Modulation of human endothelial cell proliferation and migration by fucoidan and heparin

Sulfated glyco-based hydrogels as self-healing, adhesive, and anti-inflammatory dressings for wound healing

Hydrogels have emerged as a new type of wound dressing materials that involved in different stages of the healing processes. However, most of the existing wound dressings mainly offer a protective and moisturizing layer to prevent cross-infection, while the anti-inflammatory and anti-oxidative properties are frequently induced by extra addition of other bioactive molecules. Here, a novel type of sulfated glyco-functionalized hydrogels for wound dressing was prepared through the hybrid supramolecular co-assembly of carbohydrate segments (FG, FGS and FG3S), fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF), and diphenylalanine-dopamine (FFD). Implanting sulfated carbohydrates can mimic the structure of glycosaminoglycans (GAGs), promoting cell proliferation and migration, along with anti-inflammatory effects. In situ polymerization of FFD introduced a secondary covalent network to the hydrogel, meanwhile, providing anti-oxidation and adhesion properties to wound surfaces. Furthermore, the dynamic supramolecular interactions within the hydrogels also confer self-healing capabilities to the wound dressing materials. In vivo experiments further demonstrated significantly accelerated healing rates with the multifunctional hydrogel FG3S-FFD, indicating high application potential.

Fucoidan/chitosan hydrogels as carrier for sustained delivery of platelet-rich fibrin containing bioactive molecules

Platelet-rich fibrin (PRF), derived from human blood, rich in wound healing components, has drawbacks in direct injections, such as rapid matrix degradation and growth factor release. Marine polysaccharides, mimicking the human extracellular matrix, show promising potential in tissue engineering. In this study, we impregnated the self-assembled fucoidan/chitosan (FU_CS) hydrogels with PRF obtaining PRF/FU_CS hydrogels. Our objective was to analyze the properties of a hydrogel and the sustained release of growth factors from the hydrogel that incorporates PRF. The results of SEM and BET-BJH demonstrated the relatively porous nature of the FU_CS hydrogels. ELISA data showed that combining FU_CS hydrogel with PRF led to a gradual 7-day sustained release of growth factors (VEGF, EGF, IL-8, PDGF-BB, TGF-β1), compared to pure PRF. Histology confirmed ELISA data, demonstrating uniform PRF fibrin network distribution within the FU_CS hydrogel matrix. Furthermore, the FU_CS hydrogels revealed excellent cell viability. The results revealed that the PRF/FU_CS hydrogel has the potential to promote wound healing and tissue regeneration. This would be the first step in the search for improved growth factor release.

Fucoidan/collagen composite coating on magnesium alloy for better corrosion resistance and pro-endothelialization potential

Magnesium alloy stents (MAS) have broad application prospects in the treatment of cardiovascular diseases. However, poor corrosion resistance and biocompatibility greatly limit the clinical application of MAS. In this work, the coating consisting of MgF2 layer, polydopamine layer, fucoidan and collagen IV was constructed on Mg-Zn-Y-Nd (ZE21B) alloy to improve its corrosion resistance and pro-endothelialization potential. The fucoidan and collagen IV in the coating could obviously enhance the hemocompatibility and pro-endothelialization potential respectively. Compared with bare ZE21B alloy, the fucoidan/collagen composite coating modified ZE21B alloy possessed lower corrosion current density and better corrosion resistance. Moreover, the modified ZE21B alloy exhibited relatively low hemolysis rate, fibrinogen adsorption and platelet adhesion in the blood experiments, suggesting the improved hemocompatibility. Furthermore, the modified ZE21B alloy favorably supported the adhesion and proliferation of vascular endothelial cells (ECs) and effectively regulated the phenotype of smooth muscle cells (SMCs), thus improving the pro-endothelialization potential of vascular stent materials. The fucoidan/collagen composite coating can significantly improve the corrosion resistance and pro-endothelialization potential of ZE21B alloy, showing great potential in the development of degradable MAS.

Fucoidan promotes angiogenesis and accelerates wound healing through AKT/Nrf2/HIF-1α signalling pathway

After skin injury, wound repair involves a complex process in which angiogenesis plays a crucial role. Previous research has indicated that fucoidan may aid in wound healing; we therefore hypothesised that fucoidan may speed up the process by promoting angiogenesis. In this study, we investigated the potential molecular mechanism underlying fucoidan's ability to accelerate wound healing by promoting angiogenesis. Using a full-cut wound model, we observed that fucoidan significantly intensified wound closure and promoted granulation formation and collagen deposition. Immunofluorescence staining revealed that fucoidan also promoted wound angiogenesis, specifically by accelerating the migration of new blood vessels to the middle area of the wound. Furthermore, fucoidan demonstrated the ability to enhance the proliferation of human umbilical vein endothelial cells (HUVECs) damaged by hydrogen peroxide (H2 O2 ) and to improve the formation of endothelial tubes. Mechanistic studies revealed that fucoidan upregulated the protein levels of the AKT/Nrf2/HIF-1α signalling pathway, which plays a crucial role in angiogenesis. This was further confirmed using the inhibitor LY294002, which reversed the promotion of endothelial tube formation by fucoidan. Overall, our findings suggest that fucoidan can promote angiogenesis via the AKT/Nrf2/HIF-1α signalling pathway and accelerate wound healing.

Surface Coating of Polyurethane Films with Gelatin, Aspirin and Heparin to Increase the Hemocompatibility of Artificial Vascular Grafts

Purpose: A hemocompatible substrate can offer a wonderful facility for nitric oxide (NO) production by vascular endothelial cells in reaction to the inflammation following injuries. NO inhibits platelet aggregation this is especially critical in small-diameter vessels. Methods: The substrate films were made of polyurethane (PU) in a casting process and after plasma treatments, their surface was chemically decorated with polyethylene glycol (PEG) 2000, gelatin, gelatin-aspirin, gelatin-heparin and gelatin-aspirin-heparin. The concentrations of these ingredients were optimized in order to achieve the biocompatible values and the resulting modifications were characterized by water contact angle and Fourier transform infra-red (FTIR) assays. The values of NO production and platelet adhesion were then examined. Results: The water contact angle of the modified surface was reduced to 26±4^∘ and the newly developed hydrophilic chemical groups were confirmed by FTIR. The respective concentrations of 0.05 mg/ml and 100 mg/mL were found to be the IC50 values for aspirin and heparin. However, after the surface modification with aspirin, the bioactivity of the substrate increased in compared to the other experimental groups. In addition, there was a synergistic effect between these reagents for NO synthesis. While, heparin inhibited platelet adhesion more than aspirin. Conclusion: Because of the highly hydrophilic nature of heparin, this reagent was hydrolyzed faster than aspirin and therefore its influence on platelet aggregation and cell growth was greater. Taken together, the results give the biocompatible concentrations of both biomolecules that are required for endothelial cell proliferation, NO synthesis and platelet adhesion.

