Expression of integrins and basement membrane components by wound keratinocytes

Using Platelet-Rich Fibrin to Remove Graphite Tattoos May Yield Excellent Long-Term Result

Graphite tattoos are rarely reported because they are mainly caused by an accidental injury or habits during childhood that cause a pencil to penetrate the oral mucosa. Unlike other pigmentations, it stains layers that are deeper than the subepithelial and mucosal layers, and in most cases, it takes the form of a grayish black macule. This case report describes depigmentation with the denudation technique that was followed by a novel approach of using platelet-rich fibrin to cover exposed bone. A 41-year-old male patient presented with an aesthetic complaint from a grayish black staining on the labial gingiva near the maxillary central and lateral incisors. The lesion was diagnosed as a graphite tattoo due to the patient's history of sticking his gum with pencils when he was young. The entire pigmented gingiva was surgically removed and covered with two layers of PRF membrane to protect the exposed bone surface and provide an extracellular matrix for migration of gingival fibroblasts. Healing patterns were observed at 1, 2, 4, and 8 weeks, and satisfactory clinical and aesthetic results were obtained. Creeping attachment was observed at 8 years postop, and there was no recurrence for a long-term period of 13 years.

Tissue Regeneration and Remodeling in Rat Models after Application of Hypericum perforatum L. Extract-Loaded Bigels

The wound-healing effect of St. John's Wort (SJW) is mainly attributed to hyperforin (HP), but its low stability restricts its topical administration. This study investigates how "free" HP-rich SJW extract (incorporated into a bigel; B/SJW) and extract "protected" by nanostructured lipid carriers (also included in a biphasic semisolid; B/NLC-SJW) affect tissue regeneration in a rat skin excision wound model. Wound diameter, histological changes, and tissue gene expression levels of fibronectin (Fn), matrix metalloproteinase 8 (MMP8), and tumor necrosis factor-alpha (TNF-α) were employed to quantify the healing progress. A significant wound size reduction was achieved after applying both extract-containing semisolids, but after a 21-day application period, the smallest wound size was observed in the B/NLC-SJW-treated animals. However, the inflammatory response was affected more favorably by the bigel containing the "free" SJW extract, as evidenced by histological studies. Moreover, after the application of B/SJW, the expression of Fn, MMP8, and TNF-α was significantly higher than in the positive control. In conclusion, both bigel formulations exhibited beneficial effects on wound healing in rat skin, but B/SJW affected skin restoration processes in a comprehensive and more efficient way.

Aging Skin and Wound Healing

Responsible for many essential functions of life, human skin is made up of many components, each of which undergoes significant functional changes with aging and photodamage. Wound healing was previously thought to be defective in the elderly given the higher presence of chronic wounds and the longer time required for re-epithelialization of acute wounds. However, these notions have been challenged in recent research, which has shown that wound healing in the elderly is delayed but not defective. Poor healing of chronic wounds in older populations is more often attributable to comorbid conditions rather than age alone.

Biological processes and factors involved in soft and hard tissue healing

Wound healing is a complex and iterative process involving myriad cellular and biologic processes that are highly regulated to allow satisfactory repair and regeneration of damaged tissues. This review is intended to be an introductory chapter in a volume focusing on the use of platelet concentrates for tissue regeneration. In order to fully appreciate the clinical utility of these preparations, a sound understanding of the processes and factors involved in soft and hard tissue healing. This encompasses an appreciation of the cellular and biological mediators of both soft and hard tissues in general as well as specific consideration of the periodontal tissues. In light of good advances in this basic knowledge, there have been improvements in clinical strategies and therapeutic management of wound repair and regeneration. The use of platelet concentrates for tissue regeneration offers one such strategy and is based on the principles of cellular and biologic principles of wound repair discussed in this review.

Epithelial-Mesenchymal Plasticity and Endothelial-Mesenchymal Transition in Cutaneous Wound Healing

Epithelial and endothelial cells possess the inherent plasticity to undergo morphological, cellular, and molecular changes leading to their resemblance of mesenchymal cells. A prevailing notion has been that cutaneous wound reepithelialization involves partial epithelial-to-mesenchymal transition (EMT) of wound-edge epidermal cells to enable their transition from a stationary state to a migratory state. In this review, we reflect on past findings that led to this notion and discuss recent studies that suggest a refined view, focusing predominantly on in vivo results using mammalian excisional wound models. We highlight the concept of epithelial-mesenchymal plasticity (EMP), which emphasizes a reversible conversion of epithelial cells across multiple intermediate states within the epithelial-mesenchymal spectrum, and discuss the critical importance of restricting EMT for effective wound reepithelialization. We also outline the current state of knowledge on EMP in pathological wound healing, and on endothelial-to-mesenchymal transition (EndMT), a process similar to EMT, as a possible mechanism contributing to wound fibrosis and scar formation. Harnessing epithelial/endothelial-mesenchymal plasticity may unravel opportunities for developing new therapeutics to treat human wound healing pathologies.

The basement membrane in epidermal polarity, stemness, and regeneration

The epidermis is a specialized epithelium that constitutes the outermost layer of the skin, and it provides a protective barrier against environmental assaults. Primarily consisting of multilayered keratinocytes, the epidermis is continuously renewed by proliferation of stem cells and the differentiation of their progeny, which undergo terminal differentiation as they leave the basal layer and move upward toward the surface, where they die and slough off. Basal keratinocytes rest on a basement membrane at the dermal-epidermal junction that is composed of specific extracellular matrix proteins organized into interactive and mechanically supportive networks. Firm attachment of basal keratinocytes, and their dynamic regulation via focal adhesions and hemidesmosomes, is essential for maintaining major skin processes, such as self-renewal, barrier function, and resistance to physical and chemical stresses. The adhesive integrin receptors expressed by epidermal cells serve structural, signaling, and mechanosensory roles that are critical for epidermal cell anchorage and tissue homeostasis. More specifically, the basement membrane components play key roles in preserving the stem cell pool, and establishing cell polarity cues enabling asymmetric cell divisions, which result in the transition from a proliferative basal cell layer to suprabasal cells committed to terminal differentiation. Finally, through a well-regulated sequence of synthesis and remodeling, the components of the dermal-epidermal junction play an essential role in regeneration of the epidermis during skin healing. Here too, they provide biological and mechanical signals that are essential to the restoration of barrier function.

Advances in non-invasive biosensing measures to monitor wound healing progression

Impaired wound healing is a significant financial and medical burden. The synthesis and deposition of extracellular matrix (ECM) in a new wound is a dynamic process that is constantly changing and adapting to the biochemical and biomechanical signaling from the extracellular microenvironments of the wound. This drives either a regenerative or fibrotic and scar-forming healing outcome. Disruptions in ECM deposition, structure, and composition lead to impaired healing in diseased states, such as in diabetes. Valid measures of the principal determinants of successful ECM deposition and wound healing include lack of bacterial contamination, good tissue perfusion, and reduced mechanical injury and strain. These measures are used by wound-care providers to intervene upon the healing wound to steer healing toward a more functional phenotype with improved structural integrity and healing outcomes and to prevent adverse wound developments. In this review, we discuss bioengineering advances in 1) non-invasive detection of biologic and physiologic factors of the healing wound, 2) visualizing and modeling the ECM, and 3) computational tools that efficiently evaluate the complex data acquired from the wounds based on basic science, preclinical, translational and clinical studies, that would allow us to prognosticate healing outcomes and intervene effectively. We focus on bioelectronics and biologic interfaces of the sensors and actuators for real time biosensing and actuation of the tissues. We also discuss high-resolution, advanced imaging techniques, which go beyond traditional confocal and fluorescence microscopy to visualize microscopic details of the composition of the wound matrix, linearity of collagen, and live tracking of components within the wound microenvironment. Computational modeling of the wound matrix, including partial differential equation datasets as well as machine learning models that can serve as powerful tools for physicians to guide their decision-making process are discussed.

