Hyaluronan reduces migration and proliferation in CHO cells

Poly-γ-Glutamic Acid from a Novel Bacillus subtilis Strain: Strengthening the Skin Barrier and Improving Moisture Retention in Keratinocytes and a Reconstructed Skin Model

A novel Bacillus subtilis HB-31 strain was isolated from Gotjawal Wetland in Jeju Island, Republic of Korea. A mucus substance produced by this strain was identified as high-molecular-weight poly-γ-glutamic acid (γ-PGA) using NMR, Fourier transform infrared spectroscopy, and size-exclusion chromatography/multi-angle light scattering analyses. We evaluated whether γ-PGA strengthened the skin barrier using keratinocytes and a reconstructed skin model. In keratinocytes, γ-PGA treatment dose-dependently increased the mRNA expression of skin barrier markers, including filaggrin, involucrin, loricrin, serine palmitoyl transferase, fatty acid synthase, and 3-hydroxy-3-methylglutaryl coenzyme A reductase. γ-PGA also enhanced hyaluronic acid synthesis by upregulating hyaluronic acid synthase-1, -2, and -3 mRNA levels and promoted aquaporin 3 expression, which is involved in skin hydration. In the reconstructed skin model, topical application of 1% γ-PGA elevated filaggrin, involucrin, CD44, and aquaporin 3 expression, compared to the control. These results suggest that the newly isolated HB-31 can be used as a commercial production system of high-molecular-weight γ-PGA, which can serve as an effective ingredient for strengthening the skin barrier and improving moisture retention. Further research is needed to explore the long-term effects of γ-PGA on skin health and its application in treating skin conditions.

Microbial production of N-acetyl-D-glucosamine (GlcNAc) for versatile applications: Biotechnological strategies for green process development

N-acetyl-d-glucosamine (GlcNAc) is a commercially important amino sugar for its wide range of applications in pharmaceutical, food, cosmetics and biofuel industries. In nature, GlcNAc is polymerised into chitin biopolymer, which is one of the major constituents of fungal cell wall and outer shells of crustaceans. Sea food processing industries generate a large volume of chitin as biopolymeric waste. Because of its high abundance, chitinaceous shellfish wastes have been exploited as one of the major precursor substrates of GlcNAc production, both in chemical and enzymatic means. Nevertheless, the current process of GlcNAc extraction from shellfish wastes generates poor turnover and attracts environmental hazards. Moreover, GlcNAc isolated from shellfish could not be prescribed to certain groups of people because of the allergic nature of shell components. Therefore, an alternative route of GlcNAc production is advocated. With the advancement of metabolic construction and synthetic biology, microbial synthesis of GlcNAc is gaining much attention nowadays. Several new and cutting-edge technologies like substrate co-utilization strategy, promoter engineering, and CRISPR interference system were proposed in this fascinating area. The study would put forward the potential application of microbial engineering in the production of important pharmaceuticals. Very recently, autotrophic fermentation of GlcNAc synthesis has been proposed. The metabolic engineering approaches would offer great promise to mitigate the issues of low yield and high production cost, which are major challenges in microbial bio-processes industries. Further process optimization, optimising metabolic flux, and efficient recovery of GlcNAc from culture broth, should be investigated in order to achieve a high product titer. The current study presents a comprehensive review on microbe-based eco-friendly green methods that would pave the way towards the development of future research directions in this field for the designing of a cost-effective fermentation process on an industrial setup.

The molecular weight of hyaluronic acid influences metabolic activity and osteogenic differentiation of periodontal ligament cells

OBJECTIVE

While HA is present naturally in periodontal tissues, its molecular weight can vary widely in vivo. The objective of this study was to directly compare the biological reactions of periodontal ligament cells to four distinct molecular weights of hyaluronic acid (HA).

MATERIALS AND METHODS

Immortalized human periodontal ligament cells (PDL-hTERT) were cultured for 21 days in culture medium alone (control) or enriched with osteogenic supplements (OS group). Other 4 experimental groups were cultured in OS medium with the addition of HA with different molecular weights (HMW, MMW, LMW, and ULMW). The cell morphology was examined daily. WST1 assays were performed to evaluate metabolic activity. Von Kossa staining and calcium deposition assay were used to analyze osteogenic differentiation and mineralization.