Basic fibroblast growth factor uniquely stimulates quiescent vascular smooth muscle cells and induces proliferation and dedifferentiation

Blood vessels normally remain stable over the long-term. However, in atherosclerosis, vascular cells leave the quiescent state and enter an activated state. Here, we investigated the factors that trigger breakage of the quiescent state by screening growth factors and cytokines using a vascular smooth muscle cell (SMC) line and an endothelial cell (EC) line. Despite known functions of the tested factors, only basic fibroblast growth factor (bFGF) was identified as a potent trigger of quiescence breakage in SMCs, but not ECs. bFGF disrupted tight SMC-monolayers, and caused morphological changes, proliferation and dedifferentiation. Human primary SMCs, but not ECs, also showed similar results. Aberrant SMC-proliferation is a critical histological event in atherosclerosis. We thus provide further insights into the role of bFGF in vascular pathobiology.

Bio-inspired green light crosslinked alginate-heparin hydrogels support HUVEC tube formation

Alginate is a polysaccharide which forms hydrogels via ionic and/or covalent crosslinking. The goal was to develop a material with suitable, physiologically relevant mechanical properties and biological impact for use in wound treatment. To determine if the novel material can initiate tube formation on its own, without the dependance on the addition of growth factors, heparin and/or arginyl-glycyl-aspartic acid (RGD) was covalently conjugated onto the alginate backbone. Herein, cell adhesion motifs and bioactive functional groups were incorporated covalently within alginate hydrogels to study the: 1) impact of crosslinked heparin on tubular network formation, 2) impact of RGD conjugation, and the 3) biological effect of vascular endothelial growth factor (VEGF) loading on cellular response. We investigated the structure-properties-function relationship and determined the viscoelastic and burst properties of the hydrogels most applicable for use as a healing cell and tissue adhesive material. Methacrylation of alginate and heparin hydroxyl groups respectively enabled free-radical covalent inter- and intra-molecular photo-crosslinking when exposed to visible green light in the presence of photo-initiators; the shear moduli indicate mechanical properties comparable to clinical standards. RGD was conjugated via carbodiimide chemistry at the alginate carboxyl groups. The adhesive and mechanical properties of alginate and alginate-heparin hydrogels were determined via burst pressure testing and rheology. Higher burst pressure and material failure at rupture imply physical tissue adhesion, advantageous for a tissue sealant healing material. After hydrogel formation, human umbilical vein endothelial cells (HUVECs) were seeded onto the alginate-based hydrogels; cytotoxicity, total protein content, and tubular network formation were assessed. Burst pressure results indicate that the cell responsive hydrogels adhere to collagen substrates and exhibit increased strength under high pressures. Furthermore, the results show that the green light crosslinked alginate-heparin maintained cell adhesion and promoted tubular formation.

Long-Term Sustained Drug Delivery via 3D Printed Masks for the Development of a Heparin-Loaded Interlayer in Vascular Tissue Engineering Applications

Current approaches in small-diameter vascular grafts for coronary artery bypass surgeries fail to address physiological variations along the graft that contribute to thrombus formation and ultimately graft failure. We present an innovative interlayer drug delivery system that can be utilized for the sustained delivery of heparin through a graft with a high degree of temporal and spatial control. A heparin-loaded gelatin methacrylate (gelMA) interlayer sits within a biohybrid composed of decellularized bovine pericardium (dECM) and poly(propylene fumarate) (PPF), and its UV crosslinking is controlled via three-dimensional (3D) printed shadow masks. The masks can be readily designed to modulate the incident light intensity on the graft, enabling us to control the resultant gelMA crosslinking and properties. A high heparin loading efficiency was obtained in gelMA and was independent of crosslinking. We achieved sustained heparin release over the course of 2 weeks within the biohybrid material using the 3D printed mask patterns. High doses of heparin were observed to have detrimental effects on endothelial cell function. However, when exposed to heparin in a slower, more sustained manner consistent with the masks, endothelial cells behave similarly to untreated cells. Further, slower release profiles cause significantly more release of tissue factor pathway inhibitor, an anticoagulant, than a faster release profile. The heparin-loaded gelMA interlayer we have developed is a useful tool for the temporal and spatial control of heparin release that supports endothelial function and promotes an antithrombotic environment.

Fucoidan for cardiovascular application and the factors mediating its activities

Fucoidan is a sulfated polysaccharide with various bioactivities. The application of fucoidan in cancer treatment, wound healing, and food industry has been extensively studied. However, the therapeutic value of fucoidan in cardiovascular diseases has been less explored. Increasing number of investigations in the past years have demonstrated the effects of fucoidan on cardiovascular system. In this review, we will focus on the bioactivities related to cardiovascular applications, for example, the modulation functions of fucoidan on coagulation system, inflammation, and vascular cells. Factors mediating those activities will be discussed in detail. Current therapeutic strategies and future opportunities and challenges will be provided to inspire and guide further research.

Durable endothelium-mimicking coating for surface bioengineering cardiovascular stents

Mimicking the nitric oxide (NO)-release and glycocalyx functions of native vascular endothelium on cardiovascular stent surfaces has been demonstrated to reduce in-stent restenosis (ISR) effectively. However, the practical performance of such an endothelium-mimicking surfaces is strictly limited by the durability of both NO release and bioactivity of the glycocalyx component. Herein, we present a mussel-inspired amine-bearing adhesive coating able to firmly tether the NO-generating species (e.g., Cu-DOTA coordination complex) and glycocalyx-like component (e.g., heparin) to create a durable endothelium-mimicking surface. The stent surface was firstly coated with polydopamine (pDA), followed by a surface chemical cross-link with polyamine (pAM) to form a durable pAMDA coating. Using a stepwise grafting strategy, Cu-DOTA and heparin were covalently grafted on the pAMDA-coated stent based on carbodiimide chemistry. Owing to both the high chemical stability of the pAMDA coating and covalent immobilization manner of the molecules, this proposed strategy could provide 62.4% bioactivity retention ratio of heparin, meanwhile persistently generate NO at physiological level from 5.9 ± 0.3 to 4.8 ± 0.4 × 10⁻¹⁰ mol cm⁻² min⁻¹ in 1 month. As a result, the functionalized vascular stent showed long-term endothelium-mimicking physiological effects on inhibition of thrombosis, inflammation, and intimal hyperplasia, enhanced re-endothelialization, and hence efficiently reduced ISR.

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A durable endothelium-mimicking coating was developed for surface bioengineering of cardiovascular stents.

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The durable endothelium-mimicking surface was realized by stepwise grafting of Cu-DOTA and heparin on a robust coating.

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The durable endothelium-mimicking coating endows the vascular stents with ability to dramatically reduce restenosis.

Fucoidan functionalization on poly(vinyl alcohol) hydrogels for improved endothelialization and hemocompatibility

The performance of clinical synthetic small diameter vascular grafts remains disappointing due to the fast occlusion caused by thrombosis and intimal hyperplasia formation. Poly(vinyl alcohol) (PVA) hydrogels have tunable mechanical properties and a low thrombogenic surface, which suggests its potential value as a small diameter vascular graft material. However, PVA does not support cell adhesion and thus requires surface modification to encourage endothelialization. This study presents a modification of PVA with fucoidan. Fucoidan is a sulfated polysaccharide with anticoagulant and antithrombotic properties, which was shown to potentially increase endothelial cell adhesion and proliferation. By mixing fucoidan with PVA and co-crosslinked by sodium trimetaphosphate (STMP), the modification was achieved without sacrificing mechanical properties. Endothelial cell adhesion and monolayer function were significantly enhanced by the fucoidan modification. In vitro and ex-vivo studies showed low platelet adhesion and activation and decreased thrombin generation with fucoidan modified PVA. The modification proved to be compatible with gamma sterilization. In vivo evaluation of fucoidan modified PVA grafts in rabbits exhibited increased patency rate, endothelialization, and reduced intimal hyperplasia formation. The fucoidan modification presented here benefited the development of PVA vascular grafts and can be adapted to other blood contacting surfaces.

