Controlled release of 2, 3 desulfated heparin exerts its anti-inflammatory activity by effectively inhibiting E-selectin

Surface Modification of Zn-Cu Alloy with Heparin Nanoparticles for Urinary Implant Applications

In this work, an investigation on the Zn-Cu alloy coated with heparin was conducted in order to explore the potentiality of its application as a feasible alternative for biodegradable implants, with the specific goal of addressing the issue of encrustation in the urinary system. The stability of the nanoparticles were characterized by dynamic light scattering. Typical surface characterization such as X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were used to demonstrate a successful immobilization of the NPs. The in vitro corrosion behavior was studied by potentiodynamic polarization and immersion tests in artificial urine (AU) at 37 °C. The 8 weeks in vivo degradation, encrustation resistance, hemocompatibility, and histocompatibility were investigated by means of implantation into the bladders of rats. Both in vitro and in vivo degradation tests exhibited a higher degradation rate for Zn-Cu and NPs groups when compared to pure Zn. Histological evaluations and hemocompatibility revealed that there was no tissue damage or pathological alterations caused by the degradation process. Furthermore, antiencrustation performance and urinalysis results confirmed that the modified alloy demonstrated significant encrustation inhibitory properties and bactericidal activity compared to the pure Zn control. Our findings highlight the potential of this modified alloy as an antiencrustation biodegradable ureteral stent.

A silk-based coating containing GREDVY peptide and heparin on Mg-Zn-Y-Nd alloy: improved corrosion resistance, hemocompatibility and endothelialization

Magnesium (Mg) alloys have been intensively investigated as potential absorbable coronary stent materials as their use avoids risks such as late inflammation and restenosis generated by permanent metallic implants. Besides that, clinical trials on coronary stents fabricated from Mg alloys have made great progress recently. However, the over-rapid corrosion rate, magnesium corrosion-induced thrombosis formation and delayed endothelium regeneration continue to be problematic for coronary artery stent therapy. In this study, silk fibroin blended with heparin and GREDVY (Gly-Arg-Glu-Asp-Val-Tyr) peptide was immobilized on a HF-pretreated MgZnYNd alloy surface via a polydopamine layer to improve its corrosion resistance, blood compatibility and endothelialization. Standard electrochemical measurements along with the long-term immersion results indicated that the functionalized MgZnYNd alloy had preferable anti-corrosion abilities compared with the bare MgZnYNd alloy. The modified surface exhibited outstanding hemocompatibility with reduced platelet adhesion, hemolysis rate and prolonged blood coagulation time. Human umbilical vein endothelial cell (HUVEC) and vascular smooth muscle cell (VSMC) co-culture results revealed more attached HUVECs on the functionalized samples than on the MgZnYNd alloy surfaces. The excellent corrosion retardation, hemocompatibility and re-endothelialization of the multi-functional coating indicate a promising method in the field of biodegradable magnesium-based implantable cardiovascular stents.

The Role of Heparan Sulfate in Inflammation, and the Development of Biomimetics as Anti-Inflammatory Strategies

Key events that occur during inflammation include the recruitment, adhesion, and transmigration of leukocytes from the circulation to the site of inflammation. These events are modulated by chemokines, integrins, and selectins and the interaction of these molecules with glycosaminoglycans, predominantly heparan sulfate (HS). The development of HS/heparin mimetics that interfere or inhibit the interactions that occur between glycosaminoglycans and modulators of inflammation holds great potential for use as anti-inflammatory therapeutics. This review will detail the role of HS in the events that occur during inflammation, their interaction and modulation of inflammatory mediators, and the current advances in the development of HS/heparin mimetics as anti-inflammatory biotherapeutics.

Surface biomimetic modification with laminin-loaded heparin/poly-l-lysine nanoparticles for improving the biocompatibility

Late thrombus and restenosis caused by delayed endothelialization and insufficient biocompatibility of polymer coating continue to be the greatest limitations of drug-eluting stents. In this study, based on the specific structure of vascular basement membrane, a novel biomimetic nano-coating was constructed by incorporating laminin into electrostatic-assembled heparin/poly-l-lysine nanoparticles. Alteration of heparin and poly-l-lysine concentration ratio in a certain range has no significantly influence nanoparticle size, uniformity and stability, but may affect the chemical property and subsequently the binding efficiency to dopamine-coated titanium surface. By use of this feature, four different nanoparticles were synthesized and immobilized on titanium surface for creating gradient nanoparticle binding density. According to in vitro biocompatibility evaluation, the nanoparticle modified surfaces were found to effectively block coagulation pathway and reduce thrombosis formation. Moreover, NP10L and NP15L modified surface with relatively low heparin exposing density (4.9 to 7.1μg/cm2) showed beneficial effect in selective promoting EPCs and ECs proliferation, as well as stimulating cell migration and NO synthesis.

