Next-generation drug-eluting stents in coronary artery disease: focus on everolimus-eluting stent (Xience V)

Recent advances in targeted therapy for inflammatory vascular diseases

Vascular diseases constitute a significant contributor to worldwide mortality rates, placing a substantial strain on healthcare systems and socio-economic aspects. They are closely associated with inflammatory responses, as sustained inflammation could impact endothelial function, the release of inflammatory mediators, and platelet activation, thus accelerating the progression of vascular diseases. Consequently, directing therapeutic efforts towards mitigating inflammation represents a crucial approach in the management of vascular diseases. Traditional anti-inflammatory medications may have extensive effects on multiple tissues and organs when absorbed through the bloodstream. Conversely, treatments targeting inflammatory vascular diseases, such as monoclonal antibodies, drug-eluting stents, and nano-drugs, can achieve more precise effects, including precise intervention, minimal non-specific effects, and prolonged efficacy. In addition, personalized therapy is an important development trend in targeted therapy for inflammatory vascular diseases. Leveraging advanced simulation algorithms and clinical trial data, treatment strategies are gradually being personalized based on patients' genetic, biomarker, and clinical profiles. It is expected that the application of precision medicine in the field of vascular diseases will have a broader future. In conclusion, targeting therapies offer enhanced safety and efficacy compared to conventional medications; investigating novel targeting therapies and promoting clinical transformation may be a promising direction in improving the prognosis of patients with inflammatory vascular diseases. This article reviews the pathogenesis of inflammatory vascular diseases and presents a comprehensive overview of the potential for targeted therapies in managing this condition.

REDV-Functionalized Recombinant Spider Silk for Next-Generation Coronary Artery Stent Coatings: Hemocompatible, Drug-Eluting, and Endothelial Cell-Specific Materials

Coronary artery stents are life-saving devices, and millions of these devices are implanted annually to treat coronary heart disease. The current gold standard in treatment is drug-eluting stents, which are coated with a biodegradable polymer layer that elutes antiproliferative drugs to prevent restenosis due to neointimal hyperplasia. Stenting is commonly paired with systemic antiplatelet therapy to prevent stent thrombosis. Despite their clinical success, current stents have significant limitations including inducing local inflammation that drives hyperplasia; a lack of hemocompatibility that promotes thrombosis, increasing need for antiplatelet therapy; and limited endothelialization, which is a critical step in the healing process. In this research, we designed a novel material for use as a next-generation coating for drug-eluting stents that addresses the limitations described above. Specifically, we developed a recombinant spider silk material that is functionalized with an REDV cell-adhesive ligand, a peptide motif that promotes specific adhesion of endothelial cells in the cardiovascular environment. We illustrated that this REDV-modified spider silk variant [eADF4(C16)-REDV] is an endothelial-cell-specific material that can promote the formation of a near-confluent endothelium. We additionally performed hemocompatibility assays using human whole blood and demonstrated that spider silk materials exhibit excellent hemocompatibility under both static and flow conditions. Furthermore, we showed that the material displayed slow enzyme-mediated degradation. Finally, we illustrated the ability to load and release the clinically relevant drug everolimus from recombinant spider silk coatings in a quantity and at a rate similar to that of commercial devices. These results support the use of REDV-functionalized recombinant spider silk as a coating for drug-eluting stents.

A Study of PLA Thin Film on SS 316L Coronary Stents Using a Dip Coating Technique

The dip coating process is one of the recognized techniques used to generate polymeric coatings on stents in an easy and low-cost way. However, there is a lack of information about the influence of the process parameters of this technique on complex geometries such as stents. This paper studies the dip coating process parameters used to provide a uniform coating of PLA with a 4-10 µm thickness. A stainless-steel tube (AISI 316L) was laser-cut, electropolished, and dip-coated in a polylactic acid (PLA) solution whilst changing the process parameters. The samples were characterized to examine the coating's uniformity, thickness, surface roughness, weight, and chemical composition. FTIR and Raman investigations indicated the presence of PLA on the stent's surface, the chemical stability of PLA during the coating process, and the absence of residual chloroform in the coatings. Additionally, the water contact angle was measured to determine the hydrophilicity of the coating. Our results indicate that, when using entry and withdrawal speeds of 500 mm min-1 and a 15 s immersion time, a uniform coating thickness was achieved throughout the tube and in the stent with an average thickness of 7.8 µm.

Research progress of absorbable stents

Atherosclerosis, a chronic inflammation of blood vessel walls, is a progressive pathophysiological process characterized by lipid deposition and innate adaptive immune responses. Arteriosclerosis often leads to narrowing of blood vessels. At present, interventional stent therapy is the main treatment method for vascular stenosis, which has the advantages of less trauma, less risk and faster recovery. However, atherosclerosis occurs in a complex pathophysiological environment. Stenting inevitably causes local tissue damage, leading to complications such as inflammation, intimal hyperplasia, late thrombosis, stent restenosis and other complications. It is urgent to optimize interventional therapy program. This article summarizes the advantages and disadvantages of absorbable metal scaffolds and the research progress of absorbable polymer scaffolds. The optimization strategy of stent is proposed. The status quo of drug coating was summarized. The prospect of new stent. To improve the therapeutic effect of arteriosclerosis.

Novel usage of everolimus-eluting coronary stent for intracranial atherosclerotic disease: a technical report and case series

Objectives

This report describes the use of an Everolimus-eluting stent (Xience Skypoint stent) for the treatment of medically-refractory ICAD.