Seaweed polysaccharides as macromolecular crowding agents

Development of mesenchymal stem cell-based tissue engineered implantable devices requires prolonged in vitro culture for the development of a three-dimensional implantable device, which leads to phenotypic drift, thus hindering the clinical translation and commercialisation of such approaches. Macromolecular crowding, a biophysical phenomenon based on the principles of excluded-volume effect, dramatically accelerates and increases extracellular matrix deposition during in vitro culture. However, the optimal macromolecular crowder is still elusive. Herein, we evaluated the biophysical properties of various concentrations of different seaweed in origin sulphated polysaccharides and their effect on human adipose derived stem cell cultures. Carrageenan, possibly due to its high sulphation degree, exhibited the highest negative charge values. No correlation was observed between the different concentrations of the crowders and charge, polydispersity index, hydrodynamic radius and fraction volume occupancy across all crowders. None of the crowders, but arabinogalactan, negatively affected cell viability. Carrageenan, fucoidan, galactofucan and ulvan increased extracellular matrix (especially collagen type I and collagen type V) deposition. Carrageenan induced the highest osteogenic effect and galactofucan and fucoidan demonstrated the highest chondrogenic effect. All crowders were relatively ineffective with respect to adipogenesis. Our data highlight the potential of sulphated seaweed polysaccharides for tissue engineering purposes.

CHARMM-GUI Glycan Modeler for modeling and simulation of carbohydrates and glycoconjugates

Characterizing glycans and glycoconjugates in the context of three-dimensional structures is important in understanding their biological roles and developing efficient therapeutic agents. Computational modeling and molecular simulation have become an essential tool complementary to experimental methods. Here, we present a computational tool, Glycan Modeler for in silico N-/O-glycosylation of the target protein and generation of carbohydrate-only systems. In our previous study, we developed Glycan Reader, a web-based tool for detecting carbohydrate molecules from a PDB structure and generation of simulation system and input files. As integrated into Glycan Reader in CHARMM-GUI, Glycan Modeler (Glycan Reader & Modeler) enables to generate the structures of glycans and glycoconjugates for given glycan sequences and glycosylation sites using PDB glycan template structures from Glycan Fragment Database (http://glycanstructure.org/fragment-db). Our benchmark tests demonstrate the universal applicability of Glycan Reader & Modeler to various glycan sequences and target proteins. We also investigated the structural properties of modeled glycan structures by running 2-μs molecular dynamics simulations of HIV envelope protein. The simulations show that the modeled glycan structures built by Glycan Reader & Modeler have the similar structural features compared to the ones solved by X-ray crystallography. We also describe the representative examples of glycoconjugate modeling with video demos to illustrate the practical applications of Glycan Reader & Modeler. Glycan Reader & Modeler is freely available at http://charmm-gui.org/input/glycan.

Whole liver engineering: A promising approach to develop functional liver surrogates

Liver donor shortage remains the biggest challenge for patients with end-stage liver failures. While bioartificial liver devices have been developed as temporary supports for patients waiting for transplantation, their applications have been limited clinically. Whole liver engineering is a biological scaffold based regenerative medicine approach that holds promise for developing functional liver surrogates. Significant advancements have been made since the first report in 2010. This review focuses on the recent achievements of whole liver engineering studies.

A Heparin-Mimicking Block Copolymer Both Stabilizes and Increases the Activity of Fibroblast Growth Factor 2 (FGF2)

Fibroblast growth factor 2 (FGF2) is a protein involved in cellular functions in applications such as wound healing and tissue regeneration. Stabilization of this protein is important for its use as a therapeutic since the native protein is unstable during storage and delivery. Additionally, the ability to increase the activity of FGF2 is important for its application, particularly in chronic wound healing and the treatment of various ischemic conditions. Here we report a heparin mimicking block copolymer, poly(styrenesulfonate-co-poly(ethylene glycol) methyl ether methacrylate)-b-vinyl sulfonate) (p(SS-co-PEGMA)-b-VS, that contains a segment that enhances the stability of FGF2 and one that binds to the FGF2 receptor. The FGF2 conjugate retained activity after exposure to refrigeration (4 °C) and room temperature (23 °C) for 7 days, while unmodified FGF2 was inactive after these standard storage conditions. A cell study performed with a cell line lacking native heparan sulfate proteoglycans indicated that the conjugated block copolymer facilitated binding of FGF2 to its receptor similar to the addition of heparin to FGF2. A receptor-based enzyme-linked immunosorbant assay (ELISA) confirmed the results. The conjugate also increased the migration of endothelial cells by 80% compared to FGF2 alone. Additionally, the FGF2-p(SS-co-PEGMA)-b-VS stimulated endothelial cell sprouting 250% better than FGF2 at low concentration. These data verify that this rationally designed protein-block copolymer conjugate enhances receptor binding, cellular processes such as migration and tube-like formation, and stability, and suggest that it may be useful for applications in biomaterials, tissue regeneration, and wound healing.

Fucoidans in Nanomedicine

Fucoidans are widespread cost-effective sulfated marine polysaccharides which have raised interest in the scientific community over last decades for their wide spectrum of bioactivities. Unsurprisingly, nanomedicine has grasped these compounds to develop innovative therapeutic and diagnostic nanosystems. The applications of fucoidans in nanomedicine as imaging agents, drug carriers or for their intrinsic properties are reviewed here after a short presentation of the main structural data and biological properties of fucoidans. The origin and the physicochemical specifications of fucoidans are summarized in order to discuss the strategy of fucoidan-containing nanosystems in Human health. Currently, there is a need for reproducible, well characterized fucoidan fractions to ensure significant progress.

Fibroblast growth factor 2 dimer with superagonist in vitro activity improves granulation tissue formation during wound healing

Site-specific chemical dimerization of fibroblast growth factor 2 (FGF2) with the optimal linker length resulted in a FGF2 homodimer with improved granulation tissue formation and blood vessel formation at exceptionally low concentrations. Homodimers of FGF2 were synthesized through site-specific linkages to both ends of different molecular weight poly(ethylene glycols) (PEGs). The optimal linker length was determined by screening dimer-induced metabolic activity of human dermal fibroblasts and found to be that closest to the inter-cysteine distance, 70 Å, corresponding to 2 kDa PEG. A straightforward analysis of the kinetics of second ligand binding as a function of tether length showed that, as the polymerization index (the number of monomer repeat units in the polymer, N) of the tether decreases, the mean time for second ligand capture decreases as ∼N(3/2), leading to an enhancement of the number of doubly bound ligands in steady-state for a given (tethered) ligand concentration. FGF2-PEG2k-FGF2 induced greater fibroblast metabolic activity than FGF2 alone, all other dimers, and all monoconjugates, at each concentration tested, with the greatest difference observed at low (0.1 ng/mL) concentration. FGF2-PEG2k-FGF2 further exhibited superior activity compared to FGF2 for both metabolic activity and migration in human umbilical vein endothelial cells, as well as improved angiogenesis in a coculture model in vitro. Efficacy in an in vivo wound healing model was assessed in diabetic mice. FGF2-PEG2k-FGF2 increased granulation tissue and blood vessel density in the wound bed compared to FGF2. The results suggest that this rationally designed construct may be useful for improving the fibroblast matrix formation and angiogenesis in chronic wound healing.