The Potential Role of a Surface-Modified Additive-Manufactured Healing Abutment on the Expression of Integrins α2, β1, αv, and β6 in the Peri-Implant Mucosa: A Preliminary Human Study

The stability of peri-implant soft tissues is essential for long-term success. Integrins play a vital role in biological processes through developing and maintaining cell interactions; however, few studies have evaluated the effects of modifications to abutment surfaces on cell adhesion across integrin expression. Therefore, this pilot study assessed the influence of different surface topographies of titanium healing abutments prepared by additive manufacturing (AM) on the gene expression levels of the integrin subunits α2, β1, αv, and β6 in the human peri-implant mucosa. Thirteen healthy adults were included. Depending on the number of required implants, the subjects were distributed in different groups as a function of healing abutment topography: group 1 (fully rough surface); group 2 (upper machined + lower rough); group 3 (rough upper surface + lower machined); group 4 (fully machined). A total of 40 samples (n = 10/group) of the peri-implant mucosa around the abutments were collected 30 days after implant placement, and subsequently, the gene expression levels were evaluated using real-time PCR. The levels of gene expression of β1-subunit integrin were upregulated for individuals receiving fully rough surface abutments compared with the other surface topographies (p < 0.05). However, the healing abutment topography did not affect the gene expression levels of the α2, αv, and β6 integrin subunits in the human peri-implant mucosa (p > 0.05). This preliminary study suggested that controlled modifications of the surface topography of titanium healing abutments produced by AM may influence the quality of the peri-implant mucosa in the early stages of the soft tissue healing process.

The Role of Fibrin(ogen) in Wound Healing and Infection Control

Fibrinogen, one of the most abundant plasma proteins playing a key role in hemostasis, is an important modulator of wound healing and host defense against microbes. In the current review, we address the role of fibrin(ogen) throughout the process of wound healing and subsequent tissue repair. Initially fibrin(ogen) acts as a provisional matrix supporting incoming leukocytes and acting as reservoir for growth factors. It later goes on to support re-epithelialization, angiogenesis, and fibroplasia. Importantly, removal of fibrin(ogen) from the wound is essential for wound healing to progress. We also discuss how fibrin(ogen) functions through several mechanisms to protect the host against bacterial infection by providing a physical barrier, entrapment of bacteria in fibrin(ogen) networks, and by directing immune cell function. The central role of fibrin(ogen) in defense against bacterial infection has made it a target of bacterial proteins, evolved to interact with fibrin(ogen) to manipulate clot formation and degradation for the purpose of promoting microbial virulence and survival. Further understanding of the dual roles of fibrin(ogen) in wound healing and infection could provide novel means of therapy to improve recovery from surgical or chronic wounds and help to prevent infection from highly virulent bacterial strains, including those resistant to antibiotics.

Pharmacological HIF-1 stabilization promotes intestinal epithelial healing through regulation of α-integrin expression and function

Intestinal epithelia are critical for maintaining gastrointestinal homeostasis. Epithelial barrier injury, causing inflammation and vascular damage, results in inflammatory hypoxia, and thus, healing occurs in an oxygen-restricted environment. The transcription factor hypoxia-inducible factor (HIF)-1 regulates genes important for cell survival and repair, including the cell adhesion protein β1-integrin. Integrins function as αβ-dimers, and α-integrin-matrix binding is critical for cell migration. We hypothesized that HIF-1 stabilization accelerates epithelial migration through integrin-dependent pathways. We aimed to examine functional and posttranslational activity of α-integrins during HIF-1-mediated intestinal epithelial healing. Wound healing was assessed in T84 monolayers over 24 h with/without prolyl-hydroxylase inhibitor (PHDi) (GB-004), which stabilizes HIF-1. Gene and protein expression were measured by RT-PCR and immunoblot, and α-integrin localization was assessed by immunofluorescence. α-integrin function was assessed by antibody-mediated blockade, and integrin α6 regulation was determined by HIF-1α chromatin immunoprecipitation. Models of mucosal wounding and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis were used to examine integrin expression and localization in vivo. PHDi treatment accelerated wound closure and migration within 12 h, associated with increased integrin α2 and α6 protein, but not α3. Functional blockade of integrins α2 and α6 inhibited PHDi-mediated accelerated wound closure. HIF-1 bound directly to the integrin α6 promoter. PHDi treatment accelerated mucosal healing, which was associated with increased α6 immunohistochemical staining in wound-associated epithelium and wound-adjacent tissue. PHDi treatment increased α6 protein levels in colonocytes of TNBS mice and induced α6 staining in regenerating crypts and reepithelialized inflammatory lesions. Together, these data demonstrate a role for HIF-1 in regulating both integrin α2 and α6 responses during intestinal epithelial healing.NEW & NOTEWORTHY HIF-1 plays an important role in epithelial restitution, selectively inducing integrins α6 and α2 to promote migration and proliferation, respectively. HIF-stabilizing prolyl-hydroxylase inhibitors accelerate intestinal mucosal healing by inducing epithelial integrin expression.

Fibronectin in development and wound healing

Fibronectin structure and composition regulate contextual cell signaling. Recent advances have been made in understanding fibronectin and its role in tissue organization and repair. This review outlines fibronectin splice variants and their functions, evaluates potential therapeutic strategies targeting or utilizing fibronectin, and concludes by discussing potential future directions to modulate fibronectin function in development and wound healing.

Proteoglycans in the periodontium: A review with emphasis on specific distributions, functions, and potential applications

Proteoglycans (PGs) are largely glycosylated proteins, consisting of a linkage sugar, core proteins, and glycosaminoglycans (GAGs). To date, more than 40 kinds of PGs have been identified, and they can be classified as intracellular, cell surface, pericellular, and extracellular PGs according to cellular locations. To illustrate, extracellular PGs are known for regulating the homeostasis of the extracellular matrix; cell-surface PGs play a role in mediating cell adhesion and binding various growth factors. In the field of periodontology, PGs are implicated in cellular proliferation, migration, adhesion, contractility, and anoikis, thereby exerting a profound influence on periodontal tissue development, wound repair, the immune response, biomechanics, and pathological process. Additionally, the expression patterns of some PGs are dynamic and cell-specific. Therefore, determining the roles and spatial-temporal expression patterns of PGs in the periodontium could shed light on treatments for wound healing, tissue regeneration, periodontitis, and gingival overgrowth. In this review, close attention is paid to the distributions, functions, and potential applications of periodontal PGs. Related genetically modified animal experiments and involved signal transduction cascades are summarized for improved understanding of periodontal PGs. To date, however, there is a large amount of speculation on this topic that requires rigorous experiments for validation.

