Immunohistochemical localization of the proteoglycans decorin, biglycan and versican and transforming growth factor-beta in human post-burn hypertrophic and mature scars

Hypertrophic Scar

Hypertrophic scars frequently develop post-burn, and are characterized by their pruritic, painful, raised, erythematous, dyschromic, and contractile qualities. This article aims to synthesize knowledge on the clinical and molecular development, evolution, management, and measurement of hypertrophic burn scar for both patient and clinician knowledge.

Myopathy Associated With Dermatan Sulfate-Deficient Decorin and Myostatin in Musculocontractural Ehlers-Danlos Syndrome: A Mouse Model Investigation

Carbohydrate sulfotransferase 14 (CHST14) encodes dermatan 4-O-sulfotransferase 1, a critical enzyme for dermatan sulfate (DS) biosynthesis. Musculocontractural Ehlers-Danlos syndrome (mcEDS) is associated with biallelic pathogenic variants of CHST14 and is characterized by malformations and manifestations related to progressive connective tissue fragility. We identified myopathy phenotypes in Chst14-deficient mice using an mcEDS model. Decorin is a proteoglycan harboring a single glycosaminoglycan chain containing mainly DS, which are replaced with chondroitin sulfate (CS) in mcEDS patients with CHST14 deficiency. We studied the function of decorin in the skeletal muscle of Chst14-deficient mice because decorin is important for collagen-fibril assembly and has a myokine role in promoting muscle growth. Although decorin was present in the muscle perimysium of wild-type (Chst14+/+ ) mice, decorin was distributed in the muscle perimysium as well as in the endomysium of Chst14-/- mice. Chst14-/- mice had small muscle fibers within the spread interstitium; however, histopathological findings indicated milder myopathy in Chst14-/- mice. Myostatin, a negative regulator of protein synthesis in the muscle, was upregulated in Chst14-/- mice. In the muscle of Chst14-/- mice, decorin was downregulated compared to that in Chst14+/+ mice. Chst14-/- mice showed altered cytokine/chemokine balance and increased fibrosis, suggesting low myogenic activity in DS-deficient muscle. Therefore, DS deficiency in mcEDS causes pathological localization and functional abnormalities of decorin, which causes disturbances in skeletal muscle myogenesis.

Effective Scarless Wound Healing Mediated by Erbium Borate Nanoparticles

The developments of nanoparticle-based treatments that benefit from novel discoveries have an essential place in the regeneration of acute and chronic wounds. Furthermore, research about the treatment methods which attempt to swiftly and scarless wound recovery has increased over time. In recent years, it has been shown that metallic-based nanoparticles, especially silver and gold derived, have an accelerating effect on chronic and contaminated wound healing. The crucial factors of inducing and completion of regeneration of wound are enhanced epithelialization rate and neovascularization in the tissue. In our study, the main purpose is the investigation of the boosting effects of erbium borate nanoparticles on the wound healing process, especially scarless ones. Newly syntesized erbium borate nanoparticles (ErB-Nps) were characterized by their concentration and particle size using nanoparticle tracking analysis (NTA). In order to examine the effect of ErB-Np on wound closure, scratch assay for dermal epithelial cells and tube formation assay for endothelial cells were performed. In addition, in order to examine the effect of the ErB-Np at a molecular level, the levels of genes related to both wound healing, inflammation, and scarless wound closure were determined with the RT-PCR experiment. Consequently, it has been shown that erbium borate nanoparticles have increased the melioration speed of scar tissue and have given clues about scarless healing potential. The investigation of the regeneration potential of erbium borate nanoparticles was done via MTS assay, quantitative PCR analysis, reactive oxygen species assay, and scratch assay. Our results show that ErB-Np is a proper agent that can be used for scarless wound healing.

Hypertrophic Scarring: Current Knowledge of Predisposing Factors, Cellular and Molecular Mechanisms

Hypertrophic scarring (HSc) is an age-old problem that still affects millions of people physically, psychologically, and economically. Despite advances in surgical techniques and wound care, prevention and treatment of HSc remains a challenge. Elucidation of factors involved in the development of this common fibroproliferative disorder is crucial for further progress in preventive and/or therapeutic measures. Our knowledge about pathophysiology of HSc at the cellular and molecular level has grown considerably in recent decades. In this article, current knowledge of predisposing factors and the cellular and molecular mechanisms of HSc has been reviewed.

Modeling of Old Scars: Histopathological, Biochemical and Thermal Analysis of the Scar Tissue Maturation

Simple Summary

Severe skin scars (i.e., hypertrophic and keloid) induce physical and emotional discomfort and functional disorders such as contractures and body part deformations. Scar’s response to treatment depends on “maturity”, which increases with time but is not merely proportional to it. When “fresh”, scars are relatively more treatable by conservative methods, while the treatment is only partially efficient. In contrast, surgery is a preferred approach for the older scars, but it is associated with a risk of the scar regrowth and worsening after excision if unrecognized immature scar tissue remains in the operated lesion. Therefore, to develop better treatment and diagnostics of scars, understanding of the scar maturation is essential. This requires biologically accurate experimental models of skin scarring. The current models only mimic the early stages of skin scar development. They are useful for testing new scar-preventing approaches while not addressing the problem of the older scars that exist for years. In our study, we demonstrate a new rabbit model of “old” scars and explore what happens to the scar tissue during maturation. We define measurable signs to delineate the scar development stages and discuss how this knowledge can improve scar diagnostics and treatment.

Abstract

Mature hypertrophic scars (HSs) remain a challenging clinical problem, particularly due to the absence of biologically relevant experimental models as a standard rabbit ear HS model only reflects an early stage of scarring. The current study aims to adapt this animal model for simulation of mature HS by validating the time of the scar stabilization using qualitative and quantitative criteria. The full-thickness skin and perichondrium excision wounds were created on the ventral side of the rabbit ears. The tissue samples were studied on post-operation days (PODs) 30, 60, 90 and 120. The histopathological examination and morphometry were applied in parallel with biochemical analysis of protein and glycosaminoglycans (GAGs) content and amino acid composition. The supramolecular organization of collagen was explored by differential scanning calorimetry. Four stages of the rabbit ear HS maturation were delineated and attributed with the histolomorphometrical and physicochemical parameters of the tissue. The experimental scars formed in 30 days but stabilized structurally and biochemically only on POD 90–120. This evidence-based model can be used for the studies and testing of new treatments of the mature HSs.

Gene expression profile analysis on different stages of hypertrophic scarring in a rabbit ear model

Hypertrophic scarring (HS) is one of the most common skin disorders. The study aimed to investigate the gene expression profile at day 10 (Stage 1), 21 (Stage 2), and day 40 (Stage 3) post-wounding of HS using RNA-sequencing of a scar model from rabbit ears. A total of 17,386 unigenes were annotated using the eggNOG Functional Category database. The study identified significantly differentially expressed genes (DEGs) including 261, 141, and 247 upregulated ones as well as 253, 272, and 58 downregulated ones in three stages respectively. The DEGs varies among each stage measured by Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. DEGs were enriched in 'immune system process' and 'proteinaceous extracellular matrix' in Stage 1, 'anatomical structure development', 'cell differentiation', 'cell adhesion'and some other terms in Stage 2, 'cancers', 'proteinaceous extracellular matrix' and 'signal transduction' in Stage 3. Furthermore, the Wnt signaling pathway was found to play a pivotal role in regression of HS. In conclusion, we revealed comprehensively the gene expression profiles during HS formation providing probable targets in HS treatment.