The incorporation of bFGF mediated by heparin into PCL/gelatin composite fiber meshes for guided bone regeneration

The concept of guided bone regeneration facilitated by barrier membranes has been widely considered to achieve enhanced bone healing in maxillofacial surgery. However, the currently available membranes are limited in their active regulation of cellular activities. In this study, we fabricated polycaprolactone/gelatin composite electrospun nanofibers incorporated with basic fibroblast growth factor (bFGF) to direct bone regeneration. The fibrous morphology was maintained after the crosslinking and subsequent conjugation of heparin. Release of bFGF from electrospun nanofibers without heparin resulted in a spontaneous burst, while the heparin-mediated release of bFGF decreased the burst release in 24 h. The bFGF released from the nanofibers enhanced the proliferation and migration of human mesenchymal stem cells as well as the tubule formation of human umbilical cord blood cells. The subcutaneous implantation of fibers incorporated with bFGF mobilized a large number of cells positive for CD31 and smooth muscle alpha actin within 2 weeks. The effect of the nanofibers incorporated with bFGF on bone regeneration was evaluated on a calvarial critical size defect model. As compared to the mice that received fibers without bFGF, which presented minimal new bone formation (5.36 ± 3.4 % of the defect), those that received implants of heparinized nanofibers incorporated with 50 or 100 ng/mL bFGF significantly enhanced new bone formation (10.82 ± 2.2 and 17.55 ± 6.08 %). Taken together, our results suggest that the electrospun nanofibers incorporating bFGF have the potential to be used as an advanced membrane that actively enhances bone regeneration.

Collagen-mimetic hydrogels promote human endothelial cell adhesion, migration and phenotypic maturation

This work evaluates the response of human aortic endothelial cells (HAECs) to thromboresistant collagen-mimetic hydrogel coatings toward improving the biocompatibility of existing "off-the-shelf" small-caliber vascular grafts. Specifically, bioactive hydrogels - previously shown to support α₁/α₂ integrin-mediated cell adhesion but to resist platelet activation - were fabricated by combining poly(ethylene glycol) (PEG) with a 120 kDa, triple-helical collagen-mimetic protein(Scl2-2) containing the GFPGER adhesion sequence. Analysis of HAECs seeded onto the resulting PEG-Scl2-2 hydrogels demonstrated that HAEC adhesion increased with increasing Scl2-2 concentration, while HAEC migration rate decreased over this same concentration range. In addition, evaluation of HAEC phenotype at confluence indicated significant differences in the gene expression of NOS3, thrombomodulin, and E-selectin on the PEG-Scl2-2 hydrogels relative to PEG-collagen controls. At the protein level, however, only NOS3 was significantly different between the PEG-Scl2-2 and PEG-collagen surfaces. Furthermore, PECAM-1 and VE-cadherin expression on PEG-Scl2-2 hydrogels versus PEG-collagen controls could not be distinguished at either the gene or protein level. Cumulatively, these data indicate the PEG-Scl2-2 hydrogels warrant further investigation as "off-the-shelf" graft coatings. In future studies, the Scl2-2 protein can potentially be modified to include additional extracellular matrix or cytokine binding sites to further improve endothelial cell responses.

Heparin/Heparan sulfate proteoglycans glycomic interactome in angiogenesis: biological implications and therapeutical use

Angiogenesis, the process of formation of new blood vessel from pre-existing ones, is involved in various intertwined pathological processes including virus infection, inflammation and oncogenesis, making it a promising target for the development of novel strategies for various interventions. To induce angiogenesis, angiogenic growth factors (AGFs) must interact with pro-angiogenic receptors to induce proliferation, protease production and migration of endothelial cells (ECs). The action of AGFs is counteracted by antiangiogenic modulators whose main mechanism of action is to bind (thus sequestering or masking) AGFs or their receptors. Many sugars, either free or associated to proteins, are involved in these interactions, thus exerting a tight regulation of the neovascularization process. Heparin and heparan sulfate proteoglycans undoubtedly play a pivotal role in this context since they bind to almost all the known AGFs, to several pro-angiogenic receptors and even to angiogenic inhibitors, originating an intricate network of interaction, the so called "angiogenesis glycomic interactome". The decoding of the angiogenesis glycomic interactome, achievable by a systematic study of the interactions occurring among angiogenic modulators and sugars, may help to design novel antiangiogenic therapies with implications in the cure of angiogenesis-dependent diseases.

Fucoidan promotes osteoblast differentiation via JNK- and ERK-dependent BMP2-Smad 1/5/8 signaling in human mesenchymal stem cells

Fucoidan has attracted attention as a potential drug because of its biological activities, which include osteogenesis. However, the molecular mechanisms involved in the osteogenic activity of fucoidan in human alveolar bone marrow-derived mesenchymal stem cells (hABM-MSCs) remain largely unknown. We investigated the action of fucoidan on osteoblast differentiation in hABM-MSCs and its impact on signaling pathways. Its effect on proliferation was determined using the crystal violet staining assay. Osteoblast differentiation was evaluated based on alkaline phosphatase (ALP) activity and the mRNA expression of multiple osteoblast markers. Calcium accumulation was determined by Alizarin red S staining. We found that fucoidan induced hABM-MSC proliferation. It also significantly increased ALP activity, calcium accumulation and the expression of osteoblast-specific genes, such as ALP, runt-related transcription factor 2, type I collagen-α 1 and osteocalcin. Moreover, fucoidan induced the expression of bone morphogenetic protein 2 (BMP2) and stimulated the activation of extracellular signal-related kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase by increasing phosphorylation. However, the effect of fucoidan on osteogenic differentiation was inhibited by specific inhibitors of ERK (PD98059) and JNK (SP600125) but not p38 (SB203580). Fucoidan enhanced BMP2 expression and Smad 1/5/8, ERK and JNK phosphorylation. Moreover, the effect of fucoidan on osteoblast differentiation was diminished by BMP2 knockdown. These results indicate that fucoidan induces osteoblast differentiation through BMP2-Smad 1/5/8 signaling by activating ERK and JNK, elucidating the molecular basis of the osteogenic effects of fucoidan in hABM-MSCs.

