Expression of proteoglycans and hyaluronan during wound healing

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.

More than just a filler - the role of hyaluronan for skin homeostasis

In recent years, hyaluronan (HA) has become an increasingly attractive substance as a non-immunogenic filler and scaffolding material in cosmetic dermatology. Despite its wide use for skin augmentation and rejuvenation, relatively little is known about the molecular structures and interacting proteins of HA in normal and diseased skin. However, a comprehensive understanding of cutaneous HA homeostasis is required for future the development of HA-based applications for skin regeneration. This review provides an update on HA-based structures, expression, metabolism and its regulation, function and pharmacological targeting of HA in skin.

Homeostasis of hyaluronic acid in normal and scarred vocal folds

OBJECTIVES/HYPOTHESIS

Vocal fold scarring is one of the most challenging laryngeal disorders to treat. Hyaluronic acid (HA) is the main component of lamina propria, and it plays an important role in proper vocal fold vibration and is also thought to be important in fetal wound healing without scarring. Although several animal models of vocal fold scarring have been reported, little is known about the way in which HA is maintained in vocal folds. The purpose of this study was to clarify the homeostasis of HA by examining the expression of hyaluronan synthase (Has) and hyaluronidase (Hyal), which produce and digest HA, respectively.

STUDY DESIGN

Experimental prospective animal study.

METHODS

Vocal fold stripping was performed on 38 Sprague-Dawley rats. Vocal fold tissue was collected at five time points (3 days-2 months). Expression of HA was examined by immunohistochemistry, and messenger RNA (mRNA) expression of Has and Hyal was examined by real-time polymerase chain reaction and in-situ hybridization.

RESULTS

In scarred vocal folds, expression of Has1 and Has2 increased at day 3 together with expression of HA and returned to normal at 2 weeks. At 2 months, Has3 and Hyal3 mRNA showed higher expressions than normal.

CONCLUSIONS

Expression patterns of Has and Hyal genes differed between normal, acute-scarred, and chronic-scarred vocal folds, indicating the distinct roles of each enzyme in maintaining HA. Continuous upregulation of Has genes in the acute phase may be necessary to achieve scarless healing of vocal folds.

Hyaluronic Acid as an adjunct to scaling and root planing in chronic periodontitis. A randomized clinical trail

AIM

AIM of the present study was to evaluate the adjunctive effect of local application of hyaluronon gel following scaling and root planing (SRP) in chronic periodontitis patients.

MATERIALS AND METHODS

In this randomized split mouth study 33 subjects with chronic periodontitis were evaluated after full mouth SRP. In the test sites hyaluronon gel was applied immediately after SRP and one week post therapy, the control sites were treated with SRP alone. Bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL) were recorded at baseline, 4 wk and 12 wk.

RESULTS

Significant reduction in BOP scores was observed in both the groups at 12weeks (p<0.001). The hyaluronon group showed a greater reduction in BOP (p<0.001). In the hyaluronon group the mean PPD at baseline was 6.33±0.09 which reduced to 2.49±0.51 at 12 weeks which was statistically significant (p<0.001). In the control group the mean PPD at baseline was 6.09±1.26 which reduced to 4.36±1.29 at 12 weeks which was statistically significant (p<0.001). The CAL measurements showed a significant difference between the groups (p<0.001) at 12 wk post therapy.

CONCLUSION

Hyaluronic Acid (HA) has a beneficial effect on periodontal health in patients with chronic Periodontitis. HA appears to be a suitable candidate as an adjunct to SRP in chronic periodontitis patients.

Hyaluronan and cardiac regeneration

Hyaluronan (HA) is abundantly expressed in several human tissues and a variety of roles for HA has been highlighted. Particularly relevant for tissue repair, HA is actively produced during tissue injury, as widely evidenced in wound healing investigations. In the heart HA is involved in physiological functions, such as cardiac development during embryogenesis, and in pathological conditions including atherosclerosis and myocardial infarction. Moreover, owing to its relevant biological properties, HA has been widely used as a biomaterial for heart regeneration after a myocardial infarction. Indeed, HA and its derivatives are biodegradable and biocompatible, promote faster healing of injured tissues, and support cells in relevant processes including survival, proliferation, and differentiation. Injectable HA-based therapies for cardiovascular disease are gaining growing attention because of the benefits obtained in preclinical models of myocardial infarction. HA-based hydrogels, especially as a vehicle for stem cells, have been demonstrated to improve the process of cardiac repair by stimulating angiogenesis, reducing inflammation, and supporting local and grafted cells in their reparative functions. Solid-state HA-based scaffolds have been also investigated to produce constructs hosting mesenchymal stem cells or endothelial progenitor cells to be transplanted onto the infarcted surface of the heart. Finally, applying an ex-vivo mechanical stretching, stem cells grown in HA-based 3D scaffolds can further increase extracellular matrix production and proneness to differentiate into muscle phenotypes, thus suggesting a potential strategy to create a suitable engineered myocardial tissue for cardiac regeneration.