Progress and mechanism of breaking glycoconjugates by glycosidases in skin for promoting unhairing and fiber opening-up in leather manufacture. A review

Abstract

The glycoconjugates, herein glyco-proteins, existing in animal skins are closely related to the effectiveness of unhairing and fiber opening-up. Glycosidases have been used in leather making processes to reduce pollutants and improve leather quality. But the selection of glycosidases is still blind because the related mechanisms are not well understood yet. Hence, the animal skin structures and glycoconjugates components, the advances in the methods and mechanisms of removing glycoconjugates related to unhairing and fiber opening-up in leather manufacture, the kinds, compositions, structures and functions of typical glycoconjugates in skin are summarized. Then the approaches to destroy them, possible glycosidases suitable for leather making and their acting sites are analyzed based on the recognition of glycoconjugates in skin and the specificities of glycosidases toward substrates. It is expected to provide useful information for the optimization of glycosidases and the development of new enzymes and the cleaner technologies of unhairing and opening up fiber bundles assisted by glycosidases.

Graphical abstract

Small Leucine-Rich Proteoglycans in Skin Wound Healing

Healing of cutaneous wounds is a complex and well-coordinated process requiring cooperation among multiple cells from different lineages and delicately orchestrated signaling transduction of a diversity of growth factors, cytokines, and extracellular matrix (ECM) at the wound site. Most skin wound healing in adults is imperfect, characterized by scar formation which results in significant functional and psychological sequelae. Thus, the reconstruction of the damaged skin to its original state is of concern to doctors and scientists. Beyond the traditional treatments such as corticosteroid injection and radiation therapy, several growth factors or cytokines-based anti-scarring products are being or have been tested in clinical trials to optimize skin wound healing. Unfortunately, all have been unsatisfactory to date. Currently, accumulating evidence suggests that the ECM not only functions as the structural component of the tissue but also actively modulates signal transduction and regulates cellular behaviors, and thus, ECM should be considered as an alternative target for wound management pharmacotherapy. Of particular interest are small leucine-rich proteoglycans (SLRPs), a group of the ECM, which exist in a wide range of connecting tissues, including the skin. This manuscript summarizes the most current knowledge of SLRPs regarding their spatial-temporal expression in the skin, as well as lessons learned from the genetically modified animal models simulating human skin pathologies. In this review, particular focus is given on the diverse roles of SLRP in skin wound healing, such as anti-inflammation, pro-angiogenesis, pro-migration, pro-contraction, and orchestrate transforming growth factor (TGF)β signal transduction, since cumulative investigations have indicated their therapeutic potential on reducing scar formation in cutaneous wounds. By conducting this review, we intend to gain insight into the potential application of SLRPs in cutaneous wound healing management which may pave the way for the development of a new generation of pharmaceuticals to benefit the patients suffering from skin wounds and their sequelae.

Collagenase-assisted wound bed preparation: An in vitro comparison between Vibrio alginolyticus and Clostridium histolyticum collagenases on substrate specificity

Bacterial collagenase from the aerobic non-pathogenic Vibrio alginolyticus chemovar iophagus is an extracellular metalloproteinase. This collagenase preparation is obtained through a fermentation process and is purified chromatographically, resulting in a highly purified 82-kDa single-band protein that does not contain non-specific proteases or other microbial impurities. V. alginolyticus collagenase was added to a hyaluronan (HA)-based device to develop a novel debriding agent to improve the treatment of ulcers, necrotic burns, and decubitus in the initial phase of wound bed preparation. In this study, an in vitro biochemical characterisation of V. alginolyticus collagenase versus a commercial preparation from a Clostridium histolyticum strain on various dermal extracellular matrix (ECM) substrates was performed. V. alginolyticus collagenase demonstrated its ability to carry out the enzymatic cleavage of the substrate, allowing a selective removal of necrotic tissues while sparing healthy tissue, as reported in clinical studies and through routine clinical experience. in vitro tests under physiological conditions (pH, presence of Ca++, etc.) have demonstrated that V. alginolyticus collagenase exhibits very poor/limited non-specific proteolytic activity, whereas the collagenase preparation from C. histolyticum is highly active both on collagen and on non-collagenic substrates. This finding implies that while the V. alginolyticus enzyme is fully active on the collagen filaments that anchor the necrotic tissue to the wound bed, it does not degrade other minor, but structurally important, components of the dermal ECM. This feature could explain why collagenase preparation from V. alginolyticus has been reported to be much gentler on perilesional, healthy skin.

The extracellular matrix as a multitasking player in disease

Extracellular matrices (ECMs) are highly specialized and dynamic three-dimensional (3D) scaffolds into which cells reside in tissues. ECM is composed of a variety of fibrillar components, such as collagens, fibronectin, and elastin, and non-fibrillar molecules as proteoglycans, hyaluronan, and glycoproteins including matricellular proteins. These macromolecular components are interconnected forming complex networks that actively communicate with cells through binding to cell surface receptors and/or matrix effectors. ECMs exert diverse roles, either providing tissues with structural integrity and mechanical properties essential for tissue functions or regulating cell phenotype and functions to maintain tissue homeostasis. ECM molecular composition and structure vary among tissues, and is markedly modified during normal tissue repair as well as during the progression of various diseases. Actually, abnormal ECM remodeling occurring in pathologic circumstances drives disease progression by regulating cell-matrix interactions. The importance of matrix molecules to normal tissue functions is also highlighted by mutations in matrix genes that give rise to genetic disorders with diverse clinical phenotypes. In this review, we present critical and emerging issues related to matrix assembly in tissues and the multitasking roles for ECM in diseases such as osteoarthritis, fibrosis, cancer, and genetic diseases. The mechanisms underlying the various matrix-based diseases are also discussed. Research focused on the highly dynamic 3D ECM networks will help to discover matrix-related causative abnormalities of diseases as well as novel diagnostic tools and therapeutic targets.

Topical Application of Adelmidrol + Trans-Traumatic Acid Enhances Skin Wound Healing in a Streptozotocin-Induced Diabetic Mouse Model

Impaired wound healing is considered to be one of the severe complications associated with diabetes. Adelmidrol and trans-traumatic acid are commonly called Nevamast^®. This gel consists precisely of 2% adelmidrol and 1% trans-traumatic acid. Thanks to its components, it is capable of favoring the natural process of skin re-epithelialization. This study tests the theory that topical usage of adelmidrol + trans-traumatic acid has important effects on the healing and closure of diabetic wounds in a streptozotocin (STZ)-induced diabetic mouse model. Diabetes was induced by intraperitoneal injection of STZ (60 mg/kg) in 0.01 M citrate buffer (pH 4.5) administrated for 5 consecutive days. After diabetes induction, two longitudinal incisions were made on the dorsum of the mice. The animals were killed between 6 and 12 days from wound induction. We found that diabetic mice compared to control mice presented: a retarded wound closure, characterized by an important reduction in the levels of transforming growth factor-β, plus an important increase of vascular endothelial growth factor and endothelial-type nitric oxide synthase expression, together with a reduction of adhesion molecules such as intercellular adhesion molecule-1 and P-selectin and a prolonged elevation of the levels of matrix metalloproteinase-9 and matrix metalloproteinase-2 in wound tissues. This study demonstrates that topical application of adelmidrol + trans-traumatic acid has important effects on the healing and closure of diabetic wounds in an STZ-induced diabetic mouse model.

Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing

Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed.

Are the skin scar characteristics and closure of the parietal peritoneum associated with pelvic adhesions?

Objective:

To assess whether the abdominal scar characteristics and closure of the peritoneum were associated with pelvic adhesions.

Materials and Methods:

Patients who had undergone cesarean section between December 2015 and February 2016 were assessed prospectively in terms of age, gravida, body mass index, number of living children, number of cesarean sections, time passed since the last cesarean section, closure status of the peritoneum in the last cesarean section, presence of other diseases, smoking status, location of incision in the abdomen (medial, pfannenstiel) scar dimensions (length, width), scar status with respect to skin (hypertrophic, flat, depressive), scar color [color change/no color change (hyperpigmented/hypopigmented)], adhesion of bowel-omentum-uterus, omentum-anterior abdominal wall, uterus-anterior abdominal wall, uterus-bladder, bladder-anterior abdominal wall, fixed uterus, and uterus-omentum-anterior abdominal wall in abdominal exploration.

Results:

One hundred five pregnant women who had undergone previous ceserean section surgery by the same physician, were at least in their 30th gestational week, had surgery notes about their previous operation, and had no chronic diseases were included in the study. Age, gravida, body mass index, number of children, number of cesarean sections, time passed since the previous cesarean section, closure/non-closure of peritoneum in the previous cesarean section, and smoking status had no effect on pelvic adhesions. Intraabdominal adhesion was not found to be associated with scar length [odds ratio (OR): 1.54, 95% confidence interval (CI): 1.1-2.2; p=0.02], depressive scar (OR: 9.3, 95% CI: 3.2-27.2; p<0.001), or hypopigmented scar [OR: 0.01, 95% CI: 0.003-0.11; p<0.001].

Conclusion:

Adhesions following surgical operations are of great importance due to complications for the patient, complications in relaparotomy, and high costs. Depressive and hypopigmented abdominal scars may be associated with pelvic adhesions. We believe that closure or non-closure of the parietal peritoneum is not associated with pelvic adhesions.

Lower energy radial shock wave therapy improves characteristics of hypertrophic scar in a rabbit ear model

The aim of the present study was to investigate the effects of radial extracorporeal shock wave therapy (rESWT) on scar characteristics and transforming growth factor (TGF)-β1/Smad signaling in order to explore a potential modality for the treatment of hypertrophic scars (HS). The HS model was generated in rabbit ears, then rabbits were randomly divided into 3 groups: Lower (L)-ESWT [treated with rESWT with lower energy flux density (EFD) of 0.1 mJ/mm²], higher (H)-ESWT (treated with a higher EFD of 0.18 mJ/mm²) and the sham ESWT group (S-ESWT; no ESWT treatment). Scar characteristics (wrinkles, texture, diameter, area, volume of elevation, hemoglobin and melanin) were assessed using the Antera 3D^® system. The protein and mRNA expression of TGF-β1, Smad2, Smad3 and Smad7 was assessed by enzyme-linked immunosorbent assay and reverse transcription-quantitative polymerase chain reaction, respectively. The Antera 3D^® results indicated that wrinkles and hemoglobin of the HS were significantly improved in both of the rESWT groups when compared with the S-ESWT group. However, these changes appeared much earlier in the L-ESWT group than the H-ESWT. Scar texture was also improved in the L-ESWT group. However, rESWT did not influence HS diameter, area, volume of elevation or melanin levels. rESWT had no effect on TGF-β1 or Smad7 expression in either of rESWT groups. Although no difference was observed in Smad2 mRNA expression in the L-ESWT group, the Smad3 mRNA and protein expression significantly decreased when compared with the H-ESWT and S-ESWT groups. By contrast, Smad2 and Smad3 mRNA expression were upregulated in the H-ESWT group. These results demonstrated that rESWT with 0.1 mJ/mm² EFD improved some characteristics of the HS tissue. Downregulation of Smad3 expression may underlie this inhibitory effect. Inhibition of the TGF-β1/Smad signal transduction pathway may be a potential therapeutic target for the management of HS.

Scar formation following excisional and burn injuries in a red Duroc pig model

Scar research is challenging because rodents do not naturally form excessive scars, and burn depth, size, and location cannot be controlled in human longitudinal studies. The female, red Duroc pig model has been shown to form robust scars with biological and anatomical similarities to human hypertrophic scars. To more closely mimic the mode of injury, recreate the complex chemical milieu of the burn wound environment and enhance scar development, an animal model of excessive burn-induced scarring was developed and compared with the more commonly used model, which involves excisional wounds created via dermatome. Standardized, full-thickness thermal wounds were created on the dorsum of female, red Duroc pigs. Wounds for the dermatome model were created using two different total dermatome settings: ∼1.5 mm and ≥ 1.9 mm. Results from analysis over 150 days showed that burn wounds healed at much slower rate and contracted more significantly than dermatome wounds of both settings. The burn scars were hairless, had mixed pigmentation, and displayed fourfold and twofold greater excess erythema values, respectively, compared with ∼1.5 mm and ≥ 1.9 mm deep dermatome injuries. Burn scars were less elastic, less pliable, and weaker than scars resulting from excisional injuries. Decorin and versican gene expression levels were elevated in the burn group at day 150 compared with both dermatome groups. In addition, transforming growth factor-beta 1 was significantly up-regulated in the burn group vs. the ∼1.5 mm deep dermatome group at all time points, and expression remained significantly elevated vs. both dermatome groups at day 150. Compared with scars from dermatome wounds, the burn scar model described here demonstrates greater similarity to human hypertrophic scar. Thus, this burn scar model may provide an improved platform for studying the pathophysiology of burn-related hypertrophic scarring, investigating current anti-scar therapies, and development of new strategies with greater clinical benefit.

Extracellular Matrix and Dermal Fibroblast Function in the Healing Wound

Significance: Fibroblasts play a critical role in normal wound healing. Various extracellular matrix (ECM) components, including collagens, fibrin, fibronectin, proteoglycans, glycosaminoglycans, and matricellular proteins, can be considered potent protagonists of fibroblast survival, migration, and metabolism. Recent Advances: Advances in tissue culture, tissue engineering, and ex vivo models have made the examination and precise measurements of ECM components in wound healing possible. Likewise, the development of specific transgenic animal models has created the opportunity to characterize the role of various ECM molecules in healing wounds. In addition, the recent characterization of new ECM molecules, including matricellular proteins, dermatopontin, and FACIT collagens (Fibril-Associated Collagens with Interrupted Triple helices), further demonstrates our cursory knowledge of the ECM in coordinated wound healing. Critical Issues: The manipulation and augmentation of ECM components in the healing wound is emerging in patient care, as demonstrated by the use of acellular dermal matrices, tissue scaffolds, and wound dressings or topical products bearing ECM proteins such as collagen, hyaluronan (HA), or elastin. Once thought of as neutral structural proteins, these molecules are now known to directly influence many aspects of cellular wound healing. Future Directions: The role that ECM molecules, such as CCN2, osteopontin, and secreted protein, acidic and rich in cysteine, play in signaling homing of fibroblast progenitor cells to sites of injury invites future research as we continue investigating the heterotopic origin of certain populations of fibroblasts in a healing wound. Likewise, research into differently sized fragments of the same polymeric ECM molecule is warranted as we learn that fragments of molecules such as HA and tenascin-C can have opposing effects on dermal fibroblasts.

