Hyaluronan catabolism: a new metabolic pathway

The dynamic metabolism of hyaluronan regulates the cytosolic concentration of UDP-GlcNAc

Hyaluronan, a macromolecular glycosaminoglycan, is normally synthesized by hyaluronan synthases at the plasma membrane using cytosolic UDP-GlcUA and UDP-GlcNAc substrates and extruding the elongating chain into the extracellular space. The cellular metabolism (synthesis and catabolism) of hyaluronan is dynamic. UDP-GlcNAc is also the substrate for O-GlcNAc transferase, which is central to the control of many cytosolic pathways. This Perspective outlines recent data for regulation of hyaluronan synthesis and catabolism that support a model that hyaluronan metabolism can be a rheostat for controlling an acceptable normal range of cytosolic UDP-GlcNAc concentrations in order to maintain normal cell functions.

The decreased secretion of hyaluronan by older human fibroblasts under physiological conditions is mainly associated with the down-regulated expression of hyaluronan synthases but not with the expression levels of hyaluronidases

Although it has been reported that levels of hyaluronan are decreased in the dermis of aged skin, little is known about the cellular mechanism(s) underlying that hyaluronan deficiency. Since hyaluronan is produced by dermal fibroblasts and is secreted into the surrounding dermal tissues, we examined the secretion of hyaluronan by dermal fibroblasts and characterized its cellular mechanism using real-time RT-PCR and western blotting for its synthesizing and degrading enzymes, hyaluronan synthase and hyaluronidase, respectively. The secretion of hyaluronan by dermal fibroblasts derived from differently aged human donors, was higher in the younger human fibroblasts tested (0 and 19 years old) compared to the older human fibroblasts tested (39, 56 and 77 years old). The relative secretion levels of hyaluronan by the different human fibroblasts tested were attributable to the relative expression of hyaluronan synthases 1, 2, 3 but not hyaluronidases 1, 2 enzymes at the gene and protein levels among those fibroblasts. These findings indicate that the deficiency of hyaluronan in the aged dermis might result from the down-regulation in the potential of older human fibroblasts to secrete hyaluronan and that decrease in secretory potential is mainly associated with the down-regulated expression of hyaluronan synthases, especially hyaluronan synthase 2, but not with the expression levels of hyaluronidases.

Stimulation of TLR4 by LMW-HA induces metastasis in human papillary thyroid carcinoma through CXCR7

In inflammatory sites, high molecular weight hyaluronan fragments are degraded into lower molecular weight hyaluronan fragments (LMW-HA) to regulate immune responses. However, the function of LMW-HA in PTC progression remains to be elucidated. In this study, we found that receptor of LMW-HA, TLR4, was aberrantly overexpressed in PTC tissues and cell line W3. Exposure of W3 cells to LMW-HA promoted cell proliferation and migration via TLR4. Knockdown of TLR4 has provided evidence that TLR4 is essential for LMW-HA-induced CXCR7 expression, which is responsible for LMW-HA-induced proliferation and migration of W3 cells. In tumor-bearing adult nude mice, stimulation of LMW-HA on W3 cells promotes CXCR7 expression in tumor masses (P = 0.002) and tumor growth (P < 0.001). To further confirm our findings, we investigated the clinicopathologic significance of TLR4 and CXCR7 expression using immumohistochemistry in 135 human PTC tissues and 56 normal thyroid tissue samples. Higher rates of TLR4 (53%) and CXCR7 (24%) expression were found in PTC tissues than in normal tissues. Expression of TLR4 or CXCR7 is associated with tumor size and lymph node metastasis. Therefore, LMW-HA may contribute to the development of PTC via TLR4/CXCR7 pathway, which may be a novel target for PTC immunomodulatory therapy.

A review of the metabolism of 1,4-butanediol diglycidyl ether-crosslinked hyaluronic acid dermal fillers

BACKGROUND

Cosmetic procedures are growing ever more common, and the use of soft tissue fillers is increasing. Practicing physicians need to be aware of the biological behavior of these products in tissue to enable them to respond to any safety concerns that their patients raise.

OBJECTIVES

To provide an overview of the metabolism of 1,4-butanediol diglycidyl ether (BDDE)-crosslinked hyaluronic acid (HA) dermal fillers and to examine the safety of the resulting byproducts.

METHODS

A review of available evidence was conducted.

RESULTS

After reaction with HA, the epoxide groups of BDDE are neutralized, and only trace amounts of unreacted BDDE remain in the product (<2 parts per million). When crosslinked HA, uncrosslinked HA, and unreacted BDDE degrade, they break down into harmless byproducts or into byproducts that are identical to substances already found in the skin.

CONCLUSION

Clinical and biocompatibility data from longer than 15 years support the favorable clinical safety profile of BDDE-crosslinked HA and its degradation products. Given the strength of the empirical evidence, physicians should be confident in offering these products to their patients.

Prognostic impact of hyaluronan and its regulators in pancreatic ductal adenocarcinoma

Background

Although pancreatic ductal adenocarcinoma is characterized by an abundant stroma enriched with hyaluronan (HA), the prognostic impact of HA and its regulators remains unknown.

Methods

Using immunohistochemistry, expression patterns of HA and its regulators, including a synthesizing enzyme (HAS2), and a degrading enzyme (HYAL1) were investigated in patients who received surgical resection. The prognostic significance of these markers and other clinicopathological variables was determined using univariate and multivariate analyses. The HA levels were determined quantitatively by enzyme-linked immunosorbent assay (ELISA).

Results

We found that strong expressions of HA (P=0.008) and HAS2 (P=0.022) were significantly associated with shorter survival time after surgery. By contrast, weak expression of HYAL1 was significantly associated with poor survival (P=0.001). In multivariate analysis, tumor stage (hazard ratio (HR)=2.76, 95% confidence interval (CI): 1.14-6.66 P=0.024), strong HA expression (HR=6.04, 95%CI: 1.42-25.69 P=0.015), and weak HYAL1 expression (HR=3.16, 95%CI: 1.19-8.40 P=0.021) were independent factors predicting poor survival. ELISA revealed higher concentration of HA in pancreatic cancer tissues than in normal pancreatic tissues (P=0.001).

Conclusion

These findings suggest, for the first time, that HA and its regulators may have prognostic impact in patients with pancreatic cancer.

Inhibition of adipogenesis in 3T3-L1 cells and suppression of abdominal fat accumulation in high-fat diet-feeding C57BL/6J mice after downregulation of hyaluronic acid

OBJECTIVE

Adipogenesis can be spatially and temporally regulated by extracellular matrix (ECM). We hypothesized that the regulation of hyaluronic acid (HA), a component of the ECM, can affect adipogenesis in fat cells. The effects of HA on adipogenesis were investigated in vitro in 3T3-L1 cells and in vivo in high-fat diet-feeding C57BL/6J mice.