Design

Retrospective, case-series.

Setting

In-hospital patients.

Participants

All patients in this report had a history of stroke secondary to ICAD. All patients failed aggressive medical treatments and had recurrence of symptoms despite anticoagulation or dual-antiplatelet therapy plus a statin. Diagnostic angiogram in each case showed severe vessel stenosis, therefore patients were recommended for intracranial artery stenting.

Main outcome measures

Technical feasibility of deploying Xience Skypoint stent for treatmet of ICAD.

Results

The Xience Skypoint stent was safely and effectively deployed in the vertebral artery (x1) and the internal carotid artery (x2) using trans-ulnar (x1), trans-radial (x1), and trans-femoral (x1) approaches without the use of an intermediate catheter.

Conclusion

Second-generation EES such as Xience Skypoint may be utilized for treatment of medically-refractory ICAD. This technical report serves as a proof of concept for further studies analysing long-term safety and efficacy of such stents for treatment of ICAD.

Optimize PLA/EVA Polymers Blend Compositional Coating for Next Generation Biodegradable Drug-Eluting Stents

In this research work, polymer blends of poly-lactic acid (PLA)/ethylene vinyl acetate (EVA) were prepared as the drug carrier materials for a bi-layer drug-loaded coating film for coronary stents. Different optimum compositions of blends were prepared by using an intense mixer. Then, the blends were hot-pressed and later cold-pressed to prepare for films of different thickness. The changes in weight, surface analysis and biodegradability with increasing time were studied using Scanning electron microscopy (SEM), weight loss and biodegradability tests. The mechanical and thermal properties of drug-loaded films were studied through universal testing machine (UTM) and thermo-gravimetric analysis (TGA). The effects of PLA, EVA and drug contents on in-vitro drug contents were investigated through the Ultraviolet-Visible Spectroscopy (UV-VIS) chemical analysis technique. The results obtained clearly showed that the addition of PLA promoted the unleashing of the drug whereas the addition of EVA nearly did not have the same affect. The mechanical properties of these various films can be tuned by adjusting the contents of blend parts. The factors affecting the unleashing of the drug became a serious matter of concern in evaluating the performance of bio-resorbable drug eluting stents. As a result, today’s chemical blends may be useful drug carrier materials for drug-loaded tube coatings capable delivering purgative drug in an incredibly tunable and regulated manner.

Evolutionary perspective of drug eluting stents: from thick polymer to polymer free approach

Background

Introduction of Bare Metal Stents (BMS) was itself a revolutionary step in the history of the medical industry; however, Drug Eluting Stents (DES) maintained its superiority over BMS in every aspect from restenosis rate to late lumen loss. The reason behind the magnanimous position of the DES in the stent market is the degree of improvement with which it evolves. New and better stents come into the market every year, surpassing their predecessors by many folds.

Literature review

This review paper discusses the journey of DES with supporting clinical trials in detail. In the first generation, there were stainless-steel stents with thicker coatings. Although they had superior results compared to BMS, there was still room for improvement. Afterward came the second-generation stents, which had superior metal platforms with thinner struts and thin coatings. The drugs were also changed from Paclitaxel and Sirolimus to Zotrolimus and Everolimus. These stents performed best; however, there was an issue of permanent coating, which remained intact over the stent surface after complete drug elution and started to cause issues in longer-term studies. Hence, an improved version of DES was introduced to these permanent coatings called the third generation of drug eluting stents, which initially utilized biodegradable polymer and ultimately moved towards polymer free drug coatings. This generation has introduced a unique amalgam of technologies to achieve its polymer free coatings; however, researchers have numerous prospects of growth in this field. This review paper highlights the major coups of stent technology evolution from BMS to DES, from thick polymeric coatings to thin coatings and from durable polymers to polymer free DES.

Conclusion

In conclusion, though the medical industry promptly accepted BMS as the best treatment option for cardiovascular diseases; however, DES has provided even better results than BMS. In DES, the first and second generation has ruled the technology for many years and are still on the shelves. Still, the issues aroused due to durable polymer shifted the attention towards biodegradable drug eluting stents, the third generation growing rapidly. But the scientific community has not restricted themselves and is investigating bioresorbable stents that completely eliminate the polymer intervention in drug eluting stent technology.

Double Whammy: Subacute Stent Thrombosis While Being Adherent to Dual Antiplatelet Therapy Including Ticagrelor, Followed by Multiple Coronary Artery Aneurysms in a COVID-19 Patient

Coronavirus disease 2019 (COVID-19), although predominantly a respiratory illness, can have important cardiovascular implications, which include the development of myocardial injury/myocarditis, acute coronary syndromes, arrhythmias, pericarditis, and the occurrence of arterial and venous thrombosis. We describe a rare case of a middle-aged COVID-19 patient who developed sub-acute stent thrombosis after implantation of second-generation drug-eluting stents (DES) despite being adherent to dual antiplatelet therapy including ticagrelor and who subsequently developed multiple coronary artery aneurysms within a few weeks of the DES implantation.

A heparin-functionalized covered stent prepared by plasma technology

In this study, the surface of the covered stent was treated by plasma technology to introduce amino functional groups, and glutaraldehyde and heparin were successfully grafted to prepare a heparin-functionalized covered stent (HPLCS). The preparation parameters such as plasma treatment power, plasma treatment time, concentration of glutaraldehyde and heparin, and pH of heparin solution were studied in detail. The functionalized heparin covered stent can make the titer of heparin reach 1.23 ± 0.03 IU/cm². In animal experiments, after implantation in pigs for 6 months, the titer of heparin can still reach 0.93 ± 0.05 IU/cm². This work provides a good method for preparing heparin covered stent.