RESULTS

Cell morphology remained unaltered in all groups. Cells stimulated with OS alone or with the addition of hyaluronan showed all the typical microscopic appearance of osteogenic differentiation. Metabolic activity increased in all groups over time. Hyaluronan stimulated greater metabolic activity than the control group, with LMW HA and MMW HA showing the most significant increase. All groups showed mineral deposits and calcium deposition after 21 days of stimulation.

CONCLUSION

Our results suggest that hyaluronan can promote metabolic activity and mineralization of PDL-hTERT cells, with LMW HA being the most effective.

CLINICAL RELEVANCE

These results shed light on how the various molecular weight fractions of HA promote tissue regeneration and repair, as well as help to identify an optimal molecular weight range for this application in periodontal tissues.

Hyaluronan-CD44 interactions mediate contractility and migration in periodontal ligament cells

The role of hyaluronan (HA) in periodontal healing has been speculated via its interaction with the CD44 receptor. While HA-CD44 interactions have previously been implicated in numerous cell types; effect and mechanism of exogenous HA on periodontal ligament (PDL) cells is less clear. Herein, we examine the effect of exogenous HA on contractility and migration in human and murine PDL cells using arrays of microposts and time-lapse microscopy. Our findings observed HA-treated human PDL cells as more contractile and less migratory than untreated cells. Moreover, the effect of HA on contractility and focal adhesion area was abrogated when PDL cells were treated with Y27632, an inhibitor of rho-dependent kinase, but not when these cells were treated with ML-7, an inhibitor of myosin light chain kinase. Our results provide insight into the mechanobiology of PDL cells, which may contribute towards the development of therapeutic strategies for periodontal healing and tissue regeneration.

A new strategy for the passive skin delivery of nanoparticulate, high molecular weight hyaluronic acid prepared by a polyion complex method

Restoring hyaluronic acid (HA) content is important for maintaining the function of photo-aged skin. This study aimed to evaluate the passive delivery into skin of HA nanoparticles formed by the polyion complex method. Nanoparticles were prepared by mixing and stirring anionic HA with a cationic polymer, protamine, at the charge ratio 55:45. The permeation of fluorescently-labelled HA nanoparticles (HANP) or free HA through hairless mouse skin was characterized in vitro. HANP or free HA was applied to ultraviolet (UV)-irradiated mice in vivo, and their transepidermal water loss (TEWL) was measured after 4 days. HA that had been delivered into skin was separated and characterized by molecular sieve chromatography. HANP were able to deliver HA into the dermis both in vitro and in vivo, whereas free HA penetrated no further than the stratum corneum. Following HANP application, HA within the skin was present in the form of free HA rather than nanoparticles. When applied in vivo, HANP significantly reduced the TEWL caused by UV irradiation. Thus, although free HA does not penetrate into the skin by passive diffusion, HA can be effectively delivered by nanoparticles. HA is then released from the nanoparticles and can contribute to barrier recovery following UV irradiation.

Method comparison for analyzing wound healing rates

Wound healing scratch assay is a frequently used method to characterize cell migration, which is an important biological process in the course of development, tissue repair, and immune response for example. The measurement of wound healing rate, however, varies among different studies. Here we summarized these measurements into three types: (I) direct rate average; (II) regression rate average; and (III) average distance regression rate. Using Chinese hamster ovary (CHO) cells as a model, we compared the three types of analyses on quantifying the wound closing rate, and discovered that type I & III measurements are more resistant to outliers, and type II analysis is more sensitive to outliers. We hope this study can help researchers to better use this simple yet effective assay.

