Vascular Implantation Research Articles

Development of Silk Fibroin Scaffolds for Vascular Repair.

Silk fibroin (SF) is a biocompatible natural protein with excellent mechanical characteristics. SF-based biomaterials can be structured using a number of techniques, allowing the tuning of materials for specific biomedical applications. In this study, SF films, porous membranes, and electrospun membranes were produced using solvent-casting, salt-leaching, and electrospinning methodologies, respectively. SF-based materials were subjected to physicochemical and biological characterizations to determine their suitability for tissue regeneration applications. Mechanical analysis showed stress-strain curves of brittle materials in films and porous membranes, while electrospun membranes featured stress-strain curves typical of ductile materials. All samples showed similar chemical composition, melting transition, hydrophobic behavior, and low cytotoxicity levels, regardless of their architecture. Finally, all of the SF-based materials promote the proliferation of human umbilical vein endothelial cells (HUVECs). These findings demonstrate the different relationship between HUVEC behavior and the SF sample's topography, which can be taken advantage of for the design of vascular implants.

Towards the ideal vascular implant: Use of machine learning and statistical approaches to optimise manufacturing parameters

Introduction: Electrospinning is a manufacturing technique that creates a net of nano and microfibres able to mimic the natural extracellular matrix (ECM) of biological tissue. Electrospun scaffolds' morphology and mechanical behaviour can be tailored by modifying the environmental, solution and process parameters. This study aims to produce biomimetic vascular implants optimising the manufacturing set up through two machine learning techniques and statistical approaches.Methods: Polyvinyl alcohol (PVA) based scaffolds were produced by modifying the concentration of the polymer, flow rate, voltage, type of collector, diameter of the needle, distance between needle and collector and revolutions of the mandrel. The scaffolds were morphologically and mechanically characterised using scanning electron microscopy and mechanical testing respectively to inform the morphological model (simultaneously predicting diameter of the fibres and inter-fibre separation) and mechanical model (predicting strain at rupture and ultimate tensile strength).Results: Prediction and traditional techniques led to an optimum set up of: 12% PVA, 1 ml/h flow rate, 20 kV, 8 cm between the needle, 18 G gauge needle, rotational mandrel of 15 cm and 2000 rpm. Optimised PVA scaffolds replicated the mechanical properties and morphology of the vascular tissue with an ultimate tensile strength of 6.17 ± 0.18 MPa, a strain at break of 97.39 ± 5.06, fibre diameters of 126 ± 6.11 nm and inter-fibre separation of 1488 ± 91.99 nm.Discussion: This work revealed for the first time that machine learning Chi-squared Automatic Interaction Detection (CHAID) models are a novel and visual route to elect the optimum manufacturing set up to develop biomimetic vascular implants. Novel two-output Artificial Neural Networks (ANN) and multivariate analysis of variance and covariance (MANOVA, MANCOVA) models presented comparable prediction results (R2=0.91); however, two-output ANN predicted models demonstrated to be the most powerful tool for non-parametric conditions, showing cross-validation mean squared errors (MSE) of 0.0001943. Multi Linear Regression models (MLR) exhibited the lowest accuracy in their predictions (R2=0.6). Machine learning, statistical approaches and traditional characterisation methods were studied to successfully achieve vascular substitutes with analogous biomechanical behaviour and physical structure to the native vascular tissue.

Influence of PHA Substrate Surface Characteristics on the Functional State of Endothelial Cells

The needs of modern regenerative medicine for biodegradable polymers are wide and varied. Restoration of the viability of the vascular tree is one of the most important components of the preservation of the usefulness of organs and tissues. The creation of vascular implants compatible with blood is an important task of vascular bioengineering. The function of the endothelial layer of the vessel, being largely responsible for the development of thrombotic complications, is of great importance for hemocompatibility. The development of surfaces with specific characteristics of biomaterials that are used in vascular technologies is one of the solutions for their correct endothelialization. Linear polyhydroxyalkanoates (PHAs) are biodegradable structural polymeric materials suitable for obtaining various types of implants and tissue engineering, having a wide range of structural and physicomechanical properties. The use of PHA of various monomeric compositions in endothelial cultivation makes it possible to evaluate the influence of material properties, especially surface characteristics, on the functional state of cells. It has been established that PHA samples with the inclusion of 3-hydroxyhexanoate have optimal characteristics for the formation of a human umbilical vein endothelial cell, HUVEC, monolayer in terms of cell morphology as well as the levels of expression of vinculin and VE-cadherin. The obtained results provide a rationale for the use of PHA copolymers as materials for direct contact with the endothelium in vascular implants.