Two-year safety and efficacy of Indigenous Abluminus Sirolimus Eluting Stent. Does it differ amongst diabetics? - Data from en-ABLe- REGISTRY

Introduction: To evaluate the efficacy/safety profile of the Abluminus DES+ over 2-years follow-up in the "real-world" scenario in diabetics as compared to non-diabetics.

Methods: In prospective, all-comers, open-label registry conducted at 31 sites, patients were analyzed for 1 & 2-year outcomes with the primary endpoint defined as 3P-MACE of CV death, target vessel related myocardial infarction (TV-MI), ischemia-driven target lesion revascularization (TLR)/target vessel revascularization (TVR) apart from Stent thrombosis (ST).

Results: Of 2500 patients of PCI with 3286 Abluminus-DES+, 1641 (65.64%) were non-diabetics while859 (34.36%) were diabetics. The 3-P MACE for the cohort at 1 & 2 years were 2.9%, and 3.16%; TLR/TVR - 1.4% at both the intervals for 2493 patients at 2 yrs. follow-up. TV-MI & ST were 0.36% and0.56% at 1st and 2nd year respectively. The 3P-MACE was lower in non-diabetics at 1 & 2 years (2.3%vs 4.2%; 2.4% vs 4.7% respectively). For components of MACE, CV mortality (0.9 vs 1.9% at 1 yr ; 1.0vs 2.1% at 2 years) was significant (P < 0.05) while TLR (1.1 vs 1.9% at 1 yr. & 1.1 vs 2.1% at 2 yrs.) and TV-MI (0.9 vs 1.9% at 1 yr. & 1 vs 2.1% at 2 years) were similar for diabetics and non-diabetics so was ST (P > 0.05).

Conclusion: Abluminus-DES+ showed excellent 2-year safety and efficacy with low 3-P MACE which was higher in diabetics driven by higher CV death but similar TLR, TV-MI and ST.

Second generation drug-eluting stents: a focus on safety and efficacy of current devices

Introduction: Percutaneous coronary intervention (PCI) represents the most frequent procedure performed in medicine. Second generation drug eluting stents (DES) have been developed to reduce the rates of late and very late complications of first generation DES.Areas covered: To improve long-term efficacy and safety of patients undergoing PCI, second generation DES have been developed with novel stent platforms, biocompatible durable and biodegradable polymers and newer antiproliferative agents. In this review we provide an overview of second generation DES and their clinical trials, discussing safety and effectiveness of these devices, and outlining clinical indication for use.Expert commentary: Numerous clinical trials have demonstrated the safety and efficacy of second generation DES over the last decade. These devices represent the gold standard treatment in stable and acute coronary syndromes.

10-Year Follow-Up of Patients With Everolimus-Eluting Versus Bare-Metal Stents After ST-Segment Elevation Myocardial Infarction

BACKGROUND

Outcomes data for a durable-polymer everolimus-eluting stent (EES) at extended long-term follow-up in patients with ST-segment elevation myocardial infarction (STEMI) are unknown.

OBJECTIVES

The aim of this study was to assess the 10-year outcomes of patients enrolled in the EXAMINATION (A Clinical Evaluation of Everolimus Eluting Coronary Stents in the Treatment of Patients With ST-Segment Elevation Myocardial Infarction) trial.

METHODS

The EXAMINATION-EXTEND (10-Years Follow-Up of the EXAMINATION Trial) study is an investigator-driven 10-year follow-up of the EXAMINATION trial, which randomly assigned 1,498 patients with STEMI in a 1:1 ratio to receive either EES (n = 751) or bare-metal stents (n = 747). The primary endpoint was a patient-oriented composite endpoint of all-cause death, any myocardial infarction, or any revascularization. Secondary endpoints included a device-oriented composite endpoint of cardiac death, target vessel myocardial infarction, or target lesion revascularization; the individual components of the combined endpoints; and stent thrombosis.

RESULTS

Complete 10-year clinical follow-up was obtained in 94.5% of the EES group and 95.9% of the bare-metal stent group. Rates of the patient-oriented composite endpoint and device-oriented composite endpoint were significantly reduced in the EES group (32.4% vs. 38.0% [hazard ratio: 0.81; 95% confidence interval: 0.68 to 0.96; p = 0.013] and 13.6% vs. 18.4% [hazard ratio: 0.72; 95% confidence interval: 0.55 to 0.93; p = 0.012], respectively), driven mainly by target lesion revascularization (5.7% vs. 8.8%; p = 0.018). The rate of definite stent thrombosis was similar in both groups (2.2% vs. 2.5%; p = 0.590). No differences were found between the groups in terms of target lesion revascularization (1.4% vs. 1.3%; p = 0.963) and definite or probable stent thrombosis (0.6% vs. 0.4%; p = 0.703) between 5 and 10 years.

CONCLUSIONS

At 10-year follow-up, EES demonstrated confirmed superiority in combined patient- and device-oriented composite endpoints compared with bare-metal stents in patients with STEMI requiring primary percutaneous coronary intervention. Between 5- and 10-year follow-up, a low incidence of adverse cardiovascular events related to device failure was found in both groups. (10-Years Follow-Up of the EXAMINATION Trial; NCT04462315).