Comparison of transforming growth factor beta expression in healthy and diseased human tendon

Background

Diseased tendons are characterised by fibrotic scar tissue, which adversely affects tendon structure and function and increases the likelihood of re-injury. The mechanisms and expression profiles of fibrosis in diseased tendon is understudied compared to pulmonary and renal tissues, where transforming growth factor (TGF)β and its associated superfamily are known to be key drivers of fibrosis and modulate extracellular matrix homeostasis. We hypothesised that differential expression of TGFβ superfamily members would exist between samples of human rotator cuff tendons with established disease compared to healthy control tendons.

Methods

Healthy and diseased rotator cuff tendons were collected from patients presenting to an orthopaedic referral centre. Diseased tendinopathic (intact) and healthy rotator cuff tendons were collected via ultrasound-guided biopsy and torn tendons were collected during routine surgical debridement. Immunohistochemistry and quantitative real-time polymerase chain reaction were used to investigate the protein and gene expression profiles of TGFβ superfamily members in these healthy and diseased tendons.

Results

TGFβ superfamily members were dysregulated in diseased compared to healthy tendons. Specifically, TGFβ-1, TGFβ receptor (R)1 and TGFβ R2 proteins were reduced (p < 0.01) in diseased compared to healthy tendons. At the mRNA level, TGFβ R1 was significantly reduced in samples of diseased tendons, whereas TGFβ R2 was increased (p < 0.01). BMP-2, BMP-7 and CTGF mRNA remained unchanged with tendon disease.

Conclusions

We propose that downregulation of TGFβ pathways in established tendon disease may be a protective response to limit disease-associated fibrosis. The disruption of the TGFβ axis with disease suggests associated downstream pathways may be important for maintaining healthy tendon homeostasis. The findings from our study suggest that patients with established tendon disease would be unlikely to benefit from therapeutic TGFβ blockade, which has been investigated as a treatment strategy in several animal models. Future studies should investigate the expression profile of fibrotic mediators in earlier stages of tendon disease to improve understanding of the targetable mechanisms underpinning tendon fibrosis.

Biology and principles of scar management and burn reconstruction

Hypertrophic scarring is extremely common and is the source of most morbidity related to burns. The biology of hypertrophic healing is complex and poorly understood. Multiple host and injury factors contribute, but protracted healing of partial thickness injury is a common theme. Hypertrophic scarring and heterotopic ossification may share some basic causes involving marrow-derived cells. Several traditional clinical interventions exist to modify hypertrophic scar. All have limited efficacy. Laser interventions for scar modification show promise, but as yet do not provide a definitive solution. Their efficacy is only seen when used as part of a multimodality scar management program.

Update on hypertrophic scar treatment

Scar formation is a consequence of the wound healing process that occurs when body tissues are damaged by a physical injury. Hypertrophic scars and keloids are pathological scars resulting from abnormal responses to trauma and can be itchy and painful, causing serious functional and cosmetic disability. The current review will focus on the definition of hypertrophic scars, distinguishing them from keloids and on the various methods for treating hypertrophic scarring that have been described in the literature, including treatments with clearly proven efficiency and therapies with doubtful benefits. Numerous methods have been described for the treatment of abnormal scars, but to date, the optimal treatment method has not been established. This review will explore the differences between different types of nonsurgical management of hypertrophic scars, focusing on the indications, uses, mechanisms of action, associations and efficacies of the following therapies: silicone, pressure garments, onion extract, intralesional corticoid injections and bleomycin.

Intra-articular decorin influences the fibrosis genetic expression profile in a rabbit model of joint contracture

OBJECTIVES

The goal of this study was to determine whether intra-articular administration of the potentially anti-fibrotic agent decorin influences the expression of genes involved in the fibrotic cascade, and ultimately leads to less contracture, in an animal model.

METHODS

A total of 18 rabbits underwent an operation on their right knees to form contractures. Six limbs in group 1 received four intra-articular injections of decorin; six limbs in group 2 received four intra-articular injections of bovine serum albumin (BSA) over eight days; six limbs in group 3 received no injections. The contracted limbs of rabbits in group 1 were biomechanically and genetically compared with the contracted limbs of rabbits in groups 2 and 3, with the use of a calibrated joint measuring device and custom microarray, respectively.

RESULTS

There was no statistical difference in the flexion contracture angles between those limbs that received intra-articular decorin versus those that received intra-articular BSA (66° vs 69°; p = 0.41). Likewise, there was no statistical difference between those limbs that received intra-articular decorin versus those who had no injection (66° vs 72°; p = 0.27). When compared with BSA, decorin led to a statistically significant increase in the mRNA expression of 12 genes (p < 0.01). In addition, there was a statistical change in the mRNA expression of three genes, when compared with those without injection.

CONCLUSIONS

In this model, when administered intra-articularly at eight weeks, 2 mg of decorin had no significant effect on joint contractures. However, our genetic analysis revealed a significant alteration in several fibrotic genes. Cite this article: Bone Joint Res 2014;3:82-8.

Loss of the hyaluronan receptor RHAMM prevents constrictive artery wall remodeling

OBJECTIVE

Constrictive extracellular matrix (ECM) remodeling contributes significantly to restenosis after arterial reconstruction, but its molecular regulation is poorly defined. Hyaluronan (HA) accumulates within ECM at sites of injury where it is thought to facilitate smooth muscle cell (SMC) trafficking and collagen remodeling analogous to its role in cutaneous wound healing. SMC receptors for HA include receptor for hyaluronan-mediated motility (RHAMM), which mediates HA-induced migration. We hypothesized RHAMM would also mediate SMC-matrix interactions to alter the extent of constrictive remodeling.

METHODS

We studied the role of RHAMM in SMC attachment to collagen, migration, and contraction of collagen gels using blocking antibodies and SMC from RHAMM -/- knockout mice. We then determined the role of RHAMM in constrictive artery wall remodeling by comparing changes in wall geometry in RHAMM -/- vs wild-type (WT) RHAMM +/+ controls 1 month after carotid ligation.