Heparins in ulcerative colitis: proposed mechanisms of action and potential reasons for inconsistent clinical outcomes

Current drug therapies for ulcerative colitis (UC) are not completely effective in managing moderate-to-severe UC and approximately 20% of patients with severe UC require surgical interventions. Heparins, polydisperse mixtures of non-anticoagulant and anticoagulant oligosaccharides, are widely used as anticoagulants. However, heparins are also reported to have anti-inflammatory properties. Unfractionated heparin was initially used in patients with UC for the treatment of rectal microthrombi. Surprisingly, it was found to be effective in reducing UC-associated symptoms. Since then, several pre-clinical and clinical studies have reported promising outcomes of heparins in UC. In contrast, some controlled clinical trials demonstrated no or only limited benefits, thus the potential of heparins for the treatment of UC remains uncertain. This review discusses potential mechanisms of action of heparins, as well as proposed reasons for their contradictory clinical effectiveness in the treatment of UC.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010

This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.

Sulfated glycans in inflammation

Sulfated glycans such as glycosaminoglycans on proteoglycans are key players in both molecular and cellular events of inflammation. They participate in leukocyte rolling along the endothelial surface of inflamed sites; chemokine regulation and its consequential functions in leukocyte guidance, migration and activation; leukocyte transendothelial migration; and structural assembly of the subendothelial basement membrane responsible to control tissue entry of cells. Due to these and other functions, exogenous sulfated glycans of various structures and origins can be used to interventionally down-regulate inflammation processes. In this review article, discussion is given primarily on the anti-inflammatory functions of mammalian heparins, heparan sulfate, chondroitin sulfate, dermatan sulfate and related compounds as well as the holothurian fucosylated chondroitin sulfate and the brown algal fucoidans. Understanding the underlying mechanisms of action of these sulfated glycans in inflammation, helps research programs involved in developing new carbohydrate-based drugs aimed to combat acute and chronic inflammatory disorders.

Surface modification with dopamine and heparin/poly-L-lysine nanoparticles provides a favorable release behavior for the healing of vascular stent lesions

Surface biofunctional modification of coronary artery stents to prevent thrombosis and restenosis formation, as well as accelerate endothelialization, has become a new hot spot. However, bioactive coatings on implants are not yet sufficiently developed for long-term activity, as they quickly lose efficiency in vivo and finally fail. On the basis of a novel time-ordered concept of biofunctionality for vascular stents, heparin/poly l-lysine nanoparticle (NP) was developed and immobilized on a polydopamine-coated titanium surface, with the aim of regulating and maintaining the intravascular biological response within the normal range after biomaterial implantation. An in vitro dynamic release model was established to mimic the blood flow condition in vivo with three phases: (1) An early phase (1-7 days) with release of predominantly anticoagulant and anti-inflammatory substances and to a minor degree antiproliferative effects against smooth muscle cells (SMCs); (2) this is followed by a phase (7-14 days) of supported endothelial cell (ECs) proliferation and suppressed SMC proliferation with persisting high antithrombogenicity and anti-inflammatory properties of the surface. (3) Finally, a stable stage (14-28 days) with adequate biomolecules on the surface that maintain hemocompatibility and anti inflammation as well as inhibit SMCs proliferation and promote ECs growth. In vivo animal tests further confirmed that the NP-modified surface provides a favorable release behavior to apply a stage-adjusted remedy. We suggested that these observations provide important guidance and potential means for reasonable and suitable platform construction on a stent surface.

Immobilization of heparin/poly-(L)-lysine nanoparticles on dopamine-coated surface to create a heparin density gradient for selective direction of platelet and vascular cells behavior

Restenosis, thrombosis formation and delayed endothelium regeneration continue to be problematic for coronary artery stent therapy. To improve the hemocompatibility of the cardiovascular implants and selectively direct vascular cell behavior, a novel kind of heparin/poly-l-lysine (Hep/PLL) nanoparticle was developed and immobilized on a dopamine-coated surface. The stability and structural characteristics of the nanoparticles changed with the Hep:PLL concentration ratio. A Hep density gradient was created on a surface by immobilizing nanoparticles with various Hep:PLL ratios on a dopamine-coated surface. Antithrombin III binding quantity was significantly enhanced, and in plasma the APTT and TT times as coagulation tests were prolonged, depending on the Hep density. A low Hep density is sufficient to prevent platelet adhesion and activation. The sensitivity of vascular cells to the Hep density is very different: high Hep density inhibits the growth of all vascular cells, while low Hep density could selectively inhibit smooth muscle cell hyperplasia but promote endothelial progenitor cells and endothelial cell proliferation. These observations provide important guidance for modification of surface heparinization. We suggest that this method will provide a potential means to construct a suitable platform on a stent surface for selective direction of vascular cell behavior with low side effects.