Rab10-mediated endocytosis of the hyaluronan synthase HAS3 regulates hyaluronan synthesis and cell adhesion to collagen

Hyaluronan synthases (HAS1-3) are unique in that they are active only when located in the plasma membrane, where they extrude the growing hyaluronan (HA) directly into cell surface and extracellular space. Therefore, traffic of HAS to/from the plasma membrane is crucial for the synthesis of HA. In this study, we have identified Rab10 GTPase as the first protein known to be involved in the control of this traffic. Rab10 colocalized with HAS3 in intracellular vesicular structures and was co-immunoprecipitated with HAS3 from isolated endosomal vesicles. Rab10 silencing increased the plasma membrane residence of HAS3, resulting in a significant increase of HA secretion and an enlarged cell surface HA coat, whereas Rab10 overexpression suppressed HA synthesis. Rab10 silencing blocked the retrograde traffic of HAS3 from the plasma membrane to early endosomes. The cell surface HA coat impaired cell adhesion to type I collagen, as indicated by recovery of adhesion following hyaluronidase treatment. The data indicate a novel function for Rab10 in reducing cell surface HAS3, suppressing HA synthesis, and facilitating cell adhesion to type I collagen. These are processes important in tissue injury, inflammation, and malignant growth.

In vitro evaluation of cytotoxicity of hyaluronic acid as an extracellular matrix on OFCOL II cells by the MTT assay

OBJECTIVE

To evaluate the cytotoxicity of hyaluronic acid (HA) on a tissue-engineered compound for bone grafting containing osteoblastic cells (OFCOL II), platelet-rich plasma (PRP) with or without thrombin (Thr), and hydroxyapatite (HP) by the MTT assay.

STUDY DESIGN

Studied groups were formed as follows: (A) Cells + HA + PRP with Thr + hydroxyapatite (HP); (B) Cells + HA + PRP + HP; (C) Cells + HA + HP; (D) Cells + HP; (E) Cells + HA; (F) Cells + PRP with Thr; (G) Cells + PRP; and (H) Pure Dulbecco's modified Eagle's medium (DMEM) with 15% fetal bovine serum. A 2-way ANOVA and Tukey's test were applied for statistical analysis (P < .05).

RESULTS

Results of cell viability for each group were as follows: A: 79%, B: 67%, C: 68%, D: 99%, E: 74%, G: 89%, F: 90%, and Group H: 100%.

CONCLUSIONS

Results suggested a decrease in cell viability in the presence of HA.

Gene expression profiling for mechanistic understanding of cellular aggregation in mammalian cell perfusion cultures

Aggregation of baby hamster kidney (BHK) cells cultivated in perfusion mode for manufacturing recombinant proteins was characterized. The potential impact of cultivation time on cell aggregation for an aggregating culture (cell line A) was studied by comparing expression profiles of 84 genes in the extracellular adhesion molecules (ECM) pathway by qRT-PCR from 9 and 25 day shake flask samples and 80 and 94 day bioreactor samples. Significant up-regulation of THBS2 (4.4- to 6.9-fold) was seen in both the 25 day shake flask and 80 and 94 day bioreactor samples compared to the 9 day shake flask while NCAM1 was down-regulated 5.1- to 8.9-fold in the 80 and 94 day bioreactor samples. Subsequent comparisons were made between cell line A and a non-aggregating culture (cell line B). A 65 day perfusion bioreactor sample from cell line B served as the control for 80 and 94 day samples from four different perfusion bioreactors for cell line A. Of the 84 genes in the ECM pathway, four (COL1A1, COL4A1, THBS2, and VCAN) were consistently up-regulated in cell line A while two (NCAM1 and THBS1) were consistently down-regulated. The magnitudes of differential gene expression were much higher when cell lines were compared (4.1- to 44.6-fold) than when early and late cell line B samples were compared (4.4- to 6.9-fold) indicating greater variability between aggregating and non-aggregating cell lines. Based on the differential gene expression results, two mechanistic models were proposed for aggregation of BHK cells in perfusion cultures.