RESULTS

HA increased SMC attachment to collagen-coated plates, but blocking RHAMM reduced adhesion (P = .025). RHAMM -/- SMC also demonstrated reduced adhesion (% adherent: 36.1 ± 2.2 vs 76.3 ± 1.9; P < .05). SMC contraction of collagen gels was enhanced by HA and further increased by RHAMM blockade (P < .01) or knockout (gel diameter, mm: RHAMM -/-, 6.7 ± 0.1 vs WT 9.8 ± 0.1; P < .01). RHAMM promoted constrictive remodeling in vivo as carotid artery size was significantly larger in knockout mice 1 month after ligation. Neointimal thickening, however, was not affected in RHAMM -/- (P = NS vs WT), but lumen size was significantly larger (lumen area, μm(2): 52.4 ± 1.4 × 10(3) vs 10.4 ± 1.8 × 10(3); P = .01) because artery size constricted less (external elastic lamina area, μm(2): RHAMM -/-, 92.4 ± 4.7 × 10(3) vs WT, 51.3 ± 5.9 × 10(3); P = .015). Adventitial thickening and collagen deposition were also more extensive in ligated RHAMM -/- carotids (adventitial thickness, μm: 218 ± 12.2 vs 109 ± 7.9; P = .01).

CONCLUSIONS

HA activation of RHAMM significantly impacts SMC-ECM adhesive interactions and contributes to constrictive artery wall remodeling in mice. Strategies to block RHAMM at sites of vessel injury may prove useful in the prevention of clinical restenosis.

Dynamics of Transforming Growth Factor Beta Signaling in Wound Healing and Scarring

SIGNIFICANCE

Wound healing is an intricate biological process in which the skin, or any other tissue, repairs itself after injury. Normal wound healing relies on the appropriate levels of cytokines and growth factors to ensure that cellular responses are mediated in a coordinated manner. Among the many growth factors studied in the context of wound healing, transforming growth factor beta (TGF-β) is thought to have the broadest spectrum of effects.

RECENT ADVANCES

Many of the molecular mechanisms underlying the TGF-β/Smad signaling pathway have been elucidated, and the role of TGF-β in wound healing has been well characterized. Targeting the TGF-β signaling pathway using therapeutic agents to improve wound healing and/or reduce scarring has been successful in pre-clinical studies.

CRITICAL ISSUES

Although TGF-β isoforms (β1, β2, β3) signal through the same cell surface receptors, they display distinct functions during wound healing in vivo through mechanisms that have not been fully elucidated. The challenge of translating preclinical studies targeting the TGF-β signaling pathway to a clinical setting may require more extensive preclinical research using animal models that more closely mimic wound healing and scarring in humans, and taking into account the spatial, temporal, and cell-type-specific aspects of TGF-β isoform expression and function.

FUTURE DIRECTIONS

Understanding the differences in TGF-β isoform signaling at the molecular level and identification of novel components of the TGF-β signaling pathway that critically regulate wound healing may lead to the discovery of potential therapeutic targets for treatment of impaired wound healing and pathological scarring.

Myofibroblasts and transforming growth factor-beta1 in reactive gingival overgrowths

Objectives

The purpose of this study was to evaluate the oral health-related quality of life of patients treated with implant-supported mandibular overdentures and to compare the attachment systems used.

Material and Methods

The presence of myofibroblasts as well as transforming growth factor-beta1 was examined in twenty cases of fibrous epulis and 22 ossifying fibrous epulis, using immunohistochemistry.

Results

Myofibroblasts positive for alpha smooth muscle actin and vimentin but negative to desmin were found in 20% and 45% in fibrous epulis and ossifying fibrous epulis, respectively. Myofibroblasts were distributed in areas with and without inflammatory infiltration and their presence in inflammatory areas was not related with the degree of inflammatory infiltration. A percentage of 21 - 60% of fibroblasts and chronic inflammatory cells expressed transforming growth factor-beta1 in all cases.

Conclusions

These data suggest that transforming growth factor-beta1 and myofibroblasts contribute to the formation of collagenous connective tissue in fibrous epulis and ossifying fibrous epulis. Myofibroblasts are mainly presented in ossifying fibrous epulis than in fibrous epulis. It seems to be no relationship between the presence of myofibroblasts and the degree of inflammatory infiltration of the lesions.

The molecular mechanism of hypertrophic scar

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

Novel methods for the investigation of human hypertrophic scarring and other dermal fibrosis

Hypertrophic scar (HTS) represents the dermal equivalent of fibroproliferative disorders that occur after injury involving the deep dermis while superficial wounds to the skin heal with minimal or no scarring. HTS is characterized by progressive deposition of collagen that occurs with high frequency in adult dermal wounds following traumatic or thermal injury. Increased levels of transforming growth factor-β1 (TGF-β1), decreased expression of small leucine-rich proteoglycans (SLRPs), and/or fibroblast subtypes may influence the development of HTS. The development of HTS is strongly influenced by the cellular and molecular properties of fibroblast subtypes, where cytokines such as fibrotic TGF-β1 and CTGF as well as the expression of SLRPs, particularly decorin and fibromodulin, regulate collagen fibrillogenesis and the activity of TGF-β1. Reduced anti-fibrotic molecules in the ECM of the deep dermis and the distinctive behavior of the fibroblasts in this region of the dermis which display increased sensitivity to TGF-β1's biological activity contribute to the development of HTS following injury to the deep dermis. By comparing the cellular and molecular differences involved in deep and superficial wound healing in an experimental wound scratch model in humans that has both superficial and deep injuries within the same excisional model, our aim is to increase our understanding of how tissue repair following injury to the deep dermis can be changed to promote healing with a similar pattern to healing that occurs following superficial injury that results in no or minimal scarring. Studying the characteristics of superficial dermal injuries that heal with minimal scarring will help us identify therapeutic approaches for tissue engineering and wound healing. In addition, our ability to develop novel therapies for HTS is hampered by limitations in the available animal models used to study this disorder in vivo. We also describe a nude mouse model of transplanted human skin that develops a hypertrophic proliferative scar consistent morphologically and histologically with human HTS, which can be used to test novel treatment options for these dermal fibrotic conditions.

A nude mouse model of hypertrophic scar shows morphologic and histologic characteristics of human hypertrophic scar

Hypertrophic scar (HSc) is a fibroproliferative disorder that occurs following deep dermal injury. Lack of a relevant animal model is one barrier toward better understanding its pathophysiology. Our objective is to demonstrate that grafting split-thickness human skin onto nude mice results in survival of engrafted human skin and murine scars that are morphologically, histologically, and immunohistochemically consistent with human HSc. Twenty nude mice were xenografted with split-thickness human skin. Animals were euthanized at 30, 60, 120, and 180 days postoperatively. Eighteen controls were autografted with full-thickness nude mouse skin and euthanized at 30 and 60 days postoperatively. Scar biopsies were harvested at each time point. Blinded scar assessment was performed using a modified Manchester Scar Scale. Histologic analysis included hematoxylin and eosin, Masson's trichrome, toluidine blue, and picrosirius red staining. Immunohistochemistry included anti-human human leukocyte antigen-ABC, α-smooth muscle actin, decorin, and biglycan staining. Xenografted mice developed red, shiny, elevated scars similar to human HSc and supported by blinded scar assessment. Autograft controls appeared morphologically and histologically similar to normal skin. Xenografts survived up to 180 days and showed increased thickness, loss of hair follicles, adnexal structures and rete pegs, hypercellularity, whorled collagen fibers parallel to the surface, myofibroblasts, decreased decorin and increased biglycan expression, and increased mast cell density. Grafting split-thickness human skin onto nude mice results in persistent scars that show morphologic, histologic, and immunohistochemical consistency with human HSc. Therefore, this model provides a promising technique to study HSc formation and to test novel treatment options.