Vascular endothelial and smooth muscle cell galvanotactic response and differential migratory behavior

Chronic disease or injury of the vasculature impairs the functionality of vascular wall cells particularly in their ability to migrate and repair vascular surfaces. Under pathologic conditions, vascular endothelial cells (ECs) lose their non-thrombogenic properties and decrease their motility. Alternatively, vascular smooth muscle cells (SMCs) may increase motility and proliferation, leading to blood vessel luminal invasion. Current therapies to prevent subsequent blood vessel occlusion commonly mechanically injure vascular cells leading to endothelial denudation and smooth muscle cell luminal migration. Due to this dichotomous migratory behavior, a need exists for modulating vascular cell growth and migration in a more targeted manner. Here, we examine the efficacy of utilizing small direct current electric fields to influence vascular cell-specific migration ("galvanotaxis"). We designed, fabricated, and implemented an in vitro chamber for tracking vascular cell migration direction, distance, and displacement under galvanotactic influence of varying magnitude. Our results indicate that vascular ECs and SMCs have differing responses to galvanotaxis; ECs exhibit a positive correlation of anodal migration while SMCs exhibit minimal change in directional migration in relation to the electric field direction. SMCs exhibit less motility response (i.e. distance traveled in 4 h) compared to ECs, but SMCs show a significantly higher motility at low electric potentials (80 mV/cm). With further investigation and translation, galvanotaxis may be an effective solution for modulation of vascular cell-specific migration, leading to enhanced endothelialization, with coordinate reduced smooth muscle in-migration.

The state-of-the-art coronary stent with crystallized sirolimus: the MiStent technology and its clinical program

Drug-eluting stents (DES) have been developed over recent decades and the implantation of DES is the standard of care in contemporary percutaneous coronary intervention for patients with coronary artery disease. The MiStent sirolimus-eluting stent has several unique features; ultra-thin (64 μm) struts, a bioresorbable polymer and a controlled drug release from microcrystalline sirolimus as a reservoir embedded in the vessel wall. Results of recent clinical trials demonstrated the potential performance of this state-of-the-art DES. In the present review, we provide an overview of the development of DES, in particular the design and performance of the novel MiStent sirolimus-eluting stent from technological and clinical points of view and discuss the potentials of this new type of DES.

Intelligent H2S release coating for regulating vascular remodeling

Coronary atherosclerotic lesions exhibit a low-pH chronic inflammatory response. Due to insufficient drug release control, drug-eluting stent intervention can lead to delayed endothelialization, advanced thrombosis, and unprecise treatment. In this study, hyaluronic acid and chitosan were used to prepare pH-responsive self-assembling films. The hydrogen sulfide (H₂S) releasing aspirin derivative ACS14 was used as drug in the film. The film regulates the release of the drug adjusted to the microenvironment of the lesion, and the drug balances the vascular function by releasing the regulating gas H₂S, which comparably to NO promotes the self-healing capacity of blood vessels. Drug releasing profiles of the films at different pH, and other biological effects on blood vessels were evaluated through blood compatibility, cellular, and implantation experiments. This novel method of self-assembled films which H₂S in an amount, which is adjusted to the condition of the lesion provides a new concept for the treatment of cardiovascular diseases.

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PH-responsive self-assembling films were used to intelligently release the drugs at atherosclerotic lesions.

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As a gaseous signaling molecule, H₂S donor ACS14 was loaded into the films used in the field of cardiovascular disease treatment.

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H₂S can help to regulate vascular remodeling and balance the vascular function.

The Incidence and Possible Predictors of Coronary Restenosis

Objective. Assess time and possible predictors of restenosis after the implantation of first- and second-generation coronary stents and bare metal stents (BMSs) in patients with stable coronary artery disease after elective coronary stenting.

Materials and Methods. From 2010 to 2014, 3,732 (2,897 males, 60 [53; 68] years old) patients with stable exertional angina of functional class I–III underwent coronary stenting. From 2014 to 2017, 1,487 (1,173 males and 314 females) patients returned. Repeat coronary angiography was performed in 699 patients.

Results. A total of 644 first-generation stents, 5,321 second-generation stents, and 473 BMSs were implanted. During the control coronary angiography, contrasting was repeated for 193 first-generation stents, 899 second-generation stents, and 77 BMSs. Restenosis (stenosis of 50 % or more in the previously stented segment) was detected in 28 (14 % of angiographic control) first-generation drug-eluting stents, 94 (10 %) second-generation drug-eluting stents, and 21 (27 %) BMSs. Patients with BMS restenosis returned significantly earlier than patients with restenosis of the first- and second-generation drug-eluting stents (11 [6, 27] months vs. 32 [11; 48]) months and 24 [12; 42] months, respectively; p<0.05). The initial and repeat levels of high-sensitivity C-reactive protein (hs-CRP) were higher in patients with restenosis (2.2 [1.2, 5.0] mg / L vs. 2.1 [1.0, 4.6] mg / L, respectively; p> 0.05) than in patients without restenosis (2.0 [0.9, 4.2] mg / L vs. 1.9 [0.7, 3.5] mg / L respectively, p>0.05). Blood levels of hs-CRP ≥2 mg / L according to receiver operating characteristic curve (ROC) analysis at return visit were used as a predictor to identify restenosis of stents with a diameter <3 mm and a length >25 mm – area under the curve (AUC) 0.67 (95 % confidence interval (CI) 0.51–0.84), p <0.05, odds ratio 3.7 (95 % CI 1.1–12.1), p<0.05. Stent type had a significant effect on the time to restenosis in the survival analysis (p<0.0005).