Fucoidan/FGF-2 induces angiogenesis through JNK- and p38-mediated activation of AKT/MMP-2 signalling

Angiogenesis is an important biological process in tissue development and repair. Fucoidan has previously been shown to potentiate in vitro tube formation in the presence of basic fibroblast growth factor (FGF-2). However, the underlying molecular mechanism remains largely unknown. This study was designed to investigate the action of fucoidan in angiogenesis in human umbilical vein endothelial cells (HUVECs) and to explore fucoidan-signalling pathways. First, we evaluated the effect of fucoidan on cell proliferation. Matrigel-based tube formation and wound healing assays were performed to investigate angiogenesis. Matrix metalloproteinase-2 (MMP-2) mRNA expression and activity levels were analysed by reverse transcription polymerase chain reaction (RT-PCR) and zymography, respectively. Additionally, phosphorylation of mitogen-activated protein kinases (MAPKs) and protein kinase B (AKT) was detected by Western blot. The results indicate that fucoidan treatment significantly increased cell proliferation in the presence of FGF-2. Moreover, compared to the effect of FGF-2 alone, fucoidan and FGF-2 had a greater effect on tube formation and cell migration, and this effect was found to be synergistic. Furthermore, fucoidan enhanced the phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38, and AKT. MMP-2 activation was also significantly increased. Specific inhibitors of p38 (SB203580) and JNK (SP600125) inhibited tube formation and wound healing, while an ERK inhibitor (PD98059) did not. MMP-2 activation and AKT phosphorylation were also attenuated and associated with the suppression of p38 and JNK phosphorylation, but not with that of ERK. These results indicate that fucoidan, in the presence of FGF-2, induces angiogenesis through AKT/MMP-2 signalling by activating p38 and JNK. These findings provide basic molecular information on the effect of fucoidan on angiogenesis in the presence of FGF-2.

Low-molecular-weight fucoidan protects endothelial function and ameliorates basal hypertension in diabetic Goto-Kakizaki rats

Endothelial dysfunction, characterized by impairment of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) bioavailability, has been implicated in diabetic cardiovascular pathogenesis. In this study, low-molecular-weight fucoidan (LMWF), which has multiple biological activities including anti-inflammatory and anti-oxidative properties, was investigated for its protective effect against endothelial dysfunction in Goto-Kakizaki type 2 diabetic rats. LMWF (50, 100, or 200 mg/kg/day) or probucol (100 mg/kg/day) were given to diabetic rats for 12 weeks. Basal blood pressure, acetylcholine- or flow-mediated relaxation of mesenteric and paw arteries, endothelium-dependent dilation of aorta, eNOS phosphorylation, and NO production were measured using laser Doppler flowmetry, force myograph, hematoxylin and eosin staining, western blot analysis, and an NO assay. We found that LMWF robustly ameliorated the basal hypertension and impairment of endothelium-dependent relaxation in the aorta, as well as mesenteric and paw arteries in diabetic rats. In addition, the reduction in eNOS phosphorylation at Ser1177, eNOS expression, and NO production because of diabetes were partially reversed by LMWF treatment. However, probucol, a lipid-modifying drug with antioxidant properties, displayed only mild effects. Moreover, LMWF induced, in a dose-dependent manner, endothelium-dependent vasodilation and eNOS phosphorylation at Ser1177 in normal aorta, and also promoted Ser1177 phosphorylation and NO synthesis in primary cultured vasoendothelial cells. Thus, these data demonstrate for the first time that fucoidan protects vasoendothelial function and reduces basal blood pressure in type 2 diabetes rats via, at least in part, preservation of eNOS function. Fucoidan is therefore a potential candidate drug for protection of endothelium in diabetic cardiovascular complications.

The in vitro and in vivo effects of a low-molecular-weight fucoidan on the osteogenic capacity of human adipose-derived stromal cells

Human adipose-derived stromal cells (hASCs) may hold potential for bone tissue engineering. Osteogenic differentiation of these cells is crucial to bone formation. Low-molecular-weight fucoidan (LMWF) is a sulfated polysaccharide that potentiates several growth factors, including pro-angiogenic growth factors. To investigate whether hASC preconditioning with LMWF promoted bone repair, we compared the effects of LMWF and low-molecular-weight heparin on hASC phenotype and osteogenic differentiation. LMWF did not modify the stem-cell phenotype of hASCs but enhanced their osteogenic differentiation (formation of calcium deposits, increased activity and expression of alkaline phosphatase, and increased expression of osteopontin and runt-related transcription factor 2). However, when hASCs were exposed to LMWF before their adhesion to biphasic calcium phosphate particles and implantation in a bone-growth mouse model, no bone formation was apparent after 5 or 8 weeks, probably due to cell death. In conclusion, LMWF may hold promise for enhancing the osteogenic differentiation of hASCs before their implantation. However, concomitant vascularization would be required to enhance bone formation.

Nanoparticle-induced tight-junction opening for the transport of an anti-angiogenic sulfated polysaccharide across Caco-2 cell monolayers

Fucoidan has the ability to inhibit angiogenesis by human umbilical vein endothelial cells (HUVECs). However, a major clinical limitation is its poor oral availability because fucoidan is a hydrophilic macromolecule. In this study, an oversulfation reaction of fucoidan has been performed to enhance its anti-angiogenic activities. The synthesized, oversulfated fucoidan (OFD) was characterized by Fourier transform infrared spectroscopy. The oversulfate content of OFD was estimated to be 41.7% by using a BaCl2 gelatin method. Nanoparticles (NPs) composed of chitosan (CS) and OFD were prepared by a polycation-polyanion complex method. The mean particle sizes of prepared CS/OFD NPs were in the range of 172-265nm with a negative or positive surface charge, depending on the relative concentrations of CS to OFD used. The self-assembled NPs with pH-sensitive characteristics could be used as a pH-switched nanocarrier for oral delivery of the antiangiogenic macromolecule, OFD, in response to simulated gastrointestinal (GI) tract media. Evaluation of test NPs in enhancing the intestinal paracellular transport of OFD suggested that the NPs with a positive surface charge could transiently open the tight junctions between Caco-2 cells and thus increase the paracellular permeability. Tight-junction opening and restoration were examined by monitoring the redistribution of ZO-1 tight-junction proteins using confocal laser scanning microscopy (CLSM). The transported OFD significantly inhibits the tube formation of HUVECs via competitive binding of OFD and basic fibroblast growth factor (bFGF) to bFGF receptors (bFGFRs).

Fucan effect on CHO cell proliferation and migration

Fucan is a term used to denominate sulfated L-fucose rich polysaccharides. Here, a heterofucan, named fucan B, was extracted from the Spatoglossum schröederi seaweed. This 21.5 kDa galactofucan inhibited CHO-K1 proliferation and migration when fibronectin was the substrate. Fucan B derivatives revealed that such effects depend on their degree of sulfation. Fucan B did not induce cell death, but promoted G1 cell cycle arrest. Western blotting and flow cytometry analysis suggest that fucan B binds to fibronectin and activates integrin, mainly integrin α5β1, which induces FAK/RAS/MEK/ERK activation. FAK activation inhibits CHO-K1 migration on fibronectin and ERK blocks cell cycle progression. This study indicates that fucan B could be applied in developing new antitumor drugs.