The fibrillin microfibril/elastic fibre network: A critical extracellular supramolecular scaffold to balance skin homoeostasis

Supramolecular networks composed of fibrillins (fibrillin-1 and fibrillin-2) and associated ligands form intricate cellular microenvironments which balance skin homoeostasis and direct remodelling. Fibrillins assemble into microfibrils which are not only indispensable for conferring elasticity to the skin, but also control the bioavailability of growth factors targeted to the extracellular matrix architecture. Fibrillin microfibrils (FMF) represent the core scaffolds for elastic fibre formation, and they also decorate the surface of elastic fibres and form independent networks. In normal dermis, elastic fibres are suspended in a three-dimensional basket-like lattice of FMF intersecting basement membranes at the dermal-epidermal junction and thus conferring pliability to the skin. The importance of FMF for skin homoeostasis is illustrated by the clinical features caused by mutations in the human fibrillin genes (FBN1, FBN2), summarized as "fibrillinopathies." In skin, fibrillin mutations result in phenotypes ranging from thick, stiff and fibrotic skin to thin, lax and hyperextensible skin. The most plausible explanation for this spectrum of phenotypic outcomes is that FMF regulate growth factor signalling essential for proper growth and homoeostasis of the skin. Here, we will give an overview about the current understanding of the underlying pathomechanisms leading to fibrillin-dependent fibrosis as well as forms of cutis laxa caused by mutational inactivation of FMF-associated ligands.

Chromatin changes trigger laminin genes dysregulation in aging kidneys

Dysregulation of gene expression is a hallmark of aging. We examined epigenetic mechanisms that mediate aberrant expression of laminin genes in aging rat kidneys. In old animals, no alterations were found in the levels of abundant laminin mRNAs, whereas Lama3, b3, and c2 transcripts were increased compared to young animals. Lamc2 showed the strongest changes at the mRNA and protein levels. Lamc2 upregulation was transcriptional, as indicated by the elevated RNA polymerase II density at the gene. Furthermore, aging is associated with the loss of H3K27m3 and 5mC silencing modifications at the Lamc2 gene. Western blot analysis revealed no changes in cellular levels of H3K27m3 and cognate enzyme Ezh2 in old kidneys. Thus, the decrease in H3K27m3 at Lamc2 resulted from the re-distribution of this mark among genomic sites. Studies in kidney cells in vitro showed that reducing H3K27m3 density with Ezh2 inhibitor had no effect on Lamc2 expression, suggesting that this modification plays little role in gene upregulation in aging kidney. In contrast, treatment with DNA methylation inhibitor 2'-deoxy-5-azacytidine was sufficient to upregulate Lamc2 gene. We suggest that the loss of 5mC at silenced laminin genes drives their de-repression during aging, contributing to the age-related decline in renal function.

Scarless wound healing: From development to senescence

An essential element of tissue homeostasis is the response to injuries, cutaneous wound healing being the most studied example. In the adults, wound healing aims at quickly restoring the barrier function of the skin, leading however to scar, a dysfunctional fibrotic tissue. On the other hand, in fetuses a scarless tissue regeneration takes place. During ageing, the wound healing capacity declines; however, in the absence of comorbidities a higher quality in tissue repair is observed. Senescent cells have been found to accumulate in chronic unhealed wounds, but more recent reports indicate that their transient presence may be beneficial for tissue repair. In this review data on skin wound healing and scarring are presented, covering the whole spectrum from early embryonic development to adulthood, and furthermore until ageing of the organism.

Combined epithelial marker analysis of tumour budding in stage II colorectal cancer

Tumour budding predicts survival of stage II colorectal cancer (CRC) and has been suggested to be associated with epithelial‐to‐mesenchymal transition (EMT). However, the underlying molecular changes of tumour budding remain poorly understood. Here, we performed multiplex immunohistochemistry (mIHC) to phenotypically profile tumours using known EMT‐associated markers: E‐cadherin (adherence junctions), integrin β4 (ITGB4; basement membrane), ZO‐1 (tight junctions), and pan‐cytokeratin. A subpopulation of patients showed high ITGB4 expression in tumour buds, and this coincided with a switch of ITGB4 localisation from the basal membrane of intact epithelium to the cytoplasm of budding cells. Digital image analysis demonstrated that tumour budding with high ITGB4 expression in tissue microarray (TMA) cores correlated with tumour budding assessed from haematoxylin and eosin (H&E) whole sections and independently predicted poor disease‐specific survival in two independent stage II CRC cohorts (hazard ratio [HR] = 4.50 (95% confidence interval [CI] = 1.50–13.5), n = 232; HR = 3.52 (95% CI = 1.30–9.53), n = 72). Furthermore, digitally obtained ITGB4‐high bud count in random TMA cores was better associated with survival outcome than visual tumour bud count in corresponding H&E‐stained samples. In summary, the mIHC‐based phenotypic profiling of human tumour tissue shows strong potential for the molecular characterisation of tumour biology and for the discovery of novel prognostic biomarkers.

Novel non-angiogenic role for mesenchymal stem cell-derived vascular endothelial growth factor on keratinocytes during wound healing

With chronic wounds remaining a substantial healthcare issue, new therapies are sought to improve patient outcomes. Various studies have explored the benefits of promoting angiogenesis in wounds by targeting proangiogenic factors such as Vascular Endothelial Growth Factor (VEGF) family members to improve wound healing. Along similar lines, Mesenchymal Stem Cell (MSC) secretions, usually containing VEGF, have been used to improve angiogenesis in wound healing via a paracrine mechanism. Recent evidence for keratinocyte VEGF receptor expression, as well as proliferative and chemotactic responses by keratinocytes to exogenous VEGFA in vitro implies distinct non-angiogenic actions for VEGF during wound healing. In this review, we discuss the expression of VEGF family members and their receptors in keratinocytes in relation to the potential for wound healing treatments. We also explore recent findings of MSC secreted paracrine wound healing activity on keratinocytes. We report here the concept of keratinocyte wound healing responses driven by MSC-derived VEGF that is supported in the literature, providing a new mechanism for cell-free therapy of chronic wounds.

Long non-coding RNA PICSAR decreases adhesion and promotes migration of squamous carcinoma cells by downregulating α2β1 and α5β1 integrin expression

Long non-coding RNAs (lncRNAs) regulate various cellular processes, and they have emerged as potential biomarkers and therapeutic targets in cancer. We have previously characterized the oncogenic role of lncRNA PICSAR (p38 inhibited cutaneous squamous cell carcinoma associated lincRNA) in cutaneous squamous cell carcinoma (cSCC), the most common metastatic skin cancer. In this study, we show that knockdown of PICSAR in cSCC cells upregulates expression of α2, α5 and β1 integrins, resulting in increased cell adhesion and decreased cell migration on collagen I and fibronectin. In contrast, overexpression of PICSAR in cSCC cells downregulates expression of α2, α5 and β1 integrins on cell surface, resulting in decreased cell adhesion on collagen I and fibronectin and increased cell migration. These results demonstrate a novel mechanism for regulation of the expression of collagen and fibronectin binding integrins by lncRNA PICSAR, leading to altered adhesion and migration of cSCC cells.