Conclusion. The time from coronary stenting to the return visit of patients presenting with restenosis after the implantation of first- and second-generation drug-eluting stents is consistent; median time of the return visit of patients with restenosis of the first-generation stents was 2–3 years after coronary stenting. Blood levels of hs-CRP ≥2 mg / L at the return visit is a predictor of restenosis of stents with a diameter <3 mm and a length >25 mm.

Cardiac Risk of Noncardiac Surgery After Percutaneous Coronary Intervention With Second-Generation Drug-Eluting Stents

BACKGROUND

Noncardiac surgery (NCS) following percutaneous coronary intervention (PCI) with stenting is sometimes associated with major adverse cardiac events (MACEs). Second-generation drug-eluting stents (DES) were developed to decrease the incidence of MACE seen with bare metal and first-generation DES.

METHODS

The medical records of all adult patients who underwent second-generation DES placement between July 29, 2008 and July 28, 2011 followed by NCS between September 22, 2008 and July 1, 2013 were reviewed. All episodes of MACE following surgery were recorded.

RESULTS

A total of 282 patients (74.8% male) were identified who underwent NCS after PCI with second-generation DES. MACE occurred in 15 patients (5.3%), including 11 deaths. The incidence of MACE changed significantly with time from PCI to NCS: 17.1%, 10.0%, 0.0%, and 3.1% for patients undergoing NCS at 0-90, 91-180, 181-365, and ≥366 days, respectively. Compared with those having NCS ≥366 days after PCI, the odds ratio for MACE (95% confidence interval) was 6.4 (1.9 to 21.3) at 0-90 days and 3.4 (0.8 to 15.3) at 91-180 days. Seven days prior to NCS, 146 (52%) patients were on dual antiplatelet therapy (DAPT), 106 (38%) were on aspirin, and 30 (11%) did not receive antiplatelet therapy. Excessive surgical bleeding occurred in 19 cases (6.7%). While observed bleeding rates were lowest in those not receiving antiplatelet therapy, there were no statistically significant differences based on the presence or absence of antiplatelet therapy (3% [1/30] for no antiplatelet therapy compared to 6% [6/106] for aspirin monotherapy and 8% [12/146] for DAPT; Fisher exact test: P = .655).

CONCLUSIONS

The incidence of MACE in patients with second-generation DES undergoing NCS was 5.3% and was highest in the first 180 days following DES implantation. The rate of excessive surgical bleeding was 6.7% with the highest observed rate in those on DAPT. However, differences by the presence or absence of antiplatelet therapy were not significant, and future large observational studies will be necessary to further define bleeding risk with continued DAPT.

Augmented re-endothelialization and anti-inflammation of coronary drug-eluting stent by abluminal coating with magnesium hydroxide

Drug-eluting stents (DESs) have been widely used as a treatment approach for coronary artery diseases. Generally, conventional DESs were fully covered with drugs and biodegradable polymers on both abluminal and luminal layers (i.e., conformal coating). However, uncontrolled drug release from the luminal drug-coating layer of the stent is known to inhibit re-endothelialization. Furthermore, the acidification of the surrounding tissue by the decomposed coating polymer causes inflammation, resulting in restenosis and late thrombosis. To overcome these limitations, here we demonstrated a functional DES coated with poly(lactic-co-glycolic acid) (PLGA), sirolimus (SRL), and magnesium hydroxide (Mg(OH)2, MH) precisely only on the abluminal layer. The acidic neutralization effect of MH was elucidated by measuring the pH change of the fabricated film in PBS solution. In an in vitro cell study, the stent coated with MH exhibited higher compatibility with human coronary artery endothelial cells (ECs) and a lower inflammation score as compared to the control stent. Finally, in an in vivo large porcine model, the abluminal coated DES with SRL and MH showed excellent re-endothelialization and anti-inflammatory and anti-thrombotic effects. In conclusion, it is believed that this approach has great potential for the development of functional DES for the treatment of cardiovascular diseases.

Coating of cobalt chrome substrates with thin films of polar/hydrophobic/ionic polyurethanes: Characterization and interaction with human immunoglobulin G and fibronectin

Biomaterial implants often lead to specific tissue reactions that could compromise their bio-integration and/or optimal cellular interactions. Polyurethanes (PU) are of particular interest as coatings to mask CoCr's bioactivity, since they are generally more biocompatible than metal substrates, present a broad range of chemistry, and have highly tunable-mechanical properties. In the current work, complex polyvinyl-urethanes (referred to as D-PHI materials) are studied for their surface phase structures: specifically, an original D-PHI polymer (O-D-PHI) and a differential formulation with relatively higher hydrophobic and ionic content (HHHI) are of interest. The PUs are diluted in tetrahydrofuran (THF) to generate thin films which differentially influence the physical and chemical properties of the D-PHI coatings. AFM images over time show the gradual appearance of domains exhibiting crystalline organisation, and whose shape and size were dependent on D-PHI thickness (thin films vs non-solvent cast resin materials). After three weeks, a complete stabilization of the crystal state is observed. The thin coatings are stable in an aqueous and 37 °C environment. The adsorption of two human plasmatic proteins Immunoglobulin G (IgG) and Fibronectin (Fn), involved in inflammation and coagulation, was studied. The exposure of specific protein sequences (IgG-Fab, Fn-Cell Binding Domain and Fn-N-terminal domain) were dramatically reduced on both D-PHI materials when compared to bare metal CoCr. The implications of these findings would be relevant to defining coating strategies used to improve the blood clotting and immune cell reactivity to CoCr implant materials.