The endothelialization and hemocompatibility of the functional multilayer on titanium surface constructed with type IV collagen and heparin

The type IV collagen/heparin (IVCol/Hep) multilayer was developed on amino-silanized titanium (Ti) surface layer by layer self-assembly. Ti, TiOH, TiOHA and TiOHA(HC)3H were characterized by Fourier transform infrared spectroscopy (FTIR), water contact angle measurements and scanning electron microscopy (SEM), respectively. Alcian Blue 8GX staining and immunofluorescence staining were used to characterize the heparin (Hep) and type IV collagen (IVCol), respectively. The blood compatibilities of Ti and the treated Ti were evaluated by platelet adhesion test and clotting time using PRP. Blood compatibility tests reveal that the assembled functional multilayer displayed less platelets adhesion and prolonged APTTs time compared with the controlled Ti. Endothelial cells (ECs) culture results showed more attached and proliferated ECs on the TiOHA(HC)3H than that on Ti, especially compared with that on TiOH and TiOHA. Thus, the assembled Hep and IVCol multilayer can improve the cell compatibility and the blood compatibility. We anticipate that this IVCol/Hep functional multilayer will be beneficial to enhance the biocompatibility of the Ti-based biomaterial devices.

Important role of β1-integrin in fucoidan-induced apoptosis via caspase-8 activation

Fucoidan induces apoptosis by activating caspase-8 in human MCF-7 breast cancer cells, but the detailed mechanism for this is not understood. We demonstrate here that fucoidan interacted with the cell surface, and silencing the β1-integrin gene expression inhibited fucoidan-induced apoptosis accompanied by caspase-8 activation. Fucoidan induced formation of the β1-integrin-caspase-8 complex. These data indicate that β1-integrin is an important factor for the cell-surface binding of fucoidan and plays an important role in fucoidan-induced apoptosis. Fucoidan also induced recruitment of caspase-8 to the β1-integrin intracellular domain, cleaved it into the activated protein by direct combination with β1-integrin, and induced apoptosis via the caspase cascade in MCF-7 cells.

Differential effects of fondaparinux and bemiparin on angiogenic and vasculogenesis-like processes

INTRODUCTION

Conventional therapy for venous thromboembolism or acute coronary syndrome involves the administration of glycoanticoagulants (heparins) or oligosaccharides (fondaparinux). We evaluated the effects of such drugs on angiogenesis and vasculogenesis-like models.

MATERIALS AND METHODS

Human umbilical vein endothelial cells or human endothelial progenitor cells were treated with bemiparin, fondaparinux or unfractionated heparin, at concentrations reflecting the doses used in clinical practice. After 24h, cell viability, proliferation, tubule formation and angiogenic molecular mechanisms, such as activation of the serine/threonine kinase AKT, were assessed. In vivo angiogenesis was studied using a Matrigel sponge assay in mice.

RESULTS

Bemiparin gave a significant decrease of in vitro angiogenesis as shown by the reduction of endothelial cell tubule network, while both fondaparinux and unfractionated heparin did not show any significant effect. In assays of Matrigel sponge invasion in mice, unfractionated heparin was able to stimulate angiogenesis and, conversely, bemiparin inhibited angiogenesis. Furthermore, both bemiparin and fondaparinux caused a significant reduction in an in vitro vasculogenesis-like model, as demonstrated by the decrease of tubule network after co-seeding of endothelial progenitor cells and human umbilical vein endothelial cells. In addition, unfractionated heparin but not bemiparin was able to increase AKT phosphorylation.

CONCLUSIONS

In in vitro experiments, bemiparin was the only drug to show an anti-angiogenic and vasculogenic-like effect, unfractionated heparin showed only a trend to increase in angiogenesis assay and fondaparinux affected only the vasculogenesis-like model. Notably, the in vivo experiments corroborated these data. Such results are important for the choice of a patient-tailored therapy.

Heparin-like entities from marine organisms

Polysaccharides are ubiquitous in animals and plant cells where they play a significant role in a number of physiological situations e.g. hydration, mechanical properties of cell walls and ionic regulation. This review concentrates on heparin-like entities from marine procaryotes and eukaryotes. Carbohydrates from marine prokaryotes offer a significant structural chemodiversity with novel material and biological properties. Cyanobacteria are Gram-negative photosynthetic prokaryotes considered as a rich source of novel molecules, and marine bacteria are a rich source of polysaccharides with novel structures, which may be a good starting point from which to synthesise heparinoid molecules. For example, some sulphated polysaccharides have been isolated from gamma-proteobacteria such as Alteromonas and Pseudoalteromonas sp. In contrast to marine bacteria, all marine algae contain sulphated wall polysaccharides, whereas such polymers are not found in terrestrial plants. In their native form, or after chemical modifications, a range of polysaccharides isolated from marine organisms have been described that have anticoagulant, anti-thrombotic, anti-tumour, anti-proliferative, anti-viral or anti-inflammatory activities.In spite of the enormous potential of sulphated oligosaccharides from marine sources, their technical and pharmaceutical usage is still limited because of the high complexity of these molecules. Thus, the production of tailor-made oligo- and polysaccharidic structures by biocatalysis is also a growing field of interest in biotechnology.

Release kinetics and in vitro bioactivity of basic fibroblast growth factor: effect of the thickness of fibrous matrices

In this study, we fabricated non-woven matrices using blends of polycaprolactone and gelatin with various spinning volumes to control the immobilized heparin content, which was ultimately intended to increase the immobilization efficiency of bFGF. The amount of bFGF on the heparin conjugated fibrous matrices depended on the thicknesses of the swollen matrices ranging from 35.4 ± 6.5 to 162.3 ± 14.0 ng and ≈90% of the bFGF was gradually released over a period of up to 56 d. The released bFGF enhanced the proliferation of human umbilical vein endothelial cells and human mesenchymal stem cells. In conclusion, our heparin-conjugated fibrous matrices have the potential to be used as a growth factor delivery system in tissue engineering applications.

Fucoidan film safely inhibits surgical adhesions in a rat model

BACKGROUND

The purpose of this study was to evaluate the in vivo efficacy of 13 compounds and to further characterize the load limiting and potential toxicity of the most efficacious compound. The cascade of biochemical and molecular events that results in the formation of postsurgical adhesions provides numerous theoretical opportunities for prophylactic intervention.

METHODS

Candidate agents were loaded into sodium hyaluronate (HA) films and administered to male Sprague-Dawley rats using a cecal-sidewall model of surgical adhesions. An adhesion score was obtained for each rat based on the strength and extent of the adhesions. The most efficacious agent, fucoidan, was further evaluated in a load-limiting study with a concentration range of 0.0033 to 33% w/w per film. The potential toxicity of fucoidan was evaluated in a separate study by comparison of hematology findings, blood chemistry, urinalysis, and incision thickness from rats administered control films or 33% w/w fucoidan films 1 to 4 d prior to sacrifice.

RESULTS

Fucoidan loaded films reduced adhesion scores by approximately 90% compared with control films (P<0.05). A total of 50% to 100% of animals were adhesion free at fucoidan film loadings of 0.33% to 33% w/w compared with all control film animals having adhesions. No adverse effects were observed from 33% w/w fucoidan films equivalent to approximately 30 mg fucoidan/kg body weight.