METHODS

We investigated the effects of HA by degradation of pre-existing or synthesized HA and artificial inhibition of HA synthesis in adipogenesis.

RESULTS

In vitro adipogenesis in 3T3-L1 cells was inhibited by treating them with exogenous hyaluronidase (HYAL) and with 4-methylumbelliferone, which inhibited the synthesis of HA in a concentration-dependent manner. In vivo, abdominal fat accumulation in high-fat diet-feeding C57BL/6J mice was suppressed by exogenous HYAL 10(4) IU injections, which was associated with reduction of lipid accumulation in liver and increase of insulin sensitivity.

CONCLUSION

Changes in the ECM such as accumulation of high molecular weight of HA by HAS and degradation of HA by endogenous HYAL were essential for adipogenesis both in vitro and in vivo.

Determination of sodium hyaluronate in pharmaceutical formulations by HPLC-UV

A liquid chromatography (HPLC) method with UV detection was developed for determination of sodium hyaluronate in pharmaceutical formulation. Sodium hyaluronate is a polymer of disaccharides, composed of d-glucuronic acid and d-N-acetylglucosamine, linked via alternating β-1, 4 and β-1, 3 glycosidic bonds. Being a polymer compound it lacks a UV absorbing chromophore. In the absence of a UV absorbing chromophore and highly polar nature of compound, the analysis becomes a major challenge. To overcome these problems a novel method for the determination of sodium hyaluronate was developed and validated based on size exclusion liquid chromatography (SEC) with UV detection. An isocratic mobile phase consisting of buffer 0.05 M potassium dihydrogen phosphate, pH adjusted to 7.0 using potassium hydroxide (10%) was used. Chromatography was carried out at 25 °C on a BioSep SEC S2000, 300 mm×7.8 mm column. The detection was carried out using variable wavelength UV-vis detector set at 205 nm. The compounds were eluted isocratically at a steady flow rate of 1.0 mL/min. Sodium hyaluronate retention time was about 4.9 min with an asymmetry factor of 1.93. A calibration curve was obtained from 1 to 38 g/mL (r>0.9998). Within-day % RSD was 1.0 and between-day % RSD was 1.10. Specificity/selectivity experiments revealed the absence of interference from excipients, recovery from spiked samples for sodium hyaluronate was 99-102. The developed method was applied to the determination of sodium hyaluronate in pharmaceutical drug substance and product.

Designing degradable hydrogels for orthogonal control of cell microenvironments

Degradable and cell-compatible hydrogels can be designed to mimic the physical and biochemical characteristics of native extracellular matrices and provide tunability of degradation rates and related properties under physiological conditions. Hence, such hydrogels are finding widespread application in many bioengineering fields, including controlled bioactive molecule delivery, cell encapsulation for controlled three-dimensional culture, and tissue engineering. Cellular processes, such as adhesion, proliferation, spreading, migration, and differentiation, can be controlled within degradable, cell-compatible hydrogels with temporal tuning of biochemical or biophysical cues, such as growth factor presentation or hydrogel stiffness. However, thoughtful selection of hydrogel base materials, formation chemistries, and degradable moieties is necessary to achieve the appropriate level of property control and desired cellular response. In this review, hydrogel design considerations and materials for hydrogel preparation, ranging from natural polymers to synthetic polymers, are overviewed. Recent advances in chemical and physical methods to crosslink hydrogels are highlighted, as well as recent developments in controlling hydrogel degradation rates and modes of degradation. Special attention is given to spatial or temporal presentation of various biochemical and biophysical cues to modulate cell response in static (i.e., non-degradable) or dynamic (i.e., degradable) microenvironments. This review provides insight into the design of new cell-compatible, degradable hydrogels to understand and modulate cellular processes for various biomedical applications.

Regulation of the hyaluronan system in ovine endometrium by ovarian steroids

In this study, we investigated steroid regulation of the hyaluronan (HA) system in ovine endometrium including HA synthases (HAS), hyaluronidases, and HA receptor-CD44 using 30 adult Welsh Mountain ewes. Eight ewes were kept intact and synchronized to estrous (day 0). Intact ewes were killed on day 9 (luteal phase; LUT; n=5) and day 16 (follicular phase; FOL; n=3). The remaining ewes (n=22) were ovariectomized and then treated (i.m.) with vehicle (n=6) or progesterone (n=8) for 10 days, or estrogen and progesterone for 3 days followed by 7 days of progesterone alone (n=8). Estradiol and progesterone concentrations in plasma correlated with the stage of estrous or steroid treatment. Our results showed trends (P<0.1) and statistically significant effects (P<0.05, by t-test) indicating that LUT had lower HAS1 and HAS2 and higher HAS3 and CD44 mRNA expression compared with FOL. This was reflected in immunostaining of the corresponding HAS proteins. Similarly, in ovariectomized ewes, progesterone decreased HAS1 and HAS2 and increased HAS3 and CD44, whereas estradiol tended to increase HAS2 and decrease CD44. Sometimes, HAS mRNA expression did not follow the same trend observed in the intact animals or the protein expression. HA and its associated genes and receptors were regulated by the steroids. In conclusion, these results show that the level of HA production and the molecular weight of HA in the endometrium are regulated by ovarian steroids through differential expression of different HAS both at the gene and at the protein levels.

Murine hyaluronidase 2 deficiency results in extracellular hyaluronan accumulation and severe cardiopulmonary dysfunction

Hyaluronidase (HYAL) 2 is a membrane-anchored protein that is proposed to hydrolyze hyaluronan (HA) to smaller fragments that are internalized for breakdown. Initial studies of a Hyal2 knock-out (KO) mouse revealed a mild phenotype with high serum HA, supporting a role for HYAL2 in HA breakdown. We now describe a severe cardiac phenotype, deemed acute, in 54% of Hyal2 KO mice on an outbred background; Hyal2 KO mice without the severe cardiac phenotype were designated non-acute. Histological studies of the heart revealed that the valves of all Hyal2 KO mice were expanded and the extracellular matrix was disorganized. HA was detected throughout the expanded valves, and electron microscopy confirmed that the accumulating material, presumed to be HA, was extracellular. Both acute and non-acute Hyal2 KO mice also exhibited increased HA in the interstitial extracellular matrix of atrial cardiomyocytes compared with control mice. Consistent with the changes in heart structure, upper ventricular cardiomyocytes in acute Hyal2 KO mice demonstrated significant hypertrophy compared with non-acute KO and control mice. When the lungs were examined, evidence of severe fibrosis was detected in acute Hyal2 KO mice but not in non-acute Hyal2 KO or control mice. Total serum and heart HA levels, as well as size, were increased in acute and non-acute Hyal2 KO mice compared with control mice. These findings indicate that HYAL2 is essential for the breakdown of extracellular HA. In its absence, extracellular HA accumulates and, in some cases, can lead to cardiopulmonary dysfunction. Alterations in HYAL2 function should be considered as a potential contributor to cardiac pathologies in humans.