The use of hyaluronic acid based dressings to treat burns: A review

Deep cutaneous lesions such as burns, traumas or ulcers are all conditions characterized by a massive loss of dermis, bringing several important consequences. For the treatment of these conditions, the evolution of material science has made available new dressings based on natural and synthetic polymers. Hyaluronic acid (HA) is involved in many steps of the wound healing process, such as inflammation, granulation and re-epithelialization. In order to overcome the poor physical properties of the native polymer, such as solubility and rapid degradation, insoluble molecules starting from the natural compound were produced via esterification. Thanks to their improved structural properties, the dressings based on these hyaluronic acid derivatives represent a valuable option for the treatment of deep burns. This narrative monograph describes the development and the outcome of the use of these products in burns. The currently available clinical experience suggests that these HA medical devices represent a safe therapeutic method useful for the treatment of acute wounds.

Temporal expression of hyaluronic acid and hyaluronic acid receptors in a porcine small intestinal submucosa-augmented rat bladder regeneration model

INTRODUCTION

Hyaluronic acid (HA), a non-sulfated glycosaminoglycan, is an essential component of the extracellular matrix (ECM). Since HA is involved in many phases of wound healing and may play a key role in tissue repair and regeneration, this study was intended to understand temporal and spatial expression of HA and HA receptors (HARs) during the course of bladder regeneration in rats.

MATERIALS AND METHODS

Sprague-Dawley rats were subjected to partial cystectomy followed by augmentation with porcine small intestinal submucosal (SIS) prepared from distal sections of the small intestine. SIS-augmented bladders were harvested between postoperative days 2 and 56.

RESULTS

Bladder regeneration proceeded without complications. All augmented bladders had complete urothelial lining and smooth muscle bundles by day 56 post-augmentation. Temporal and spatial distributions of HA and HARs were studied by immunohistochemistry in regenerating bladders. The strongest HA immunoreactivity was observed in the ECM on postoperative days 28 and 56. Cluster of differentiation 44 (CD44) immunoreactivity was detected in the cytoplasm of urothelial cells on day 56; and LYVE-1 immunoreactivity was exclusively limited to lymphatic vessels on days 28 and 56.

CONCLUSIONS

We demonstrated that HA was synthesized throughout the course of bladder wound healing and regeneration; and HA deposition coincided with urothelial differentiation. Expression of CD44 and LYVE-1 followed the same temporal pattern as HA deposition. Therapeutic modalities through local delivery of exogenous HA to improve the outcome of SIS-mediated bladder regeneration might need to be coordinated with HAR expression in order to achieve maximal regenerative responses as opposed to fibrosis.

Opposite role of CD44-standard and CD44-variant-3 in tubular injury and development of renal fibrosis during chronic obstructive nephropathy

Chronic kidney diseases (CKDs) are characterized by tubular atrophy and interstitial fibrosis. We previously showed that in obstructive nephropathy de novo CD44 renal expression contributes to renal fibrosis but attenuates tubular damage/apoptosis. As CD44-standard (CD44s) has been linked to TGF-β1-mediated actions and CD44-variant-3 (CD44v3) favors HGF-c-Met binding, we compared the functional properties of these CD44 isoforms in the progression of obstructive nephropathy, using specific CD44-variant knockout/knockin mice. The presence of CD44v3 diminished tubular damage during obstructive nephropathy, decreased apoptosis, and increased proliferation of tubular epithelial cells, and prevented renal fibrosis development. In contrast, expression of CD44s led to increased tubular damage and tubular epithelial cell apoptosis, and more renal fibrosis. A relative increase in renal β-catenin expression, HGF production, and HGF/c-Met signaling, together with a relative inhibition of TGF-β1 downstream signaling and TGF-β type I receptor expression, was found in CD44v3 mice compared with CD44s littermates. In line with this, Wnt3a/HGF treatment of tubular cells resulted in higher β-catenin/p-AKT levels in CD44v3(+) tubular epithelial cells, whereas TGF-β1 induced a mild collagen I upregulation in CD44v3(+) mouse embryonic fibroblasts as compared with CD44s(+) cells. Thus, CD44s and CD44v3 exert opposite roles in the progression of obstructive nephropathy, with CD44v3-v10 being the protective isoform that delays evolution of the renal pathology.

Hydrocellular foam dressing promotes wound healing along with increases in hyaluronan synthase 3 and PPARα gene expression in epidermis

BACKGROUND

Hydrocellular foam dressing, modern wound dressing, induces moist wound environment and promotes wound healing: however, the regulatory mechanisms responsible for these effects are poorly understood. This study was aimed to reveal the effect of hydrocellular foam dressing on hyaluronan, which has been shown to have positive effects on wound healing, and examined its regulatory mechanisms in rat skin.

METHODOLOGY/PRINCIPAL FINDINGS

We created two full-thickness wounds on the dorsolateral skin of rats. Each wound was covered with either a hydrocellular foam dressing or a film dressing and hyaluronan levels in the periwound skin was measured. We also investigated the mechanism by which the hydrocellular foam dressing regulates hyaluronan production by measuring the gene expression of hyaluronan synthase 3 (Has3), peroxisome proliferator-activated receptor α (PPARα), and CD44. Hydrocellular foam dressing promoted wound healing and upregulated hyaluronan synthesis, along with an increase in the mRNA levels of Has3, which plays a primary role in hyaluronan synthesis in epidermis. In addition, hydrocellular foam dressing enhanced the mRNA levels of PPARα, which upregulates Has3 gene expression, and the major hyaluronan receptor CD44.