Inhibition of in-stent restenosis after graphene oxide double-layer drug coating with good biocompatibility

In this study, we designed a double layer-coated vascular stent of 316L stainless steel using an ultrasonic spray system to achieve both antiproliferation and antithrombosis. The coating included an inner layer of graphene oxide (GO) loaded with docetaxel (DTX) and an outer layer of carboxymethyl chitosan (CMC) loaded with heparin (Hep). The coated surface was uniform without aggregation and shedding phenomena before and after stent expanded. The coating treatment was able to inhibit the adhesion and activation of platelets and the proliferation and migration of smooth muscle cells, indicating the excellent biocompatibility and antiproliferation ability. The toxicity tests showed that the GO/DTX and CMC/Hep coating did not cause deformity and organ abnormalities in zebrafish under stereomicroscope. The stents with GO double-layer coating were safe and could effectively prevent thrombosis and in-stent restenosis after the implantation into rabbit carotid arteries for 4–12 weeks.

Comparison of the vessel healing process after everolimus-eluting stent and bare metal stent implantations in patients with ST-elevation myocardial infarction

Cobalt-chromium everolimus-eluting stent (CoCr EES) is associated with a lower rate of stent thrombosis even in patients with ST-elevation myocardial infarction (STEMI). However, the time-serial changes of endothelial coverage of the stent struts in the extremely early period have never been reported, especially in patients with STEMI. The aim of this study was to compare the vessel healing process between CoCr EES and cobalt-chromium bare metal stent (CoCr BMS) implantations using optical coherence tomography (OCT) in patients with STEMI. Sixty-three patients who had primary emergent percutaneous coronary intervention (PCI) with CoCr EES (42 patients) or CoCr BMS (21 patients) were enrolled in this study for 3 years. OCT was performed just after, 2 and 12 weeks after EES or BMS implantations. Time-serial changes in the neointimal coverage (NIC), the neointimal thickness, and malapposition of stent struts were evaluated. NIC of stent struts did not differ between CoCr EES (23.2%, 99.4%) and CoCr BMS (24.0%, 97.8%) at 2 weeks and 12 weeks after PCI, respectively. Thicknesses of the neointima on the stent strut was significantly thinner in CoCr EES (34.0 ± 13.8, 107.0 ± 32.4 µm) than in CoCr BMS (40.0 ± 14.6, 115.7 ± 33.8 µm) at 2 weeks and 12 weeks after PCI (p = 0.011, p = 0.008), respectively. The malapposition did not differ just after PCI, and was completely resolved at 12 weeks after PCI in both groups. Thrombus was significantly less in CoCr EES than in CoCr BMS at 2 weeks (19.0% vs 42.9%, p < 0.01), and decreased over time in both groups, but at 12 weeks, disappeared only in CoCr EES (CoCr EES: 0% vs. CoCr BMS: 4.8%, p = 0.56). This study demonstrated that NIC and apposition of the stent struts almost completed at 12 weeks after EES and BMS implantations, while the neointimal thickness on the stent struts were thinner in EES than in BMS. Moreover, thrombus was significantly less in EES than in BMS implantations 2 weeks after PCI, which may explain the lower rate of acute and subacute stent thrombosis of EES compared with BMS.

An asymmetrical dual coating on the stent prepared by ultrasonic atomization

This study aims to design an asymmetric dual coating (ADC) on the stent by ultrasonic atomization to solve the problem of delayed endothelialization and late or very late stent thrombosis which caused by drug eluting stent (DES) with symmetric coating. Chitosan-loaded monoclonal platelet glycoprotein IIIa receptor antibody SZ-21 coating (CSC) was sprayed on inner surface of stents, and outer surface was sprayed CSC and poly(lactic-co-glycolic acid) (PLGA) loaded with docetaxel (DTX) coating (PDC). The coated surface was uniform without aggregation and no shedding phenomenon either before or after stent expanded. Fluorescence labeling has confirmed that the coating has an asymmetric structure. The cumulative release for SZ-21 and DTX was 40.11% and 27.22% within first 24 h, then DTX became the major released drug from 24 h to 7 d, after released for 28 d about 40% of the SZ-21 and 50% DTX still remained on the coated stent. It achieved that ADC can inhibit thrombosis at earlier period and inhibit vascular smooth muscle cells (VSMCs) proliferation at later period. And that ADC has good hemocompatibility and can significantly inhibit VSMCs proliferation. Finally, 4 and 12 weeks after the stent with ADC implanted into rabbit carotid arteries, it showed that the stent with ADC was safe and could effectively prevent thrombosis and in-stent restenosis. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 825-837, 2019.