TSG-6 protein is crucial for the development of pulmonary hyaluronan deposition, eosinophilia, and airway hyperresponsiveness in a murine model of asthma

Hyaluronan (HA) deposition is often correlated with mucosal inflammatory responses, where HA mediates both protective and pathological responses. By modifying the HA matrix, Tnfip6 (TNF-α-induced protein-6; also known as TSG-6 (TNF-stimulated gene-6)) is thought to potentiate anti-inflammatory and anti-plasmin effects that are inhibitory to leukocyte extravasation. In this study, we examined the role of endogenous TSG-6 in the pathophysiological responses associated with acute allergic pulmonary inflammation. Compared with wild-type littermate controls, TSG-6(-/-) mice exhibited attenuated inflammation marked by a significant decrease in pulmonary HA concentrations measured in the bronchoalveolar lavage and lung tissue. Interestingly, despite the equivalent induction of both humoral and cellular Th2 immunity and the comparable levels of cytokines and chemokines typically associated with eosinophilic pulmonary inflammation, airway eosinophilia was significantly decreased in TSG-6(-/-) mice. Most importantly, contrary to their counterpart wild-type littermates, TSG-6(-/-) mice were resistant to the induction of airway hyperresponsiveness and manifested improved lung mechanics in response to methacholine challenge. Our study demonstrates that endogenous TSG-6 is dispensable for the induction of Th2 immunity but is essential for the robust increase in pulmonary HA deposition, propagation of acute eosinophilic pulmonary inflammation, and development of airway hyperresponsiveness. Thus, TSG-6 is implicated in the experimental murine model of allergic pulmonary inflammation and is likely to contribute to the pathogenesis of asthma.

Role of hyaluronan in angiogenesis and its utility to angiogenic tissue engineering

Angiogenesis represents the outgrowth of new blood vessels from existing ones, a physiologic process that is vital to supply nourishment to newly forming tissues during development and tissue remodeling and repair (wound healing). Regulation of angiogenesis in the healthy body occurs through a fine balance of angiogenesis-stimulating factors and angiogenesis inhibitors. When this balance is disturbed, excessive or deficient angiogenesis can result and contribute to development of a wide variety of pathological conditions. The therapeutic stimulation or suppression of angiogenesis could be the key to abrogating these diseases. In recent years, tissue engineering has emerged as a promising technology for regenerating tissues or organs that are diseased beyond repair. Among the critical challenges that deter the practical realization of the vision of regenerating functional tissues for clinical implantation, is how tissues of finite size can be regenerated and maintained viable in the long-term. Since the diffusion of nutrients and essential gases to cells, and removal of metabolic wastes is typically limited to a depth of 150-250 microm from a capillary (3-10 cells thick), tissue constructs must mandatorily permit in-growth of a blood capillary network to nourish and sustain the viability of cells within. The purpose of this article is to provide an overview of the role and significance of hyaluronan (HA), a glycosaminoglycan (GAG) component of connective tissues, in physiologic and pathological angiogenesis, its applicability as a therapeutic to stimulate or suppress angiogenesis in situ within necrotic tissues in vivo, and the factors determining its potential utility as a pro-angiogenic stimulus that will enable tissue engineering of neo-vascularized and functional tissue constructs for clinical use.

6-Mer hyaluronan oligosaccharides increase IL-18 and IL-33 production in mouse synovial fibroblasts subjected to collagen-induced arthritis

Hyaluronan (HA) oligosaccharides stimulate pro-inflammatory responses in different cell types by modulating both cluster determinant 44 (CD44) and TLR4. The activation of these receptors is also mediated by collagen-induced arthritis (CIA) that, via two different pathways, culminates in the liberation of NF-κB. This then stimulates the production of pro-inflammatory cytokines, including IL-18 and IL-33, that are greatly involved in rheumatoid arthritis. The aim of this study was to investigate the effects of 6-mer HA oligosaccharides on mouse synovial fibroblasts obtained from normal DBA/J1 mice or mice subjected to CIA. Compared with normal synovial fibroblasts (NSF), rheumatoid arthritis synovial fibroblasts (RASF) showed no up-regulation of CD44 and TLR4 mRNA expression and the related proteins, as well as no activation of NF-κB. Very low levels of both mRNA and related proteins were also detected for IL-18 and IL-33. Treatment of NSF and RASF with 6-mer HA oligosaccharides significantly increased all the parameters in both fibroblast groups, although to a greater extent in RASF. The addition of hyaluronan binding protein to both NSF and RASF inhibited HA activity and was able to reduce the effects of 6-mer HA oligosaccharides and the consequent inflammatory response.

Initial events in the degradation of hyaluronan catalyzed by hyaluronate lyase from Streptococcus [corrected] pneumoniae: QM/MM simulation

Hyaluronate lyase from Spectrococcus pneumonia can degrade hyaluronic acid, which is one of the major components in the extracellular matrix. The major functions of hyaluronan are to regulate water balance and osmotic pressure and act as an ion-exchange resin. In this work, we focus on the prerequisite issue of the enzymatic reaction, i.e., the initial reactive conformer. Based on the quantum mechanical and molecular mechanical molecular dynamic simulations and free energy profiles, a near attack conformer was obtained for the degradation of hyaluronan catalyzed by the hyaluronate lyase. Along with the substrate binding, the phenylhydroxyl hydrogen atom of Tyr408 will transfer to nearby His399 via a near barrierless transition state, which results in a negatively charged Tyr408 and positively charged His399. The Tyr408, rather than the previously proposed His399, was suggested to act as the general base for the subsequent β-elimination reaction. The His399 was suggested to have the function of neutralizing the C5-carboxyl group.

Amphiphilic polymeric micelles as the nanocarrier for peroral delivery of poorly soluble anticancer drugs

INTRODUCTION

Many amphiphilic copolymers have recently been synthesized as novel promising micellar carriers for the delivery of poorly water-soluble anticancer drugs. Studies on the formulation and oral delivery of such micelles have demonstrated their efficacy in enhancing drug uptake and absorption, and exhibit prolonged circulation time in vitro and in vivo.

AREAS COVERED

In this review, literature on hydrophobic modifications of several hydrophilic polymers, including polyethylene glycol, chitosan, hyaluronic acid, pluronic and tocopheryl polyethylene glycol succinate, is summarized. Parameters influencing the properties of polymeric micelles for oral chemotherapy are discussed and strategies to overcome main barriers for polymeric micelles peroral absorption are proposed.