Reconstructive vascular surgery in pediatric oncology: literature review

Background. In some rare cases pediatric solid tumors may infiltrate or incase major vessels, which may require vascular plastics as part of radical tumor resection. As these situations are rare in pediatric surgeon practice, there is no common approach to this problem. In order to analyze the available experience we reviewed published cases concerning vascular plastics in pediatric oncosurgery. Materials and methods. The references from MEDLINE (PubMed), HighWire Press, and eLibrary electronic databases were analyzed for references describing practical vascular surgery experience with vascular implants published in 2002–2022. Results. There is few published data on major vessels reconstruction in patients with pediatric solid tumors. Most publications describe single cases or small case series. The vascular plastics in these children is difficult due to small vessel diameter, difficulties in choosing the right graft, risk of thrombosis, and the need to provide adequate circulation in a rapidly growing child. As there are no major studies of this subject we still have no consensus on optimal vascular reconstruction tactics in children with solid tumors. Therefore, new systematic studies are needed. Conclusion. We provide a brief review on currently used methods of vascular plastics and reconstruction available for use in children with solid tumors.

Multi-functional plant flavonoids regulate pathological microenvironments for vascular stent surface engineering.

In-stent restenosis (ISR) and late thrombosis, usually caused by excessive smooth muscle cell (SMC) proliferation and delayed endothelial layer repair, respectively, are the main risks for the failure of vascular stent implantation. For years, modification of stents with biomolecules that could selectively inhibit SMC proliferation and support endothelial cell (EC) growth had drawn extensive attention. However, the modulatory effect of these biomolecules faces the impact of oxidative stress, inflammation, and hyperlipidemia of the pathological vascular microenvironment, which is caused by the stent implantation injury and atherosclerosis lesions. Here, we modified stents with a natural and multi-functional flavonoid, baicalin (BCL), using poly-dopamine (PDA) coating technology to combat the harmful impact of the pathological microenvironment. Stent with an appropriate BCL immobilization density (approximately 2.03μg/cm2) successfully supported ECs growth while inhibited SMC proliferation. Furthermore, baicalin-modified surfaces regulated the oxidative stress, inflammation, and high-lipid of the pathological microenvironment to inhibit endothelial dysfunction and the oxidized low-density lipoprotein (ox-LDL)-induced macrophage foam cells formation. In vivo results showed that baicalin-modified stents exhibited significant anti-ISR, anti-inflammatory, and endothelialization-promoting functions. Our study suggests that the multi-functional baicalin with pathological microenvironment-regulation (PMR) effect has potential use in the surface engineering of cardiovascular devices. STATEMENT OF SIGNIFICANCE: Empowering vascular stents with selective modulation of smooth muscle cells and endothelial cells by surface technology has become an important research direction for stent surface engineering. However, stent coatings that can furthermodulate the pathological microenvironment of blood vessels have been rarely reported. In this study, we constructed a multifunctional coating based on a flavonoid, baicalin, which can selectively modulate vascular wall cells and improve the pathological microenvironment. This study may provide a reference for developing advanced vascular stents.

Antiplatelet Agents and Oral Anticoagulant Use in Patients with Atrial Fibrillation and Carotid Artery Disease After First-Time Ischaemic Stroke