This article has an associated First Person interview with the first author of the paper.

Summary: Long non-coding RNA PICSAR decreases adhesion and promotes migration of cutaneous squamous cell carcinoma cells by regulating the expression of collagen and fibronectin binding α2β1 and α5β1 integrins.

Mechanisms of integrin αVβ5 clustering in flat clathrin lattices

The family of integrin transmembrane receptors is essential for the normal function of multicellular organisms by facilitating cell-extracellular matrix adhesion. The vitronectin-binding integrin αVβ5 localizes to focal adhesions (FAs) as well as poorly characterized flat clathrin lattices (FCLs). Here, we show that, in human keratinocytes, αVβ5 is predominantly found in FCLs, and formation of the αVβ5-containing FCLs requires the presence of vitronectin as ligand, Ca2+, and the clathrin adaptor proteins ARH (also known as LDLRAP1), Numb and EPS15/EPS15L1. Integrin chimeras, containing the extracellular and transmembrane domains of β5 and the cytoplasmic domains of β1 or β3, almost exclusively localize in FAs. Interestingly, lowering actomyosin-mediated contractility promotes integrin redistribution to FLCs in an integrin tail-dependent manner, while increasing cellular tension favors αVβ5 clustering in FAs. Our findings strongly indicate that clustering of integrin αVβ5 in FCLs is dictated by the β5 subunit cytoplasmic domain, cellular tension and recruitment of specific adaptor proteins to the β5 subunit cytoplasmic domains.

Expanding and characterizing esophageal epithelial cells obtained from children with eosinophilic esophagitis

BACKGROUND

The role of epithelial cells in eosinophilic esophagitis (EoE) is not well understood. In this study, our aim was to isolate, culture, and expand esophageal epithelial cells obtained from patients with or without EoE and characterize differences observed over time in culture.

METHODS

Biopsies were obtained at the time of endoscopy from children with EoE or suspected to have EoE. We established patient-derived esophageal epithelial cell (PDEEC) lines utilizing conditional reprogramming methods. We determined integrin profiles, gene expression, MHC class II expression, and reactivity to antigen stimulation.

RESULTS

The PDEECs were found to maintain their phenotype over several passages. There were differences in integrin profiles and gene expression levels in EoE-Active compared to normal controls and EoE-Remission patients. Once stimulated with antigens, PDEECs express MHC class II molecules on their surface, and when co-cultured with autologous T-cells, there is increased IL-6 and TNF-α secretion in EoE-Active patients vs. controls.

CONCLUSION

We are able to isolate, culture, and expand esophageal epithelial cells from pediatric patients with and without EoE. Once stimulated with antigens, these cells express MHC class II molecules and behave as non-professional antigen-presenting cells. This method will help us in developing an ex vivo, individualized, patient-specific model for diagnostic testing for causative antigens.

Novel Regulation of Integrin Trafficking by Rab11-FIP5 in Aggressive Prostate Cancer

The laminin-binding integrins, α3β1 and α6β1, are needed for tumor metastasis and their surface expression is regulated by endocytic recycling. β1 integrins share the Rab11 recycling machinery, but the trafficking of α3β1 and α6β1 are distinct by an unknown mechanism. Using a mouse PDX tumor model containing human metastatic prostate cancer, Rab11 family interacting protein 5 (Rab11-FIP5) was identified as a lead candidate for α6β1 trafficking. Rab11-FIP5 and its membrane-binding domain were required for α6β1 recycling, without affecting the other laminin-binding integrin (i.e., α3β1) or unrelated membrane receptors like CD44, transferrin receptor, or E-cadherin. Depletion of Rab11-FIP5 resulted in the intracellular accumulation of α6β1 in the Rab11 recycling compartment, loss of cell migration on laminin, and an unexpected loss of α6β1 recycling in cell-cell locations. Taken together, these data demonstrate that α6β1 is distinct from α3β1 via Rab11-FIP5 recycling and recycles in an unexpected cell-cell location.Implications: Rab11-FIP5-dependent α6β1 integrin recycling may be selectively targeted to limit migration of prostate cancer cells into laminin-rich tissues. Mol Cancer Res; 16(8); 1319-31. ©2018 AACR.

Role of integrins in wound repair and its periodontal implications

Wound healing in human periodontium is a complex process which involves both cell-cell and cell-matrix interactions. Integrins play a major role in regulation of these cell-cell, cell-matrix interaction. Wound healing involves two major events i.e. re-epithelialization and connective tissue repair. In this concise review, we will discuss the role of integrins in these major events as well as their impIications in periodontal wound repair. Integrins are differentially expressed in both of these major events. In re-epithelialization, keratinocytes express novel integrins receptors αvβ1, α5β1and αvβ6 which are not expressed in normal healthy epithelium. Re-epithelialization also involves interaction of integrins with TGF-β and fibronectin. Similarly, in connective tissue repair, the activation of fibroblast as well as the expression of integrins α5β1 and α3β1 is upregulated. In healthy periodontium, integrin αvβ6 is normally expressed in junctional epithelium which is generally expressed only at wound sites in other parts of the body. The epithelialization at implant surface has not been yet fully explored with respect to interactions among integrins and other extra-cellular matrix molecules.

Histatins, wound healing, and cell migration

Wounds in the oral mucosa heal faster and more efficiently than those in the skin, although the mechanisms underlying these differences are not completely clear. In the last 10 years, a group of salivary peptides, the histatins, has gained attention on behalf of their ability to improve several phases of the wound-healing process. In addition to their roles as anti-microbial agents and in enamel maintenance, histatins elicit other biological effects, namely by promoting the migration of different cell types contained in the oral mucosa and in non-oral tissues. Histatins, and specifically histatin-1, promote cell adhesion and migration in oral keratinocytes, gingival and dermal fibroblasts, non-oral epithelial cells, and endothelial cells. This is particularly relevant, as histatin-1 promotes the re-epithelialization phase and the angiogenic responses by increasing epithelial and endothelial cell migration. Although the molecular mechanisms associated with histatin-dependent cell migration remain poorly understood, recent studies have pointed to the control of signaling endosomes and the balance of small GTPases. This review aimed to update the literature on the effects of histatins in cell migration, with a focus on wound healing. We will also discuss the consequences that this increasing field will have in disease and therapy design.

Extracellular matrix contribution to skin wound re-epithelialization

The ability of skin to act as a barrier is primarily determined by cells that maintain the continuity and integrity of skin and restore it after injury. Cutaneous wound healing in adult mammals is a complex multi-step process that involves overlapping stages of blood clot formation, inflammation, re-epithelialization, granulation tissue formation, neovascularization, and remodeling. Under favorable conditions, epidermal regeneration begins within hours after injury and takes several days until the epithelial surface is intact due to reorganization of the basement membrane. Regeneration relies on numerous signaling cues and on multiple cellular processes that take place both within the epidermis and in other participating tissues. A variety of modulators are involved, including growth factors, cytokines, matrix metalloproteinases, cellular receptors, and extracellular matrix components. Here we focus on the involvement of the extracellular matrix proteins that impact epidermal regeneration during wound healing.