EXPERT OPINION

During the design of polymeric micelles for peroral chemotherapy, selecting or synthesizing copolymers with good compatibility with the drug is an effective strategy to increase drug loading and encapsulation efficiency. Stability of the micelles can be improved in different ways. It is recommended to take permeability, mucoadhesion, sustained release, and P-glycoprotein inhibition into consideration during copolymer preparation or to consider adding some excipients in the formulation. Furthermore, both the copolymer structure and drug loading methods should be controlled in order to get micelles with appropriate particle size for better absorption.

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.

Estradiol protects dermal hyaluronan/versican matrix during photoaging by release of epidermal growth factor from keratinocytes

Hyaluronan (HA) and versican are key components of the dermis and are responsive to ultraviolet (UV)B-induced remodeling. The aim of this study was to explore the molecular mechanisms mediating the effects of estrogen (E(2)) on HA-rich extracellular matrix during photoaging. Hairless skh-1 mice were irradiated with UVB (three times, 1 minimal erythema dose (80 mJ/cm(2)), weekly) for 10 weeks, and endogenous sex hormone production was abrogated by ovariectomy. Subcutaneous substitution of E(2) by means of controlled-release pellets caused a strong increase in the dermal HA content in both irradiated and nonirradiated skin. The increase in dermal HA correlated with induction of HA synthase HAS3 by E(2). Expression of splice variant 2 of the HA-binding proteoglycan versican was also increased by E(2). In search of candidate mediators of these effects, it was found that E(2) strongly induced the expression of epidermal growth factor (EGF) in UVB-irradiated epidermis in vivo and in keratinocytes in vitro. EGF in turn up-regulated the expression of HAS3 and versican V2 in dermal fibroblasts. HAS3 knockdown by shRNA caused inhibition of fibroblast proliferation. Furthermore, HAS3 and versican V2 induction by E(2) correlated positively with proliferation in vivo. In addition, the accumulation of inflammatory macrophages, expression of inducible cyclooxygenase 2, as well as proinflammatory monocyte chemotactic protein 1 were decreased in response to E(2) in the dermis. Collectively, these data suggest that E(2) treatment increases the amount of dermal HA and versican V2 via paracrine release of EGF, which may be implicated in the pro-proliferative and anti-inflammatory effects of E(2) during photoaging.

Hyaluronidase 1 and β-hexosaminidase have redundant functions in hyaluronan and chondroitin sulfate degradation

Hyaluronan (HA), a member of the glycosaminoglycan (GAG) family, is a critical component of the extracellular matrix. A model for HA degradation that invokes the activity of both hyaluronidases and exoglycosidases has been advanced. However, no in vivo studies have been done to determine the extent to which these enzymes contribute to HA breakdown. Herein, we used mouse models to investigate the contributions of the endoglycosidase HYAL1 and the exoglycosidase β-hexosaminidase to the lysosomal degradation of HA. We employed histochemistry and fluorophore-assisted carbohydrate electrophoresis to determine the degree of HA accumulation in mice deficient in one or both enzyme activities. Global HA accumulation was present in mice deficient in both enzymes, with the highest levels found in the lymph node and liver. Chondroitin, a GAG similar in structure to HA, also broadly accumulated in mice deficient in both enzymes. Accumulation of chondroitin sulfate derivatives was detected in mice deficient in both enzymes, as well as in β-hexosaminidase-deficient mice, indicating that both enzymes play a significant role in chondroitin sulfate breakdown. Extensive accumulation of HA and chondroitin when both enzymes are lacking was not observed in mice deficient in only one of these enzymes, suggesting that HYAL1 and β-hexosaminidase are functionally redundant in HA and chondroitin breakdown. Furthermore, accumulation of sulfated chondroitin in tissues provides in vivo evidence that both HYAL1 and β-hexosaminidase cleave chondroitin sulfate, but it is a preferred substrate for β-hexosaminidase. These studies provide in vivo evidence to support and extend existing knowledge of GAG breakdown.

Modeling neural differentiation on micropatterned substrates coated with neural matrix components

Topographical and biochemical characteristics of the substrate are critical for neuronal differentiation including axonal outgrowth and regeneration of neural circuits in vivo. Contact stimuli and signaling molecules allow neurons to develop and stabilize synaptic contacts. Here we present the development, characterization and functional validation of a new polymeric support able to induce neuronal differentiation in both PC12 cell line and adult primary skin-derived precursor cells (SKPs) in vitro. By combining a photolithographic technique with use of neural extracellular matrix (ECM) as a substrate, a biocompatible and efficient microenvironment for neuronal differentiation was developed.

The use of sodium hyaluronate-carboxymethylcellulose to prevent postoperative mastication pain from harvesting of temporalis fascia

OBJECTIVE

To evaluate the anti-adhesive and anti-inflammatory effects of sodium hyaluronate-carboxymethylcellulose (HA-CMC) in reducing postoperative pain after temporalis fascia harvest during tympanomastoid surgery.

MATERIALS AND METHODS

Between January and December 2009, 27 patients underwent tympanoplasty and open cavity mastoidectomy involving the harvesting of temporalis fasciae (more than 3×4cm). At the end of surgery, patients were injected with 1.5g HA-CMC or normal saline around the fascia harvest area. Beginning immediately postoperatively and for 2 months after surgery, patients scored their pain in the temporal area on a visual analogue scale (VAS).

RESULTS

There were no significant postoperative complications, such as bleeding or hematoma, in either control group. VAS scores of both groups decreased over time and were negligible after 2 months. VAS scores of the HA-CMC and control groups differed significantly (p<0.001 by repeated measures ANOVA for all VAS scores).

CONCLUSION

HA-CMC can decrease immediate postoperative pain arising from tissue adhesion and inflammation, thus reducing postoperative mastication pain.

Inhibition of hyaluronan synthesis reduced inflammatory response in mouse synovial fibroblasts subjected to collagen-induced arthritis

Hyaluronan (HA) fragments are able to induce inflammation by stimulating both CD44 and toll-like receptor 4 (TLR-4). CD44 and TLR-4 activation stimulates the liberation of NF-kB and pro-inflammatory cytokine responses. The aim of this study was to investigate the effects of hyaluronidase (HYAL) treatment, which depolymerises HA into small fragments, and of the addition of specific hyaluronan synthases-1, 2, and 3 small interference RNA (HASs siRNA), which silence HASs activity, on normal mouse synovial fibroblasts (NSF) and on rheumatoid arthritis synovial fibroblasts (RASF) obtained from mice subjected to collagen induced arthritis (CIA). The addition of HYAL to NSF and/or RASF significantly increased the TLR-4, CD44 and NF-kB activity, as well as the pro-inflammatory cytokines, interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and interleukin-33 (IL-33) in both groups, but to a greater extent in RASF. The addition to NSF and/or RASF of the HASs siRNA, which block HASs activity and therefore the availability of HA substrate for HYAL, was able to reduce HYAL effects in both NSF and RASF. Finally, the HA evaluation confirmed the increment of HA at low molecular weight after HYAL treatment.

