Nitric oxide: implications for vascular and endovascular surgery

Commercial and novel anticoagulant ECMO coatings: a review

Extracorporeal membrane oxygenation (ECMO) is an invasive and last-resort treatment for circulatory and respiratory failure. Prolonged ECMO support can disrupt the coagulation and anticoagulation systems in a patient, leading to adverse consequences, such as bleeding and thrombosis. To address this problem, anticoagulation coatings have been developed for use in ECMO circuits. This article reviews commonly used commercial and novel anticoagulant coatings developed in recent years and proposes a new classification of coatings based on the current state. While commercial coatings have been used clinically for decades, this review focuses on comparing the effectiveness and stability of coatings to support clinical selections. Furthermore, novel anticoagulation coatings often involve complex mechanisms and elaborate design strategies, and this review summarises representative studies on mainstream anticoagulation coatings to provide a point of reference for future studies.

Polymeric Nitric Oxide Delivery Nanoplatforms for Treating Cancer, Cardiovascular Diseases, and Infection

The shortened Abstract is as follows: Therapeutic gas nitric oxide (NO) has demonstrated the unique advances in biomedical applications due to its prominent role in regulating physiological/pathophysiological activities in terms of vasodilation, angiogenesis, chemosensitizing effect, and bactericidal effect. However, it is challenging to deliver NO, due to its short half-life (<5 s) and short diffusion distances (20-160 µm). To address these, various polymeric NO delivery nanoplatforms (PNODNPs) have been developed for cancer therapy, antimicrobial and cardiovascular therapeutics, because of the important advantages of polymeric delivery nanoplatforms in terms of controlled release of therapeutics and the extremely versatile nature. This reviews highlights the recent significant advances made in PNODNPs for NO storing and targeting delivery. The ideal and unique criteria that are required for PNODNPs for treating cancer, cardiovascular diseases and infection, respectively, are summarized. Hopefully, effective storage and targeted delivery of NO in a controlled manner using PNODNPs could pave the way for NO-sensitized synergistic therapy in clinical practice for treating the leading death-causing diseases.

In Situ Generated Medical Devices

Medical devices play a major role in all areas of modern medicine, largely contributing to the success of clinical procedures and to the health of patients worldwide. They span from simple commodity products such as gauzes and catheters, to highly advanced implants, e.g., heart valves and vascular grafts. In situ generated devices are an important family of devices that are formed at their site of clinical function that have distinct advantages. Among them, since they are formed within the body, they only require minimally invasive procedures, avoiding the pain and risks associated with open surgery. These devices also display enhanced conformability to local tissues and can reach sites that otherwise are inaccessible. This review aims at shedding light on the unique features of in situ generated devices and to underscore leading trends in the field, as they are reflected by key developments recently in the field over the last several years. Since the uniqueness of these devices stems from their in situ generation, the way they are formed is crucial. It is because of this fact that in this review, the medical devices are classified depending on whether their in situ generation entails chemical or physical phenomena.

Biomineralized hybrid nanoparticles for imaging and therapy of cancers

In this review, we describe the research trends of hybrid nanocarriers developed based on a biomimetic mineralization process, and their recent applications in imaging and therapy of cancers. Organic-inorganic hybrid nanostructures formed by diverse biomimetic mineralization approaches are briefly reviewed, and particularly, the biomedical applications of these hybrid nanocarriers for the diagnosis and therapy of cancers are discussed. Biomineralization is an important process in which living organisms produce biominerals, such as calcium phosphate (CaP), calcium carbonate (CaCO3), and silica (SiO2), to strengthen their tissues, as found in the formation of bone and teeth. Introducing the artificial biomimetic mineralization process to nanobiotechnology has inspired researchers to develop smart stimuli-responsive nanoparticles for multiple purposes, such as improved therapeutic activity and activatable imaging of cancers.