Rapamycin regulates macrophage activation by inhibiting NLRP3 inflammasome-p38 MAPK-NFκB pathways in autophagy- and p62-dependent manners

Excessive and prolonged activation of macrophages underlies many inflammatory and autoimmune diseases. To regulate activation and maintain homeostasis, macrophages have multiple intrinsic mechanisms, one of which is modulation through autophagy. Here we demonstrate that autophagy induction by rapamycin suppressed the production of IL-1β and IL-18 in lipopolysaccharide- and adenosine triphosphate-activated macrophages at the post-transcriptional level by eliminating mitochondrial ROS (mtROS) and pro-IL1β in a p62/SQSTM1-dependent manner. In addition, rapamycin activated Nrf2 through up-regulation of p62/SQSTM1, which further contributed to the reduction of mtROS. Reduced IL-1β subsequently diminished the activation of p38 MAPK-NFκB pathways, leading to transcriptional down-regulation of IL-6, IL-8, MCP-1, and IκBα in rapamycin-treated macrophages. Therefore, our results suggest that rapamycin negatively regulates macrophage activation by restricting a feedback loop of NLRP3 inflammasome-p38 MAPK-NFκB pathways in autophagy- and p62/SQSTM1-dependent manners.

Crystalline paclitaxel coated DES with bioactive protective layer development

Drug eluting stents (DES) based on polymeric-carriers currently lead the market, however, reports on clinical complications encourage the development of safer and more effective DES. We recently reported on carrier-free DES based on rapamycin crystalline coating as a potential therapeutic solution. Here, we report for the first time surface crystallization of paclitaxel (PT) onto metallic stents. The physicochemical principles of crystallization and key process parameters were extensively studied for fabrication of controllable and homogeneous crystalline coatings on stent scaffolds. Stents loaded with nearly 100μg PT were chosen as a potential therapeutic device with a multilayer coating of 4-7μm thickness. In vitro PT release from these coated stents shows constant release for at least 28days with 10% cumulatively released. The effect of fast dissolving top coating on the physical stability of the coated stent was determined. The top coating enhances the mechanical stability of the crystalline coating during deployment and expansion simulations. Also, incorporating PT in the protective top coating for developing bioactive top coating for multilayer controlled release purpose was intensively studied. This process has wide applications that can be further implemented for other drugs for effective local drug delivery from implantable medical devices.

Undesired Outcomes of the Catania Stent Compared to the Xience Stent in Patients Undergoing Angioplasty: A Double-Blind Randomized Controlled Trial

Background

The present study tries to compare the unintended outcomes of the Catania stent versus Xience stent in patients undergoing angioplasty.

Materials and Methods

In a three month, follow-up, double-blinded, randomized controlled trial, 83 patients undergoing angioplasty, who met the inclusion criteria were entered into the study. After randomization 43 patients were treated with the Xience stent and 40 patients with the Catania stent. Stent-related outcomes such as Cardiac and Non-Cardiovascular Death, Myocardial Infarction (MI), Target Lesion Revascularization (TLR), Stent Thrombosis (ST), Coronary Artery Bypass Grafting (CABG), Peripheral vasculopathy, and Cerebral Vascular Accident (CVA) were compared between the groups.

Results

There was no statistically significant difference in the incidence rate of complications and clinical outcomes between the two treatment groups (P > 0.05). The incidence of MI, TLR, CABG operation, peripheral vasculopathy, or CVA was not observed in any patient and there was no statistically difference in mortality (4.7% vs. 2.5%; P = 0.527) and stent thrombosis (2.3% vs. 2.5%; P = 0.735).

Conclusion

All in all, the present study could not find the significant differences between the Catania stent and Xience stent in terms of clinical outcomes during the follow-up period.

In vitro and in vivo degradation of microfiber bioresorbable coronary scaffold

The degradation of Mirage Bioresorbable Microfiber Scaffold was evaluated in vitro and in vivo. The degradation in polymer molecular weight (MW), strut morphology, and integrity was accessed using gel permeation chromatography (GPC), X‐ray micro‐computed tomography (micro‐CT) evaluation. To simulate the physiological degradation in vitro, scaffolds were deployed in silicone mock vessels connected to a peristaltic pumping system, which pumps 37°C phosphate‐buffered saline (PBS, pH 7.4) at a constant rate. At various time points (30D, 60D, 90D, 180D, 270D, and 360D), the MW of microfibers decreased to 57.3, 49.8, 36.9, 13.9, 6.4, and 5.1% against the baseline. The in vivo degradation study was performed by implanting scaffolds in internal thoracic arteries (ITAs) of mini‐swine. At the scheduled sacrifice time points (30D, 90D, 180D, 270D, 360D, and 540D), the implanted ITAs were excised for GPC analysis; the MW of the implanted scaffolds dropped to 58.5, 34.7, 24.8, 16.1, 12.9, and 7.1, respectively. Mass loss of scaffolds reached 72.4% at 540D of implantation. Two stages of hydrolysis were observed in in vitro and in vivo degradation kinetics, and the statistical analysis suggested a positive correlation between in vivo and in vitro degradation. After 6 months of incubation in animals, significant strut degradation was seen in the micro‐CT evaluation in all sections as strut fragments and separations. The micro‐CT results further confirmed that every sample at 720D had X‐ray transmission similar to surrounding tissue, thereby indicating full degradation within 2 years. © 2017 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1842–1850, 2018.

Comparison of Efficacy and Safety between First and Second Generation Drug-eluting Stents in Patients with Stable Coronary Artery Disease: A Single-center Retrospective Study

BACKGROUND

Lots of trials demonstrate that second-generation drug-eluting stents (G2-DES), with their improved properties, offer significantly superior efficacy and safety profiles compared to first generation DES (G1-DES) for patients with coronary artery disease (CAD) receiving percutaneous coronary intervention (PCI). This study aimed to verify the advantage of G2-DES over G1-DES in Chinese patients with stable CAD (SCAD).