Appraisal on the wound healing and anti-inflammatory activities of the essential oils obtained from the cones and needles of Pinus species by in vivo and in vitro experimental models

ETHNOPHARMACOLOGICAL RELEVANCE

According to ethnobotanical data, Pinus species have been used against rheumatic pain and for wound healing in Turkish folk medicine. Essential oils from the cones and needles of five different Pinus species (Pinus brutia Ten., Pinus halepensis Mill., Pinus nigra Arn., Pinus pinea L. and Pinus sylvestris L.) were evaluated for their in vivo wound healing and anti-inflammatory activities.

MATERIALS AND METHODS

In vivo wound healing activity of the ointments prepared from essential oils was evaluated by linear incision and circular excision experimental wound models subsequently histopathological analysis and hydroxyproline content. Furthermore, the essential oils were screened for anti-hyaluronidase activity. Additionally anti-inflammatory activity was assessed by using the method of Whittle, which is based on the inhibition of acetic acid-induced increase in capillary permeability.

RESULTS

The essential oils obtained from the cones of Pinus pinea and Pinus halepensis demonstrated the highest effects on the wound healing activity models. On the other hand, the rest of the essential oils did not show any significant wound healing and anti-inflammatory activities.

CONCLUSION

The experimental study revealed that essential oils obtained from the cones of Pinus pinea and Pinus halepensis display remarkable wound healing activity.

[Role of the extracellular matrix in extrinsic skin aging]

Photoaged skin is clinically characterized by wrinkling, laxity and a leather-like appearance. These symptoms of actinic aging are causally connected to histological and ultrastructural changes of the connective tissue of the dermis. Changes include both enzymatic degradation and reduced de novo synthesis of collagen which cause premature wrinkling of the skin. Changes in the hyaluronan and proteoglycan matrix lead to reduced water content and thereby increased laxity of the skin. Furthermore, the UV-induced remodeling of the extracellular matrix strongly affects the cellular phenotypes such as the regenerative capacity of dermal fibroblasts. In recent years considerable progress has been made towards the understanding of molecular and cellular mechanisms underlying the UV-induced changes of the extracellular matrix. Current findings in this field reveal interesting insights in the dermal aging and provide new targets and strategies for the treatment of photoaging.

Chain gangs: new aspects of hyaluronan metabolism

Hyaluronan is a matrix polymer prominent in tissues undergoing rapid growth, development, and repair, in embryology and during malignant progression. It reaches 10⁷ Daltons in size but also exists in fragmented forms with size-specific actions. It has intracellular forms whose functions are less well known. Hyaluronan occurs in all vertebrate tissues with 50% present in skin. Hyaluronan provides a scaffold on which sulfated proteoglycans and matrix proteins are organized. These supramolecular structures are able to entrap water and ions to provide tissues with hydration and turgor. Hyaluronan is recognized by membrane receptors that trigger intracellular signaling pathways regulating proliferation, migration, and differentiation. Cell responses are often dependent on polymer size. Catabolic turnover occurs by hyaluronidases and by free radicals, though proportions between these have not been determined. New aspects of hyaluronan biology have recently become realized: involvement in autophagy, in the pathology of diabetes., the ability to modulate immune responses through effects on T regulatory cells and, in its fragmented forms, by being able to engage several toll-like receptors. It is also apparent that hyaluronan synthases and hyaluronidases are regulated at many more levels than previously realized, and that the several hyaluronidases have functions in addition to their enzymatic activities.

Intravesical chondroitin sulfate inhibits recruitment of inflammatory cells in an acute acid damage "leaky bladder" model of cystitis

OBJECTIVE

To investigate whether a physiologic effect of "glycosaminoglycan (GAG) replenishment therapy" altered recruitment of inflammatory cells in an acute bladder damage model. Replacement of the GAG layer with intravesically administered GAGs is an effective therapy for interstitial cystitis in at least some patients. Intravesically administered chondroitin sulfate was previously shown to bind to and restore the impermeability of surface-damaged ("leaky") urothelium to small ions.

METHODS

Rat bladders were damaged with 10 mM HCl. Negative control bladders were treated with phosphate-buffered saline. On the following day, the animal bladders were treated with 20 mg/mL chondroitin sulfate in phosphate-buffered saline, and the negative and positive controls were treated with phosphate-buffered saline alone. At 2 and 4 days after treatment with chondroitin sulfate, the rats were killed, and sections of their bladders were analyzed using toluidine blue staining for mast cell immunohistochemical labeling using antibodies against CD45 for lymphocytes and myeloperoxidase for neutrophils.

RESULTS

Chondroitin sulfate treatment reduced the recruitment, in a statistically significant manner, of inflammatory cells, including neutrophils and mast cells to the suburothelial space but did not alter recruitment of CD45-positive lymphocytes.

CONCLUSION

For the first time, we have demonstrated that intravesical GAG replenishment therapy also produces a physiologic effect of decreasing recruitment of inflammatory cells in an acute model of the damaged bladder. These findings support the use of intravesically administered GAG for bladder disorders that result from a loss of impermeability, including interstitial, radiation, and chemical cystitis, and possibly others as well.

Hyaluronan in intestinal homeostasis and inflammation: implications for fibrosis

The causes of fibrosis, or the inappropriate wound healing, that follows chronic intestinal inflammation are not well defined and likely involve the contributions of multiple cellular mechanisms. As other articles in this series confirm, inflammatory cytokines clearly play a role in driving cell differentiation to the myofibroblast phenotype, promoting proliferation and extracellular matrix deposition that are characteristic of fibrotic tissue. However, controlling the balance of cytokines produced and process of myofibroblast differentiation appears to be more complex. This review considers ways in which hyaluronan, an extracellular matrix component that is remodeled during the progression of colitis, may provide indirect as well as direct cues that influence the balancing act of intestinal wound healing.

A comprehensive model of hyaluronan turnover in the mouse

The metabolism of hyaluronan (HA), especially its catabolism, is still far from being elucidated. Although several studies suggest that HA is degraded locally in tissues and through the lymphatic or circulatory systems, much needs to be learned about the enzymes, receptors and cell types that support this dynamic process. In the current work, the clearance of exogenously administered HA was examined in a C57BL/6 mouse model. Hyaluronidase-sensitive fluorescein-labeled 1.2MDa hyaluronan (flHA) was administered either intravenously (i.v.) or subcutaneously (s.c.) into wild type C57BL/6 mice. Plasma was sampled for pharmacokinetic analysis and tissues were harvested for histological examination of the cell types responsible for uptake using immunofluorescent localization and for size exclusion chromatography analysis. We observed that flHA could be degraded locally in the skin or be taken up by sinusoidal cells in lymph nodes, liver and spleen. I.v. administration of flHA revealed non-linear Michaelis-Menten pharmacokinetics compatible with a saturable, receptor-mediated clearance system (K(m)=11.6μg/ml±46.0%, V(max)=1.69μg/ml/min±59.7%). Through a combination of immunofluorescence microscopy, pharmacokinetic, and chromatographic analyses of labeled substrate in vivo, our results shed additional light on the mechanisms by which HA is catabolized in mammals, and serve as a basis for future studies.

