A nitric oxide-eluting and REDV peptide-conjugated coating promotes vascular healing

Promotion of endothelialization of silk functionalized with IKVAV peptide and production of silk containing IKVAV-REDV sequence by transgenic silkworms

Early endothelialization and the prevention of platelet adhesion are crucial in the development of small-diameter vascular grafts to prevent thrombus formation and intimal thickening. Silk fibroin (SF) from Bombyx mori is commonly used for such grafts. In our previous study, we found that silk vascular grafts coated with sponge-like transgenic (TG) silk incorporating the arginine-glutamic acid-aspartate-valine (REDV) peptide and transplanted into rats yielded favorable results. In this study, we aimed to achieve even better results by incorporating additional peptides into TG silk containing REDV and coating silk vascular grafts with this sponge. Initially, we sought to identify such peptides. We attempted to immobilize several peptides containing REDV onto silk using cyanuric chloride. Cell culture experiments with normal human umbilical vein endothelial cells (HUVECs) were performed on SF, SF+REDV, SF + arginine-glycine- aspartate (RGD), SF+cysteine-alanine-glycine (CAG), and SF + isoleucine-lysine- valine- alanine-valine (IKVAV) films to assess adhesion, proliferation, and extensibility; SF+RGD and SF+IKVAV films demonstrated high adhesion behavior of HUVECs. In addition, platelet adhesion on these SF+peptide films was evaluated. Platelet adhesion strength was much higher on SF+RGD films than on other SF+peptide films. These results suggest that IKVAV may be the most suitable peptide for coating SF vascular grafts. Subsequently, we successfully produced TG silk incorporating IKVAV+REDV. We then coated small-diameter silk vascular grafts with sponge-like TG silk incorporating IKVAV+REDV and measured its physical properties.

Bioprosthetic heart valves with zwitterionic copolymer grafting to improve the properties of endothelialization and anti-calcification

Heart valve replacement surgery has been the most effective treatment for severe valvular heart disease. Bioprosthetic heart valves (BHVs) crosslinked by glutaraldehyde (GA) have non-negligible advantages in clinical applications. However, structural valve degeneration, calcification, insufficient re-endothelialization and other factors lead to a shortened service life of BHVs. In this study, GA-crosslinked decellularized heart valves (GADHVs) were grafted with zwitterionic copolymer (PSBG) of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and glycidyl methacrylate, and further treated with Arg-Glu-Asp-Val (REDV) peptide to obtain REDV-PSBG-GADHVs with anti-fouling ability and endothelial cell affinity. REDV-PSBG-GADHVs exhibited good collagen stability, reliable mechanical property and excellent hemocompatibility. Moreover,in vitroandin vivoexperiments demonstrated that REDV-PSBG-GADHVs exhibited better endothelialization property, lower immune responses and reduced calcification than GADHVs. This modified strategy for heart valve fabrication, which can improve the effect of anti-calcification and endothelialization while maintaining the original advantages of BHVs, shows great potential for application in heart valve replacement.

Biomimicry-inspired zwitterionic polyurethane used for vascular implants showing water-induced stiffening and preventing intimal hyperplasia in stent

Polymeric vascular implants with ideal mechanical properties and biocompatibility are essential for dilating blood vessels and reducing the risk of secondary implant diseases. However, traditional polymer materials are still limited for vascular stents by diminished radial support post-expansion and inadequate surface modification techniques. Herein, we synthesized zwitterionic polyurethanes (ZPUs) featuring hydrophilic side chains derived from betaine sulfonate and full-hard main chains. These ZPUs demonstrate a remarkable increase in modulus during shape recovery in 37 °C warm water, ensuring that the stent remains soft during implantation for easy delivery, but becomes stiff once positioned at the lesion site to provide adequate radial support. The distinctive architecture promotes the migration of hydrophilic side chains to the surface upon hydration, establishing a "core-shell structure" with a hard interior and a highly hydrophilic surface that enhances antithrombotic properties, mitigates inflammation, and curbs intimal hyperplasia. Consequently, ZPUE20 stent showed significantly better blood flow patency than traditional PLA stent in carotid artery implantation for at least 3 months, ensuring the long-term biological safety of implantation. Compared to surface modification of bare stents, ZPU stents avoid the complex and unstable surface modifications. All in all, ZPUs represent a promising material for vascular implants, markedly improving both mechanical performance and biocompatibility.

Biophysiochemically favorable, antithrombotic and pro-endothelial coordination compound nanocoating of copper (II) with protocatechuic acid & nattokinase on flow-diverting stents

Neurovascular flow-diverting stents (FDSs) are revolutionizing the paradigm for treatment of intracranial aneurysms, but they still face great challenges like post- implantation acute thrombosis and delayed reendothelialization. Surface modification is of crucial relevance in addressing such key issues. In this study, we fabricated an ultrathin nanocoating out of copper (II) together with protocatechuic acid (PCA) and nattokinase (NK) bioactive molecules on NiTi FDSs via a coordination chemistry approach, with favorable biophysiochemical interactions, to fulfill this goal. This coating was identified as covalently-anchored and compactly covering the FDSs substrate, with unique nano-structured morphology as well as superhydrophilicity. The in vitro coagulation and whole blood assays demonstrated that the modified FDS's surfaces showed improved antithrombogenicity, with reduced platelet and fibrinogen adhesion, as well as their aggregation and activation, and consequently prolonged clotting time leading to decreased thrombosis occurrence. Human umbilical vein endothelial cell cultures confirmed the modified capability of FDSs to promote endothelial cell proliferation and migration. The ex vivo experiments verified that modified FDSs had clearly in-stent patency without thrombi formation, as compared to the bare FDSs bearing thromboembolic blockage. It was postulated that these enhanced biocompatibilities can be attributable to the copper-catalyzed nitric oxide (NO) released as a functional mediator, the nature of the PCA and NK molecules, as well as the synergic biophysiochemical surface/interface interactions. Our strategy may not only open a new avenue for surface-functionalizing neurovascular FDSs for medical purpose but also help better-understand interfacial phenomena on the advanced biomaterials.

