs at 2 months and three dogs at 6 months. The untouched vocal fold was used as a control, and the stripped vocal fold as scarred. Subsequently, the expressions of fibronectin, cadherin, syndecan-1 and syndecan-4 on both vocal folds were examined by immunohistochemical and image analysis.

RESULTS

Compared with the control vocal folds, fibronectin significantly increased in the superficial layer of the lamina propria on the scarred vocal folds at both 2 and 6 months. Co-deposition of collagen was observed only at 6 months. Syndecan-4 was significantly overexpressed at the basal layer cells of the epithelium at both 2 and 6 months. No significant expression of either cadherin or syndecan-1 was detected.

CONCLUSIONS

Scar characteristics at 2 and 6 months are not identical, suggesting that a 2-month period may not be a sufficient to study vocal fold scarring. Adhesion molecules are important in reorganization of extracellular matrix during wound healing because of their binding and adhesion characteristics. The results indicate that fibronectin might be important in providing a scaffold for the deposition of other proteins such as collagen, and the binding characteristics might affect the stiffness of the scarred vocal fold. Prolonged expression of syndecan-4 may reflect the role of focal adhesion during the assembly of scar structure. Ultimately, better understanding of the histological features of the scarred vocal fold might lead to new approaches to treatment.