Hyal2 is a glycosylphosphatidylinositol-anchored, lipid raft-associated hyaluronidase

The rapid turnover rate of hyaluronan (HA), the major unbranched glycosaminoglycan of the extracellular matrix, is dependent on hyaluronidases. One of them, hyaluronidase-2 (Hyal2), degrades HA into smaller fragments endowed with specific biological activities such as inflammation and angiogenesis. Yet the cellular environment of Hyal2, a purported glycosylphosphatidylinositol (GPI)-anchored protein, remains uncertain. We have examined the membrane association of Hyal2 in MDA-MB231 cancer cells where it is highly expressed and in COS-7 cells transfected with native or fluorescent Hyal2 constructs. In both cell types, Hyal2 was strongly associated with cell membrane fractions from which it could be extracted using a Triton X-114 treatment (hydrophobic phase) but not an osmotic shock or an alkaline carbonate solution. Treatment of membrane preparations with phosphatidylinositol-specific phospholipase C released immunoreactive Hyal2 into the aqueous phase, confirming the protein is attached to the membrane through a functional GPI anchor. Hyal2 transfected in COS-7 cells was associated with detergent-resistant, cholesterol-rich membranes known as lipid rafts. The cellular immunofluorescent pattern of Hyal2 was conditioned by the presence of a GPI anchor. In summary, the strong membrane association of Hyal2 through its GPI anchor demonstrated in this study using biochemical methods suggests that the main activity of this enzyme is located at the level of the plasma membrane in close contact with the pericellular HA-rich glycocalyx, the extracellular matrix, or possibly endocytic vesicles.

Differentiation of cardiomyocytes from human embryonic stem cells is accompanied by changes in the extracellular matrix production of versican and hyaluronan

Proteoglycans and hyaluronan play critical roles in heart development. In this study, human embryonic stem cells (hESC) were used as a model to quantify the synthesis of proteoglycans and hyaluronan in hESC in the early stages of differentiation, and after directed differentiation into cardiomyocytes. We demonstrated that both hESC and cardiomyocyte cultures synthesize an extracellular matrix (ECM) enriched in proteoglycans and hyaluronan. During cardiomyocyte differentiation, total proteoglycan and hyaluronan decreased and the proportion of proteoglycans bearing heparan sulfate chains was reduced. Versican, a chondroitin sulfate proteoglycan, accumulated in hESC and cardiomyocyte cultures. Furthermore, versican synthesized by hESC contained more N- and O-linked oligosaccharide than versican from cardiomyocytes. Transcripts for the versican variants, V0, V1, V2, and V3, increased in cardiomyocytes compared to hESC, with V1 most abundant. Hyaluronan in hESC had lower molecular weight than hyaluronan from cardiomyocyte cultures. These changes were accompanied by an increase in HAS-1 and HAS-2 mRNA in cardiomyocyte cultures, with HAS-2 most abundant. Interestingly, HAS-3 was absent from the cardiomyocyte cultures, but expressed by hESC. These results indicate that human cardiomyocyte differentiation is accompanied by specific changes in the expression and accumulation of ECM components and suggest a role for versican and hyaluronan in this process.

Anti-Flt1 peptide - hyaluronate conjugate for the treatment of retinal neovascularization and diabetic retinopathy

Anti-angiogenic therapeutics has been investigated extensively for the treatment of retinal and choroidal vascular diseases, and diabetic retinopathy. Anti-Flt1 peptide of GNQWFI is an antagonistic peptide for vascular endothelial growth factor receptor 1 (VEGFR1 or Flt1) inhibiting VEGFR1-mediated endothelial cell migration and tube formation. In this work, anti-Flt1 peptide (GGNQWFI) was chemically conjugated to tetra-n-butyl ammonium modified hyaluronate (HA-TBA) via amide bond formation in dimethyl sulfoxide (DMSO) using benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP). The resulting HA - GGNQWFI conjugate self-assembled to form micelle-like nanoparticles in aqueous solution, as confirmed and characterized by transmission electron microscopy (TEM). According to in vitro biological activity tests, HA - GGNQWFI conjugate exhibited a dose-dependent inhibition effect on the binding of Flt1-Fc to VEGF(165) coated on the well. Furthermore, anti-Flt1 peptide - HA conjugate effectively inhibited retinal choroidal neovascularization (CNV) in laser induced CNV model rats. The retinal vascular permeability and the deformation of retinal vascular structure were also significantly reduced in diabetic retinopathy model rats after treatment with anti-Flt1 peptide - HA conjugate. Pharmacokinetic analysis confirmed the increased mean residence time of anti-Flt1 peptide after conjugation to HA longer than 2 weeks.

Hyaluronic acid stimulates neovascularization during the regeneration of bone marrow after ablation

Restoration of vasculature is a critical component for successful integration of implants in musculoskeletal tissue. Sodium hyaluronate (NaHY) has been used as a carrier for demineralized bone matrix (DBM). DBM is osteoinductive and osteoconductive, but whether NaHY by itself has an effect is not known. NaHY has been reported to promote neovascularization, suggesting it may increase neovasculature when used with DBM as well. To test this, we used a rat tibial marrow ablation model to assess neovascularization during bone formation and regeneration of marrow with different combinations of NaHY alone and NaHY+DBM. To assess neovascularization during normal healing, animals were euthanized at 3-, 6-, 14-, 21-, and 28-days post-ablation, and the vasculature perfused using a radio-opaque contrast agent. Vascular morphology was assessed using μCT and histology. Peak vessel volume within the marrow cavity was observed on day-14 post-ablation. Test materials were injected into the ablated marrow space as follows: (A) empty defect controls; (B) high MW (700-800 kDa) NaHY + heat inactivated DBM; (C) DBM in PBS; (D) low MW NaHY (35 kDa) + DBM; (E) high MW NaHY + DBM; (F) D:E 50:50; (G) low MW NaHY; (H) high MW NaHY; and (I) G:H 50:50. Neovascularization varied with bone substitute formulation. μCT results revealed that addition of NaHY resulted in an increase in vessel number compared to empty defects. Total blood vessel volume in all NaHY only groups were similar to DBM alone. Histomorphometry of sagittal sections showed that all three formulations of NaHY increased blood vessel number within the marrow cavity, confirming that NaHY promotes neovascularization.