Insights on Localized and Systemic Delivery of Redox-Based Therapeutics

Reactive oxygen and nitrogen species are indispensable in cellular physiology and signaling. Overproduction of these reactive species or failure to maintain their levels within the physiological range results in cellular redox dysfunction, often termed cellular oxidative stress. Redox dysfunction in turn is at the molecular basis of disease etiology and progression. Accordingly, antioxidant intervention to restore redox homeostasis has been pursued as a therapeutic strategy for cardiovascular disease, cancer, and neurodegenerative disorders among many others. Despite preliminary success in cellular and animal models, redox-based interventions have virtually been ineffective in clinical trials. We propose the fundamental reason for their failure is a flawed delivery approach. Namely, systemic delivery for a geographically local disease limits the effectiveness of the antioxidant. We take a critical look at the literature and evaluate successful and unsuccessful approaches to translation of redox intervention to the clinical arena, including dose, patient selection, and delivery approach. We argue that when interpreting a failed antioxidant-based clinical trial, it is crucial to take into account these variables and importantly, whether the drug had an effect on the redox status. Finally, we propose that local and targeted delivery hold promise to translate redox-based therapies from the bench to the bedside.

Synthesis and Characterization of Nitric Oxide-Releasing Platinum(IV) Prodrug and Polymeric Micelle Triggered by Light

Herein, we report the proof of concept of photoresponsive chemotherapeutics comprising nitric oxide-releasing platinum prodrugs and polymeric micelles. Photoactivatable nitric oxide-releasing donors were integrated into the axial positions of a platinum(IV) prodrug, and the photolabile hydrophobic groups were grafted in the block copolymers. The hydrophobic interaction between nitric oxide donors and the photolabile groups allowed for the loading of platinum drugs and nitric oxide-releasing donors in the photolabile polymeric micelles. After cellular uptake of micelles, light irradiation induced the release of nitric oxide, which sensitized the cancer cells. Simultaneously, photolabile hydrophobic groups were cleaved from micelles, and the nitric oxide-releasing donor was altered to be more hydrophilic, resulting in the rapid release of platinum(IV) prodrugs. The strategy of using platinum(IV) prodrugs and nitric oxide led to enhanced anticancer effects.

Combination of nitric oxide and drug delivery systems: tools for overcoming drug resistance in chemotherapy

Chemotherapeutic drugs have made significant contributions to anticancer therapy, along with other therapeutic methods including surgery and radiotherapy over the past century. However, multidrug resistance (MDR) of cancer cells has remained as a significant obstacle in the achievement of efficient chemotherapy. Recently, there has been increasing evidence for the potential function of nitric oxide (NO) to overcome MDR. NO is an endogenous and biocompatible molecule, contrasting with other potentially toxic chemosensitizing agents that reverse MDR effects, which has raised expectations in the development of efficient therapeutics with low side effects. In particular, nanoparticle-based drug delivery systems not only facilitate the delivery of multiple therapeutic agents, but also help bypass MDR pathways, which are conducive for the efficient delivery of NO and anticancer drugs, simultaneously. Therefore, this review will discuss the mechanism of NO in overcoming MDR and recent progress of combined NO and drug delivery systems.

Study of Crystal Formation and Nitric Oxide (NO) Release Mechanism from S-Nitroso-N-acetylpenicillamine (SNAP)-Doped CarboSil Polymer Composites for Potential Antimicrobial Applications

Stable and long-term nitric oxide (NO) releasing polymeric materials have many potential biomedical applications. Herein, we report the real-time observation of the crystallization process of the NO donor, S-nitroso-N-acetylpenicillamine (SNAP), within a thermoplastic silicone-polycarbonate-urethane biomedical polymer, CarboSil 20 80A. It is demonstrated that the NO release rate from this composite material is directly correlated with the surface area that the CarboSil polymer film is exposed to when in contact with aqueous solution. The decomposition of SNAP in solution (e.g. PBS, ethanol, THF, etc.) is a pseudo-first-order reaction proportional to the SNAP concentration. Further, catheters fabricated with this novel NO releasing composite material are shown to exhibit significant effects on preventing biofilm formation on catheter surface by Pseudomonas aeruginosa and Proteus mirabilis grown in CDC bioreactor over 14 days, with a 2 and 3 log-unit reduction in number of live bacteria on their surfaces, respectively. Therefore, the SNAP-CarboSil composite is a promising new material to develop antimicrobial catheters, as well as other biomedical devices.