Non-anticoagulant derivatives of heparin for the management of asthma: distant dream or close reality?

INTRODUCTION

Approximately 300 million people worldwide are currently affected by asthma. Improvements in the understanding of the mechanisms involved in such inflammatory airway disorders has led to the recognition of new therapeutic approaches. Heparin, a widely used anticoagulant, has been shown to be beneficial in the management of asthma. It belongs to the family of highly sulphated polysaccharides referred to as glycosaminoglycans, containing a heterogeneous mixture of both anticoagulant and non-anticoagulant polysaccharides. Experimental findings have suggested that heparin has potential anti-asthmatic properties owing to the ability of its non-anticoagulant oligosaccharides to bind and modulate the activity of a wide range of biological molecules involved in the inflammatory process.

AREAS COVERED

This review focuses on the potential mechanisms of action and clinical application of heparin as an anti-inflammatory agent for the management of asthma.

EXPERT OPINION

Heparin may play a significant role in the management of asthma. However, these properties are often hindered by the presence of anticoagulant oligosaccharides, which possess a significant risk of bleeding. Therefore, its therapeutic potential must be explored using well-designed clinical studies that focus on identifying and isolating the anti-inflammatory oligosaccharides of heparin and further elucidating the structure and mechanisms of actions of these non-anticoagulant oligosaccharides.

Heparosan-derived heparan sulfate/heparin-like compounds: one kind of potential therapeutic agents

Heparan sulfate (HS) is a highly sulfated glycosaminoglycan and exists in all animal tissues. HS and heparin are very similar, except that heparin has higher level of sulfation and higher content of iduronic acid. Despite the fact that it is a century-old drug, heparin remains as a top choice for treating thrombotic disorders. Pharmaceutical heparin is derived from porcine intestine or bovine lung via a long supply chain. This supply chain is vulnerable to the contamination of animal pathogens. Therefore, new methods for manufacturing heparin or heparin-like substances devoid of animal tissues have been explored by many researchers, among which, modifications of heparosan, the capsular polysaccharide of Escherichia coli K5 strain, is one of the promising approaches. Heparosan has a structure similar to unmodified backbone of natural HS and heparin. It is feasible to obtain HS or heparin derivatives by modifying heparosan with chemical or enzymatic methods. These derivatives display different biological activities, such as anticoagulant, anti-inflammatory, anticancer, and antiviral activities. This review focuses on the recent studies of synthesis, activity, and structure-activity relationship of HS/heparin-like derivatives prepared from heparosan.

A PEGylated fibrin-based wound dressing with antimicrobial and angiogenic activity

Wounds sustained under battlefield conditions are considered to be contaminated and their initial treatment should focus on decreasing this contamination and thus reducing the possibility of infection. The early and aggressive administration of antimicrobial treatment starting with intervention on the battlefield has resulted in improved patient outcomes and is considered the standard of care. Chitosan microspheres (CSM) loaded with silver sulfadiazine (SSD) were developed via a novel water-in-oil emulsion technique to address this problem. The SSD-loaded spheres were porous with needle-like structures (attributed to SSD) that were evenly distributed over the spheres. The average particle size of the SSD-CSM was 125-180 μm with 76.50 ± 2.8% drug entrapment. As a potential new wound dressing with angiogenic activity SSD-CSM particles were impregnated in polyethylene glycol (PEGylated) fibrin gels. In vitro drug release studies showed that a burst release of 27.02% in 6h was achieved, with controlled release for 72 h, with an equilibrium concentration of 27.7% (70 μg). SSD-CSM-PEGylated fibrin gels were able to exhibit microbicidal activity at 125 and 100 μg ml(-1) against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. The in vitro vasculogenic activity of this composite dressing was shown by seeding adipose-derived stem cells (ASC) in SSD-CSM-PEGylated fibrin gels. The ASC spontaneously formed microvascular tube-like structures without the addition of any exogenous factors. This provides a method for the extended release of an antimicrobial drug in a matrix that may provide an excellent cellular environment for revascularization of infected wounds.