CONCLUSIONS/SIGNIFICANCE

These findings suggests that hydrocellular foam dressing may be beneficial for wound healing along with increases in hyaluronan synthase 3 and PPARα gene expression in epidermis. We believe that the present study would contribute to the elucidation of the mechanisms underlying the effects of hydrocellular foam dressing-induced moist environment on wound healing and practice evidence-based wound care.

Mechanical and biocompatible characterization of a cross-linked collagen-hyaluronic acid wound dressing

Collagen scaffolds have been widely employed as a dermal equivalent to induce fibroblast infiltrations and dermal regeneration in the treatment of chronic wounds and diabetic foot ulcers. Cross-linking methods have been developed to address the disadvantages of the rapid degradation associated with collagen-based scaffolds. To eliminate the potential drawbacks associated with glutaraldehyde cross-linking, methods using a water soluble carbodiimide have been developed. In the present study, the glycosaminoglycan (GAG) hyaluronic acid (HA), was covalently attached to an equine tendon derived collagen scaffold using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) to create ntSPONGE™. The HA was shown to be homogeneously distributed throughout the collagen matrix. In vitro analyses of the scaffold indicated that the cross-linking enhanced the biological stability by decreasing the enzymatic degradation and increasing the thermal denaturation temperature. The material was shown to support the attachment and proliferation of mouse L929 fibroblast cells. In addition, the cross-linking decreased the resorption rate of the collagen as measured in an intramuscular implant model in rabbits. The material was also shown to be biocompatible in a variety of in vitro and in vivo assays. These results indicate that this cross-linked collagen-HA scaffold, ntSPONGE™, has the potential for use in chronic wound healing.

Severe hidradenitis suppurativa treatment using platelet-rich plasma gel and Hyalomatrix

Hidradenitis suppurativa (HS) can be a debilitating chronic disease. The underlying cause of the disease is still not clear. HS may be managed through numerous different medical or surgical procedures. Surgical treatment may consist of local excisions and reconstruction using a variety of methods: perforator flaps, skin grafts, local flaps, primary closure or secondary wound healing with vacuum and other devices. This report describes our experience with surgical excision and closure using platelet-rich plasma (PRP) gel and Hyalomatrix PA (HPA) in a patient with severe HS involving most of the body surface. We treated the patient with resection of severe HS of the nuchae and closure with PRP gel prepared with the RegenKit(®) to promote neovascularisation and HPA, a delivery system for hyaluronic acid, to induce a neodermis at the wound bed and to stimulate regeneration in a humid and protected environment. Complete wound healing was achieved after 2 months. The obtained result proved the efficacy of this treatment without complications. No recurrence was observed during the 1 year after the surgical procedure. Severe HS can be safely and effectively managed with wide excision, PRP gel and Hyalomatrix to achieve a successful outcome.

Hyaluronic Acid: a boon in periodontal therapy

Hyaluronic acid is a naturally occurring linear polysaccharide of the extracellular matrix of connective tissue, synovial fluid, and other tissues. Its use in the treatment of the inflammatory process is established in medical areas such as orthopedics, dermatology, and ophthalmology. The Pubmed/Medline database was searched for keywords “Hyaluronic acid and periodontal disease” and “Hyaluronic acid and gingivitis” which resulted in 89 and 22 articles respectively. Only highly relevant articles from electronic and manual search in English literature were selected for the present review article. In the field of dentistry, hyaluronic acid has shown anti-inflammatory and anti-bacterial effects in the treatment of periodontal diseases. Due to its tissue healing properties, it could be used as an adjunct to mechanical therapy in the treatment of periodontitis. Further studies are required to determine the clinical efficacy of hyaluronic acid in healing of periodontal lesion. The aim of the present review, article is to discuss the role of hyaluronic acid in periodontal therapy.

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.

Laminin 332 processing impacts cellular behavior

Laminin 332, composed of the α3, β3 and γ2 chains, is an epithelial-basement membrane specific laminin variant. Its main role in normal tissues is the maintenance of epithelial-mesenchymal cohesion in tissues exposed to external forces, including skin and stratified squamous mucosa. After being secreted and deposited in the extracellular matrix, laminin 332 undergoes physiological maturation processes consisting in the proteolytic processing of domains located within the α3 and the γ2 chains. These maturation events are essential for laminin 332 integration into the basement membrane where it plays an important function in the nucleation and maintenance of anchoring structures. Studies in normal and pathological situations have revealed that laminin 332 can trigger distinct cellular events depending on the level of its proteolytic cleavages. In this review, the biological and structural characteristics of laminin 332 domains are presented and we discuss whether they trigger specific functions.

The role of hyaluronan in wound healing

The polysaccharide hyaluronan (HA) (synonyms - hyaluronic acid, hyaluronate) is a versatile, polymorphic, glycosoaminoglycan with vast biological functions. HA is found throughout the body, primarily residing in skin, thus playing an important role in wound healing. Research regarding HA's function has changed over the years, primarily focussing on a particular aspect or function. The contribution of HA in each stage of normal wound healing as well as its clinical wound dressing applications will be examined.