A self-sacrificing anti-inflammatory coating promotes simultaneous cardiovascular repair and reendothelialization of implanted devices

During interventional surgeries of implantable cardiovascular devices in addressing cardiovascular diseases (CVD), the inevitable tissue damage will trigger host inflammation and vascular lumen injury, leading to delayed re-endothelization and intimal hyperplasia. Endowing cardiovascular implants with anti-inflammatory and endothelialization functions is conducive to the target site, offering significant tissue repair and regeneration benefits. Herein, inspired by the snake's molting process, a ShedWise device was developed by using the poly(propylene fumarate) polyurethane (PPFU) as the foundational material, which was clicked with hyperbranched polylysine (HBPL) and followed by conjugation with pro-endothelial functional Arg-Glu-Asp-Val peptide (REDV), and finally coated with a "self-sacrificing" layer having reactive oxygen species (ROS)-scavenging ability and degradability. During the acute inflammation in the initial stage of implantation, the ROS-responsive hyperbranched poly(acrylate-capped thioketone-containing ethylene glycol (HBPAK) coating effectively modulated the level of environmental inflammation and resisted initial protein adsorption, showcasing robust tissue protection. As the coating gradually "sacrificed", the exposed hyperbranched HBPL-REDV layer recruited specifically endothelial cells and promoted surface endothelialization. In a rat vascular injury model, the ShedWise demonstrated remarkable efficiency in reducing vascular restenosis, protecting the injured tissue, and fostering re-endothelization of the target site. This innovative design will introduce a novel strategy for surface engineering of cardiovascular implants and other medical devices.

Electrospun Biomimetic Periosteum Promotes Diabetic Bone Defect Regeneration through Regulating Macrophage Polarization and Sequential Drug Release

The inadequate vascularization and abnormal immune microenvironment in the diabetic bone defect region present a significant challenge to osteogenic regulation. Inspired by the distinctive characteristics of healing staged in diabetic bone defects and the structure-function relationship in the natural periosteum, we fabricated an electrospun bilayer biomimetic periosteum (Bilayer@E) to promote regeneration of diabetic bone defects. Here, the inner layer of biomimetic periosteum was fabricated using coaxial electrospinning fibers, with a shell incorporating zinc oxide nanoparticles (ZnO NPs) and a core containing silicon dioxide nanoparticles (SiO2 NPs) mimicking the cambium of periosteum; the outer layer consisted of randomly aligned electrospun fibers loaded with deferoxamine (DFO), simulating the fibrous layer of periosteum; finally, epigallocatechin-3-gallate (EGCG) was coated onto the bilayer membrane to obtain Bilayer@E. The presence of EGCG on the Bilayer@E surface efficiently triggers a phenotypic transition in macrophages, shifting them from an M1 proinflammatory state to an M2 anti-inflammatory state. Moreover, the sequential release of ZnO NPs, DFO, and SiO2 NPs exhibits antimicrobial characteristics while coordinating angiogenesis and promoting osteogenic mineralization in cells. Importantly, the biomimetic periosteum shows strong in vivo bone tissue and periosteal regeneration properties in diabetic rats. The integration of sequential drug release and immunomodulation, tailored to meet the specific healing requirements during bone regeneration, offers new insights for advancing the application of biomaterials in this field.

Construction of small-diameter vascular grafts by electrospun zwitterionic diselenide-containing poly(ester urethane)urea with enhanced endothelialization

Cardiovascular diseases are the leading threat to human health. However, as an essential tool of vascular transplantation, small-diameter vascular grafts are still needed to intensify in rapid endothelialization and enhanced elasticity for vascular reconstruction. Herein, a series of zwitterionic diselenide-containing poly(ester urethane)ureas (zSePEUUs) are synthesized through modulation of the molar ratios of sulfobetaine-diol (SB-diol) and poly(ε-caprolactone)-diol (PCL-diol) (SB-diol/PCL-diol=1/0∼0/1) as diol components, along with selenocystamine and 1,4-butanediamine (7:3) as chain extenders. At the equal amount of SB-diol and PCL-diol, the synthesized zSePEUU polymer with enhanced hydrophilicity and suitable mechanical properties is subsequently utilized for preparation of electrospun tubular scaffolds. In vitro assays demonstrate that the zSePEUU electrospun membranes can inhibit protein adsorption and facilitate cell proliferation. Due to the in situ catalysis of diselenide, it is supposed that vasoregulatory nitric oxide (NO) can be generated to promote endothelialization. Then, the zSePEUU electrospun tubular scaffold remains vascular patency with formation of endothelial coverage and collagen deposition during in vivo implantation in a rat abdominal aorta interposition model for 4 weeks in comparison with the PCL control. Therefore, zwitterionic diselenide-containing zSePEUU with controllable NO generation provides a synergistic strategy for vascular regeneration. STATEMENT OF SIGNIFICANCE: Transplantation of vascular grafts is one of the effective approaches for treating cardiovascular diseases, however, this remains a challenge with the small-diameter vascular grafts. Herein, electrospun fibrous scaffolds made from elastic zwitterionic diselenide-containing poly(ester urethane)urea (zSePEUU) are reported, displaying increased hydrophilicity and compliance. By using equal amounts of sulfobetaine-diol and poly(ε-caprolactone)-diol, the zSePEUU electrospun scaffold exhibits optimal mechanical properties and nitric oxide-generating ability. Evaluation in a rat abdominal aorta interposition model suggests that the zSePEUU electrospun scaffold can achieve a high level of endothelial coverage and vascular regeneration. This finding provides a feasible method to address the issue of rapid endothelialization for long-term patency in vascular regeneration.