Expression of Laminin 332 in Vesicant Skin Injury and Wound Repair

Sulfur Mustard (SM) is a potent vesicant or blistering agent. It is a highly reactive bi-functional alkylating agent that cross links proteins, DNA, and other cellular components. Laminin 332 is a heterotrimer glycoprotein and a crucial skin component that attaches the epidermal basal keratinocytes to the dermis. SM wounds histologically appear similar to Epidermolysis Bullosa (EB), human genetic blistering diseases that involve genetic changes in laminin 332. The specific mechanism of action of SM exposure is unknown, but there are several key similarities between vesicant induced cutaneous injury and the Junctional form of EB (JEB) cutaneous injury: 1) Initial alkylation causes blistering similar to JEB; 2) Initial injury is followed by protease activation and prolonged inflammation similar to the chronic inflammation observed in EB; 3) The blister plane is at the level of the lamina lucida in the Basement Membrane Zone (BMZ) for both JEB and SM-induced injury. This suggests that injury induced by vesicants is not unique and probably involves malformation of laminin 332. Understanding the role of laminin 332 in SM induced blisters may provide perspectives for future molecular therapeutic countermeasures against SM exposure.

Fundamental aspects of arm repair phase in two echinoderm models

Regeneration is a post-embryonic developmental process that ensures complete morphological and functional restoration of lost body parts. The repair phase is a key step for the effectiveness of the subsequent regenerative process: in vertebrates, efficient re-epithelialisation, rapid inflammatory/immune response and post-injury tissue remodelling are fundamental aspects for the success of this phase, their impairment leading to an inhibition or total prevention of regeneration. Among deuterostomes, echinoderms display a unique combination of striking regenerative abilities and diversity of useful experimental models, although still largely unexplored. Therefore, the brittle star Amphiura filiformis and the starfish Echinaster sepositus were here used to comparatively investigate the main repair phase events after injury as well as the presence and expression of immune system and extracellular matrix (i.e. collagen) molecules using both microscopy and molecular tools. Our results showed that emergency reaction and re-epithelialisation are similar in both echinoderm models, being faster and more effective than in mammals. Moreover, in comparison to the latter, both echinoderms showed delayed and less abundant collagen deposition at the wound site (absence of fibrosis). The gene expression patterns of molecules related to the immune response, such as Ese-fib-like (starfishes) and Afi-ficolin (brittle stars), were described for the first time during echinoderm regeneration providing promising starting points to investigate the immune system role in these regeneration models. Overall, the similarities in repair events and timing within the echinoderms and the differences with what has been reported in mammals suggest that effective repair processes in echinoderms play an important role for their subsequent ability to regenerate. Targeted molecular and functional analyses will shed light on the evolution of these abilities in the deuterostomian lineage.

Effect of Allogeneic Bone Marrow-mesenchymal Stem Cells (BM-MSCs) to Accelerate Burn Healing of Rat on the Expression of Collagen Type I and Integrin α2β1

BACKGROUND AND OBJECTIVE

Burn is a public health problem, it causes physical disability even death. Treatment of burn wound has been conducted in various ways, but the satisfactory healing has not been provided. Bone marrow-derived mesenchymal stem cells (BM-MSCs) treatment is one of attempt to burn recovery, accelerate wound healing and angiogenesis. This study aimed to investigate the effect of allogeneic BM-MSC treatment on the expression of collagen type I and integrin α2β1 in burn skin tissue of rat observed on day 14.

MATERIALS AND METHODS

Twelve Wistar rats divided into two groups, control group (injected with phospate buffer solution) and treatment group (injected with BM-MSC). Rat was anaesthetized with xylazine and ketamine (ratio 1:1), fur of rat's back was shaved and full thickness burn was made by boiling plate in hot water for 30 min and patched on the back for 20 min. The burns were covered by tegaderm film and elastomult haft. Antalgin as an analgetic was injected to rats during observation process. Burns of rat was observed on day 14. In this study one-way analysis of variance test and Tukey as a further test were analyzed.

RESULTS

The results showed that the healing time of allogeneic BM-MSC treatment on burn skin tissue rats was faster, the thickness of collagen type I in burn skin tissue of rats was thicker (0.977 μm) than controls (0.475 μm) and statistically demonstrated significant differences (p = 0.000). The average percentage of integrin α2β1 expression was higher (2.94%) than control group (2.34%), but the differences were not statistically significant (p = 0.176).

CONCLUSION

The study concluded that BM-MSC treatment was able to accelerate the healing process of burns by increasing the thickness of the collagen and the percentage of integrin α2β1, thus accelerated the cell migration involved during wound healing.

Restoration of the basement membrane after wounding: a hallmark of young human skin altered with aging

In skin, the basement membrane at the dermal-epidermal junction (DEJ-BM) is an important structure that tightly binds the epidermis to the dermis, and acts as a permeability barrier that controls exchange of macromolecules. Repair of the DEJ-BM during wound healing is important for restoration of skin functional properties after wounding. Here, we used a CO₂ laser to perform partial thickness wounds in human volunteers, and directly compared wound repair in healthy young and aged individuals, focusing on the DEJ-BM. Our results show that the DEJ-BM is restored within four weeks after partial thickness wounds in young adults. We identified laminin-γ2 as preferred substrate for keratinocytes during reepithelialization of partial thickness human wounds. Laminin-γ2 is expressed continuously by migrating keratinocytes during reepithelialization, whereas collagen IV and collagen VII are deposited after wound closure. In contrast, our study shows that the DEJ-BM restoration following wounding is deficient in elderly individuals. Specifically, COL7A2 was barely increased during wound repair in aged skin and, as a result, the DEJ-BM in elderly skin was not restored and showed abnormal structure. Our data suggest that ameliorating the quality of the DEJ-BM restoration is a promising therapeutic approach to improve the quality of repaired skin in the elderly.

Strategies for Optimizing the Soft Tissue Seal around Osseointegrated Implants

Percutaneous and permucosal devices such as catheters, infusion pumps, orthopedic, and dental implants are commonly used in medical treatments. However, these useful devices breach the soft tissue barrier that protects the body from the outer environment, and thus increase bacterial infections resulting in morbidity and mortality. Such associated infections can be prevented if these devices are effectively integrated with the surrounding soft tissue, and thus creating a strong seal from the surrounding environment. However, so far, there are no percutaneous/permucosal medical devices able to prevent infection by achieving strong integration at the soft tissue-device interface. This review gives an insight into the current status of research into soft tissue-implant interface and the challenges associated with these interfaces. Biological soft/hard tissue interfaces may provide insights toward engineering better soft tissue interfaces around percutaneous devices. In this review, focus is put on the history and current findings as well as recent progress of the strategies aiming to develop a strong soft tissue seal around osseointegrated implants, such as orthopedic and dental implants.