Cell proliferation and apoptosis in the fusion of human primary and secondary palates

The markers of cell proliferation (Ki-67) and apoptosis [caspase-3, TdT-mediated biotin-dUTP nick-end labelling (TUNEL)] and the expression of syndecan-1 and heat shock protein 70 (Hsp70) were analyzed immunohistochemically in 11 developing human palates, from developmental weeks 6 to 10. During fusion of the primary palate, the proportion of proliferating cells decreased from 42 to 32% and the proportion of apoptotic cells decreased from 11 to 7% in the medial-edge epithelium. At later stages, the proportions of both types of cells decreased in the ectomesenchyme, except for proliferating cells in its non-condensing part. At developmental weeks 9-10, the epithelial seam in the secondary palate comprised 28% proliferative cells and 5% apoptotic cells. While condensing ectomesenchyme contained more apoptotic cells than proliferating cells, the opposite was observed for the non-condensing ectomesenchyme. Co-expression of syndecan-1 and Hsp70 was detected in cells budding from the epithelial seam. Our study indicates similar principles for human primary palate and secondary palate fusion, and parallel persistence of proliferation and apoptotic activity. While proliferation enables growth and fusion of different palatal primordia, apoptosis results in the removal of of large numbers epithelial cells at the fusion point. The disintegration of seam remnants seems to be executed through the processes of change in protein content and cell migration, probably leading to cell death as their final outcome.

Sugar-coating wound repair: a review of FGF-10 and dermatan sulfate in wound healing and their potential application in burn wounds

Thousands of patients suffer from burn injuries each year, yet few therapies have been developed to accelerate the wound healing process. Most fibroblast growth factors (FGFs) have been extensively evaluated but only a few have been found to participate in the wound healing process. In particular, FGF-10 is robustly increased in the wound microenvironment after injury and has demonstrated some ability to promote wound healing in vitro and in vivo. Glycosaminoglycans are linear carbohydrates that participate in wound repair by influencing cytokine/growth factor localization and interaction with cognate receptors. Dermatan sulfate (DS) is the most abundant glycosaminoglycan in human wound fluid and has been postulated to be directly involved in the healing process. Recently, the combination of FGF-10 and DS demonstrated the potential to accelerate wound healing via increased keratinocyte proliferation and migration. Based on these preliminary studies, DS may serve as a cofactor for FGF-10, and together they are likely to expedite the healing process by stimulating keratinocyte activity. As a specific subtype of wounds, the overall healing process of burn injuries does not significantly differ from other types of wounds, where optimal repair results in matrix regeneration and complete reepithelialization. At present, standard burn treatment primarily involves topical application of antimicrobial agents, while no routine therapies target acceleration of reepithelialization, the key to wound closure. Thus, this novel therapeutic combination could be used in conjunction with some of the current therapies, but it would have the unique ability to initiate wound healing by stimulating keratinocyte epithelialization.

Renal interstitial hyaluronan: functional aspects during normal and pathological conditions

The glycosaminoglycan (GAG) hyaluronan (HA) is recognized as an important structural component of the extracellular matrix, but it also interacts with cells during embryonic development, wound healing, inflammation, and cancer; i.e., important features in normal and pathological conditions. The specific physicochemical properties of HA enable a unique hydration capacity, and in the last decade it was revealed that in the interstitium of the renal medulla, where the HA content is very high, it changes rapidly depending on the body hydration status while the HA content of the cortex remains unchanged at very low amounts. The kidney, which regulates fluid balance, uses HA dynamically for the regulation of whole body fluid homeostasis. Renomedullary HA elevation occurs in response to hydration and during dehydration the opposite occurs. The HA-induced alterations in the physicochemical characteristics of the interstitial space affects fluid flux; i.e., reabsorption. Antidiuretic hormone, nitric oxide, angiotensin II, and prostaglandins are classical hormones/compounds involved in renal fluid handling and are important regulators of HA turnover during variations in hydration status. One major producer of HA in the kidney is the renomedullary interstitial cell, which displays receptors and/or synthesis enzymes for the hormones mentioned above. During several kidney disease states, such as ischemia-reperfusion injury, tubulointerstitial inflammation, renal transplant rejection, diabetes, and kidney stone formation, HA is upregulated, which contributes to an abnormal phenotype. In these situations, cytokines and other growth factors are important stimulators. The immunosuppressant agent cyclosporine A is nephrotoxic and induces HA accumulation, which could be involved in graft rejection and edema formation. The use of hyaluronidase to reduce pathologically overexpressed levels of tissue HA is a potential therapeutic tool since diuretics are less efficient in removing water bound to HA in the interstitium. Although the majority of data describing the role of HA originate from animal and cell studies, the available data from humans demonstrate that an upregulation of HA also occurs in diabetic kidneys, in transplant-rejected kidneys, and during acute tubular necrosis. This review summarizes the current knowledge regarding interstitial HA in the role of regulating kidney function during normal and pathological conditions. It encompasses mechanistic insights into the background of the heterogeneous intrarenal distribution of HA; i.e., late nephrogenesis, its regulation during variations in hydration status, and its involvement during several pathological conditions. Changes in hyaluronan synthases, hyaluronidases, and binding receptor expression are discussed in parallel.

Wound healing through synergy of hyaluronan and an iodine complex

Hyaluronan, a glycosaminoglycan (GAG), is a polysaccharide found in many locations in the human body, such as eye, skin and soft tissue. It is also found in other mammals and bacteria. As a component of the extracellular matrix, its role in wound repair, among others, is that of providing a temporary structure to support new tissue formation. Harnessing the therapeutic action of hyaluronan into a topical application of proven clinical benefit has proved challenging. A new development in hyaluronan technology, comprising sodium hyaluronate and iodine complex, offers a novel approach in exploiting the benefits of hyaluronan and delivering real clinical benefits for a wide range of wound types.