Prodrug-based intracellular delivery of anticancer agents

There are numerous anticancer agents based on a prodrug approach. However, no attempt has been made to review the ample available literature with a specific focus on the altered cell uptake pathways enabled by the conjugation and on the intracellular drug-release mechanisms. This article focuses on the cellular interactions of a broad selection of parenterally administered anticancer prodrugs based on synthetic polymers, proteins or lipids. The report also aims to highlight the prodrug design issues, which are key points to obtain an efficient intracellular drug delivery. The chemical basis of these molecular concepts is put into perspective with the uptake and intracellular activation mechanisms, the in vitro and in vivo proofs of concepts and the clinical results. Several active targeting strategies and stimuli-responsive architectures are discussed throughout the article.

Induction of apoptosis in glioma cells requires cell-to-cell contact with human umbilical cord blood stem cells

We have previously demonstrated the multipotent nature of human umbilical cord blood stem cells (hUCB). In this study, we have attempted to show the use of hUCB in glioma therapy. We used hUCB enriched in CD44 and CD133 cells for our studies and observed that glioma cells co-cultured with hUCB undergo apoptosis. To prove the role of cell-to-cell contact in the induction of apoptotic events, we used a modified 0.22 microm Boyden's chamber where the upper surface was used to culture glioma cells (SNB19 or U87) or xenografts (4910 or 5310) and the lower surface to culture hUCB. TUNEL assay was carried out to determine the degree of apoptotic induction and we observed that glioma or xenograft cells co-cultured with hUCB had a higher number of TUNEL-positive characteristics (63+/-6%) compared to the controls. Further, we co-cultured glioma cells labeled with lipophilic green fluorescent dye and hUCB labeled with lipophilic red fluorescent dye. FACS analysis of cells collected from the upper and lower surfaces revealed that glioma cells had taken up red fluorescent dye from the stem cells (70+/-3%) when compared to glioma cells co-cultured with fibroblast cells (15+/-4%). The apoptotic events in the glioma and xenograft cells co-cultured with hUCB were also confirmed by Western blot analysis for the cleavage of PARP and activation of caspase 8. In addition, elevated levels of CHK-2 levels and downregulation of MAP2K1 were observed in glioma cells co-cultured with hUCB indicating the DNA damage and decrease in cell survival. Nude mice, intracranially implanted with luciferase-expressing U87 cells followed by implantation of hUCB or human fibroblast cells showed retardation of intracranial tumors in hUCB-implanted mice. Taken together, these results demonstrate that hUCB have therapeutic potential with possible clinical implications.

High-molecular weight hyaluronan reduced renal PKC activation in genetically diabetic mice

The cluster determinant (CD44) seems to play a key role in tissues injured by diabetes type 2. CD44 stimulation activates the protein kinase C (PKC) family which in turn activates the transcriptional nuclear factor kappa B (NF-κB) responsible for the expression of the inflammation mediators such as tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), interleukin-18 (IL-18), inducible nitric oxide synthase (iNOS), and matrix metalloproteinases (MMPs). Regulation of CD44 interaction with its ligands depends greatly upon PKC. We investigated the effect of the treatment with high-molecular weight hyaluronan (HA) on diabetic nephropathy in genetically diabetic mice. BKS.Cg-m+/+Lepr(db) mice had elevated plasma insulin from 15 days of age and high blood sugar levels at 4 weeks. The severe nephropathy that developed was characterized by a marked increased in CD44 receptors, protein kinase C betaI, betaII, and epsilon (PKC(βI), PKC(βII), and PKCε) mRNA expression and the related protein products in kidney tissue. High levels of mRNA and related protein levels were also detected in the damaged kidney for NF-κB, TNF-α, IL-6, IL-18, MMP-7, and iNOS. Chronic daily administration of high-molecular mass HA for 2 weeks significantly reduced CD44, PKC(βI), PKC(βII), and PKCα gene expression and the related protein production in kidney tissue and TNF-α, IL-6, IL-18, MMP-7, and iNOS expression and levels also decreased. Histological analysis confirmed the biochemical data. However, blood parameters of diabetes were unchanged. These results suggest that the CD44 and PKC play an important role in diabetes and interaction of high-molecular weight HA with these proteins may reduce inflammation and secondary pathologies due to this disease.

Angiotensin converting enzyme inhibition blocks interstitial hyaluronan dissipation in the neonatal rat kidney via hyaluronan synthase 2 and hyaluronidase 1

A functional renin-angiotensin system (RAS) is required for normal kidney development. Neonatal inhibition of the RAS in rats results in long-term pathological renal phenotype and causes hyaluronan (HA), which is involved in morphogenesis and inflammation, to accumulate. To elucidate the mechanisms, intrarenal HA content was followed during neonatal completion of nephrogenesis with or without angiotensin converting enzyme inhibition (ACEI) together with mRNA expression of hyaluronan synthases (HAS), hyaluronidases (Hyal), urinary hyaluronidase activity and cortical lymphatic vessels, which facilitate the drainage of HA from the tissue. In 6-8days old control rats cortical HA content was high and reduced by 93% on days 10-21, reaching adult low levels. Medullary HA content was high on days 6-8 and then reduced by 85% to 12-fold above cortical levels at day 21. In neonatally ACEI-treated rats the reduction in HA was abolished. Temporal expression of HAS2 corresponded with the reduction in HA content in the normal kidney. In ACEI-treated animals cortical HAS2 remained twice the expression of controls. Medullary Hyal1 increased in controls but decreased in ACEI-treated animals. Urine hyaluronidase activity decreased with time in control animals while in ACEI-treated animals it was initially 50% lower and did not change over time. Cells expressing the lymphatic endothelial mucoprotein podoplanin in ACEI-treated animals were increased 18-fold compared to controls suggesting compensation. In conclusion, the high renal HA content is rapidly reduced due to reduced HAS2 and increased Hyal1 mRNA expressions. Normal angiotensin II function is crucial for inducing these changes. Due to the extreme water-attracting and pro-inflammatory properties of HA, accumulation in the neonatally ACEI-treated kidneys may partly explain the pathological renal phenotype of the adult kidney, which include reduced urinary concentration ability and tubulointerstitial inflammation.

Experimental assessment of pro-lymphangiogenic growth factors in the treatment of post-surgical lymphedema following lymphadenectomy

Introduction

Lymphedema is a frequent consequence of lymph node excision during breast cancer surgery. Current treatment options are limited mainly to external compression therapies to limit edema development. We investigated previously, postsurgical lymphedema in a sheep model following the removal of a single lymph node and determined that autologous lymph node transplantation has the potential to reduce or prevent edema development. In this report, we examine the potential of lymphangiogenic therapy to restore lymphatic function and reduce postsurgical lymphedema.