Tailored extracellular matrix-mimetic coating facilitates reendothelialization and tissue healing of cardiac occluders

Minimally invasive transcatheter interventional therapy utilizing cardiac occluders represents the primary approach for addressing congenital heart defects and left atrial appendage (LAA) thrombosis. However, incomplete endothelialization and delayed tissue healing after occluder implantation collectively compromise clinical efficacy. In this study, we have customized a recombinant humanized collagen type I (rhCol I) and developed an rhCol I-based extracellular matrix (ECM)-mimetic coating. The innovative coating integrates metal-phenolic networks with anticoagulation and anti-inflammatory functions as a weak cross-linker, combining them with specifically engineered rhCol I that exhibits high cell adhesion activity and elicits a low inflammatory response. The amalgamation, driven by multiple forces, effectively serves to functionalize implantable materials, thereby responding positively to the microenvironment following occluder implantation. Experimental findings substantiate the coating's ability to sustain a prolonged anticoagulant effect, enhance the functionality of endothelial cells and cardiomyocyte, and modulate inflammatory responses by polarizing inflammatory cells into an anti-inflammatory phenotype. Notably, occluder implantation in a canine model confirms that the coating expedites reendothelialization process and promotes tissue healing. Collectively, this tailored ECM-mimetic coating presents a promising surface modification strategy for improving the clinical efficacy of cardiac occluders.

Engineering anti-thrombogenic and anti-infective catheters through a stepwise metal-catechol-(amine) surface engineering strategy

Thrombosis and infection are pivotal clinical complications associated with interventional blood-contacting devices, leading to significant morbidity and mortality. To address these issues, we present a stepwise metal-catechol-(amine) (MCA) surface engineering strategy that efficiently integrates therapeutic nitric oxide (NO) gas and antibacterial peptide (ABP) onto catheters, ensuring balanced anti-thrombotic and anti-infective properties. First, copper ions were controllably incorporated with norepinephrine and hexanediamine through a one-step molecular/ion co-assembly process, creating a NO-generating and amine-rich MCA surface coating. Subsequently, azide-polyethylene glycol 4-N-hydroxysuccinimidyl and dibenzylcyclooctyne modified ABP were sequentially immobilized on the surface via amide coupling and bioorthogonal click chemistry, ensuring the dense grafting of ABP while maintaining the catalytic efficacy for NO. This efficient integration of ABP and NO-generating ability on the catheter surface provides potent antibacterial properties and ability to resist adhesion and activation of platelets, thus synergistically preventing infection and thrombosis. We anticipate that this synergistic modification strategy will offer an effective solution for advancing surface engineering and enhancing the clinical performance of biomedical devices.

Atherogenic Effect of Homocysteine, a Biomarker of Inflammation and Its Treatment

Hyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis. Ischemic stroke and heart disease, coronary heart disease, and cardiovascular disease are events resulting from long-lasting and silent atherosclerosis. This paper deals with the synthesis of homocysteine (Hcy), causes of HHcy, mechanism of HHcy-induced atherosclerosis, and treatment of HHcy. Synthesis and metabolism of Hcy involves demethylation, transmethylation, and transsulfuration, and these processes require vitamin B 6 and vitamin B 12 folic acid (vitamin B 9 ). Causes of HHcy include deficiency of vitamins B 6 , B 9 , and B 12 , genetic defects, use of smokeless tobacco, cigarette smoking, alcohol consumption, diabetes, rheumatoid arthritis, low thyroid hormone, consumption of caffeine, folic acid antagonist, cholesterol-lowering drugs (niacin), folic acid antagonist (phenytoin), prolonged use of proton pump inhibitors, metformin, and hypertension. HHcy-induced atherosclerosis may be mediated through oxidative stress, decreased availability of nitric oxide (NO), increased expression of monocyte chemoattractant protein-1, smooth muscle cell proliferation, increased thrombogenicity, and induction of arterial connective tissue. HHcy increases the generation of atherogenic biomolecules such as nuclear factor-kappa B, proinflammatory cytokines (IL-1β, IL-6, and IL-8), cell adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selection), growth factors (IGF-1 and TGF-β), and monocyte colony-stimulating factor which lead to the development of atherosclerosis. NO which is protective against the development of atherosclerosis is reduced by HHcy. Therapy with folic acid, vitamin B 6 , and vitamin B 12 lowers the levels of Hcy, with folic acid being the most effective. Dietary sources of folic acid, vitamin B 6 , vitamin B 12 , omega-3 fatty acid, and green coffee extract reduce Hcy. Abstaining from drinking coffee and alcohol, and smoking also reduces blood levels of Hcy. In conclusion, HHcy induces atherosclerosis by generating atherogenic biomolecules, and treatment of atherosclerosis-induced diseases may be by reducing the levels of Hcy.

Endothelium-Inspired Hemocompatible Silicone Surfaces: An Elegant Balance between Antifouling Properties and Endothelial Cell Selectivity

To address the adverse reactions caused by the implantation of blood-contacting materials, researchers have developed different strategies, of which mimicking multiple key features of endothelial cells is the most effective. However, simultaneously immobilizing multiple chemical components on a single material surface and maintaining the effects of individual components are challenging. In this work, endothelium-mimicking silicone surfaces were developed by incorporating the antifouling polymer poly(oligo(ethylene glycol) methacrylate), the glycosaminoglycan analog poly(sodium 4-vinyl-benzenesulfonate) and a nitric oxide catalyst (selenocystamine dihydrochloride). Through the rational regulation of multiple chemical components, the surfaces harmoniously resisted nonspecific protein adsorption, platelet adhesion and activation and smooth muscle cell hyperproliferation while promoting endothelial cell proliferation and migration. The coculture experiment with HUVECs and HUVSMCs showed that the optimum selectivity of HUVECs/HUVSMCs was ∼1.7. This work contributes insight into the control of antifouling properties and endothelial selectivity, providing a new avenue for the development of blood-contacting materials.