Suppression of αvβ6 Integrin Expression by Polymicrobial Oral Biofilms in Gingival Epithelial Cells

Periodontal diseases manifest by the formation of deep pockets between the gingiva and teeth where multispecies bacterial biofilms flourish, causing inflammation and bone loss. Epithelial cell receptor αvβ6 integrin that regulates inflammation by activating the anti-inflammatory cytokine transforming growth factor-β1, is highly expressed in healthy junctional epithelium that connects the gingiva to the tooth enamel. However, its expression is attenuated in human periodontal disease. Moreover, Itgb6^−/− mice display increased periodontal inflammation compared to wild-type mice. We hypothesized that bacterial biofilms present in the periodontal pockets suppress αvβ6 integrin levels in periodontal disease and that this change aggravates inflammation. To this end, we generated three-week-old multi-species oral biofilms in vitro and treated cultured gingival epithelial cells (GECs) with their extracts. The biofilm extracts caused suppression of β6 integrin expression and upregulation of pro-inflammatory cytokines, including interleukin-1β and -6. Furthermore, GECs with β6 integrin siRNA knockdown showed increased interleukin-1β expression, indicating that αvβ6 integrin-deficiency is associated with pro-inflammatory cytokine responsiveness. FSL-1, a synthetic bacterial lipopeptide, also suppressed β6 integrin expression in GECs. Therefore, biofilm components, including lipopeptides, may downregulate αvβ6 integrin expression in the pocket epithelium and thus promote epithelial cell-driven pro-inflammatory response in periodontal disease.

Disruption of Rab8a and Rab11a causes formation of basolateral microvilli in neonatal enteropathy

Misplaced formation of microvilli to basolateral domains and intracellular inclusions in enterocytes are pathognomonic features in congenital enteropathy associated with mutation of the apical plasma membrane receptor syntaxin 3 (STX3). Although the demonstrated binding of Myo5b to the Rab8a and Rab11a small GTPases in vitro implicates cytoskeleton-dependent membrane sorting, the mechanisms underlying the microvillar location defect remain unclear. By selective or combinatory disruption of Rab8a and Rab11a membrane traffic in vivo, we demonstrate that transport of distinct cargo to the apical brush border rely on either individual or both Rab regulators, whereas certain basolateral cargos are redundantly transported by both factors. Enterocyte-specific Rab8a and Rab11a double-knockout mouse neonates showed immediate postnatal lethality and more severe enteropathy than single knockouts, with extensive formation of microvilli along basolateral surfaces. Notably, following an inducible Rab11a deletion from neonatal enterocytes, basolateral microvilli were induced within 3 days. These data identify a potentially important and distinct mechanism for a characteristic microvillus defect exhibited by enterocytes of patients with neonatal enteropathy.

Bioactive Antimicrobial Peptides as Therapeutics for Corneal Wounds and Infections

Significance: More than 2 million eye injuries and infections occur each year in the United States that leave civilians and military members with reduced or complete vision loss due to the lack of effective therapeutics. Severe ocular injuries and infections occur in varied settings including the home, workplace, and battlefields. In this review, we discuss the potential of developing antimicrobial peptides (AMPs) as therapeutics for the treatment of corneal wounds and infections for which the current treatment options are inadequate.

Recent Advances: Standard-of-care employs the use of fluorescein dye for the diagnosis of ocular defects and is followed by the use of antibiotics and/or steroids to treat the infection and reduce inflammation. Recent advances for treating corneal wounds include the development of amniotic membrane therapies, wound chambers, and drug-loaded hydrogels. In this review, we will discuss an innovative approach using AMPs with the dual effect of promoting corneal wound healing and clearing infections.

Critical Issues: An important aspect of treating ocular injuries is that treatments need to be effective and administered expeditiously. This is especially important for injuries that occur during combat and in individuals who demonstrate delayed wound healing. To overcome gaps in current treatment modalities, bioactive peptides based on naturally occurring cationic antimicrobial proteins are being investigated as new therapeutics.

Future Directions: The development of new therapeutics that can treat ocular infections and promote corneal wound healing, including the healing of persistent corneal epithelial defects, would be of great clinical benefit.

Defining stem cell dynamics and migration during wound healing in mouse skin epidermis

Wound healing is essential to repair the skin after injury. In the epidermis, distinct stem cells (SCs) populations contribute to wound healing. However, how SCs balance proliferation, differentiation and migration to repair a wound remains poorly understood. Here, we show the cellular and molecular mechanisms that regulate wound healing in mouse tail epidermis. Using a combination of proliferation kinetics experiments and molecular profiling, we identify the gene signatures associated with proliferation, differentiation and migration in different regions surrounding the wound. Functional experiments show that SC proliferation, migration and differentiation can be uncoupled during wound healing. Lineage tracing and quantitative clonal analysis reveal that, following wounding, progenitors divide more rapidly, but conserve their homoeostatic mode of division, leading to their rapid depletion, whereas SCs become active, giving rise to new progenitors that expand and repair the wound. These results have important implications for tissue regeneration, acute and chronic wound disorders.

Wound healing is essential to repair the skin after injury and distinct stem cells in the epidermis are known to contribute to the process. Here the authors perform molecular, functional and clonal analysis and reveal the individual contribution of stem cells coming from different epidermal compartments to the wound-healing process in mice.

Differential uPA Expression by TGF-β1 in Gingival Fibroblasts

Transforming Growth Factor-β1 (TGF-β1) plays a key role in connective tissue remodeling and inflammation. Under pathological conditions, like periodontal disease, fibroblasts may display an altered response to this growth factor. To investigate this question, we have studied whether TGF-β1 may differentially regulate the expression of urokinase at the protein level in primary cultures of fibroblasts derived from healthy gingiva, granulation tissue from gingival wounds, and chronic periodontal disease. We observed that TGF-β1 may repress urokinase expression in healthy gingival fibroblasts and promote its production in granulation-tissue fibroblasts. A significant correlation was found between expression of the myofibroblast marker α-smooth-muscle actin and stimulation of urokinase production by TGF-β1. Immunostaining of gingival wounds showed that myofibroblasts were involved in urokinase production. TGF-β1-stimulated urokinase expression was blocked after inhibition of the c-jun-NH2 terminal kinase signaling pathway. We propose that stimulation of urokinase production by TGF-β1 is involved in the responses of activated fibroblasts to tissue injury.

Cellular mechanisms of skin repair in humans and other mammals

The increased incidence of non-healing skin wounds in developed societies has prompted tremendous research efforts on the complex process known as "wound healing". Unfortunately, the weak relevance of modern wound healing research to human health continues to be a matter of concern. This review summarizes the current knowledge of the cellular mechanisms that mediate wound closure in the skin of humans and laboratory animals. The author highlights the anatomical singularities of human skin vs. the skin of other mammals commonly used for wound healing research (i.e. as mice, rats, rabbits, and pigs), and discusses the roles of stem cells, myofibroblasts, and the matrix environment in the repair process. The majority of this review focuses on reepithelialization and wound closure. Other aspects of wound healing (e.g. inflammation, fibrous healing) are referred to when relevant to the main topic. This review aims at providing the reader with a clear understanding of the similarities and differences that have been reported over the past 100 years between the healing of human wounds and that of other mammals.