Expression of MMP-2, TIMP-2, TGF-β1, and decorin in Dupuytren's contracture

To investigate the mechanisms underlying matrix deposition in Dupuytren's disease, the expression of gelatinase A (MMP-2), the tissue inhibitor of metalloproteinase-2 (TIMP-2), transforming growth factor beta 1 (TGF-β1), decorin (DCN), and periostin was studied. The level of relative MMP-2 activation was investigated using zymography. The mRNA expression of MMP-2, TIMP-2, TGF-β1, and DCN was detected using reverse transcription polymerase chain reaction (RT-PCR), while the presence of protein was detected using immunohistochemical (IHC) and Western blot techniques. The level of MMP-2 activation was significantly elevated in tissues with Dupuytren's contracture. RT-PCR demonstrated significantly higher expression of MMP-2, TIMP-2, TGF-β1, and DCN mRNA in the pathological tissues; and the IHC and immunoblotting studies revealed elevated expression of TGF-β1, DCN, and periostin. The balance between MMP-2 and TIMP-2 was disrupted in patients with Dupuytren's disease. TGF-β1, DCN, and periostin are involved in extracellular matrix (ECM) homeostasis in Dupuytren's contracture.

Circulating fibrocytes--biology and mechanisms in wound healing and scar formation

Fibrocytes were first described in 1994 as fibroblast-like, peripheral blood cells. These bone marrow-derived mesenchymal progenitor cells migrate into regions of tissue injury. They are unique in their expression of hematopoietic and monocyte lineage markers and extracellular matrix proteins. Several studies have focused on the specific role of fibrocytes in the process of wound repair and tissue regeneration. We discuss herein the biology and mechanistic action of fibrocytes in wound healing, scar formation, and maintenance of tissue integrity. Fibrocytes synthesize and secrete different cytokines, chemokines, and growth factors, providing a wound milieu that supports tissue repair. They further promote angiogenesis and contribute to wound closure via pathways involving specific cytokines, leukocyte-specific protein-1, serum amyloid P, and adenosine A(2A) receptors. Fibrocytes are involved in inflammatory fibrotic processes in such diseases as systemic fibrosis, atherosclerosis, asthma, hypertrophic scarring, and keloid formation. Accumulating literature has emphasized the important role of fibrocytes in wound healing and fibrosis. Detailed mechanisms nevertheless remain to be investigated to elucidate the full therapeutic potential of fibrocytes in the treatment of fibrosing disorders and the enhancement of tissue repair.

Smad ubiquitination regulatory factor 2 expression is enhanced in hypertrophic scar fibroblasts from burned children

Transforming growth factor-β1 (TGF-β1) plays a key role in hypertrophic scar formation. A lot of studies have shown that TGF-β1 stimulates fibroblast proliferation, collagen production, and α-smooth muscle actin (α-SMA) expression, inhibits matrix degradation and eventually leads to scar formation. Smad proteins are important intracellular mediators of TGF-β1 signaling, and Smad ubiquitination regulatory factor 2 (Smurf2), an ubiquitin ligase for Smads, plays critical roles in the regulation of TGF-β1/Smad signaling. It was reported that Smurf2 was abnormally expressed during the process of liver fibrosis and lung fibrosis. Hypertrophic scarring is a fibroproliferative disorder of the dermis that occurs following wounding. However, little is known about the expression of Smurf2 in hypertrophic scarring. We hypothesized that TGF-β1 signaling cannot be disrupted after wound epithelialization probably due to abnormal expression of Smurf2 in hypertrophic scar fibroblasts. In the present study, we found that hypertrophic scar fibroblasts exhibited increased Smurf2 protein and mRNA levels compared with normal fibroblasts, and the expression of Smurf2 gradually increased in hypertrophic scar fibroblasts after TGF-β1 stimulation. Furthermore, we transfected Smurf2 siRNA into hypertrophic scar fibroblasts, and we found that silencing the expression of Smurf2 in hypertrophic scar fibroblasts dramatically reduced TGF-β1 production, inhibited TGF-β1-induced α-SMA expression and inhibited TGF-β1-induced collagen I synthesis. Our results suggest that the enhanced expression of Smurf2 is involved in the progression of hypertrophic scarring.

Small leucine-rich proteoglycans, decorin and fibromodulin, are reduced in postburn hypertrophic scar

Small leucine-rich proteoglycans (SLRPs) are extracellular matrix molecules that regulate collagen fibrillogenesis and inhibit transforming growth factor-β activity; thus, they may play a critical role in wound healing and scar formation. Hypertrophic scarring is a dermal form of fibroproliferative disorders, which occurs in over 70% of burn patients and leads to disfigurement and limitations in function. By understanding the cellular and molecular mechanisms that lead to scarring after injury, new clinical therapeutic approaches can by developed to minimize abnormal scar formation in hypertrophic scarring and other fibroproliferative disorders. To study the expression and localization of SLRPs with connective tissue cells in tissue immunohistochemistry, immunofluorescence staining, immunoblotting, and reverse-transcription polymerase chain reaction were used in normal skin and hypertrophic scar (HTS). In normal skin, there was more decorin and fibromodulin accumulation in the superficial layers than in the deeper dermal layers. The levels of decorin and fibromodulin were significantly lower in HTS, whereas biglycan was increased when compared with normal skin. There was an increased expression of biglycan, fibromodulin, and lumican in the basement membrane and around basal epithelial cells. In contrast, these proteoglycans were absent or weakly expressed in HTS. The findings suggest that down-regulation of SLRPs after wound healing in deep injuries to the skin plays an important role in the development of fibrosis and HTS.

Molecular and structural mapping of collagen fibril interactions

The fibrous collagens form the structural basis of all mammalian connective tissues, including the vasculature, dermis, bones, tendons, cartilage, and those tissues that support organs such as the heart, kidneys, liver, and lungs. The helical structure of collagen has been extensively studied but in addition to its helical character, its molecular packing arrangement (in its aggregated or fibrillar form) and the presence of specific amino acid sequences govern collagen's in vivo functions. Collagen's molecular packing arrangement helps control cellular communication, attachment and movement, and conveys its tissue-specific biomechanical properties. Recent progress in understanding collagen's molecular packing, fibrillar structure, domain organization, and extracellular matrix (ECM) interactions in light of X-ray fiber diffraction data provides significant new insights into how the ECM is organized and functions. In this review, the hierarchy of fibrillar collagen structure is discussed in the context of how this organization affects ECM-"ligand" interactions, with specific attention to collagenolysis, integrins, fibronection, glycoprotein VI receptor (GPVI), and proteoglycans (PG). Understanding the complex structure of collagen and its attached ligands should provide new insights into tissue growth, development, regeneration, and disease.

Mechanical evaluation of the resistance and elastance of post-burn scars after topical treatment with tretinoin

OBJECTIVE

After burn injuries, scarred skin lacks elasticity, especially in hypertrophic scars. Topical treatment with tretinoin can improve the appearance and quality of the skin (i.e., texture, distensibility, color, and hydration). The objective of this prospective study was to examine the effects of treatment with 0.05% tretinoin for one year on the biomechanical behavior and histological changes undergone by facial skin with post-burn scarring.