"Synergistic anticoagulant and endothelial regeneration strategy" based on mussel-inspired phospholipid copolymer coating and bioactive zeolitic imidazolate frameworks-90 to maintain the patency of CoCr stent

Given the risks of poor patient compliance and bleeding associated with current dual antiplatelet therapies, it is urgent to develop the next generation of cardiovascular stents with anticoagulation and rapid endothelialization capabilities. Inspired by the prominent bioactivity and bioavailability of zeolitic imidazolate framework-90 (ZIF-90) in driving endothelial cell (EC) morphogenesis, this research proposes a "synergistic anticoagulant and endothelial regeneration strategy" depending on mussel-inspired phospholipid copolymer (MIPC) and ZIF-90. Depending on the copolymerization of the catechol with dopamine (Dopa) monomers, Dopa/MIPC coating was immobilized on the surface of CoCr via a one-pot process for resisting the initial thrombosis induced by platelets and fibrinogen. Meanwhile, ZIF-90 was loaded on the coating via coordination effect, aiming to accelerate the proliferation and migration of ECs. Compared with CoCr, the well-designed CoCr-Dopa/MIPC@ZIF-90 not only reduced fibrinogen adhesion by approximately 40 % and platelet adhesion by almost 55 %, but also promoted the proliferation and migration of ECs significantly in vitro. Furthermore, the blood flow velocity of CoCr-Dopa/MIPC@ZIF-90 stent was similar to natural aorta and ECs coverage on it was greatly strengthened after 30 days in a rat aorta vascular stent implantation model. Collectively, CoCr-Dopa/MIPC@ZIF-90 exhibited obvious superiority in reducing the formation of thrombus and promoting endothelial regeneration, which might meet the high requirement for the next generation of vascular stent.

Endothelium-Mimicking Materials: A "Rising Star" for Antithrombosis

The advancement of antithrombotic materials has significantly mitigated the thrombosis issue in clinical applications involving various medical implants. Extensive research has been dedicated over the past few decades to developing blood-contacting materials with complete resistance to thrombosis. However, despite these advancements, the risk of thrombosis and other complications persists when these materials are implanted in the human body. Consequently, the modification and enhancement of antithrombotic materials remain pivotal in 21st-century hemocompatibility studies. Previous research indicates that the healthy endothelial cells (ECs) layer is uniquely compatible with blood. Inspired by bionics, scientists have initiated the development of materials that emulate the hemocompatible properties of ECs by replicating their diverse antithrombotic mechanisms. This review elucidates the antithrombotic mechanisms of ECs and examines the endothelium-mimicking materials developed through single, dual-functional and multifunctional strategies, focusing on nitric oxide release, fibrinolytic function, glycosaminoglycan modification, and surface topography modification. These materials have demonstrated outstanding antithrombotic performance. Finally, the review outlines potential future research directions in this dynamic field, aiming to advance the development of antithrombotic materials.

Balancing functions of antifouling, nitric oxide release and vascular cell selectivity for enhanced endothelialization of assembled multilayers

Surface endothelialization is a promising way to improve the hemocompatibility of biomaterials. However, current surface endothelialization strategies have limitations. For example, various surface functions are not well balanced, leading to undesirable results, especially when multiple functional components are introduced. In this work, a multifunctional surface was constructed by balancing the functions of antifouling, nitric oxide (NO) release and endothelial cell promotion via layer-by-layer (LBL) self-assembly. Poly(sodium p-styrenesulfonate-co-oligo(ethylene glycol) methacrylate) (negatively charged) and polyethyleneimine (positively charged) were deposited on silicon substrates to construct multilayers by LBL self-assembly. Then, organic selenium, which has a NO-releasing function, and the cell-adhesive peptide Gly-Arg-Glu-Asp-Val-Tyr, which selectively promotes endothelial cells, were introduced on the assembled multilayers. Poly(oligo(ethylene glycol) methacrylate) is a hydrophilic component for antifouling properties, and poly(sodium p-styrenesulfonate) is a heparin analog that provides negative charges. By modulating the contents of poly(oligo(ethylene glycol) methacrylate) and poly(sodium p-styrenesulfonate) in the copolymers, the NO release rates catalyzed by the modified surfaces were regulated. Moreover, the behaviors of endothelial cells and smooth muscle cells on modified surfaces were well controlled. The optimized surface strongly promoted endothelial cells and inhibited smooth muscle cells to achieve endothelialization effectively.

Polyphenol-Reinforced Glycocalyx-Like Hydrogel Coating Induced Myocardial Regeneration and Immunomodulation

Although minimally invasive interventional occluders can effectively seal heart defect tissue, they still have some limitations, including poor endothelial healing, intense inflammatory response, and thrombosis formation. Herein, a polyphenol-reinforced medicine/peptide glycocalyx-like coating was prepared on cardiac occluders. A coating consisting of carboxylated chitosan, epigallocatechin-3-gallate (EGCG), tanshinone IIA sulfonic sodium (TSS), and hyaluronic acid grafted with 3-aminophenylboronic acid was prepared. Subsequently, the mercaptopropionic acid-GGGGG-Arg-Glu-Asp-Val peptide was grafted by the thiol-ene "click" reaction. The coating showed good hydrophilicity and free radical-scavenging ability and could release EGCG-TSS. The results of biological experiments suggested that the coating could reduce thrombosis by promoting endothelialization, and promote myocardial repair by regulating the inflammatory response. The functions of regulating cardiomyocyte apoptosis and metabolism were confirmed, and the inflammatory regulatory functions of the coating were mainly dependent on the NF-kappa B and TNF signaling pathway.