IntroductionPeople with atrial fibrillation (AF) frequently have competing mechanisms for ischaemic stroke, including extracranial carotid atherosclerosis. The objective of this study was to determine associations between use of oral anticoagulants (OACs) plus antiplatelet agents (APA) after ischaemic stroke and outcomes for patients with AF and carotid artery disease.Patients and MethodsA retrospective cohort study was conducted. Participants receiving OACs with or without APA were propensity score–matched for age, sex, ethnicity, co-morbidities and presence of cardiac and vascular implants and grafts. Outcomes were 1-year mortality, recurrent stroke and major bleeding.ResultsOf 5708 patients, 24.1% (n=1628) received non-vitamin K antagonist OACs (NOACs) with no APA, 26.0% (n=1401) received NOACs plus APA, 20.7% (n=1243) received warfarin without APA and 29.2% (n=1436) received warfarin plus APA. There was no significant difference in risk of recurrent stroke between the groups. Compared to receiving NOACs without APA, receiving warfarin plus APA was associated with a higher risk of mortality (hazard ratio (HR) 1.51 (95% confidence interval (CI) 1.20, 1.89)) and major bleeding (HR 1.66 (95% CI 1.40, 1.96)). Receiving NOACs plus APA was also associated with a higher risk of major bleeding compared to NOACs without APA (HR 1.27 (95% CI 1.07, 1.51), respectively).ConclusionsThe results suggest for patients with AF and carotid artery disease after ischaemic stroke, receiving NOACs without APA is associated with a lower risk of major bleeding with no negative impact on recurrent stroke or mortality. Evidence from randomised trials is needed to confirm this finding.

Structure and properties of Co‑Cr alloys for biocompatible medical products

The results of studies of Co‑Cr alloys for biocompatible medical products are presented. The article shows that alloys of CoCr‑W system are promising for the manufacture of coronary and vascular small‑sized stents with high radial rigidity of the structure. Ensuring the corrosion resistance of the material is one of the general requirements for implants of the Co‑Cr alloys. The main influence on the corrosion resistance, biocompatibility and mechanical properties of coronary and vascular implants subjected to increased cyclic loads is exerted by the state and structure of the surface of the Co‑Cr alloy. Effective ways to change the surface structure and improve the properties of Co‑Cr alloys are heat treatment processes, including those in vacuum, mechanical and electrochemical methods of surface treatment.

Operative and long-term outcomes of combined and staged carotid endarterectomy and coronary bypass

ObjectiveOptimal temporal surgical management of significant carotid stenosis and coronary artery disease remains unknown. Carotid endarterectomy (CEA) and coronary artery bypass (CABG) are performed concurrently (CCAB) or in a staged (CEA-CABG or CABG-CEA) approach. Using the Vascular Quality Initiative-Vascular Implant Surveillance and Interventional Outcomes Coordinated Registry Network-Medicare-linked dataset, this study compared operative and long-term outcomes after CCAB and staged approaches. MethodsThe Vascular Quality Initiative-Vascular Implant Surveillance and Interventional Outcomes Coordinated Registry Network dataset was used to identify CEAs from 2011 to 2018 with combined CABG or CABG within 45 days preceding or after CEA. Patients were stratified based on concurrent or staged approach. Primary outcomes were stroke, myocardial infarction (MI), all-cause mortality, stroke and death as composite (SD) and all as composite within 30 days from the last procedure as well as in the long term. Univariate analysis and risk-adjusted analysis using inverse propensity weighting were performed. Kaplan-Meier curves of stroke, MI, and death were created and compared. ResultsThere were 1058 patients included: 643 CCAB and 415 staged (309 CEA-CABG and 106 CABG-CEA). Compared with staged patients, those undergoing CCAB had a higher preoperative rate of congestive heart failure (24.8% vs 18.4%; P = .01) and decreased renal function (14.9% vs 8.5%; P < .01), as well as fewer prior neurological events (23.5% vs 31.4%; P < .01). Patients undergoing CCAB had similar weighted rate of 30-day stroke (4.6% vs 4.1%; P = .72), death (7.0% vs 5.0%; P = .32), and composite outcomes (stroke and death, 9.8% vs 8.5%; P = .56; stroke, death, and MI, 14.7% vs 17.4%; P = .31), but a lower weighted rate of MI (5.5% vs 11.5%; P < .01) vs the staged cohort. Long-term adjusted risks of stroke (hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.54-1.36; P = .51) and mortality (HR, 1.02; 95% CI, 0.76-1.36; P=.91) were similar between groups, but higher risk of MI long-term was seen in those staged (HR, 1.49; 95% CI, 1.07-2.08; P = .02). ConclusionsIn patients undergoing CCAB or staged open revascularization for carotid stenosis and coronary artery disease, the staged approach had an increased risk of postoperative cardiac event, but the short- and long-term rates of stroke and mortality seem to be comparable. Adverse cardiovascular event risk is high between operations when staged and should be a consideration when selecting an approach. Although factors leading to staged sequencing performance need further clarity, CCAB seems to be safe and should be considered an equally reasonable option.