Downregulation of miR-205 in migrating epithelial tongue facilitates skin wound re-epithelialization by derepressing ITGA5

Keratinocyte migration is essential for re-epithelialization during skin wound healing, but the molecular mechanisms regulating this cellular response remain to be completely clarified. Here we show that keratinocyte-specific miR-205 is significantly downregulated in the leading edge of the migrating epithelial tongue after skin injury in mice. In HaCaT keratinocytes, miR-205 could be downregulated by TGF-β1 stimulation. And similar to the effect of TGF-β1, miR-205 knockdown could promote keratinocyte migration in wound scratch model in vitro. Furthermore, topical inhibition of miR-205 by administrating Pluronic gel containing antagomir-205 could accelerate re-epithelialization in mouse skin wound model in vivo. Moreover, we identified integrin alpha 5 (ITGA5) as one key functional miR-205 target in the re-epithelialization process and epidermal downregulation of miR-205 may desilence ITGA5 to promote keratinocyte migration. And knockdown of ITGA5 would abolish the pro-migratory effects of miR-205 inhibition in vitro. What's more, we found dysregulation of miR-205 and its target ITGA5 in epidermis of clinical chronic wound samples with persistence of high level miR-205 and absence of ITGA5. Our findings indicate that downregulation of miR-205 in the leading migrating keratinocytes is critical for re-epithelialization and miR-205 may be a potential therapeutic target for chronic wounds.

Breast Cancer-Derived Extracellular Vesicles: Characterization and Contribution to the Metastatic Phenotype

The study of extracellular vesicles (EVs) in cancer progression is a complex and rapidly evolving field. Whole categories of cellular interactions in cancer which were originally presumed to be due solely to soluble secreted molecules have now evolved to include membrane-enclosed extracellular vesicles (EVs), which include both exosomes and shed microvesicles (MVs), and can contain many of the same molecules as those secreted in soluble form but many different molecules as well. EVs released by cancer cells can transfer mRNA, miRNA, and proteins to different recipient cells within the tumor microenvironment, in both an autocrine and paracrine manner, causing a significant impact on signaling pathways, mRNA transcription, and protein expression. The transfer of EVs to target cells, in turn, supports cancer growth, immunosuppression, and metastasis formation. This review focuses exclusively on breast cancer EVs with an emphasis on breast cancer-derived exosomes, keeping in mind that breast cancer-derived EVs share some common physical properties with EVs of other cancers.

Epidermal Basement Membrane in Health and Disease

Skin, as the organ protecting the individual from environmental aggressions, constantly meets external insults and is dependent on mechanical toughness for its preserved function. Accordingly, the epidermal basement membrane (BM) zone has adapted to enforce tissue integrity. It harbors anchoring structures created through unique organization of common BM components and expression of proteins exclusive to the epidermal BM zone. Evidence for the importance of its correct assembly and the nonredundancy of its components for skin integrity is apparent from the multiple skin blistering disorders caused by mutations in genes coding for proteins associated with the epidermal BM and from autoimmune disorders in which autoantibodies target these molecules. However, it has become clear that these proteins not only provide mechanical support but are also critically involved in tissue homeostasis, repair, and regeneration. In this chapter, we provide an overview of the unique organization and components of the epidermal BM. A special focus will be given to its function during regeneration, and in inherited and acquired diseases.

Biofunctionalized surface-modified silver nanoparticles for gene delivery

Silver nanoparticles (AgNPs) find use in different biomedical applications including wound healing and cancer. We propose that the efficacy of the nanoparticles can be further augmented by using these particles for gene delivery applications. The objective of this work was to engineer biofunctionalized stable AgNPs with good DNA binding ability for efficient transfection and minimal toxicity. Herein, we report on the one-pot facile green synthesis of polyethylene glycol (PEG) stabilized chitosan-g-polyacrylamide modified AgNPs. The size of the PEG stabilized AgNPs was 38 ± 4 nm with a tighter size distribution compared to the unstabilized nanoparticles which showed bimodal distribution of particle sizes of 68 ± 5 nm and 7 ± 4 nm. To enhance the efficiency of gene transfection, the Arg-Gly-Asp-Ser (RGDS) peptide was immobilized on the silver nanoparticles. The transfection efficiency of AgNPs increased significantly after immobilization of the RGDS peptide reaching up to 42 ± 4% and 30 ± 3% in HeLa and A549 cells, respectively, and significantly higher than 34 ± 3% and 23 ± 2%, respectively, with the use of polyethyleneimine (25 kDa). These nanoparticles were found to induce minimal cellular toxicity. Differences in cellular uptake mechanisms with RGDS immobilization resulting in improved efficiency are elucidated. This study presents biofunctionalized AgNPs for potential use as efficient nonviral carriers for gene delivery with minimal cytotoxicity toward augmenting the therapeutic efficacy of AgNPs used in different biomedical products.

Context-Dependent Regulation of Collagen XVII Ectodomain Shedding in Skin

Pemphigoid is a common autoimmune blistering disorder in which autoantibodies target transmembrane collagen XVII (COL17), a component of hemidesmosomes in basal keratinocytes. The ectodomain of COL17 can be cleaved from the cell surface within the juxtamembranous extracellular NC16A domain, and, interestingly, certain autoantibodies of pemphigoid patients preferentially react with the shed ectodomain. These findings suggest that COL17 ectodomain shedding generates neoepitopes on the shed form; however, the regulatory mechanism of the shedding in in vivo skin and the pathogenicity of the neoepitope-targeting antibodies still are uncertain. To address these issues, we produced rabbit antibodies specifically reacting with N-terminal cleavage sites of the shed COL17 ectodomain. The antibodies showed that certain amounts of the human COL17 ectodomain are cleaved physiologically at Gln(525) in in vivo skin. In contrast, migrating human keratinocytes cleave COL17 at Leu(524) but not at Gln(525). The passive transfer of antibodies reacting with an N-terminal cleavage site of the mouse COL17 ectodomain into neonatal wild-type mice failed to induce blister formation, even though the antibodies bound to the dermal-epidermal junctions, indicating that cleavage site-specific antibodies have reduced or absent pathogenicity for blister formation. This study shows the ectodomain shedding of COL17 to be a physiological event in in vivo human skin that probably generates nonpathologic epitopes on the cleavage sites.

Characterization of the human α9 integrin subunit gene: Promoter analysis and transcriptional regulation in ocular cells

α9β1 is the most recent addition to the integrin family of membrane receptors and consequently remains the one that is the least characterized. To better understand how transcription of the human gene encoding the α9 subunit is regulated, we cloned the α9 promoter and characterized the regulatory elements that are required to ensure its transcription. Transfection of α9 promoter/CAT plasmids in primary cultured human corneal epithelial cells (HCECs) and uveal melanoma cell lines demonstrated the presence of both negative and positive regulatory elements along the α9 promoter and positioned the basal α9 promoter to within 118 bp from the α9 mRNA start site. In vitro DNaseI footprinting and in vivo ChIP analyses demonstrated the binding of the transcription factors Sp1, c-Myb and NFI to the most upstream α9 negative regulatory element. The transcription factors Sp1 and NFI were found to bind the basal α9 promoter individually but Sp1 binding clearly predominates when both transcription factors are present in the same extract. Suppression of Sp1 expression through RNAi also caused a dramatic reduction in the expression of the α9 gene. Most of all, addition of tenascin-C (TNC), the ligand of α9β1, to the tissue culture plates prior to seeding HCECs increased α9 transcription whereas it simultaneously decreased expression of the α5 integrin subunit gene. This dual regulatory action of TNC on the transcription of the α9 and α5 genes suggests that both these integrins must work together to appropriately regulate cell adhesion, migration and differentiation that are hallmarks of tissue wound healing.