Stimuli-responsive polymer-based nanosystems for cardiovascular disease theranostics

Stimulus-responsive polymers have found widespread use in biomedicine due to their ability to alter their own structure in response to various stimuli, including internal factors such as pH, reactive oxygen species (ROS), and enzymes, as well as external factors like light. In the context of atherosclerotic cardiovascular diseases (CVDs), stimulus-response polymers have been extensively employed for the preparation of smart nanocarriers that can deliver therapeutic and diagnostic drugs specifically to inflammatory lesions. Compared with traditional drug delivery systems, stimulus-responsive nanosystems offer higher sensitivity, greater versatility, wider applicability, and enhanced biosafety. Recent research has made significant contributions towards designing stimulus-responsive polymer nanosystems for CVDs diagnosis and treatment. This review summarizes recent advances in this field by classifying stimulus-responsive polymer nanocarriers according to different responsiveness types and describing numerous stimuli relevant to these materials. Additionally, we discuss various applications of stimulus-responsive polymer nanomaterials in CVDs theranostics. We hope that this review will provide valuable insights into optimizing the design of stimulus-response polymers for accelerating their clinical application in diagnosing and treating CVDs.

Comparison study of surface-initiated hydrogel coatings with distinct side-chains for improving biocompatibility of polymeric heart valves

Polymeric heart valves (PHVs) present a promising alternative for treating valvular heart diseases with satisfactory hydrodynamics and durability against structural degeneration. However, the cascaded coagulation, inflammatory responses, and calcification in the dynamic blood environment pose significant challenges to the surface design of current PHVs. In this study, we employed a surface-initiated polymerization method to modify polystyrene-block-isobutylene-block-styrene (SIBS) by creating three hydrogel coatings: poly(2-methacryloyloxy ethyl phosphorylcholine) (pMPC), poly(2-acrylamido-2-methylpropanesulfonic acid) (pAMPS), and poly(2-hydroxyethyl methacrylate) (pHEMA). These hydrogel coatings dramatically promoted SIBS's hydrophilicity and blood compatibility at the initial state. Notably, the pMPC and pAMPS coatings maintained a considerable platelet resistance performance after 12 h of sonication and 10 000 cycles of stretching and bending. However, the sonication process induced visible damage to the pHEMA coating and attenuated the anti-coagulation property. Furthermore, the in vivo subcutaneous implantation studies demonstrated that the amphiphilic pMPC coating showed superior anti-inflammatory and anti-calcification properties. Considering the remarkable stability and optimal biocompatibility, the amphiphilic pMPC coating constructed by surface-initiated polymerization holds promising potential for modifying PHVs.

A Cu(Ⅱ)-eluting coating through silk fibroin film on ZE21B alloy designed for in situ endotheliazation biofunction

In the cardiovascular field, coating containing copper used to catalyze NO (nitric oxide) production on non-degradable metal surfaces have shown unparalleled expected performance, but there are few studies on biodegradable metal surfaces. Magnesium-based biodegradable metals have been applied in cardiovascular field in large-scale because of their excellent properties. In this study, the coating of copper loaded in silk fibroin is fabricated on biodegradable ZE21B alloy. Importantly, the different content of copper is set to investigate the effects of on the degradation performance and cell behavior of magnesium alloy. Through electrochemical and immersion experiments, it is found that high content of copper will accelerate the corrosion of magnesium alloy. The reason is the spontaneous micro-batteries between copper and magnesium with the different standard electrode potentials, that is, the galvanic corrosion accelerates the corrosion of magnesium alloy. Moreover, the coating formed through silk fibroin by the right amount copper not only have a protective effect on the ZE21B alloy substrate, but also promotes the adhesion and proliferation of endothelial cells in blood vessel micro-environment. The production of NO catalyzed by copper ions makes this trend more significant, and inhibits the excessive proliferation of smooth muscle cells. These findings can provide guidance for the amount of copper in the coating on the surface of biodegradable magnesium alloy used for cardiovascular stent purpose.

Long-term observation of polycaprolactone small-diameter vascular grafts with thickened outer layer and heparinized inner layer in rabbit carotid arteries

In our previous study, the pristine bilayer small-diameterin situtissue engineered vascular grafts (pTEVGs) were electrospun from a heparinized polycaprolactone (PCL45k) as an inner layer and a non-heparinized PCL80k as an outer layer in the thickness of about 131 μm and 202 μm, respectively. However, the hydrophilic enhancement of inner layer stemmed from the heparinization accelerated the degradation of grafts leading to the early formation of arterial aneurysms in a period of 3 months, severely hindering the perennial observation of the neo-tissue regeneration, host cell infiltration and graft remodeling in those implanted pTEVGs. Herein to address this drawback, the thickness of the outer layers was increased with PCL80k to around 268 μm, while the inner layer remained unchangeable. The thickened TEVGs named as tTEVGs were evaluated in six rabbits via a carotid artery interpositional model for a period of 9 months. All the animals kept alive and the grafts remained patent until explantation except for one whose one side of arterial blood vessels was occluded after an aneurysm occurred at 6 months. Although a significant degradation was observed in the implanted grafts at 9 month, the occurrence of aneurysms was obviously delayed compared to pTEVGs. The tissue stainings indicated that the endothelial cell remodeling was substantially completed by 3 months, while the regeneration of elastin and collagen remained smaller and unevenly distributed in comparison to autologous vessels. Additionally, the proliferation of macrophages and smooth muscle cells reached the maximum by 3 months. These tTEVGs possessing a heparinized inner layer and a thickened outer layer exhibited good patency and significantly delayed onset time of aneurysms.