An extracellular matrix-mimetic coating with dual bionics for cardiovascular stents.

Anti-inflammation and anti-coagulation are the primary requirements for cardiovascular stents and also the widely accepted trajectory for multi-functional modification. In this work, we proposed an extracellular matrix (ECM)-mimetic coating for cardiovascular stents with the amplified functionalization of recombinant humanized collagen type III (rhCOL III), where the biomimetics were driven by structure mimicry and component/function mimicry. Briefly, the structure-mimic was constructed by the formation of a nanofiber (NF) structure via the polymerization of polysiloxane with a further introduction of amine groups as the nanofibrous layer. The fiber network could function as a three-dimensional reservoir to support the amplified immobilization of rhCoL III. The rhCOL III was tailored for anti-coagulant, anti-inflammatory and endothelialization promotion properties, which endows the ECM-mimetic coating with desired surface functionalities. Stent implantation in the abdominal aorta of rabbits was conducted to validate the in vivo re-endothelialization of the ECM-mimetic coating. The mild inflammatory responses, anti-thrombotic property, promotion of endothelialization and suppression of excessive neointimal hyperplasia confirmed that the ECM-mimetic coating provided a promising approach for the modification of vascular implants.

Fused Deposition Modeling and Characterization of Heat Shape Memory Poly(lactic) Acid-Based Porous Vascular Scaffold.

Shape memory polymers have received widespread attention from researchers because of their low density, shape variety, responsiveness to the environment, and transparency. This study deals with heat-shape memory polymers (SMPs) based on polylactic acid (PLA) for designing and fabricating a novel porous vascular scaffold to treat vascular restenosis. The solid isotropic material penalization method (SIMP) was applied to optimize the vascular scaffolds. Based on the torsional torque loading of Hyperworks Optistruct and the boundary conditions, the topological optimization model of a vascular scaffold unit was established. Forward and reverse hybrid modeling technology was applied to complete the final stent structure's assembly. The glass transition temperature for the present SMPs is 42.15 °C. With the increase in temperature, the ultimate tensile strength of the SMPs is reduced from 29.5 MPa to 11.6 MPa. The maximum modulus at room temperature was around 34 MPa. Stress relaxation curves show that the material classification is a "thermoset" polymer. The superb mechanical properties, the transition temperature of the SMPs, and the recovery ratio made it a feasible candidate for a vascular scaffold. A circular tube based on the shape memory polymers was presented as an example for analyzing the recovery ratio in an unfolding state. A higher recovery ratio was obtained at a temperature of 65 °C with a tube thickness of 2 mm. Finally, the proposed porous vascular scaffold was successfully fabricated, assessed, and compared with the original and previously developed vascular scaffolds. The proposed scaffold structure regains its initial shape with a recovery ratio of 98% (recovery temperature of 47 °C) in 16 s. The tensile strength, Young's modulus, and bending strength of the proposed scaffold were 29.5 MPa, 695.4 MPa, and 6.02 MPa, respectively. The results showed that the proposed scaffold could be regarded as a potential candidate for a vascular implantation.

Application of decellularized vascular matrix in small-diameter vascular grafts.

Coronary artery bypass grafting (CABG) remains the most common procedure used in cardiovascular surgery for the treatment of severe coronary atherosclerotic heart disease. In coronary artery bypass grafting, small-diameter vascular grafts can potentially replace the vessels of the patient. The complete retention of the extracellular matrix, superior biocompatibility, and non-immunogenicity of the decellularized vascular matrix are unique advantages of small-diameter tissue-engineered vascular grafts. However, after vascular implantation, the decellularized vascular matrix is also subject to thrombosis and neoplastic endothelial hyperplasia, the two major problems that hinder its clinical application. The keys to improving the long-term patency of the decellularized matrix as vascular grafts include facilitating early endothelialization and avoiding intravascular thrombosis. This review article sequentially introduces six aspects of the decellularized vascular matrix as follows: design criteria of vascular grafts, components of the decellularized vascular matrix, the changing sources of the decellularized vascular matrix, the advantages and shortcomings of decellularization technologies, modification methods and the commercialization progress as well as the application prospects in small-diameter vascular grafts.