N-acetylglucosamine: production and applications

N-Acetylglucosamine (GlcNAc) is a monosaccharide that usually polymerizes linearly through (1,4)-β-linkages. GlcNAc is the monomeric unit of the polymer chitin, the second most abundant carbohydrate after cellulose. In addition to serving as a component of this homogeneous polysaccharide, GlcNAc is also a basic component of hyaluronic acid and keratin sulfate on the cell surface. In this review, we discuss the industrial production of GlcNAc, using chitin as a substrate, by chemical, enzymatic and biotransformation methods. Also, newly developed methods to obtain GlcNAc using glucose as a substrate in genetically modified microorganisms are introduced. Moreover, GlcNAc has generated interest not only as an underutilized resource but also as a new functional material with high potential in various fields. Here we also take a closer look at the current applications of GlcNAc, and several new and cutting edge approaches in this fascinating area are thoroughly discussed.

Inducible Hyaluronan Production Reveals Differential Effects on Prostate Tumor Cell Growth and Tumor Angiogenesis

Prostate cancer progression can be predicted in human tumor biopsies by abundant hyaluronan (HA) and its processing enzyme, the hyaluronidase HYAL1. Accumulation of HA is dictated by the balance between expression levels of HA synthases, the enzymes that produce HA polymers, and hyaluronidases, which process polymers to oligosaccharides. Aggressive prostate tumor cells express 20-fold higher levels of the hyaluronan synthase HAS3, but the mechanistic relevance of this correlation has not been determined. We stably overexpressed HAS3 in prostate tumor cells. Adhesion to extracellular matrix and cellular growth kinetics in vitro were significantly reduced. Slow growth in culture was restored either by exogenous addition of hyaluronidase or by stable HYAL1 coexpression. Coexpression did not improve comparably slow growth in mice, however, suggesting that excess hyaluronan production by HAS3 may alter the balance required for induced tumor growth. To address this, we used a tetracycline-inducible HAS3 expression system in which hyaluronan production could be experimentally controlled. Adjusting temporal parameters of hyaluronan production directly affected growth rate of the cells. Relief from growth suppression in vitro but not in vivo by enzymatic removal of HA effectively uncoupled the respective roles of hyaluronan in growth and angiogenesis, suggesting that growth mediation is less critical to establishment of the tumor than early vascular development. Collectively results also imply that HA processing by elevated HYAL1 expression in invasive prostate cancer is a requirement for progression.

Overexpression of hyaluronan synthases alters vascular smooth muscle cell phenotype and promotes monocyte adhesion

Hyaluronan (HA) accumulates in vascular disease but its functional role is not fully understood. To investigate the impact of HA enriched extracellular matrices (ECM) on cell phenotype, arterial smooth muscle cells (ASMCs) were transduced with retroviral constructs (LXSN) encoding murine has-1, has-2, and has-3. HA synthesis was significantly elevated in has transduced ASMCs. Metabolically labeled HA from has-1 and has-2 transduced cells was present mostly in high molecular weight (HWA) fractions (2-10x10(6) Da), whereas HA produced by has-3 and control cells was present in lower molecular weight fractions (approximately 2x10(6) Da). Both has-1 and has-3 transduced ASMCs accumulated more pericellular HA than has-2 transduced ASMCs. All has transduced ASMCs had attenuated growth and migration rates, and a decreased detachment response. Affinity histochemistry revealed that has-1 transduced ASMCs accumulated the greatest amount of HA containing ECM than the other transduced ASMCs. This ECM was hyaluronidase sensitive and bound a significantly greater number of monocytes than the ECM generated by has-2 or has-3 transduced ASMCs. Confocal microscopy showed CD44 positive monocytes bound to hyaluronidase sensitive ECM in has-1 transduced ASMCs. These data implicate specific has isoforms in the formation of HA enriched pro-inflammatory ECMs.