Characterization and promotion of endothelialization of Bombyx mori silk fibroin functionalized with REDV peptide

In the development of small-diameter vascular grafts, it is crucial to achieve early-stage endothelialization to prevent thrombus formation and intimal hyperplasia. Silk fibroin (SF) from Bombyx mori is commonly used for such grafts. However, there is a need to expedite endothelialization post-implantation. In this study, we functionalized SF with Arg-Glu-Asp-Val (REDV) (SF + REDV) using cyanuric chloride to enhance endothelialization. The immobilization of REDV onto SF was confirmed and the amount of immobilized REDV could be calculated by 1H NMR. Furthermore, the conformational changes in Tyr, Ser, and Ala residues in [3-13C]Tyr- and [3-13C]Ser-SF due to REDV immobilization were monitored using 13C solid-state NMR. The REDV immobilized onto the SF film was found to be exposed on the film's surface, as confirmed by biotin-avidin system. Cell culture experiments, including adhesiveness, proliferation, and extensibility, were conducted using normal human umbilical vein endothelial cells (HUVEC) and normal human aortic smooth muscle cells (HAoSMC) on both SF and SF + REDV films to evaluate the impact of REDV on endothelialization. The results indicated a trend towards promoting HUVEC proliferation while inhibiting HAoSMC proliferation. Therefore, these findings suggest that SF + REDV may be more suitable than SF alone for coating small-diameter SF knitted tubes made of SF threads.

Engineering Immunomodulatory Stents Using Zinc Ion-Lysozyme Nanoparticle Platform for Vascular Remodeling

Rapid endothelialization of cardiovascular materials can enhance the vascular remodeling performance. In this work, we developed a strategy for amyloid-like protein-assembly-mediated interfacial engineering to functionalize a biomimetic nanoparticle coating (BMC). Various groups (e.g., hydroxyl and carboxyl) on the BMC are responsible for chelating Zn2+ ions at the stent interface, similar to the glutathione peroxidase-like enzymes found in vivo. This design could reproduce the release of therapeutic nitric oxide gas (NO) and an aligned microenvironment nearly identical with that of natural vessels. In a rabbit abdominal aorta model, BMC-coated stents promoted vascular healing through rapid endothelialization and the inhibition of intimal hyperplasia in the placement sites at 4, 12, and 24 weeks. Additionally, better anticoagulant activity and immunomodulation in the BMC stents were also confirmed, and vascular healing was mainly dependent on cell signaling through the cyclic guanosine monophosphate-protein kinase G (cGMP-PKG) cascade. Overall, a metal-polypeptide-coated stent was developed on the basis of its detailed molecular mechanism of action in vascular remodeling.

Nanomedicine for Diagnosis and Treatment of Atherosclerosis

With the changing disease spectrum, atherosclerosis has become increasingly prevalent worldwide and the associated diseases have emerged as the leading cause of death. Due to their fascinating physical, chemical, and biological characteristics, nanomaterials are regarded as a promising tool to tackle enormous challenges in medicine. The emerging discipline of nanomedicine has filled a huge application gap in the atherosclerotic field, ushering a new generation of diagnosis and treatment strategies. Herein, based on the essential pathogenic contributors of atherogenesis, as well as the distinct composition/structural characteristics, synthesis strategies, and surface design of nanoplatforms, the three major application branches (nanodiagnosis, nanotherapy, and nanotheranostic) of nanomedicine in atherosclerosis are elaborated. Then, state-of-art studies containing a sequence of representative and significant achievements are summarized in detail with an emphasis on the intrinsic interaction/relationship between nanomedicines and atherosclerosis. Particularly, attention is paid to the biosafety of nanomedicines, which aims to pave the way for future clinical translation of this burgeoning field. Finally, this comprehensive review is concluded by proposing unresolved key scientific issues and sharing the vision and expectation for the future, fully elucidating the closed loop from atherogenesis to the application paradigm of nanomedicines for advancing the early achievement of clinical applications.

A bio-inspired nanoparticle coating for vascular healing and immunomodulatory by cGMP-PKG and NF-kappa B signaling pathways

Drug-eluting stents (DESs) implantation is an effective method to tackle in-stent restenosis (ISR), which has been considered as an efficient treatment for coronary atherosclerosis. Although fruitful results have been achieved in treating coronary artery diseases (CAD), concern has arisen regarding the long-term safety and efficacy of DESs, primarily due to adverse events such as delayed re-endothelialization, persistent inflammatory response, and late stent thrombosis (LST). Taking inspiration from the immunomodulatory functions of camouflage strategies, this study designed a bio-inspired nanoparticle-coated stent. Briefly, the platelet membrane-coated poly (lactic-co-glycolic acid)/Rapamycin nanoparticles (PNP) were sprayed onto stents, forming a homogenous nanoparticle coating. The bilayer of poly (lactic-co-glycolic acid) (PLGA) and platelet membrane works synergistically to promote the sustained-release effect of rapamycin. In vitro studies revealed that the PNP-coated surfaces promoted the competitive adhesion of endothelia cells while inhibiting smooth muscle cells. Subsequent in vivo studies demonstrated that these surfaces expedite re-endothelialization and elicit immunomodulatory effects by regulating the cGMP-PKG and NF-kappa B signaling pathways, influencing the biosynthesis cofactors and immune system signaling. The study successfully deviced a novel and biomimetic drug-eluting stent system, unraveling its detailed functions and molecular mechanism of action for enhanced vascular healing.