Methods

Lymphangiogenic growth factors (vascular endothelial growth factor C (VEGF-C)) and angiopoietin-2 (ANG-2) were loaded into a gel-based drug delivery system (HAMC; a blend of hyaluronan and methylcellulose). Drug release rates and lymphangiogenic signaling in target endothelial cells were assessed in vitro and vascular permeability biocompatibility tests were examined in vivo. Following, the removal of a single popliteal lymph node, HAMC with the growth factors was injected into the excision site. Six weeks later, lymphatic functionality was assessed by injecting ¹²⁵Iodine radiolabeled bovine serum albumin (¹²⁵I-BSA) into prenodal vessels and measuring its recovery in plasma. Circumferential leg measurements were plotted over time and areas under the curves used to quantify edema formation.

Results

The growth factors were released over a two-week period in vitro by diffusion from HAMC, with 50% being released in the first 24 hr. The system induced lymphangiogenic signaling in target endothelial cells, while inducing only a minimal inflammatory response in sheep. Removal of the node significantly reduced lymphatic functionality (nodectomy 1.9 ± 0.9, HAMC alone 1.7 ± 0.8) compared with intact groups (3.2 ± 0.7). In contrast, there was no significant difference between the growth factor treatment group (2.3 ± 0.73) and the intact group indicating improved function with the molecular factors. An increase in the number of regenerated lymphatic vessels at treatment sites was observed with fluoroscopy. Groups receiving HAMC plus growth factors displayed significantly reduced edema (107.4 ± 51.3) compared with nontreated groups (nodectomy 219.8 ± 118.7 and HAMC alone 162.6 ± 141).

Conclusions

Growth factor therapy has the potential to increase lymphatic function and reduce edema magnitude in an animal model of lymphedema. The application of this concept to lymphedema patients warrants further examination.

Small hyaluronan oligosaccharides induce inflammation by engaging both toll-like-4 and CD44 receptors in human chondrocytes

Small degradation fragments of hyaluronan (HA) may stimulate an inflammatory response in a variety of tissues at the injury site. HA oligosaccharides are endogenous ligands for the cluster determinant 44 (CD44) receptor as well as for toll-like receptor 4 (TLR-4). Previous data have shown that HA fragments may induce pro-inflammatory cytokine expression by interacting with both the CD44 receptor and TLR-4. CD44 and TLR-4 stimulation activates different inflammatory pathways that culminate with the activation of the transcriptional nuclear factor kappaB (NF-kappaB) which is responsible for the expression of inflammation mediators such as tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-1 beta (IL-1beta). The aim of this study was to investigate the inflammatory effects of very small HA oligosaccharides on both TLR-4 and CD44 involvement in normal human articular chondrocytes. Adding HA fragments to chondrocyte cultures up-regulated CD44 and TLR-4 expression, activated NF-kappaB translocation and increased the pro-inflammatory cytokines TNF-alpha, IL-6 and IL-1beta. The addition of a specific CD44 blocking antibody reduced CD44 and all inflammatory cytokine expression as well as protein production. However, cytokine expression remained significantly higher than in untreated chondrocytes. TLR-4 expression was not affected. The treatment with TLR-4 blocking antibody decreased TLR-4 and inflammatory cytokine expression, although cytokine expression was significantly higher than in control cells. CD44 expression was unaffected. The addition of both CD44 and TLR-4 blocking antibodies significantly reduced CD44, TLR-4 and inflammatory cytokine expression.

Bacteriophage hyaluronidase effectively inhibits growth, migration and invasion by disrupting hyaluronan-mediated Erk1/2 activation and RhoA expression in human breast carcinoma cells

Aberrant hyaluronan production has been implicated in many types of tumor. In this context, hyaluronidase has been explored as a viable therapeutic approach to reduce tumoral hyaluronan. However, elevated levels of hyaluronan in tumors are often associated with high expression levels of cellular hyaluronidases, which consequently produce various sizes of saturated hyaluronan fragments with divergent pro-tumoral activities. The current study shows that different hyaluronan metabolisms of mammalian and microbial hyaluronidases could elicit distinct alterations in cancer cell behavior. Unlike saturated hyaluronan metabolites, unsaturated hyaluronan oligosaccharides produced by bacteriophage hyaluronidase, HylP, had no biological effect on growth of breast carcinoma cells. More importantly, HylP's metabolic process of hyaluronan into non-detrimental oligosaccharides significantly decreased breast cancer cell proliferation, migration and invasion by disrupting Erk1/2 activation and RhoA expression. Our results suggest that it may be possible to exploit HylP's unique enzymatic activity in suppressing hyaluronan-mediated tumor growth and progression.

4-Methylumbelliferone inhibits tumour cell growth and the activation of stromal hyaluronan synthesis by melanoma cell-derived factors

BACKGROUND

There is a close correlation between tumour progression and hyaluronan production, either by tumour cells or by stromal cells that are stimulated by tumour-derived factors. Inhibition of tumour stimulation of fibroblast hyaluronan may suppress tumour growth and invasion.

OBJECTIVES

To examine the effect of the hyaluronan synthesis inhibitor 4-methylumbelliferone (4-MU) on the growth of and hyaluronan synthesis by fibroblasts and C8161 and MV3 melanoma cell lines, invasion, and inhibition of tumour cell-derived factor activation of fibroblasts.

METHODS

Effects of 4-MU on growth and hyaluronan synthesis by fibroblasts and melanoma cells were examined in monolayer culture and fibroblast-contracted collagen lattices, and their effects on the growth and invasion of tumour cells into collagen lattices were also studied.

RESULTS

4-MU caused a dose-dependent growth inhibition of fibroblast and melanoma cells with maximum inhibition at 0·5 mmol L(-1) 4-MU. At this dose, 4-MU inhibited (3) H-glucosamine incorporation into fibroblast glycosaminoglycans by 52%, and hyaluronan synthesis by 64%. The relative inhibition was more pronounced when fibroblasts were stimulated with C8161 melanoma cell-conditioned medium. 4-MU reduced the level of hyaluronan in fibroblast-contracted collagen lattices, and inhibited both the growth on and invasion into the lattices by melanoma cells. This growth inhibition appears to be predominantly independent of inhibition of hyaluronan synthesis. The effect on growth inhibition was reversible, and 4-MU had no effect on apoptosis.

CONCLUSIONS

4-MU is a potent inhibitor of hyaluronan synthesis, induction of stromal hyaluronan accumulation by tumour cells, and fibroblast and melanoma cell proliferation, and results suggest that 4-MU may have potential as a tumour cell anti-invasive and antiproliferative agent.