Cartilage lesion size and number of stromal vascular fraction (SVF) cells strongly influenced the SVF implantation outcomes in patients with knee osteoarthritis

PurposeThis study evaluated outcomes in patients with knee osteoarthritis following stromal vascular fraction implantation and assessed the associated prognostic factors.MethodsWe retrospectively evaluated 43 patients who underwent follow-up magnetic resonance imaging 12 months after stromal vascular fraction implantation for knee osteoarthritis. Pain was assessed using the visual analogue scale and measured at baseline and 1-, 3-, 6-, and 12-month follow-up appointments. In addition, cartilage repair was evaluated based on the Magnetic Resonance Observation of Cartilage Repair Tissue scoring system using the magnetic resonance imaging from the 12-month follow-up. Finally, we evaluated the effects of various factors on outcomes following stromal vascular fraction implantation.ResultsCompared to the baseline value, the mean visual analogue scale score significantly and progressively decreased until 12 months post-treatment (P < 0.05 for all, except n.s. between the 1 and 3-month follow-ups). The mean Magnetic Resonance Observation of Cartilage Repair Tissue score was 70.5 ± 11.1. Furthermore, the mean visual analogue scale and Magnetic Resonance Observation of Cartilage Repair Tissue scores significantly correlated 12 months postoperatively (P = 0.002). Additionally, the cartilage lesion size and the number of stromal vascular fraction cells significantly correlated with the 12-month visual analogue scale scores and the Magnetic Resonance Observation of Cartilage Repair Tissue score. Multivariate analyses determined that the cartilage lesion size and the number of stromal vascular fraction cells had a high prognostic significance for unsatisfactory outcomes.ConclusionStromal vascular fraction implantation improved pain and cartilage regeneration for patients with knee osteoarthritis. The cartilage lesion size and the number of stromal vascular fraction cells significantly influenced the postoperative outcomes. Thus, these findings may serve as a basis for preoperative surgical decisions.Level of evidenceIV.

An Overview on recent trends in Biopolymer Base Composites for Tissue Regeneration

This paper focused on the short review of biopolymer based composite for tissue regeneration. Biopolymers have been slowly introduced into medical applications as a result of their ability to be bio-degradable and to be easily made. By selecting the appropriate biopolymer containing the selected additives to facilitate the polymer-filler interaction, composites with the desired properties can be obtained. Interfacial interactions between biopolymers, and thus Nano-fillers, significantly control the mechanical properties of biopolymer composites and these biopolymer composites such as bone, cartilage, vascular implants, and others.

Freedom From Stent Fracture–Related Complications of Vascular Longitudinal Remodeling in a Patient With Heart Failure and a Degraded Bioresorbable Vascular Scaffold

Because vascular geometric change during the long-term process of cardiac chamber remodeling in heart failure is usually unpredictable after coronary stenting, the risk of acquired metallic stent fracture can persist. This rare but possible complication could be minimized with the implantation of bioresorbable vascular scaffold because of its unique properties. Here, the authors report on 1 patient with heart failure who received optical coherence tomography evaluation between 3 and 3.5 years after bioresorbable vascular scaffold implantation. Measurement of the discernible struts of bioresorbable vascular scaffold provided evidence of coronary longitudinal remodeling without serious risk of complications related to metallic stent fracture resulting from cardiac remodeling.