Poly(l-lactide)/polycaprolactone based multifunctional coating to deliver paclitaxel/VEGF and control the degradation rate of magnesium alloy stent

Despite significant advancements made in cardiovascular stents, restenosis, thrombosis, biocompatibility, and clinical complications remain a matter of concern. Herein, we report a biodegradable Mg alloy stent with a dual effect of the drug (Paclitaxel) and growth factor (VEGF) release. To mitigate the fast degradation of Mg alloy, inorganic and organic coatings were formed on the alloy surface. The optimized hierarchal sequence of the coating was the first layer consisting of magnesium fluoride, followed by poly(l-lactide) and hydroxyapatite coating, and finally sealed by a polycaprolactone layer (MgC). PLLA and HAp were used to increase the adhesion strength and biocompatibility of the coating. Paclitaxel and VEGF were loaded in the final PCL layer (Mg-C/PTX-VEGF). As compared to bare Mg alloy (28 % weight loss), our MgC system showed (3.1 % weight loss) successful decrease in the degradation rate. Further, the in vitro biocompatibility illustrated the highly biocompatible nature of our drug and growth factor-loaded system. The in vivo results displayed that the drug loading decreased the inflammation and neointimal hyperplasia as indicated by the α-SMA and CD-68 antibody staining. The growth factor helped in the endothelialization which was established by the FLKI and ICAM antibody staining of the tissue.

Surface Engineering of Central Venous Catheters via Combination of Antibacterial Endothelium-Mimicking Function and Fibrinolytic Activity for Combating Blood Stream Infection and Thrombosis

Long-term blood-contacting devices (e.g., central venous catheters, CVCs) still face the highest incidence of blood stream infection and thrombosis in clinical application. To effectively address these complications, this work reports a dual-functional surface engineering strategy for CVCs by organic integration of endothelium-mimicking and fibrinolytic functions. In this proposal, a lysine (Lys)/Cu2+ -incorporated zwitterionic polymer coating (defined as PDA/Lys/Cu-SB) is designed and robustly fabricated onto commercial CVCs using a facile two-step process. Initially, adhesive ene-functionalized dopamine is covalently reacted with Lys and simultaneously coordinated with bactericidal Cu2+ ions, leading to the deposition of a PDA/Lys/Cu coating on CVCs through mussel foot protein inspired surface chemistry. Next, zwitterionic poly(sulfobetaine methacrylate) (pSB) brushes are grafted onto the PDA/Lys/Cu coating to endow lubricant and antifouling properties. In the final PDA/Lys/Cu-SB coating, endothelium-mimicking function is achieved by combining the catalytic generation of nitric oxide from the chelated Cu2+ with antifouling pSB brushes, which led to significant prevention of thrombosis, and bacterial infection in vivo. Furthermore, the immobilized Lys with fibrinolytic activity show remarkably enhanced long-term anti-thrombogenic properties as evidenced in vivo by demonstrating the capability to lyse nascent clots. Therefore, this developed strategy provides a promising solution for long-term blood-contacting devices to combat thrombosis and infection.

A novel glycyrrhizin acid-coated stent reduces neointimal formation in a rabbit iliac artery model

Introduction: Most drug-eluting stents (DESs) inhibit intimal hyperplasia but impair re-endothelialization. This study aimed to evaluate in vivo strut coverage and neointimal growth in a new glycyrrhizin acid (GA)-eluting stent. Methods: New Zealand White rabbits (n = 20) with atherosclerotic plaques were randomly divided into three groups based on implanted iliac artery stents: bare-metal stents (BMSs), rapamycin-eluting stents, and GA-eluting stents. After the in vivo intravascular ultrasound (IVUS) assessment at 28 days, the vessels were harvested for scanning electron microscopy (SEM) and histology. After 4 weeks of follow-up, the stent and external elastic lamina (EEL) areas were compared among the groups. Results: The rapamycin- or GA-eluting stents significantly reduced the neointimal area compared with BMSs, though GA-eluting stents had the lowest reduction. There were more uncovered struts for rapamycin-eluting stents than those for GA-eluting stents and bare-metal stents. The endothelial nitric oxide synthase (eNOS) expression in GA-eluting stents was much higher than that in BMSs and rapamycin-eluting stents, even though the endothelial coverage between struts was equivalent between BMSs and GA-eluting stents. Moreover, GA-eluting stents markedly promoted re-endothelialization and improved arterial healing compared to rapamycin-eluting stents in a rabbit atherosclerotic model. Conclusion: In conclusion, the novel GA-coated stent used in this study inhibited intimal hyperplasia and promoted re-endothelialization.

The Role of Oxidants in Percutaneous Coronary Intervention-Induced Endothelial Dysfunction: Can We Harness Redox Signaling to Improve Clinical Outcomes?

Significance: Coronary artery disease (CAD) is commonly treated using percutaneous coronary interventions (PCI). However, PCI with stent placement damages the endothelium, and failure to restore endothelial function may result in PCI failure with poor patient outcomes. Recent Advances: Oxidative signaling is central to maintaining endothelial function. Potentiation of oxidant production, as observed post-PCI, results in endothelial dysfunction (ED). This review delves into our current understanding of the physiological role that endothelial-derived oxidants play within the vasculature and the effects of altered redox signaling during dysfunction. We then examine the impact of PCI and intracoronary stent placement on oxidant production in the endothelium, which can culminate in stent failure. Finally, we explore how recent advances in PCI and stent technologies aim to mitigate PCI-induced oxidative damage and improve clinical outcomes. Critical Issues: Current PCI technologies exacerbate cellular oxidant levels, driving ED. If left uncontrolled, oxidative signaling leads to increased intravascular inflammation, restenosis, and neoatherosclerosis. Future Directions: Through the development of novel biomaterials and therapeutics, we can limit PCI-induced oxidant production, allowing for the restoration of a healthy endothelium and preventing CAD recurrence.