Topical high molecular weight hyaluronan reduces radicular pain post laminectomy in a rat model

BACKGROUND CONTEXT

A controversy exists about the mechanism of causation of the post-laminectomy pain syndrome. Some believe that epidural scarring, and attendant spinal nerve and nerve root scarring and tethering to the disc or pedicle at the site of surgery contributes to post-laminectomy pain in such patients. However, clinical outcome studies on this question are inconclusive and the assertion remains controversial. Definitive studies to help resolve the question are needed. Previously our laboratory has reported on a preclinical post-laminectomy model that mimics the postoperative proliferative fibrotic response grossly, as well as by biochemical assessment of the collagen content within the spinal canal. The post-laminectomy fibrotic response was attenuated in that study by application of a topical antifibrotic (high molecular weight hyaluronan gel) or by insertion of an absorbable roofing barrier (0.2-mm-thick Macropore sheet material) over the laminectomy defect before wound closure. The question remains of relevance of the attenuation of the fibrotic response to post-laminectomy chronic pain syndromes.

PURPOSE

The purpose of this study is to evaluate the effect of therapeutic attenuation of proliferative scar within the spinal canal post laminectomy on the pain-related behavioral response in a preclinical rat model.

STUDY DESIGN/SETTING

An established L5-L6 rat laminectomy model with a unilateral L5-6 disc injury was employed to assess postoperative proliferative fibrosis of the L5 spinal nerves using quantitative biochemical hydroxyproline assessment of the collagen content in four experimental groups. These observations were correlated with gross descriptions of spinal nerve scarring or tethering. Associated manifestations of a sensory pain-related response in the L5 spinal nerve receptor area of the hind paws was studied using standard tactile allodynia assessment with the von Frey hair technique. The tactile allodynia findings were supplemented by weekly descriptors of behavioral pain manifestations.

METHODS

Bilateral laminectomies at L5 and L6 and a unilateral right disc injury (L5-6) were performed on 35 male adult Sprague-Dawley rats, weighing 400+ grams (approved by the VA Institutional Animal Care Use Committee). The study consisted of four groups: 1) normal nonoperative control; 2) a sham-operated group; 3) an untreated laminectomy-disc injury group; and 4) a laminectomy-disc injury treatment group in which 0.1 cc topical high molecular weight hyaluronan (HMW HA) gel was layered over the dura and into the laminectomy canal before closure. Before animals were entered into the study, they were checked for the presence of abnormal response to the tactile testing procedure of the L5 sensory receptor area. Animals exhibiting anomalous responses were excluded from the study. Behavioral testing for tactile allodynia was performed at weekly intervals post laminectomy beginning at 3 weeks. Pain-related behavior was characterized at weekly intervals. A behavioral test cage with a wire mesh floor allowed for tactile allodynia testing. Graduated von Frey hairs whose stiffness increased logarithmically from 0.41 to 15 g were used for tactile allodynia tests. The animals were killed 8 weeks postoperatively for analysis. The dissected spinal nerve and nerve root specimens were studied biochemically for hydroxyproline content to estimate total collagen in and around the L5 neural structures. Statistical analyses were performed using analysis of variance and a Fisher comparison t test.

RESULTS

The major observations on the untreated preclinical post-laminectomy rat model previously described by this laboratory were confirmed. All untreated animals developed a tail contracture concave toward the right (disc injury side) consistent with asymmetrical lumbar muscle spasm. Only one animal in the HA gel treatment group had a tail contracture. It was of mild degree and occurred in an animal that demonstrated slightly increased right L5 tactile sensitivity. Gross inspection of the dissected specimens demonstrated spinal nerve scarring and tethering to the disc and pedicle greater on the right than the left in untreated animals, findings that were markedly reduced in the treatment group. Collagen content of the L5 spinal nerve and nerve roots with attached scar were significantly lower in the HA gel treatment group than in the untreated laminectomy group (p=.0014). Pain behavioral testing of the L5 receptor area of the right hind paw in the untreated laminectomy group showed markedly increased sensitivity to tactile allodynia testing compared with the corresponding limb of the control group (p=.0001), to the corresponding limb of the sham group (p=.0001), and compared with the HMW HA gel treatment group (p=.0010). Comparisons of the pain behavioral data between the sham and the post-laminectomy HA gel treatment group and the control animals lacked statistical significance.