The effect of hyaluronan on airway mucus transport and airway epithelial barrier integrity: potential application to the cytoprotection of airway tissue

The lubricating abilities and the protective functions of hyaluronan, a structural component of interstitial and connective tissues, were assessed in in vitro models of airway mucus transport and epithelial barrier. We found that hyaluronan enhanced the transport of airway mucus by cilia and by cough: the lower the hyaluronan molecular weight, the higher the increase. By immunofluorescence and western blot, we observed a significant dose-dependent (0.1, 1, 5 and 10 mg/ml) increase by low molecular weight hyaluronan (40 kDa) in the expression of tight junction proteins such as ZO-1, as well as an increase in the trans-epithelial resistance. Incubation of airway epithelial cells with hyaluronan 40 kDa also significantly increased the gap junction functionality. Finally, we demonstrated that hyaluronan 40 kDa protects the airway epithelium against injury induced by bacterial products during infection. These results demonstrate that the expression and functionality of intercellular adhesion molecules are increased by hyaluronan which can also act as a lubricant at the airway epithelium surface and suggest that hyaluronan may play a therapeutic role in a variety of respiratory diseases.

Syndecan-1 immunohistochemical expression in gingival tissues of chronic periodontitis patients correlated with various putative factors

BACKGROUND AND OBJECTIVE

Limited information is available on the expression and distribution of syndecan-1 within human gingival tissues/cells and on putative factors that might affect its expression. Therefore, the objective of the present study was to determine immunohistochemically the expression and distribution of syndecan-1 in the gingival tissues of patients with chronic periodontitis and to examine the correlation of syndecan-1 expression with various putative factors (environmental, patient/systemic and local factors).

MATERIAL AND METHODS

Gingival specimens were surgically excised from the area of the junctional/pocket epithelium (study group 1, including 30 chronic periodontitis patients) or the gingival oral epithelium (study group 2, comprising another 30 chronic periodontitis patients), adjacent to teeth with poor prognosis. Standard two-step immunohistochemistry and semi-quantitative evaluation of immunohistochemical staining were used to determine syndecan-1 expression. Statistical analyses on the impact of various putative factors were performed.

RESULTS

In the junctional/pocket epithelium or the oral epithelium, syndecan-1 expression was weak to moderate in the suprabasal and basal epithelial cells and absent to weak in the internal basal lamina, external basal lamina and gingival connective tissue matrix. Syndecan-1 expression in the junctional/pocket epithelium was statistically significantly stronger than in the oral epithelium in inflammatory cells within the underlying gingival connective tissue (primarily plasma cells and lymphocytes) and in scattered fibroblast-like cells.

CONCLUSIONS

Syndecan-1 expression in the junctional/pocket epithelium or the oral epithelium can exhibit a significant positive correlation with the severity/degree of histologically evaluated local gingival inflammation, but in general is not significantly correlated with age, smoking, full-mouth and local clinical (probing pocket depth and clinical attachment level) and radiographical parameters (radiographical bone loss) of periodontal status.

Glycosaminoglycans restrained in a fibrin matrix improve ECM remodelling by endothelial cells grown for vascular tissue engineering

The success of a biocompatible vascular graft depends upon its mechanical attributes and post-implantation healing responses. Mechanical strength is a paramount issue because grafts placed in the arterial circulation must be capable of withstanding long-term haemodynamic stress without graft failure. Extracellular matrix (ECM) proteins that are deposited by the cells to remodel the environment play a major role in determining the construct stability and strength. A suitable scaffold that stimulates ECM deposition and remodelling by cells grown in vitro may generate tissues with normal function. The objective of this study was to prove that fibrin matrix composition can be modified with growth factors (GFs) and glycosaminoglycans (GAGs) to promote ECM remodelling coupled with endothelial cell (EC) growth. Effect of GFs and GAGs on ECM production and remodelling was studied separately and in combination. Matrices recovered after EC cultures were analysed after immunochemical staining and it was observed that GFs and GAGs influence collagen IV and elastin deposition. Quantitative PCR analysis of mRNA after specific periods of culture demonstrated significant upregulation of elastin and collagen expression in EC by combination of GFs and GAGS when compared to their individual effects. The results of experiments conducted with various combinations of GFs and GAGs show that a biomimetic approach of immobilization of signalling molecules in fibrin can upregulate ECM remodelling with simultaneous degradation of the fibrin matrix and deposition of collagen IV and elastin. Hence, this combination may be suitable for cardiovascular tissue generation in vitro.

Differential binding patterns to host cells associated with particles of several human alphapapillomavirus types

The focus of this research was to compare the binding profiles of human papillomavirus (HPV) 11, 16, 18 and 45 virus-like particles (VLPs) to HaCaT cells and to the extracellular matrix (ECM) secreted by these cells. All four HPV types tested bind to a component(s) of the ECM. HPV11 VLP binding is blocked when the ECM is pretreated with an anti-laminin 5 (LN5) polyclonal antibody. A series of treatments utilizing heparins and heparinase revealed that HPV18 VLPs are dependent on heparan sulfates (HS) for binding to cells and ECM. HPV16 and HPV45 VLPs are dependent on HS for binding to HaCaT cells and dependent on both HS and LN5 for binding to ECM. These studies emphasize the need to study the binding characteristics of different HPV types before applying universal binding principles to all papillomaviruses.