SETTING

Tertiary, Institutional.

METHOD

Fifteen female patients who had suffered partial thickness burns with more than two years of evolution were selected. Skin biopsies were obtained initially and after one year of treatment. The resistance and elastance of these skin biopsies were measured using a mechanical oscillation analysis system. The density of collagen fibers, elastic fibers, and versican were determined using immunohistochemical analysis.

RESULTS

Tretinoin treatment significantly lowered skin resistance and elastance, which is a result that indicates higher distensibility of the skin. However, tretinoin treatment did not significantly affect the density of collagen fibers, elastic fibers, or versican.

CONCLUSION

Topical tretinoin treatment alters the mechanical behavior of post-burn scarred skin by improving its distensibility and thus leads to improved quality of life for patients.

Pathophysiology and management of the burn scar

Fibroproliferative disorders (FPDs) are common and serious disorders. Hypertrophic scar (HSc) and keloids represent the dermal equivalents of FPD and impose lower mortality but great morbidity. This article reviews current knowledge in the pathophysiology and molecular and cellular characteristics of postburn HSc. Additionally, current treatment modalities and future treatment options based on advancements in the understanding of the pathophysiology of HSc are discussed.

Molecular dissection of abnormal wound healing processes resulting in keloid disease

Keloids are locally aggressive scars that typically invade into healthy surrounding skin and cause both physical and psychosocial distress to the patient. These pathological scars occur following minimal skin trauma after a variety of causes including burns and trauma. Although the pathogenesis of keloid disease is not well understood, it is considered to be the end product of an abnormal healing process. The aim of this review was to investigate the molecular and cellular pathobiology of keloid disease in relation to the normal wound healing process. The molecular aberrances in keloids that correlate with the molecular mechanisms in normal wound healing can be categorized into three groups: (1) extracellular matrix proteins and their degradation, (2) cytokines and growth factors, and (3) apoptotic pathways. With respect to cellular involvements, fibroblasts are the most well-studied cell population. However, it is unclear whether the fibroblast is the causative cell; they are modulated by other cell populations in wound repair, such as keratinocytes and macrophages. This review presents a detailed account of individual phases of the healing process and how they may potentially be implicated in aberrant raised scar formation, which may help in clarifying the mechanisms involved in keloid disease pathogenesis.

Potential cellular and molecular causes of hypertrophic scar formation

A scar is an expected result of wound healing. However, in some individuals, and particularly in burn victims, the wound healing processes may lead to a fibrotic hypertrophic scar, which is raised, red, inflexible and responsible for serious functional and cosmetic problems. It seems that a wide array of subsequent processes are involved in hypertrophic scar formation, like an affected haemostasis, exaggerated inflammation, prolonged reepithelialization, overabundant extracellular matrix production, augmented neovascularization, atypical extracellular matrix remodeling and reduced apoptosis. Platelets, macrophages, T-lymphocytes, mast cells, Langerhans cells and keratinocytes are directly and indirectly involved in the activation of fibroblasts, which in turn produce excess extracellular matrix. Following the chronology of normal wound healing, we unravel, clarify and reorganize the complex molecular and cellular key processes that may be responsible for hypertrophic scars. It remains unclear whether these processes are a cause or a consequence of unusual scar tissue formation, but raising evidence exists that immunological responses early following wounding play an important role. Therefore, when developing preventive treatment modalities, one should aim to put the early affected wound healing processes back on track as quickly as possible.

Review of the female Duroc/Yorkshire pig model of human fibroproliferative scarring

Hypertrophic scarring after burns is an unsolved problem and remains as devastating today as it was in the 40s and it may be that the main reason for this is the lack of an accepted, useful animal model. The female, red Duroc pig was described as a model of hypertrophic scarring nearly 30 years ago but then vanished from the literature. This seemed strange since the authors reported that 12 of 12 pigs developed thick scar. In the mid 90s we explored the model and found that, indeed, the red Duroc pig does make thick scar. Other authors have established that the Yorkshire pig does not heal in this fashion so there is the possibility of a same species control. We have continued to explore the Duroc/Yorkshire model and herein describe our experiences. Is it a perfect model of hypertrophic scarring? No. Is it a useful model of hypertrophic scarring? Time will tell. We have now obtained gene expression data from the Duroc/Yorkshire model and analysis is underway.

Recombinant human decorin inhibits cell proliferation and downregulates TGF-beta1 production in hypertrophic scar fibroblasts

Hypertrophic scarring remains a major problem for patients who have suffered deep burns. The pathophysiology underlying hypertrophic scar formation may be driven by the biological activity of transforming growth factor beta1 (TGF-beta(1)). Decorin is a human proteoglycan that inactivates the effect of TGF-beta(1) and therefore displays a beneficial effect of antifibrosis in various tissues. Hypertrophic scarring is a fibroproliferative disorder of the dermis that occurs following wounding. This study investigated the effects of decorin on cell proliferation, TGF-beta(1) production, and collagen synthesis in hypertrophic scar fibroblasts. The cell proliferation rates, cell cycle distribution, low-molecular-weight apoptotic DNA and TGF-beta(1) levels, and contents of type I and type III collagen amino-terminal propeptide (PINP, PIIINP) in supernatants were assessed. Fibroblast proliferation was significantly (P<0.05) inhibited by decorin, and this effect was dose-dependent. The fibroblast population became stationary at decorin concentrations of 100 and 200 nM. Decorin inhibited fibroblast proliferation by inducing cell growth arrest but not apoptosis. TGF-beta(1) and PINP levels were significantly (P<0.05) lower in fibroblasts treated with 10, 50, 100, 200 nM of decorin compared with fibroblasts without decorin addition. However, there was no significant difference in PIIINP concentration between the decorin-treated group and the control group. These results suggest that decorin has a down-regulatory effect on cell proliferation, TGF-beta(1) production, and collagen synthesis in hypertrophic scar fibroblasts. Improved understanding of such a regulatory mechanisms may eventually be of therapeutic significance in the control of hypertrophic scarring.

A porcine deep dermal partial thickness burn model with hypertrophic scarring

We developed a reproducible model of deep dermal partial thickness burn injury in juvenile Large White pigs. The contact burn is created using water at 92 degrees C for 15s in a bottle with the bottom replaced with plastic wrap. The depth of injury was determined by a histopathologist who examined tissue sections 2 and 6 days after injury in a blinded manner. Upon creation, the circular wound area developed white eschar and a hyperaemic zone around the wound border. Animals were kept for 6 weeks or 99 days to examine the wound healing process. The wounds took between 3 and 5 weeks for complete re-epithelialisation. Most wounds developed contracted, purple, hypertrophic scars. On measurement, the thickness of the burned skin was approximately 1.8 times that of the control skin at week 6 and approximately 2.2 times thicker than control skin at 99 days after injury. We have developed various methods to assess healing wounds, including digital photographic analysis, depth of organising granulation tissue, immunohistochemistry, electron microscopy and tensiometry. Immunohistochemistry and electron microscopy showed that our porcine hypertrophic scar appears similar to human hypertrophic scarring. The development of this model allows us to test and compare different treatments on burn wounds.