CONCLUSION

This study supports the concept of a relationship between perineural fibrosis and radicular neuropathy in the model described, and emphasizes the role of disc injury and spinal nerve retraction in the post-laminectomy fibrotic process. Furthermore, it shows promise for preliminary assessment of interventions with other anti-inflammatory agents, for characterization of the neurochemical profile of the post-laminectomy pain state, and for exploration of newer pharmaceutical agents potentially useful in the prevention or management of the post-laminectomy syndrome. Post-laminectomy scar is but one of many potential causes of the post-laminectomy pain syndrome. Furthermore, a cautionary note must be emphasized as in all studies using preclinical models, conclusions drawn from the studies cannot be extended directly to patients without confirmatory clinical follow-up studies.

Disordered enterocyte signaling and intestinal barrier dysfunction in the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in neonates, and is characterized by the development of diffuse intestinal necrosis in the stressed, pre-term infant. Systemic stress causes a breakdown in the intestinal mucosal barrier, which leads to translocation of bacteria and endotoxin and the initiation of a signaling response within the enterocyte. This review summarizes recent evidence defining a clear role that defective enterocyte signaling plays in the pathogenesis of NEC through the following mechanisms: 1) The localized production of nitric oxide by villus enterocytes results in an increase in enterocyte apoptosis and impaired proliferation; 2) The translocation of endotoxin results in a PI3K-dependent activation of RhoA-GTPase within the enterocyte leading to decreased enterocyte migration and impaired restitution; 3) Dysregulated sodium-proton exchange within the enterocyte by endotoxin renders the enterocyte monolayer more susceptible to damage in the face of the acidic microenvironment characteristic of systemic sepsis; and 4) Endotoxin causes a p38-dependent release of the pro-inflammatory molecule COX-2 by the enterocyte, which potentiates the systemic inflammatory response. An understanding of the mechanisms by which disordered enterocyte signaling contributes to the pathogenesis of barrier failure and NEC--through these and other mechanisms--may lead to the identification of novel therapeutic approaches for this devastating disease.

Hyaluronic acid of high molecular weight inhibits proliferation and induces cell death in U937 macrophage cells

Hyaluronic acid (HA), a major glycosaminoglycan component of the extracellular matrix, has regulatory influences on cells and cellular activities. To explore the effects of a high concentration (1 mg/mL) of high molecular weight HA (500-730 kD) on U937 macrophage growth dynamics, three factors that influence overall cellular growth, namely proliferation, apoptosis, and cell death, were examined. Cells were cultured with HA and were analyzed by flow cytometry every 24 hours during a 168-hour period for proliferation and the presence of apoptotic and dead cells. These analyses demonstrated that HA inhibits U937 macrophage proliferation in a time-dependent manner. Through the first 72 hours, cells exhibited slowed proliferation. However, no evidence of cell division arrest or reduced cell viability was observed. Thereafter, HA continued to diminish proliferation, but induced apoptosis. This data is consistent with regulatory influences secondary to HA binding to CD44 and/or RHAMM cell surface receptors, both of which were shown to be expressed on U937 macrophages. This study demonstrates that a high concentration of high molecular weight HA greatly inhibits macrophage population growth by the dual actions of impeding cell proliferation and inducing apoptosis.

Synergistic Effect of N-Acetylglucosamine and Retinoids on Hyaluronan Production in Human Keratinocytes

Hyaluronan (HA) is well known to reside in the extracellular matrix as a water-sorbed macromolecule. The aims of this study were twofold: to investigate the regulation of HA synthesis in keratinocytes, and to develop a method to modulate this regulatory process. We found that N-acetylglucosamine (NAG) increased the production of HA by cultured keratinocytes dose dependently, but had no effect on the production by skin fibroblasts. The effect of NAG in keratinocytes was found to be specific for HA production, as there was no change in sulfated glycosaminoglycan formation. The copresence of NAG with either of two retinoids, retinoic acid (RA) or retinol, exerted a synergistic effect on HA production. To investigate whether human HA synthase (HAS) genes were regulated by NAG or retinoids, total RNA extracted from cells treated with these agents was subjected to Northern blot analysis. We observed that RA and retinol markedly induced the expression of HA synthase-3 (HAS3) mRNA. Moreover, beta-carotene, a provitamin A, influenced HA production and HAS3 gene expression in a manner similar to the retinoids. Conversely, NAG had no effect on the expression of HAS3 transcripts. Pretreatment of cells with RA stimulated the activity of membrane-associated HAS, whereas pretreatment with NAG did not. These results suggest that HA production is regulated by at least two pathways: one involving the regulation of HAS gene expression, and the other independent of such a regulatory effect. Taken together, our findings suggest that NAG is a new modulator of HA synthesis.