Effect of exercise rehabilitation on hemodynamic performance after 5 carotid artery stenting: a numerical study

Purpose A high in-stent restenosis rate and thrombosis have compromised clinical benefits after vascular stent placement. Exercise rehabilitation after stenting emerges as a promising and practical therapeutic strategy to improve the clinical performance of this therapy, although it remains controversial. The present study aims to explore the impact of exercise training on hemodynamic performance after vascular stent implantation. Methods Different 3-dimensional computational models based on the patient-specific carotids were constructed to calculate hemodynamic parameters, including flow velocity, time-averaged wall shear (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT). Results The results demonstrated that exercise training increased TAWSS but decreased OSI and RRT in some cases after the intervention, and high-intensity exercise would further suppress the adverse blood flow. However, exercise training would remarkably reduce TAWSS and elevate OSI and RRT in patients with mild stenosis at upstream of stented segment. Additionally, we discovered that the hemodynamic environment change induced by exercise training was not significant compared to the stent position in some cases. Exercise would have a less beneficial impact on the disturbed blood flow after the distal common carotid artery (CCA) stenting. Conclusions These findings highlight that exercise-induced hemodynamic changes differ under different conditions. The exercise training for the intervention patients should only be performed after a comprehensive vascular function assessment.

Co-Cr alloys for biocompatible medical products

The results of the analysis of the Co-Cr alloys properties for biocompatible medical products are presented. The article shows that alloys of the Co-Cr system doped with molybdenum are mainly used as the main materials for the manufacture of orthopedic and dental implants, alloys of the Co-Cr-W system are promising for the manufacture of coronary and vascular small-sized stents with high radial rigidity of the structure. Ensuring the corrosion resistance of the material is one of the general requirements for implants of the Co-Cr alloys. The main influence on the corrosion resistance, biocompatibility and mechanical properties of coronary and vascular implants subjected to increased cyclic loads is exerted by the state and structure of the surface of the Co-Cr alloy. Effective ways to change the surface structure and improve the properties of Co-Cr alloys are heat treatment processes, including those in vacuum, mechanical and electrochemical methods of surface treatment.

Perioperative and long-term outcomes after open conversion of endovascular aneurysm repair versus primary open aortic repair.

The use of endovascular abdominal aortic aneurysm repair (EVAR) has superseded that of open aneurysm repair (OAR) as the procedure of choice for abdominal aortic aneurysm repair. However, significant rates of late reintervention and aneurysm rupture have been reported after EVAR, resulting in the need for conversion to OAR (C-OAR). To assess the relative effects of C-OAR on patients, we compared the outcomes of these patients to those of patients who had undergone P-OAR. The data from all patients who had undergone C-OAR and P-OAR in the Vascular Quality Initiative Vascular Implant Surveillance and Interventional Outcomes Network database from 2003 to 2018 were queried. Multivariable logistic regression and Kaplan-Meier survival and Cox proportional hazard regression analyses were used to assess the perioperative long-term outcomes. A total of 4763 patients were included (91.4%, P-OAR; 8.6%, C-OAR). C-OAR was associated with a significant increase in the odds of perioperative mortality (odds ratio, 1.7; 95% confidence interval [CI], 1.1-2.7; P= .027) and renal complications (odds ratio, 1.5; 95% CI, 1.1-2; P= .004) vs P-OAR. At 5years, conversion was associated with a higher risk of mortality (hazard ratio [HR], 1.5; 95% CI, 1.3-1.9; P< .001), aneurysmal rupture (HR, 1.9; 95% CI, 1.2-3.1; P= .007), and reintervention (HR, 1.4; 95% CI, 1.05-1.97; P= .022) compared with P-OAR. These results also persisted at 10years, with conversion associated with a higher risk of mortality (HR, 1.5; 95% CI, 1.2-1.8; P< .001), rupture (HR, 1.8; 95% CI, 1.1-2.8; P= .018), and reintervention (HR, 1.5; 95% CI, 1.1-2.1; P= .010). The results from the present study have demonstrated that C-OAR is associated with a significantly higher risk of perioperative morbidity and mortality compared with P-OAR. We found a significant increase in mortality, aneurysm rupture, and reintervention at 5 and 10years of follow-up.