Lipophilic NO-Driven Nanomotors as Drug Balloon Coating for the Treatment of Atherosclerosis

Drug-coated balloons (DCB) intervention is an important approach for the treatment of atherosclerosis (AS). However, this therapeutic approach has the drawbacks of poor drug retention and penetration at the lesion site. Here, a lipophilic drug-loaded nanomotor as a modified balloon coating for the treatment of AS is reported. First, a lipophilic nanomotor PMA-TPP/PTX loaded with drug PTX and lipophilic triphenylphosphine (TPP) compounds is synthesized. The PMA-TPP/PTX nanomotors use nitric oxide (NO) as the driving force, which is produced from the reaction between arginine on the motor substrate and excess reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS) in the AS microenvironment. The final in vitro and in vivo experimental results confirm that the introduction of the lipophilic drug-loaded nanomotor technology can greatly enhance the drug retention and permeability in atherosclerotic lesions. In particular, NO can also play an anti-AS role in improving endothelial cell function and reducing oxidative stress. The chemotherapeutic drug PTX loaded onto the nanomotors can inhibit cell division and proliferation, thereby exerting the effect of inhibiting vascular intimal hyperplasia, which is helpful for the multiple therapies of AS. Using nanomotor technology to solve cardiovascular diseases may be a promising research direction.

Preparation of a novel glucose oxidase-N-succinyl chitosan nanospheres and its antifungal mechanism of action against Colletotrichum gloeosporioides

In this work, a new glucose oxidase-N-succinyl chitosan (GOD-NSCS) nanospheres was prepared through the immobilization of glucose oxidase (GOD) on N-succinyl chitosan (NSCS) nanospheres. Compared to the free GOD, GOD-NSCS nanospheres demonstrated the excellent anti-Colletotrichum gloeosporioides activity with the EC₅₀ values of 211.2 and 10.7 μg/mL against mycelial growth and spores germination. The computational biology analysis demonstrated that the substrate presented the similar binding free energy with GOD-NSCS nanospheres (-27.64 kcal/mol) compared with the free GOD (-24.04 kcal/mol), indicating that GOD-NSCS nanospheres had the same oxidation efficiency and produced more H₂O₂. Moreover, the enzyme activity stability of GOD-NSCS nanospheres could be prolonged to 10 d. The cell membrane was destructed by the treatment of H₂O₂ produced by GOD, leading to the cell death. In vivo test, GOD-NSCS nanospheres treatment significantly prolonged the preservation period of mangoes 2-fold. Collectively, these results suggested that GOD-NSCS nanospheres suppresses anthracnose in postharvest mangoes by inhibiting the growth of C. gloeosporioides and might become a potential natural preservative for fruits and vegetables.

Silk fibroin/chitosan coating with tunable catalytic nitric oxide generation for surface functionalization of cardiovascular stents

Developing a functional coating for vascular stents with sustainable and tunable NO release remains challenging. In this work, we report a silk fibroin/chitosan-based biopolymer coating incorporating copper ions as a catalyst for NO generation and demonstrate its potential for the surface functionalization of cardiovascular stents. Based on the differences in silk fibroin and chitosan coordinating with copper ions, the loading, bonding, and release of copper ions could be precisely regulated over a wide range by controlling the ratio of silk fibroin and chitosan. This system shows good cytocompatibility for endothelial cells and tunable catalytic activity to decompose S-nitroso-N-acetyl-D-penicillamine (SNAP) for NO generation. Consequently, a functionalized coating with sustainable and tunable NO catalysis generation was developed on the metallic stent. Based on good biocompatibility, tunable NO release, and simple processing, the coating is expected to have great promise in the field of intervention therapy of cardiovascular disease.

Mechanism of homocysteine-mediated endothelial injury and its consequences for atherosclerosis

Homocysteine (Hcy) is an intermediate amino acid formed during the conversion from methionine to cysteine. When the fasting plasma Hcy level is higher than 15 μmol/L, it is considered as hyperhomocysteinemia (HHcy). The vascular endothelium is an important barrier to vascular homeostasis, and its impairment is the initiation of atherosclerosis (AS). HHcy is an important risk factor for AS, which can promote the development of AS and the occurrence of cardiovascular events, and Hcy damage to the endothelium is considered to play a very important role. However, the mechanism by which Hcy damages the endothelium is still not fully understood. This review summarizes the mechanism of Hcy-induced endothelial injury and the treatment methods to alleviate the Hcy induced endothelial dysfunction, in order to provide new thoughts for the diagnosis and treatment of Hcy-induced endothelial injury and subsequent AS-related diseases.

Development of Innovative Biomaterials and Devices for the Treatment of Cardiovascular Diseases

Cardiovascular diseases have become the leading cause of death worldwide. The increasing burden of cardiovascular diseases has become a major public health problem and how to carry out efficient and reliable treatment of cardiovascular diseases has become an urgent global problem to be solved. Recently, implantable biomaterials and devices, especially minimally invasive interventional ones, such as vascular stents, artificial heart valves, bioprosthetic cardiac occluders, artificial graft cardiac patches, atrial shunts, and injectable hydrogels against heart failure, have become the most effective means in the treatment of cardiovascular diseases. Herein, an overview of the challenges and research frontier of innovative biomaterials and devices for the treatment of cardiovascular diseases is provided, and their future development directions are discussed.

An organic selenium and VEGF-conjugated bioinspired coating promotes vascular healing

The introduction of drug-eluting stents (DESs) have yield a significant reduction in the incidence of re-stenosis, however, challenges remain including incomplete healing of the endothelium, inflammatory response and thrombogenesis at the site of vascular wall injury. Here, we developed a novel stent with polyphenol-polyamine surface combining the biological functions of nitric oxide gas and VEGF, selectively promoting the proliferation and migration of endothelial cells while suppressing smooth muscle cells. Compared with bare PLLA stents and traditional DESs, the functionalized stents enhanced vascular healing through remarkable inhibiting intimal hyperplasia and occurrence of thrombosis, accelerating the in-situ endothelium repair. Moreover, it showed a down-regulation of injury vascular inflammation response and reduction of the vessel wall injury in New Zealand Rabbits after 1- and 3-month implantation.