Influence of NO and (NO)2 adsorption on the properties of Fe-N4 porphyrin-like graphene sheets

Fe-N4 porphyrin-like graphene catalysis and spin filter characteristics toward NO and (NO)₂ dimer adsorption.

Characterization and in vivo performance of nitric oxide-releasing extracorporeal circuits in a feline model of thrombogenicity

Infection and thrombosis are the two leading complications associated with blood contacting medical devices, and have led to the development of active materials that can delivery antibiotics or antithrombotic agents. Two key characteristics of these materials are the ability to produce controlled delivery, as well as minimal systemic delivery of the agent outside of the device site. Nitric oxide (NO) releasing materials are attractive as NO plays pivotal roles in the body's natural defense against bacterial infection, as well as regulation of platelet adhesion and activation. This work characterizes an NO-releasing extracorporeal circuit (ECC) under flow conditions for the first time, examining the effect of incubation and application of the top coating on leaching of NO donor and NO-release kinetics. Top coated ECCs with incubation delivered ca. 1% of the total NO potential over the 4-h period, whereas uncoated ECCs delivered over 4.5% of the total NO. Incubated ECC loops maintained a flux of 1.83 ± 0.50 × 10^-10 mol min^-1 cm^-2 for the full 4 h duration. The NO-releasing ECC loops significantly increased the time-to-clot as compared to the corresponding control (11 ± 3.6 min control, 132 ± 93.0 min NO-releasing) when evaluated in vivo in a feline animal model. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 539-546, 2017.

Recent advances in thromboresistant and antimicrobial polymers for biomedical applications: just say yes to nitric oxide (NO)

Biomedical devices are essential for patient diagnosis and treatment; however, when blood comes in contact with foreign surfaces or homeostasis is disrupted, complications including thrombus formation and bacterial infections can interrupt device functionality, causing false readings and/or shorten device lifetime. Here, we review some of the current approaches for developing antithrombotic and antibacterial materials for biomedical applications. Special emphasis is given to materials that release or generate low levels of nitric oxide (NO). Nitric oxide is an endogenous gas molecule that can inhibit platelet activation as well as bacterial proliferation and adhesion. Various NO delivery vehicles have been developed to improve NO's therapeutic potential. In this review, we provide a summary of the NO releasing and NO generating polymeric materials developed to date, with a focus on the chemistry of different NO donors, the polymer preparation processes, and in vitro and in vivo applications of the two most promising types of NO donors studied thus far, N-diazeniumdiolates (NONOates) and S-nitrosothiols (RSNOs).

Characterization of an S-nitroso-N-acetylpenicillamine-based nitric oxide releasing polymer from a translational perspective

Due to the role of nitric oxide (NO) in regulating a variety of biological functions in humans, numerous studies on different NO releasing/generating materials have been published over the past two decades. Although NO has been demonstrated to be a strong antimicrobial and potent antithrombotic agent, NO-releasing (NOrel) polymers have not reached the clinical setting. While increasing the concentration of the NO donor in the polymer is a common method to prolong the NO-release, this should not be at the cost of mechanical strength or biocompatibility of the original material. In this work, it was shown that the incorporation of S-nitroso-penicillamine (SNAP), an NO donor molecule, into Elast-eon E2As (a copolymer of mixed soft segments of polydimethylsiloxane and poly(hexamethylene oxide)), does not adversely impact the physical and biological attributes of the base polymer. Incorporating 10 wt % of SNAP into E2As reduces the ultimate tensile strength by only 20%. The inclusion of SNAP did not significantly affect the surface chemistry or roughness of E2As polymer. Ultraviolet radiation, ethylene oxide, and hydrogen peroxide vapor sterilization techniques retained approximately 90% of the active SNAP content, where sterilization of these materials did not affect the NO-release profile over an 18 day period. Furthermore, these NOrel materials were shown to be biocompatible with the host tissues as observed through hemocompatibility and cytotoxicity analysis. In addition, the stability of SNAP in E2As was studied under a variety of storage conditions, as they pertain to translational potential of these materials. SNAP-incorporated E2As stored at room temperature for over 6 months retained 87% of its initial SNAP content. Stored and fresh films exhibited similar NO release kinetics over an 18 day period. Combined, the results from this study suggest that SNAP-doped E2As polymer is suitable for commercial biomedical applications due to the reported physical and biological characteristics that are important for commercial and clinical success.