Resection of inferior vena cava, abdominal aorta, bilateral common iliac arteries, and bilateral partial external iliac arteries with artificial vessel replacement during radical endometrial cancer surgery: a case report

BackgroundEndometrial carcinoma (EC) is a common malignant tumor of the female reproductive system, often accompanied by lymph node metastasis. Artificial vascular implantation is a common surgical treatment for mediastinal tumors and abdominal aortic aneurysms but is rarely used in gynecological surgery.Case presentationA 54-year-old female patient was first admitted to the hospital in January 2018 due to “irregular vaginal bleeding over 3 months”. CT showed a mass in the uterine cavity, and several swollen lymph nodes in the retroperitoneum and pelvic cavity. The initial diagnosis was an endometrial malignant tumor. We performed radical endometrial cancer surgery with parallel resection of inferior vena cava, abdominal aorta, bilateral common iliac arteries, bilateral external iliac arteries, and artificial vessel replacement, which was successful, with good postoperative recovery and no lesion progression at 3 years postoperative follow-up.ConclusionThis is an early case of gynecological clinical use of prostheses. Through multidisciplinary cooperation, the surgical resection rate of patients with EC in radical surgery was improved without serious fatal complications and achieved a high long-term postoperative survival rate.

Inflammation-directed nanozyme-eluting hydrogel coating promotes vascular tissue repair by restoring reactive oxygen species homeostasis

Thrombosis and stenosis remain two of the most prevalent complications of vascular implants. The most effective strategy in clinics to inhibit stenosis is based on the eluting of anti-hyperplasia drugs such as sirolimus and everolimus while it also has been known to hinder vascular healing and regeneration. Selectively inhibiting intimal hyperplasia and promoting endothelialization remains a highly challenging target for vascular implants. Due to auto-regenerative antioxidant activity nanoceria as a nanozyme has been widely used to regulate oxidative stress in the treatment of inflammation-related diseases. Yet the application of nanozyme in vascular implants has not hitherto been reported. In this study we constructed a reactive oxygen species (ROS)-targeted nanoceria-eluting degradable zwitterion hydrogel coating on membrane-covered stents with favorable anti-coagulation pro-endothelialization and immunomodulation properties. The hydrogel coating exhibited excellent hemocompatibility and simultaneously promoted the growth of endothelial cells. Nanoceria embedded in hydrogel could be released in response to matrix metalloproteinase (MMP) and effectively scavenge artificial and intracellular ROS via mimicking the activity of natural superoxide dismutase (SOD) and catalase (CAT). In addition the incorporation of nanoceria increased the expression levels of anti-inflammation cytokines and growth factors and reduced the expression levels of pro-inflammation cytokines in macrophages inducing a switch of macrophage phenotype from M1 to M2. The membrane-covered stent based on nanozyme-integrated hydrogel-coated PLLA membrane exhibited a high patency rate and slight intima hyperplasia degree upon implantation into rabbits' iliac arteries/abdominal aortas. This advanced hydrogel coating may provide a new low-cost and drug-free strategy for effectively inhibiting vascular stenosis and promoting vascular repair.

Multimodal effects of asymmetric coating of coronary stents by electrospinning and electrophoretic deposition

Drug-eluting stents (DESs) are drug-coated vascular implants that inhibit smooth muscle cell proliferation and limit in-stent re-stenosis. However, traditional DESs release a single drug into the blood and cannot cope with complex mechanisms in atherosclerosis and body responses. The present study aimed to develop a novel multimodal stent by fabricating asymmetric coating with electrophoretic deposition and electrospinning. Herein, we use heparin-loaded alginate (Hep/Alg) and atorvastatin calcium-loaded polyurethane (AtvCa/PU) coatings on the stent luminal and abluminal surfaces, respectively. Scanning electron microscopy (SEM) micrographs showed that the alginate coatings had uniformity and thin thickness. Meanwhile, the PU fibers were formed without beads, with an acceptable diameter and suitable mechanical properties. PU nanofiber revealed minimal degradation in a 1-month study. The release of AtvCa and Hep continued for 8 days without a significant initial burst release. None of the stent coatings were cytotoxic or hemolytic, and PU nanofibers supported the survival of human umbilical endothelial cells (HUVEC) with high adhesion and flattened morphologies. The results indicate that electrophoretic deposition and electrospinning have significant potential for achieving asymmetric coating on stents and a promising approach for dual drug release for multimodal effects in vascular stent applications.