Keratinocyte growth factor stimulates migration and hyaluronan synthesis in the epidermis by activation of keratinocyte hyaluronan synthases 2 and 3

Keratinocyte growth factor (KGF) activates keratinocyte migration and stimulates wound healing. Hyaluronan, an extracellular matrix glycosaminoglycan that accumulates in wounded epidermis, is known to promote cell migration, suggesting that increased synthesis of hyaluronan might be associated with the KGF response in keratinocytes. Treatment of monolayer cultures of rat epidermal keratinocytes led to an elongated and lifted cell shape, increased filopodial protrusions, enhanced cell migration, accumulation of intermediate size hyaluronan in the culture medium and within keratinocytes, and a rapid increase of hyaluronan synthase 2 (Has2) mRNA, suggesting a direct influence on this gene. In stratified, organotypic cultures of the same cell line, both Has2 and Has3 with the hyaluronan receptor CD44 were up-regulated and hyaluronan accumulated in the epidermis, the spinous cell layer in particular. At the same time the expression of the early differentiation marker keratin 10 was inhibited, whereas filaggrin expression and epidermal permeability were less affected. The data indicate that Has2 and Has3 belong to the targets of KGF in keratinocytes, and support the idea that enhanced hyaluronan synthesis acts an effector for the migratory response of keratinocytes in wound healing, whereas it may delay keratinocyte terminal differentiation.

Hyalgan has a dose-dependent differential effect on macrophage proliferation and cell death

The intra-articular injection of high molecular weight hyaluronic acid (HA) has been reported to be an effective treatment for pain of osteoarthritis of the knee. However, the mechanism by which HA exerts its effect is unknown. To explore HA's influence on the growth of U937 human macrophages, cells were incubated for 168 h with three concentrations, 1, 0.1 and 0.01 mg/mL, of Hyalgan, a high molecular weight HA preparation. At 24-h increments, the cells were examined for proliferation, cell cycle distribution as well as the number of apoptotic and dead cells. Exposing macrophages to 1 mg/mL Hyalgan significantly reduced the rate of cellular proliferation and altered the cell cycle distribution to yield decreased proportions of G0/G1 cells but increased S and G2/M cells. Concomitantly, a 10-fold increase in apoptotic cells and a 12-fold increase in dead cells were observed. The population doubling time (PDT) for cells treated with 1.0 mg/mL Hyalgan increased from 23.6 to 52.9 h. By contrast, the two lower Hyalgan concentrations significantly promoted macrophage proliferation in a dose-dependent manner. They also increased the proportion of G2/M cells, but had no effect on the number of apoptotic or dead cells. The PDTs of 21.5 and 22.2 h were less than the control time of 23.6 h. These results demonstrate that Hyalgan concentrations have a differential effect on macrophage growth dynamics and suggest an anti-inflammatory effect at high HA concentrations.

The properties of chitosan-gelatin membranes and scaffolds modified with hyaluronic acid by different methods

The objective of the present study was to investigate the properties of chitosan-gelatin membranes or scaffolds, which were modified by incorporation of hyaluronic acid in the surface or bulk phase through co-crosslinking with N,N-(3-dimethylamino-propyl)-N'-ethyl carbodiimide (EDC) and N-hydroxysuccinimide (NHS) in 2-morpholinoethane sulfonic acid (MES) buffer. The comparative study on properties of surface modification (HA(S)) and polyblend membranes (HA(C)) revealed that gelatin was enriched on the surface of HA(C), while hyaluronic acid was enriched on the surface of the HA(S). The HA(S) membranes made by surface modification method had a characteristic surface morphology. The corresponding scaffolds were prepared through freeze-drying. The incorporation of hyaluronic acid improved flexibility and fibroblasts adhesion, while slowing down the rate of biodegradation of chitosan-gelatin scaffold. Human fibroblasts adhered and proliferated well on the membranes or scaffolds in vitro.