A Bilayer Hyaluronic Acid Wound Dressing to Promote Wound Healing in Diabetic Ulcer

Several spongy wound dressings composed of various hyaluronic acid (HA) materials were developed: HA aqueous solution with cross-linking agent (epoxy compound (HAWC), without cross-linking agent (HAWOC), and combined bilayer material HAWC and HAWOC (2LHA). The microstructure, sensitivity to hyaluronidase, sensitivity to free radicals, in vitro cytotoxicity, healing potential on full-thickness defect on and diabetic ulcers were evaluated. Scanning electron micrograph views of all HA wound dressings showed an interconnected channel and high porosity structure. HAWOC was degraded rapidly in hyaluronidase and free radical solution. The in vitro cytotoxicity of HAWC was significantly (p<0.05) higher than other HA wound dressings and reduced the released amount of VEGF from human fibroblast. The HAWOC remarkably facilitated the formation of vascularized granulation tissue and provided a HA enrichment wound healing process of either a full-thickness defect or a diabetic ulcer. In contrast, the presence of un-degradable products of HAWC seemed to interfere dermal tissue restoration. Nevertheless, because of the fragile properties, rapid degradation and wound adhesion of HAWOC, the 2LHA should be developed for diabetic ulcer therapy.

MMP7 shedding of syndecan-1 facilitates re-epithelialization by affecting alpha(2)beta(1) integrin activation

Background

Lung injury promotes the expression of matrix metalloproteinase-7 (MMP7, matrilysin), which is required for neutrophil recruitment and re-epithelialization. MMP7 governs the lung inflammatory response through the shedding of syndecan-1. Because inflammation and repair are related events, we evaluated the role of syndecan-1 shedding in lung re-epithelialization.

Methodology/Principal Finding

Epithelial injury induced syndecan-1 shedding from wild-type epithelium but not from Mmp7^−/− mice in vitro and in vivo. Moreover, cell migration and wound closure was enhanced by MMP7 shedding of syndecan-1. Additionally, we found that syndecan-1 augmented cell adhesion to collagen by controlling the affinity state of the α₂β₁ integrin.

Conclusion/Significance

MMP7 shedding of syndecan-1 facilitates wound closure by causing the α₂β₁ integrin to assume a less active conformation thereby removing restrictions to migration. MMP7 acts in the lungs to regulate inflammation and repair, and our data now show that both these functions are controlled through the shedding of syndecan-1.

Clustering of syndecan-4 and integrin beta1 by laminin alpha 3 chain-derived peptide promotes keratinocyte migration

Syndecans function as receptors for extracellular matrix (ECM) with integrins in cell spreading. However, the molecular mechanism of their specific involvement in cell migration or in wound healing has not been elucidated yet. Here, we report that a synthetic peptide, PEP75, which contains the syndecan-binding sequence of the laminin alpha 3LG4 module, induces keratinocyte migration in in vitro and in vivo. Soluble PEP75 induced the clustering of syndecan-4 and conformation-modified integrin beta1 colocalized with syndecan-4 in soluble PEP75-induced clusters. Treatment of cells in solution with PEP75 resulted in the exposure of the P4G11 antibody epitope of integrin beta1 in immunostaining as well as in flow cytometry and augmented integrin beta1-dependent cell adhesion to ECM. Pulldown assays demonstrated that PEP75 bound to syndecan-4, but not to integrin beta1. A siRNA study revealed a role for syndecan-4 in PEP75-induced up-regulation of P4G11 antibody binding and migration of HaCaT cells. We conclude that binding of soluble PEP75 to syndecan-4 induces the coupling of integrin beta1, which is associated with integrin beta1-conformational changes and activation, and leads to keratinocyte migration. To activate integrin function through syndecans could be a novel therapeutic approach for chronic wound.

Esterified hyaluronic acid and autologous bone in the surgical correction of the infra-bone defects

We study the osteoinductive effect of the hyaluronic acid (HA) by using an esterified low-molecular HA preparation (EHA) as a coadjuvant in the grafting processes to produce bone-like tissue in the presence of employing autologous bone obtained from intra-oral sites, to treat infra-bone defects without covering membrane. We report on 9 patients with periodontal defects treated by EHA and autologous grafting (4 males and 5 females, all non smokers, with a mean age of 43.8 years for females, 40.0 years for males and 42 years for all the group, in good health) with a mean depth of 8.3 mm of the infra-bone defects, as revealed by intra-operative probes. Data were obtained at baseline before treatment and after 10 days, and subsequently at 6, 9, and 24 months after treatment. Clinical results showed a mean gain hi clinical attachment (gCAL) of 2.6mm of the treated sites, confirmed by radiographic evaluation. Such results suggest that autologous bone combined with EHA seems to have good capabilities in accelerating new bone formation in the infra-bone defects.

uPAR-deficient mouse keratinocytes fail to produce EGFR-dependent laminin-5, affecting migration in vivo and in vitro