Light-Induced Acid Generation on a Gatekeeper for Smart Nitric Oxide Delivery

We report herein the design of a light-responsive gatekeeper for smart nitric oxide (NO) delivery. The gatekeeper is composed of a pH-jump reagent as an intermediary of stimulus and a calcium phosphate (CaP) coating as a shielding layer for NO release. The light irradiation and subsequent acid generation are used as triggers for uncapping the gatekeeper and releasing NO. The acids generated from a light-activated pH-jump agent loaded in the mesoporous nanoparticles accelerated the degradation of the CaP-coating layers on the nanoparticles, facilitating the light-responsive NO release from diazeniumdiolate by exposing a NO donor to physiological conditions. Using the combination of the pH-jump reagent and CaP coating, we successfully developed a light-responsive gatekeeper system for spatiotemporal-controlled NO delivery.

Nitric oxide-generatingl-cysteine-grafted graphene film as a blood-contacting biomaterial

With polyethylenimine molecules as the linker,l-cysteine was grafted on the surface of graphene nanosheets, endowing the functionalized graphene film with the ability to catalytically decompose nitric oxide donors to reduce platelet adhesion.

Nitric oxide as a surgical adjuvant

Advances in surgical technology have allowed for previously unconsidered therapeutic interventions. However, the complexity and invasiveness of surgical procedures are not without adverse consequences. Nitric oxide's fundamental role in a host of physiological processes, including angiogenesis, wound and bone healing, thromboresistance, smooth muscle relaxation and inflammation makes it a significant player in accelerating wound healing and mitigating the inflammation of ischemia reperfusion injury common to surgical procedures. In addition, the therapeutic properties of NO have been harnessed for the prophylactic treatment of implant infection and graft failure. In this article, we will discuss the mechanism by which NO mediates these processes, and its perioperative translational applications.

Rapid in situ endothelialization of a small diameter vascular graft with catalytic nitric oxide generation and promoted endothelial cell adhesion

Rapidin situendothelialization of a small diameter vascular graft with catalytic nitric oxide generation and promoted endothelial cell adhesion.

Effect of lower extremity bypass surgery on inflammatory reaction and endothelial dysfunction in type 2 diabetic patients

Diabetes mellitus (DM) is a metabolic disorder characterized by hyperglycemia and dyslipidemia. The abnormalities in nutrient metabolism and elevated inflammatory mediators resulting from DM lead to impairment of wound healing and vulnerability to infection and foot ulcers. Diabetic lower limb ischemia often leads to limb necrosis. Lower extremity bypass surgery (LEBS) is indicated to prevent limb loss in patients with critical leg ischemia. This study investigated the alteration of inflammatory and endothelium dysfunction markers before and after LEBS in DM patients. Twenty one type 2 DM patients with LEBS were included. Blood was drawn before and at 1 day and 7 days after surgery in the patients. Plasma soluble cellular adhesion molecule levels and blood leukocyte integrin expressions were measured. Also, plasma concentrations of endothelin-1 and nitric oxide were analyzed to evaluate the vascular endothelial function. The results showed that there were no significant differences in plasma cellular adhesion molecules, endothelin-1 and nitric oxide levels, nor did any differences in leukocyte integrin expressions before and after the operation. These results suggest that the efficacy of LEBS on alleviating inflammatory reaction and improving endothelial function in DM patients was not obvious.

Intra-arterial infusion of nitric oxide (NO) - first animal trial

OBJECTIVE

Nitric oxide (NO) is an important signaling molecule that acts in many tissues to regulate a diverse range of physiological processes. NO has been implicated in a number of cardiovascular diseases. Reduced basal NO synthesis or function may lead to: vasoconstriction, elevated blood pressure and thrombus formation. By contrast, overproduction of NO results in vasodilatation, hypotension, vascular leakage, and disruption of cell metabolism. The purpose of this study was to determine the effects of NO gas directly infused into the arteries.