Cell-matrix interactions of in vitro human skin fibroblasts upon addition of hyaluronan

Normal human skin fibroblasts were grown in a three-dimensional collagen gel or in monolayer in the presence or absence of high molecular weight hyaluronan (HA) to assess the influence of extracellular HA on cell-matrix interactions. HA incorporated into the collagen gel or added to the culture medium did not modify lattice retraction with time. The effect was independent from HA molecular weight (from 7.5 x 10(5) to 2.7 x 10(6) Da) and concentration (from 0.1 up to 1 mg/ml). HA did not affect shape and distribution of fibroblasts within the gel, whereas it induced the actin filaments to organise into thicker cables running underneath the plasma membrane. The same phenomenon was observed in fibroblasts grown in monolayer. By contrast, vimentin cytoskeleton and cell-substrate focal adhesions were not modified by exogenous HA. The number of fibroblasts attached to HA-coated dishes was always significantly lower compared to plastic and to collagen type I-coated plates. By contrast, adhesion was not affected by soluble HA added to the medium nor by anti-CD44 and anti-RHAMM-IHABP polyclonals. After 24-h seeding on collagen type I or on plastic, cells were large and spread. Conversely, cells adherent to HA-coated surfaces were long, thin and aligned into rows; alcian blue showed that cells were attached to the plastic in between HA bundles. Therefore, normal human skin fibroblasts exhibit very scarce, if any, adhesion to matrix HA, either soluble or immobilised. Moreover, even at high concentration, HA molecules do not exert any visco-mechanical effect on lattice retraction and do not interfere with fibroblast-collagen interactions nor with focal adhesion contacts of fibroblasts with the substrate. This is probably relevant in organogenesis and wound repair. By contrast, HA greatly modifies the organisation of the actin cytoskeleton, suggesting that CD44-mediated signal transduction by HA may affect cell locomotion and orientation, as indicated by the fusiform shape of fibroblasts grown in the presence of immobilised HA. A role of HA in cell orientation could be relevant for the deposition of collagen fibrils in regeneration and tissue remodelling.

Inhibition of prostate tumor cell hyaluronan synthesis impairs subcutaneous growth and vascularization in immunocompromised mice

Hyaluronan (HA), a secreted glycosaminoglycan component of extracellular matrices, is critical for cellular proliferation and motility during development. However, elevated circulating and cell-associated levels correlate with various types of cancer, including prostate. We have previously shown that aggressive PC3M-LN4 prostate tumor cells synthesize excessive HA relative to less aggressive cells, and express correspondingly higher levels of the HA biosynthetic enzymes HAS2 and HAS3. Inhibition of these enzymes by stable transfection of PC3M-LN4 cells with anti-sense HAS2 or HAS3 expression constructs diminishes HA synthesis and surface retention. In this report, we used these HA-deficient cell lines to examine the role of HA in tumorigenicity. Subcutaneous injection of SCID mice with hyaluronan synthase (HAS) antisense-transfected cells produced tumors threefold to fourfold smaller than control transfectants. Tumors from HAS antisense transfectants were histologically HA-deficient relative to controls. HA deficiency corresponded to threefold reduced cell numbers per tumor, but comparable numbers of apoptotic and proliferative cells. Percentages of apoptotic cells in cultured transfectants were identical to those of control cells, but antisense inhibition of HA synthesis effected slower growth rate of cells in culture. Quantification of blood vessel density within tumor sections revealed 70 to 80% diminished vascularity of HAS antisense tumors. Collectively, the results suggest HAS overexpression by prostate tumor cells may facilitate their growth and proliferation in a complex environment by enhancing intrinsic cell growth rates and promoting angiogenesis. Furthermore, this is the first report of a role for inhibition of HA synthesis in reducing tumor growth kinetics.