The urokinase receptor (uPAR) is involved in a series of pathological processes, from inflammation to cancer. We have analyzed in detail the role of uPAR and the mechanisms involved in keratinocyte behavior during wound healing by exploiting uPAR-knockout (KO) mice. In vivo, uPAR-KO mice showed delayed wound healing, with abnormal keratinocyte migration and proliferation. In vitro, unlike wild-type cells, primary uPAR-KO keratinocytes did not proliferate in response to epidermal growth factor (EGF), their growth and migration were not inhibited by EGF-receptor (EGFR) inhibitors, and they did not adhere to uncoated surfaces. Whereas EGFR levels in uPAR-KO keratinocytes were normal, there was no tyrosine phosphorylation upon addition of EGF, and its downstream targets, extracellular-signal-regulated kinases 1 and 2 (ERK1/2), were not activated. Re-introduction of mouse uPAR rescued all phenotypes. In vitro adhesion and migration defects were associated with the failure of uPAR-KO keratinocytes to normally produce and secrete laminin-5 (LN5), an event that requires EGFR signaling. These results were confirmed in vivo, with LN5 being upregulated during wound healing in wild-type but not in uPAR-KO epidermis.

Physical properties of crosslinked hyaluronic acid hydrogels

In order to improve the mechanical properties and control the degradation rate of hyaluronic acid (HA) an investigation of the structural and mechanical properties of the hydrogels crosslinked using divinyl sulfone (DVS), glutaraldehyde (GTA) and freeze-thawing, or autocrosslinking has been carried out. The thermal and mechanical properties of the gels were characterised by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and compression tests. The solution degradation products of each system have been analysed using size exclusion chromatography (SEC) and the Zimm-Stockmayer theory applied. Autocrosslinked gels swell the most quickly, whereas the GTA crosslinked gels swell most slowly. The stability of the autocrosslinked gels improves with a reduction in solution pH, but is still poor. GTA and DVS crosslinked gels are robust and elastic when water swollen, with glass transition values around 20 degrees C. SEC results show that the water soluble degradation products of the gels show a reduction in the radius of gyration at any particular molecular weight and this is interpreted as indicating increased hydrophobicity arising from chemical modification.

Lamininα3 LG4 Module Induces Keratinocyte Migration: Involvement of Matrix Metalloproteinase-9

Laminin alpha3 chain, a functionally key subunit of laminin-5, contains a large globular module (G module) which consists of a tandem repeat of five homologous LG modules (LG1-5). We previously demonstrated that the LG4 module of laminin alpha3 chain (alpha3 LG4) induces a matrix metalloproteinase-1 (MMP-1) expression through the interaction with syndecans leading to MAPK activation/IL-1beta expression signaling loop (Utani et al., J. Biol. Chem. 278, 34483-34490, 2003). Here, we show that a recombinant alpha3 LG4 and synthetic peptides containing syndecan binding motif induced a cell motility and a MMP-9 expression in ketarinocytes. The synthetic peptide (A3G756)-induced cell migration and MMP-9 upregulation were inhibited by each application of a heparin and an IL-1 receptor antagonist (IL-1RA), suggesting the involvement of syndecans and IL-1beta autocrine. Furthermore, the A3G756-induced cell motility was inhibited by an MMP-9 inhibitor and a neutralizing antibody of MMP-9, indicating induced cell motility was dependent on an MMP-9 activity. Taken these together, laminin-5 alpha3 LG4 module may play an important role in re-epithelialization at tissue remodeling.

Deregulation of versican and elastin binding protein in solar elastosis

Several changes in skin appearance including loss of elasticity and wrinkle formation are associated with alterations in the composition of the dermal extracellular matrix. They are induced by intrinsic aging or by environmental factors such as UV light referred to as photoaging. A general characteristic in the histology of photoaged skin is the accumulation of elastotic material suggesting impaired formation and/or massive breakdown of elastic fibres. In order to shed light on some of the underlying mechanisms we tracked two of the major players in elastic fibre formation in different skin conditions: EBP (elastin binding protein), a regulator of elastic fibre assembly and VER (versican), a component of functional elastic fibres as well as non-functional elastotic material. Using quantitative RT-PCR on skin biopsies we found that the expression levels of VER and EBP were unaltered during intrinsic skin aging. Upon acute UV stress however, VER and EBP showed different regulation patterns: VER mRNA increased after 6 h and was further up-regulated until 24 h. The EBP mRNA by contrast was reduced after 6 h but showed massive induction at 24 h after acute UV stress. In chronically sun-exposed skin, VER protein was accumulated similar to elastotic material in the extracellular space, whereas its mRNA level was consistently reduced compared to sun-protected skin. The EBP mRNA by contrast showed slightly increased expression levels in the sun-exposed area compared to its sun-protected counterpart. Based on these data we propose a model which may help to explain parts of the mechanisms leading to the formation of elastotic masses. We further hypothesize that the presence of elastotic material triggers some yet unknown feedback mechanism(s) resulting in altered expression patterns of VER and EBP in chronically sun-exposed skin.