METHODS

The study was performed on 28 rabbits and 10 pigs. We developed a device that enables quantitatively controlled infusion of NO gas, directly into the arteries.

RESULTS

We found that administration of NO gas via arteries caused widening of the blood vessels as well as increasing blood flow in the extremity. It emerges that. These effects persist up to 2-3 h after the NO infusion ceased. Although the NO breaks down when diffused in blood, its influence commences rapidly and continues for a relatively long time.

CONCLUSIONS

Our findings indicate that, administration of NO into blood vessels causes a long lasting vasodilatation and enhanced blood flow. Despite the fact that NO is broken down rapidly.

Nitric oxide-releasing polyurethane–PEG copolymer containing the YIGSR peptide promotes endothelialization with decreased platelet adhesion

Thrombosis and intimal hyperplasia are the principal causes of small-diameter vascular graft failure. To improve the long-term patency of polyurethane vascular grafts, we have incorporated both poly(ethylene glycol) and a diazeniumdiolate nitric oxide (NO) donor into the backbone of polyurethane to improve thromboresistance. Additionally, we have incorporated the laminin-derived cell adhesive peptide sequence YIGSR to encourage endothelial cell adhesion and migration, while NO release encourages endothelial cell proliferation. NO production by polyurethane films under physiological conditions demonstrated biphasic release, in which an initial burst of 70% of the incorporated NO was released within 2 days, followed by sustained release over 2 months. Endothelial cell proliferation in the presence of the NO-releasing material was increased as compared to control polyurethane, and platelet adhesion to polyethylene glycol-containing polyurethane was decreased significantly with the addition of the NO donor.

Effects of Resveratrol in Storage Solution on Adhesion Molecule Expression and Nitric Oxide Synthesis in Vein Grafts

BACKGROUND

Endothelial injury in human saphenous vein grafts may occur during harvesting and storage, which may have an adverse effect on coronary artery bypass grafting outcome. In this study, we sought to determine whether resveratrol, a natural antioxidant enriched in grape, can limit endothelial activation and reduce endothelial injury in human saphenous vein grafts.

METHODS

Human saphenous vein grafts, obtained from 8 patients and divided into two equal groups of control and study specimens, were stored in either heparinized blood (group A) or heparinized blood containing 50 microg/mL resveratrol (group B) for 1 hour at room temperature. Specimens were analyzed by Western blotting to quantify intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and inducible nitric oxide synthase-2 expression, as well as tissue cyclic guanylate monophosphate levels. Myeloperoxidase activity, a marker of neutrophil sequestration in human saphenous vein grafts, was also measured in each group.

RESULTS

Intercellular adhesion molecule-1 expression (1,674 +/- 332 versus 559 +/- 282; p = 0.003), vascular cell adhesion molecule-1 expression (753 +/- 183 versus 472 +/- 151; p = 0.025), and myeloperoxidase activity (7.00 +/- 1.05 versus 1.33 +/- 0.45 nm/min; p = 0.004) were significantly lower in group B. In contrast, inducible nitric oxide synthase-2 expression (548 +/- 237 versus 2,234 +/- 726; p = 0.004) and tissue cyclic guanylate monophosphate levels (2.02 +/- 0.53 versus 5.61 +/- 0.89 pmol/mL; p = 0.001) were significantly higher in group B.

CONCLUSIONS

Resveratrol reduced upregulation of leukocyte-endothelial cell adhesion molecule expression in human saphenous vein graft endothelium and decreased neutrophil adhesion to saphenous vein graft endothelium. Resveratrol also augmented inducible nitric oxide synthase-2 expression and increased cyclic guanylate monophosphate levels. These results suggest that resveratrol might improve vascular homeostasis and reduce endothelial injury during the hypoxic storage period of human saphenous vein grafts for coronary artery bypass grafting.