CONCLUSIONS

Local administration of fucoidan film during rat cecal-sidewall surgery safely reduced adhesion scores by approximately 90% and resulted in 50% to 100% of animals being adhesion free.

Culture of human cells and synthesis of extracellular matrix on materials compatible with direct analysis by mass spectrometry

The extracellular matrix (ECM) is a complex three-dimensional network of macromolecules synthesized by cells and is essential for the structure and the function of a tissue. The aim of our approach was to propose a surface allowing cell culture and subsequent analysis of ECM produced by cells directly on materials compatible with Surface Enhanced Laser Desorption Ionization-Time Of Flight (SELDI-TOF) mass spectrometry on a 96-well format. Surfaces were made of aluminium and spots of 2 mm in diameter were covered with specific chemical groups (silica, C(6) and C(12) alkyl groups, carboxyl, quaternary amine, or nitrilotriacetic acid groups). We found that among the chemically modified aluminium spots, only silica groups allowed the culture of human vascular cells. The wettability was an essential parameter for cell culture on the surfaces. Indeed, cells could only be cultured on surfaces presenting a moderate wettability with water contact angles of ca. 60 degrees. Then, by treatment of confluent cells with detergents (Triton X100 and deoxycholate), we were able to obtain ECM on the surfaces that were subsequently analyzed using a mass spectrometer, which is currently impossible with any type of cell culture system. As an example, the analysis of ECM from human vascular smooth muscle cells (hVSMCs) and human umbilical vein endothelial cells (HUVECs) appeared to be reproducible and evidenced different ECM patterns from the two cell types. Applications based on these materials can be proposed for biomarker discovery or characterization of cells for biomedical/diagnostic purposes.

Effect of covalent antithrombin-heparin complex on developmental mechanisms in the lung

We have developed a potent antithrombin (AT)-heparin conjugate (ATH) that is retained in the lung to prevent pulmonary thrombosis associated with respiratory distress in premature newborns. During continuing maturation, pulmonary angiogenesis in premature infants would be a crucial process in lung development. A naturally occurring latent form of antithrombin (L-AT) has antiangiogenic effects on lung vascularization. However, impact of latent ATH (L-ATH) on developing lung vascularization is unknown. Thus, effects of L-AT and L-ATH on fetal murine lung development were compared. Lung buds from embryonic day 11.5 (E11.5) Tie2-LacZ mouse embryos were incubated in DMEM plus FBS supplemented with PBS, AT, L-AT, heparin, ATH, or L-ATH. Vasculature of cultured explants was quantified by X-galactosidase staining. RNA was analyzed with murine gene probes for angiopoietin (Ang)-1, Ang-2, fibroblast growth factor 2 (FGF2), platelet endothelial cell adhesion molecule (PECAM), and vascular endothelial growth factor (VEGF). FGF2-supplemented medium was used to test contribution to effects of L-AT and L-ATH on angiogenesis. Epithelial branching morphogenesis was inhibited by L-AT (P = 0.003) and heparin (P < 0.001). L-AT and heparin decreased relative vascular area compared with PBS, ATH, and L-ATH. Expressions of all genes studied were downregulated by L-AT. However, L-AT and L-ATH inhibited branching morphogenesis and vasculature with added FGF2. These findings indicate that covalent linkage of AT to heparin negates disruptive effects of these moieties on lung morphology, vascularization, and growth factor gene expression. ATH may have enhanced safety as an anticoagulant during vascular development.

Angiogenesis alteration by defibrotide: implications for its mechanism of action in severe hepatic veno-occlusive disease

Defibrotide (DF) is a mixture of porcine-derived single-stranded phosphodiester oligonucleotides (9-80-mer; average, 50-mer) that has been successfully used to treat severe hepatic veno-occlusive disease (sVOD) with multiorgan failure (MOF) in patients who have received cytotoxic chemotherapy in preparation for bone marrow transplantation. However, its mechanism of action is unknown. Herein, we show that DF and phosphodiester oligonucleotides can bind to heparin-binding proteins (eg, basic fibroblast growth factor [bFGF] but not vascular endothelial growth factor [VEGF] 165) with low nanomolar affinity. This binding occurred in a length- and concentration-dependent manner. DF can mobilize proangiogenic factors such as bFGF from their depot or storage sites on bovine corneal endothelial matrix. However, these molecules do not interfere with high-affinity binding of bFGF to FGFR1 IIIc but can replace heparin as a required cofactor for binding and hence cellular mitogenesis. DF also protects bFGF against digestion by trypsin and chymotrypsin and from air oxidation. In addition, DF binds to collagen I with low nanomolar affinity and can promote human microvascular endothelial cell-1 (HMEC-1) cell mitogenesis and tubular morphogenesis in three-dimensional collagen I gels. Thus, our data suggest that DF may provide a stimulus to the sinusoidal endothelium of a liver that has suffered a severe angiotoxic event, thus helping to ameliorate the clinical sVOD/MOF syndrome.

Polyanionic drugs and viral oncogenesis: a novel approach to control infection, tumor-associated inflammation and angiogenesis

Polyanionic macromolecules are extremely abundant both in the extracellular environment and inside the cell, where they are readily accessible to many proteins for interactions that play a variety of biological roles. Among polyanions, heparin, heparan sulfate proteoglycans (HSPGs) and glycosphingolipids (GSLs) are widely distributed in biological fluids, at the cell membrane and inside the cell, where they are implicated in several physiological and/or pathological processes such as infectious diseases, angiogenesis and tumor growth. At a molecular level, these processes are mainly mediated by microbial proteins, cytokines and receptors that exert their functions by binding to HSPGs and/or GSLs, suggesting the possibility to use polyanionic antagonists as efficient drugs for the treatment of infectious diseases and cancer. Polysulfated (PS) or polysulfonated (PSN) compounds are a heterogeneous group of natural, semi-synthetic or synthetic molecules whose prototypes are heparin and suramin. Different structural features confer to PS/PSN compounds the capacity to bind and inhibit the biological activities of those same heparin-binding proteins implicated in infectious diseases and cancer. In this review we will discuss the state of the art and the possible future development of polyanionic drugs in the treatment of infectious diseases and cancer.

Effect of controlled release of fibroblast growth factor-2 from chitosan/fucoidan micro complex-hydrogel onin vitro andin vivo vascularization

We produced a chitosan/fucoidan micro complex-hydrogel as a carrier for controlled release of heparin binding growth factors such as fibroblast growth factor (FGF)-2. Material consisting of a soluble chitosan (CH-LA) mixed with fucoidan yielded a water-insoluble and injectable hydrogel with filamentous particles. In this study, we examined the ability of the chitosan/fucoidan complex-hydrogel to immobilize FGF-2 and to protect its activity, as well as the controlled release of FGF-2 molecules. The chitosan/fucoidan complex-hydrogel has high affinity for FGF-2 (K(d) = 5.4 x 10(-) (9)M). The interaction of FGF-2 with chitosan/fucoidan complex-hydrogel substantially prolonged the biological half-life time of FGF-2. It also protected FGF-2 from inactivation, for example by heat and proteolysis, and enhance FGF-2 activity. When FGF-2-containing complex-hydrogel was subcutaneously injected into the back of mice, significant neovascularization and fibrous tissue formation were induced near the site of injection at 1 week, and the complex-hydrogel was biodegraded and disappeared by 4 weeks. These findings indicate that controlled release of biologically active FGF-2 molecules is caused by both slow diffusion and biodegradation of the complex-hydrogel, and that subsequent induction of vascularization occurs. FGF-2-containing chitosan/fucoidan micro complex-hydrogel is thus useful and convenient for treatment of ischemic disease.