Altered oxidative status and integrin expression in cyclosporine A-treated oral epithelial cells

BACKGROUND AND OBJECTIVE

Cyclosporine A (CsA) is an immunosuppressive agent administered to transplant patients. A well-known reported oral side effect of CsA consumption is gingival overgrowth (GO). Changes in the expression of integrins occurring in the gingiva following CsA treatment have been reported but these reports are mainly concerned with the connective tissue of the gingiva. In this study we targeted the alterations in the oral epithelium using KB cells, an oral epithelial cell line.

METHODS

Cultured oral epithelial cells were treated with increasing concentrations of CsA (0.1, 1 and 10 µg/mL) and the molecular changes involving antioxidant enzymes [glutathione peroxidase (GPx) and glutathione reductase (GR)] and the level of reactive oxygen species (ROS) were measured. Quantitative real-time PCR was used to assess the expression of selected integrins (α2, α5 and β1).

RESULTS

At CsA concentration above 0.1 µg/mL GPx demonstrated an increase in activity while GR activity and the level of reduced glutathione were diminished (p < 0.05). α5 and β1 integrin were downregulated at all treatment concentrations of CsA while α2 integrin presented this effect at concentrations above 1 µg/mL (p < 0.05).

CONCLUSION

The results suggest a possible role for oxidative stress and the altered expression of integrins in the pathology of CsA-induced gingival overgrowth.

Integrins in Wound Healing

Significance: Regulation of cell adhesions during tissue repair is fundamentally important for cell migration, proliferation, and protein production. All cells interact with extracellular matrix proteins with cell surface integrin receptors that convey signals from the environment into the nucleus, regulating gene expression and cell behavior. Integrins also interact with a variety of other proteins, such as growth factors, their receptors, and proteolytic enzymes. Re-epithelialization and granulation tissue formation are crucially dependent on the temporospatial function of multiple integrins. This review explains how integrins function in wound repair. Recent Advances: Certain integrins can activate latent transforming growth factor beta-1 (TGF-β1) that modulates wound inflammation and granulation tissue formation. Dysregulation of TGF-β1 function is associated with scarring and fibrotic disorders. Therefore, these integrins represent targets for therapeutic intervention in fibrosis. Critical Issues: Integrins have multifaceted functions and extensive crosstalk with other cell surface receptors and molecules. Moreover, in aberrant healing, integrins may assume different functions, further increasing the complexity of their functionality. Discovering and understanding the role that integrins play in wound healing provides an opportunity to identify the mechanisms for medical conditions, such as excessive scarring, chronic wounds, and even cancer. Future Directions: Integrin functions in acute and chronic wounds should be further addressed in models better mimicking human wounds. Application of any products in acute or chronic wounds will potentially alter integrin functions that need to be carefully considered in the design.

Concentration of fibrin and presence of plasminogen affect proliferation, fibrinolytic activity, and morphology of human fibroblasts and keratinocytes in 3D fibrin constructs

Fibrin is a hemostatic protein found in the clotting cascade. It is used in the operating room to stop bleeding and deliver cells and growth factors to heal wounds. However, formulations of clinically approved fibrin are optimized for hemostasis, and the extent to which biochemical and physical cues in fibrin mediate skin cell behavior is not fully understood nor utilized in the design of biomaterials. To determine if the concentration of fibrinogen and the presence of plasminogen affect cell behavior relevant to wound healing, we fabricated three-dimensional fibrin constructs made from 5, 10, or 20 mg/mL of clinical fibrin or plasminogen-depleted (PD) fibrin. We cultured dermal fibroblasts or epidermal keratinocytes in these constructs. Fibroblasts proliferated similarly in both types of fibrin, but keratinocytes proliferated more in low concentrations of clinical fibrin and less in PD fibrin. Clinical fibrin constructs with fibroblasts were less stiff and degraded faster than PD fibrin constructs with fibroblasts. Similarly, keratinocytes degraded clinical fibrin, but not PD fibrin. Fibroblast spreading varied with fibrin concentration in both types of fibrin. In conclusion, the concentration of fibrinogen and the presence of plasminogen affect fibroblast and keratinocyte proliferation, morphology, and fibrin degradation. Creating materials with heterogeneous regions of fibrin formulations and concentrations could be a novel strategy for controlling the phenotype of encapsulated fibroblasts and keratinocytes, and the subsequent biomechanical properties of the construct. However, other well-investigated aspects of wound healing remain to be utilized in the design of fibrin biomaterials, such as autocrine and paracrine signaling between fibroblasts, keratinocytes, and immune cells.

Human epidermal keratinocyte cell response on integrin-specific artificial extracellular matrix proteins

Cell-matrix interactions play critical roles in regulating cellular behavior in wound repair and regeneration of the human skin. In particular, human skin keratinocytes express several key integrins such as alpha5beta1, alpha3beta1, and alpha2beta1 for binding to the extracellular matrix (ECM) present in the basement membrane in uninjured skin. To mimic these key integrin-ECM interactions, artificial ECM (aECM) proteins containing functional domains derived from laminin 5, type IV collagen, fibronectin, and elastin are prepared. Human skin keratinocyte cell responses on the aECM proteins are specific to the cell-binding domain present in each construct. Keratinocyte attachment to the aECM protein substrates is also mediated by specific integrin-material interactions. In addition, the aECM proteins are able to support the proliferation of keratinocyte stem cells, demonstrating their promise for use in skin tissue engineering.

Biological effects of soft denture reline materials on L929 cells in vitro

Soft denture reline materials have been developed to help patients when their oral mucosa is damaged or affected due to ill-fitting dentures or post-implant surgery. Although reports have indicated that these materials leach monomers and other components that do affect their biocompatibility, there is little information on what cell molecules may be implicated in these material/tissue interactions. The biocompatibility of six soft liners (Ufi Gel P, Sofreliner S, Durabase Soft, Trusoft, Softone and Coe Comfort) was evaluated using a mouse fibroblast cell line, L929. Within 2 h of material disc preparation, each of the materials was exposed by direct contact to L929 cells for periods of 24 and 48 h. The effect of this interaction was assessed by alamarBlue assay (for cell survival). The expression of integrin α5β1 and transforming growth factor β1 was also assessed using plate assays such as enzyme-linked immunosorbent assay. Trusoft, Softone and Coe Comfort showed significantly reduced cell survival compared with the other soft lining materials at each incubation period. Furthermore, there were significant differences with these same materials in the expression of both integrin α5β1 and transforming growth factor β1. Soft liner materials may affect cell viability and cellular proteins that have important roles in wound healing and the preservation of cell viability and function in the presence of environmental challenges and stresses.