Ginsenosides block HIV protease inhibitor ritonavir-induced vascular dysfunction of porcine coronary arteries

Human immunodeficiency virus (HIV) protease inhibitor ritonavir (RTV) may induce vascular dysfunction through oxidative stress. Ginsenosides have been shown to have potential benefits on the cardiovascular system through diverse mechanisms, including antioxidative property. The objective of this study was to determine whether ginsenosides could prevent coronary arteries from RTV-induced dysfunction. Porcine coronary artery rings were incubated with RTV and ginsenosides Rb1, Rc, and Re for 24 h. Vasomotor function was recorded by a myograph tension system. In response to the thromboxane A(2) analog U-46619, the contraction of the vessel rings was significantly reduced. When cocultured with Rb1, Rc, and Re, the contractility significantly increased. In response to bradykinin at 10(-5) M, the endothelium-dependent relaxation of vessel rings was significantly reduced by 59% for RTV compared with controls (P < 0.05). When cocultured with Rb1, Rc, and Re, the relaxation significantly increased 100%, 90%, and 134%, respectively, compared with the RTV-alone groups (P > 0.05). In response to sodium nitroprusside, RTV significantly reduced vasorelaxation. In addition, the endothelial nitric oxide synthase (eNOS) mRNA levels were significantly reduced by 78% for RTV group (P < 0.05) by real-time PCR analysis. The eNOS protein levels measured by Western blot analysis and nitrite concentrations measured by Griess assay were also decreased, whereas O(2)(-) production by lucigenin-enhanced chemiluminescence was significantly increased in the RTV-treated group. These effects of RTV were effectively blocked by ginsenosides. Thus HIV protease inhibitor RTV significantly impaired the vasomotor function of porcine coronary arteries. This effect may be mediated by the downregulation of eNOS and overproduction of O(2)(-). These results suggest that ginsenosides can effectively block RTV-induced vascular dysfunction.

Progress toward clinical application of the nitric oxide-releasing diazeniumdiolates

Diazeniumdiolates, compounds of structure R(1)R(2)NN(O)=NOR(3), which have also been called NONOates, have proven useful for treating an increasing diversity of medical disorders in relevant animal models. Here, I review the chemical features that make them such excellent starting points for designing materials capable of targeting reliable and controllable fluxes of bioactive NO for in vitro and in vivo applications. This is followed by a consideration of recent proof-of-concept studies that underscore what I believe to be the substantial clinical promise of such materials. Examples covered include progress toward inhibiting restenosis after angioplasty, preparing thromboresistant medical devices, reversing vasospasm, and relieving pulmonary hypertension. Together with a very recent report describing the beneficial effects of diazeniumdiolate therapy in a patient with acute respiratory distress syndrome, the results of the animal experiments support the prediction that a broad selection of problems in clinical medicine can be solved by judiciously mining the enormous variety of possible R(1)R(2)NN(O)=NOR(3) structures.

Stent implantation alters coronary artery hemodynamics and wall shear stress during maximal vasodilation

Coronary stents improve resting blood flow and flow reserve in the presence of stenoses, but the impact of these devices on fluid dynamics during profound vasodilation is largely unknown. We tested the hypothesis that stent implantation affects adenosine-induced alterations in coronary hemodynamics and wall shear stress in anesthetized dogs (n = 6) instrumented for measurement of left anterior descending coronary artery (LAD) blood flow, velocity, diameter, and radius of curvature. Indexes of fluid dynamics and shear stress were determined before and after placement of a slotted-tube stent in the absence and presence of an adenosine infusion (1.0 mg/min). Adenosine increased blood flow, Reynolds (Re) and Dean numbers (De), and regional and oscillatory shear stress concomitant with reductions in LAD vascular resistance and segmental compliance before stent implantation. Increases in LAD blood flow, Re, De, and indexes of shear stress were observed after stent deployment (P < 0.05). Stent implantation reduced LAD segmental compliance to zero and potentiated increases in segmental and coronary vascular resistance during adenosine. Adenosine-induced increases in coronary blood flow and reserve, Re, De, and regional and oscillatory shear stress were attenuated after the stent was implanted. The results indicate that stent implantation blunts alterations in fluid dynamics during coronary vasodilation in vivo.