Efficacy and safety of a new-class hemostatic drug candidate, AV513, in dogs with hemophilia A

AV513 is a select fucoidan, a sulfated polysaccharide of botanical origin. It inhibits tissue factor pathway inhibitor (TFPI) activity and accelerates clotting of human hemophilia A and B plasma. In prior work, subcutaneous administration of AV513 to mice with hemophilia A improved hemostasis. The current studies were designed to evaluate potential efficacy and safety in dogs with hemophilia A (hemophilia A dogs) with minimally increased hemostasis after adenoassociated viral-FVIII gene transfer and in treatment-naive severe hemophilia A dogs. AV513 administered subcutaneously to low-FVIII dogs for multiple weeks improved hemostasis as exhibited in thromboelastography (TEG) and cuticle bleeding time (CBT) tests. Moreover, AV513 administered orally to AAV-FVIII dogs and treatment-naive severe hemophilia A dogs for a multiweek dose-escalating period yielded correction to normal ranges in both TEG and CBT end points at 5 to 15 mg/kg and 15 to 20 mg/kg dose levels, respectively. In all 3 separate studies, throughout their duration, AV513 was well tolerated by the dogs without any adverse events. Additional pharmacologic characterization of AV513 included intravenous pharmacokinetic analysis in rats. In summary, the combination of safety and efficacy in 2 global tests of hemostasis in the hemophilia A dog model indicate that further evaluation of AV513 as a hemostatic agent in hemophilia A patients is warranted.

Low Molecular Weight Fucoidan Increases VEGF165-induced Endothelial Cell Migration by Enhancing VEGF165 Binding to VEGFR-2 and NRP1

Therapeutic induction of angiogenesis is a potential treatment for chronic ischemia. Heparan sulfate proteoglycans are known to play an important role by their interactions with proangiogenic growth factors such as vascular endothelial growth factor (VEGF). Low molecular weight fucoidan (LMWF), a sulfated polysaccharide from brown seaweeds that mimic some biological activities of heparin, has been shown recently to promote revascularization in rat critical hindlimb ischemia. In this report, we first used cultured human endothelial cells (ECs) to investigate the possible ability of LMWF to enhance the actions of VEGF(165). Data showed that LMWF greatly enhances EC tube formation in growth factor reduced matrigel. LMWF is a strong enhancer of VEGF(165)-induced EC chemotaxis, but not proliferation. In addition, LMWF has no effect on VEGF(121)-induced EC migration, a VEGF isoform that does not bind to heparan sulfate proteoglycans. Then, with binding studies using (125)I-VEGF(165), we observed that LMWF enhances the binding of VEGF(165) to recombinant VEGFR-2 and Neuropilin-1 (NRP1), but not to VEGFR-1. Surface plasmon resonance analysis showed that LMWF binds with high affinity to VEGF(165) (1.2 nm) and its receptors (5-20 nm), but not to VEGF(121). Pre-injection of LMWF on immobilized receptors shows that VEGF(165) has the highest affinity for VEGFR-2 and NRP1, as compared with VEGFR-1. Overall, the effects of LMWF were much more pronounced than those of LMW heparin. These findings suggested an efficient mechanism of action of LMWF by promoting VEGF(165) binding to VEGFR-2 and NRP1 on ECs that could help in stimulating therapeutic revascularization.

Antiangiogenesis response of endothelial cells to the antitumour drug 10-methoxy-9-nitrocamptothecin

10-Methoxy-9-nitrocamptothecin (MONCPT), a topoisomerase I inhibitor, exhibited high anticancer activity in solid tumour xenograft animal models in our previous study. We hypothesized that this phenomenon was associated with antiangiogenesis response. In the present study, we found that MONCPT exhibited high antiproliferation action in human EA.hy926 endothelial cells and the IC(50) value was 0.13+/-0.04microM (MTT assay). With AO/EB stain, MONCPT (50-5000nM)-mediated apoptosis was observed in EA.hy926 cells, and the similar results were shown in flow cytometry assay, the percentage of apoptotic cells induced by MONCPT (50-5000nM) was 9.2-58.5%. In Chick embryo chorioallantoic membrane (CAM) assay, MONCPT (1-5microg) resulted in a dose-dependent angiogenic inhibition. In addition, MONCPT significantly inhibited chemotactic-migration invasion on gelatin and tube formation on Matrigel of HUVECs. These results suggest that MONCPT has potential property for inhibiting angiogenesis which is involved in its antitumour activity.

Inostamycin suppresses vascular endothelial growth factor-stimulated growth and migration of human umbilical vein endothelial cells

Angiogenesis involves multiple steps including proliferation and migration of endothelial cells. In the present study, we determined the effect of inostamycin (an inhibitor of phosphatidylinositol synthesis) on vascular endothelial growth factor (VEGF)-induced proliferation and migration of human umbilical vein endothelial cells (HUVECs). Inostamycin significantly attenuated both VEGF-induced proliferation and migration of HUVECs. Inostamycin inhibited activation of mitogen-activated kinases (ERK and p38) and elevation of cyclin D1 induced by VEGF. These data suggest that inostamycin reduced both proliferation and migration of HUVECs by targeting ERK-cyclin D1 and p38, respectively.

Effect of an oversulfated exopolysaccharide on angiogenesis induced by fibroblast growth factor-2 or vascular endothelial growth factor in vitro

The aim of this study was to determine the angiogenic properties of an oversulfated exopolysaccharide (OS-EPS) derived from a polysaccharide secreted by the mesophilic bacterium Alteromonas infernus. We compared the effect of this OS-EPS with that of a non-oversulfated exopolysaccharide (EPS) on human umbilical vein endothelial cell (HUVEC) proliferation, migration and differentiation induced by basic fibroblast growth factor (FGF-2) or vascular endothelial growth factor (VEGF). OS-EPS enhanced HUVEC proliferation by 58% when used alone, and by respectively 30% and 70% in the presence of FGF-2 and VEGF. OS-EPS also increased the density of tubular structures on Matrigel in the presence of FGF-2 or VEGF. Vascular tube formation was related to alpha(6) integrin subunit expression, which was enhanced by 50% in the presence of the growth factors. Indeed, a monoclonal anti-alpha(6) blocking antibody abolished this vascular tube formation. EPS had no effect in any of the experimental conditions, underlying the importance of sulfation in the angiogenic effects of exopolysaccharide. By potentiating the angiogenic activity of FGF-2 and/or VEGF, OS-EPS, which possesses low anticoagulant activity and thus a low hemorrhagic risk, could potentially be used to accelerate vascular wound healing or to promote the growth of collateral blood vessels in ischemic tissues.