Hyalomatrix: a temporary epidermal barrier, hyaluronan delivery, and neodermis induction system for keratinocyte stem cell therapy

Keratinocyte stem cell technology provides at least an adjuvant therapy to clinically close large cutaneous wounds (e.g., burn wounds). Here, the performance of keratinocyte cultures depends primarily on the quality of the bed to which they are applied. Clinical take rates for cultured keratinocyte grafts are optimal when applied to a vascularized dermal bed with minimal bacterial colonization. In the absence of autologous dermis, staged reconstruction with a dermal equivalent or dermal regeneration template is required. A novel product, Hyalomatrix, is a bilayer of an esterified hyaluronan scaffold beneath a silicone membrane. The scaffold delivers hyaluronan to the wound bed, and the silicone membrane acts as a temporary epidermal barrier. The product has been investigated in a controlled, porcine, acute full-thickness excisional wound model. Cultured autologous keratinocytes (CAKs) were delivered on Laserskin to acute full-thickness wounds treated with Hyalomatrix within chambers, and graft take rates were assessed longitudinally using image analysis. In the absence of chambers, wound contraction was assessed. Clinical CAK take rates fall sequentially with delay in application post-Hyalomatrix pre-treatment, but repeated pre-treatment removed this, with maximal take of 57.2% at 5 weeks post-wounding. In the absence of chambers, more-complete wound closure resulted from edge re-epithelialization and contraction, by a factor of 5 at 1 month, and was achieved at least 2 weeks sooner in the gold standard controls of split-thickness autograft to an acute or pre-treated wound bed. Wound contraction and late neodermal morphology (1 year) were similar in pre-treated CAKs and split-thickness autograft wounds. In this model, the Hyalomatrix wound bed pre-treatment increase in CAK take appeared to be dose dependent. The product appeared to act as a hyaluronan delivery system rather than a dermal regeneration template. The silicone membrane may limit wound bed colonization, and the combination of this temporary barrier with hyaluronan delivery and neodermis induction has been termed a barrier-delivery-induction system. The development of similar systems for serial application offers an alternative to a dermal regeneration template when CAKs are engrafted in the hostile, colonized environment of large burn wounds.

Syndecan-1 interaction with the LG4/5 domain in laminin-332 is essential for keratinocyte migration

Laminin 5/laminin 332 (LN332) is an adhesion substrate for epithelial cells. After secretion of LN332, a regulated cleavage occurs at the carboxy-terminus of its alpha3 subunit, which releases a tandem of two globular modules named LG4/5. We show that the presence of the LG4/5 domain in precursor LN332 decreases its integrin-mediated cell adhesion properties in comparison with mature LN332. Whereas cell adhesion to the recombinant LG4/5 fragment relies solely on the heparan sulfate proteoglycan (HSPG) receptor syndecan-1, we reveal that both syndecan-1 and the alpha3beta1 integrin bind to precursor LN332. We further demonstrate that syndecan-1 mediated cell adhesion to the LG4/5 fragment and pre-LN332 allows the formation of fascin-containing protrusions, depending on the GTPases Rac and Cdc42 activation. Reducing syndecan-1 expression in normal keratinocytes prevents cell protrusions on pre-LN332 with subsequent failure of the peripheral localization of the alpha3beta1 integrin. We finally show that cell migration on pre-LN332 requires syndecan-1. Therefore, the LG4/5 domain in precursor LN332 appears to trigger intracellular signaling events, which participate in keratinocyte motility.

The extracellular matrix in wound healing: a closer look at therapeutics for chronic wounds

Disappointing results with the use of exogenous recombinant growth factors in chronic wounds have redirected the focus to the extracellular matrix (ECM). Newer research has clearly changed our view on the role of the ECM in tissue repair and dismissed the dogma that the sole function of ECM is a passive physical support for cells. It is now clear that intact or fragmented ECM molecules are capable of transducing signals pivotal for cell processes in wound healing primarily via integrin interactions in concert with growth factor activation. In addition, our knowledge about ECM molecules in minute concentrations with biological activity, but devoid of significant structural influence, is increasing. This article reviews the multifaceted molecular roles of ECM in the normal wound-healing process and some molecular abnormalities in chronic wounds, and touches on potential therapies based on the developments of tissue biology.

Immunohistochemical Localization of Syndecan-1 in the Dental Follicle of Postnatal Mouse Teeth

BACKGROUND

Syndecans are cell surface heparan sulfate proteoglycans that modulate the action of growth factors and extracellular matrix components. Syndecan-1 plays important roles during early tooth development, and it is expressed in the dental follicle of fetal tooth germ. However, no studies have followed its expression in the dental follicle during the postnatal period. We hypothesized that syndecan-1 protein expression in the dental follicle may be important for postnatal tooth development, and, thus, examined its expression patterns.

METHODS

Syndecan-1 protein expression in the dental follicle of the lower first molar was investigated by immunohistochemistry using embryonic day (E) 18.5 to 21-day-old (d 21) mice. Immunoelectron microscopy was applied to the dental follicle and pulp cells to confirm its membrane localization in mesenchymal cells.

RESULTS

Strong syndecan-1 immunostaining was maintained in the dental follicle and the adjacent dental pulp surrounded by the Hertwig's epithelial root sheath (HERS) from d 4 to d 14, but reduced staining was noted at d 21 with the near-completion of tooth eruption. Three dimensionally, syndecan-1-positive areas plugged the apical foramina surrounded by HERS. However, immunostaining was detected constantly in the dental follicle and the dental pulp of the lower incisor at d 21. In addition, membrane localization of syndecan-1 protein was confirmed for the first time in mesenchymal cells, including dental follicle and pulp cells, by immunoelectron microscopy.

CONCLUSION

The spatial and temporal expression of syndecan-1 in the dental follicle suggests that this proteoglycan is important for the maintenance of proliferation and/or movement of cells in this region during tooth eruption.