Vocal Fold Wound Healing: A Review for Clinicians

SUMMARY

The basic science of wound healing is largely omitted from the curriculum of many voice clinicians. This fact is relatively disheartening as most therapeutic manipulation in the realm of laryngology and voice disorders deals with injured tissue. Therefore, the selection of therapeutic tasks for persons with vocal injury should ideally be informed by basic science in wound healing. Recently, several investigators have initiated lines of research to determine the course of vocal fold wound healing and the potential role of therapeutic agents, including behavioral agents. The current review seeks to provide a foundation of basic wound healing science and present the most current data regarding the wound healing process in the vocal folds.

Combined tretinoin and glycolic acid treatment improves mouth opening for postburn patients

Postburn tissue repair progresses late, with changes in the skin's physical properties. Clinically, the skin appears dry, scaly, and dyschromic, with diminished elasticity, particularly in the presence of hypertrophic scars. Improvement of postburn skin can be obtained by using topical agents normally used in pathologies such as acne and photoaging. This study analyzed 77 patients, ages 6 to 46 years, with late perioral burn sequelae. The resulting integument was classified as grafted or restored when it epithelialized spontaneously. Topical treatment consisted of tretinoin (0.01-0.05%) and glycolic acid (5-7%) over a 3-month period. With the mouth opened maximally, the interdental (D) and interlabial (L) distances were measured using a digital caliper. Significant increases in D and L distances were observed after treatment, as compared with controls (p < 0.01). These results were similar in the restored and skin-grafted groups.

Suppression of inflammatory and fibrotic responses in allergic inflammation by the amniotic membrane stromal matrix

BACKGROUND

The amniotic membrane (AM), which is the innermost layer of the placenta, was shown to possess anti-inflammatory and anti-fibrotic properties in various in vitro and clinical studies.

PURPOSE

To evaluate the anti-fibrotic and anti-inflammatory effects of the AM matrix (AMM) on human conjunctival and lung fibroblasts in an in vitro system that tests fibrotic and inflammatory responses at the effector stages of allergic inflammation.

METHODS

Human conjunctival or lung fibroblasts were seeded on plastic or on the stromal aspect of the AM, which was mounted on plastic inserts. Sonicates of human peripheral blood eosinophils activated with lipopolysaccharide (LPS), or human mast cell (HMC-1) leukaemia cell sonicates, were added to sub-confluent fibroblast monolayers. Proliferation of the sub-confluent fibroblasts was assessed using the [3H]-thymidine incorporation assay. The production of transforming growth factor (TGF)-beta1, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-8 in conjunctival or lung fibroblasts was measured in conditioned media from these cultures by ELISA.

RESULTS

After 4 days in culture, the [3H]-thymidine incorporation assay indicated a reduced proliferation of activated conjunctival and lung fibroblasts when cultured directly on the AMM. The production of both TGF-beta1 and IL-8 was significantly suppressed in activated conjunctival fibroblasts cultured on the AMM compared with those cultured on plastic, while the production of both TGF-beta1 and GM-CSF was decreased in human lung fibroblast cultured on the AMM.

CONCLUSIONS

The AMM is capable of suppressing fibrotic responses in an in vitro system of effector stages of ocular allergic inflammation. These data may provide a basis for exploring matrix components in the AM for the treatment of allergic eye disease.

Dermatopontin, a novel player in the biology of the extracellular matrix

Dermatopontin is a widely distributed small molecular weight protein in the extracellular matrix (ECM) and today its homologues are known in five mammals and several invertebrates. The structures of these homologues are relatively well conserved among the species. In the skin, dermatopontin is located mainly on the surface of the collagen fibers. It is found in the conditioned medium and also in the cytoplasm of cultured fibroblasts. Early studies focused on ECM assembly (collagen fibrillogenesis) and interactions (with the proteoglycan decorin). Subsequently, a targeted disruption of dermatopontin resulted in a phenotype similar to Ehlers-Danlos syndrome. In addition, a cell adhesion activity of this protein for dermal fibroblasts and several other cells was found, and this activity might suggest this protein's involvement in wound healing. The expression of dermatopontin around an infarct zone of experimental myocardial infarction may support this possibility. In invertebrates, dermatopontin homologues act mainly as adhesion/agglutination molecules. In addition, we found that transforming growth factor-beta1 interacts with dermatopontin and the function of this cytokine is modified by dermatopontin. Recently, the involvement of this protein in cell proliferation has been indicated. In this review we describe the reported functions of this protein and speculate on the multiple roles of this largely uncharacterized matrix molecule.

The bioactivity of transforming growth factor-beta1 can be regulated via binding to dermal collagens in mink lung epithelial cells

BACKGROUND

The bioactivity of transforming growth factor-beta1 (TGF-beta1) is known to be regulated by some components of the extracellular matrix (ECM), but the possibility that it might be regulated by collagen, the richest ECM component, has never been previously reported.

OBJECTIVE

This study was designed to investigate the possible role that different types of collagens might play on the bioactivity of TGF-beta1.

METHODS

The interaction of 125I-TGF-beta1 and various types of collagen was examined by a solid-phase assay and by a co-precipitation assay. The bioactivity of TGF-beta1 was assessed by a proliferation assay in which mink lung epithelial cells were examined in the presence and absence of collagens.

RESULTS

Activated native dimeric TGF-beta1 bound to type I collagen in a dose-dependent manner, while monomeric TGF-beta1 bound poorly to the collagen. Type III collagen, and type I gelatin, a heat-denatured type I collagen, also showed a similar interaction with TGF-beta1, however, type IV collagen showed a weak interaction. In the presence of types I and III collagens, the inhibitory effect of TGF-beta1 on the proliferation of mink lung epithelial cells was sustained, thus suggesting that the bioactivity of TGF-beta1 had been enhanced. Type I gelatin also enhanced the inhibition of cell growth, but its effect was weak in comparison with that of type I collagen. The amount of TGF-beta1 which remained intact in the conditioned medium after incubation with MLEC in the presence of types I and III collagens was more than that incubated without collagen.

CONCLUSIONS

Our results suggest that types I and III collagens, the two most abundant components of the interstitial collagens, can potentially bind to activated TGF-beta1 and regulate the bioactivity of this growth factor, thereby possibly maintaining the biologically available TGF-beta1 level.

Advances in the Modulation of Cutaneous Wound Healing and Scarring

Cutaneous wounds inevitably heal with scars, which can be disfiguring and compromise function. In general, the greater the insult, the worse the scarring, although genetic make up, regional variations and age can influence the final result. Excessive scarring manifests as hypertrophic and keloid scars. At the other end of the spectrum are poorly healing chronic wounds, such as foot ulcers in diabetic patients and pressure sores. Current therapies to minimize scarring and accelerate wound healing rely on the optimization of systemic conditions, early wound coverage and closure of lacerations, and surgical incisions with minimal trauma to the surrounding skin. The possible benefits of topical therapies have also been assessed. Further major improvements in wound healing and scarring require an understanding of the molecular basis of this process. Promising strategies for modulating healing include the local administration of platelet derived growth factor (PDGF)-BB to accelerate the healing of chronic ulcers, and increasing the relative ratio of transforming growth factor (TGF)beta-3 to TGFbeta-1 and TGFbeta-2 in order to minimize scarring.