METHODS

For this retrospective observational analysis, 2709 SCAD patients with either G1-DES (n = 863) or G2-DES (n = 1846) were enrolled consecutively throughout 2013. Propensity score matching (PSM) was applied to control differing baseline factors. Two-year outcomes, including major adverse coronary events as well as individual events, including target vessel-related myocardial infarction, target lesion revascularization (TLR), target vessel revascularization, and cardiogenic death were evaluated.

RESULTS

The incidence of revascularization between G1- and G2-DES showed a trend of significant difference with a threshold P - value (8.6% vs. 6.7%, χ2 = 2.995, P = 0.084). G2-DES significantly improved TLR-free survival compared to G1-DES (96.6% vs. 97.9%, P = 0.049) and revascularization-free survival curve showed a trend of improvement of G2-DES (92.0% vs. 93.8%, P = 0.082). These differences diminished after PSM. Multivariate Cox proportional hazard regression analysis showed a trend for G1-associated increase in revascularization (hazard ratio: 1.28, 95% confidence interval: 0.95-1.72, P = 0.099) while no significance was found after PSM. Other endpoints showed no significant differences after multivariate adjustment regardless of PSM.

CONCLUSIONS

G1-DES showed the same safety as G2-DES in this large Chinese cohort of real-world patients. However, G2-DES improved TLR-free survival of SCAD patients 2 years after PCI. The advantage was influenced by baseline clinical factors. G1-DES was associated with a trend of increase in revascularization risk and was not an independent predictor of worse medium-term prognosis compared with G2-DES.

Restenosis of the Coronary Arteries: Past, Present, Future Directions

Restenosis is a pathologic response to vascular injury, characterized by neointimal hyperplasia and progressive narrowing of a stented vessel segment. Although advances in stent design have led to a dramatic reduction in the incidence of restenosis, it continues to represent the most common cause of target lesion failure following percutaneous coronary intervention. Efforts to maximize restenosis prevention, through careful consideration of modifiable risk factors and an individualized approach, are critical, as restenosis, once established, can be particularly difficult to treat. Novel approaches are on the horizon that have the potential to alter the natural history of this stubborn disease.

Stent-induced tracheal stenosis can be predicted by IL-8 expression in rabbits

BACKGROUND

Bare metal stents may cause complications like fibrous encapsulation, granulation and tracheal stenosis. We investigated the behaviour of three commercially available stents in vivo (rabbits) and in vitro (coculture of those stents with epithelial and fibroblast cell lines). Also, we investigated whether development of tracheal stenosis could be predicted by any biological marker.

MATERIALS AND METHODS

The tracheae of 30 rabbits were implanted with either nitinol stents, with or without paclitaxel elution, or a cobalt-based stent. An additional ten rabbits underwent mock implantation (controls). Serial peripheral venous blood samples were taken throughout the study, and several cytokines measured. Animals were euthanized on day 90, with immediate tracheal endoscopy and lavage performed, then necropsy.

RESULTS

Rabbits with cobalt-based stent exhibited more inflammation and the highest stenosis incidence, with reduced survival. Both in vivo and in vitro, this stent induced higher IL-8 levels than nitinol stents. Most important, the presence of stent-induced tracheal stenosis was closely associated to increase in IL-8 expression in blood just 1 day after tracheal stent implantation: a 1·19-fold increase vs. baseline had 83% sensitivity, 83% specificity, 77% positive predictive value, 88% negative predictive value and 83% accuracy to predict development of stenosis.

CONCLUSIONS

The cobalt-based stent had the highest incidence of tracheal inflammation and stenosis. On the other hand, the paclitaxel-eluting nitinol stent did not prevent those complications and provoked a marked reaction compared with the bare nitinol stent. Early increase in IL-8 expression in blood after stent implantation could predict development of tracheal stenosis in rabbits.

Revolution of Drug-Eluting Coronary Stents: An Analysis of Market Leaders

Percutaneous coronary intervention with drug-eluting stents (DES) is a well-established and widely-accepted treatment approach in patients with coronary artery disease. Although the underlying principle of DES remains constant for different stents available on the market, certain factors may offer variations with respect to deliverability (ease of placement), efficacy (preventing restenosis), and safety (thrombosis rates). These factors may include the type of drug (sirolimus, everolimus, biolimus, zotarolimus, novolimus, paclitaxel, docetaxel), type of stent platforms (stainless steel, platinum, cobalt-chromium, cobalt-nickel, platinum-chromium), type of polymers (permanent, biodegradable, polymer-free), thickness of stent struts (thick, thin, ultra-thin), type of coating (abluminal, conformal), and type of stent design (open-cell, closed-cell, combination of open-closed cell). In this context, we present a review on characteristic features of several of the most widely used coronary stents worldwide. Furthermore, the advancements of completely biodegradable stents are discussed. In addition, the future directions for the development of creating an ideal or perfect DES are debated.

One-Year Outcome of Everolimus-Eluting Stents Versus Biolimus-Eluting Stents in Patients Undergoing Percutaneous Coronary Intervention

Background: The biolimus-eluting stent (BES), with a biodegradable polymer, has not been previously compared with the everolimus-eluting stent (EES), as a second-generation drug-eluting stent (DES).We sought to compare the 1-year outcome between the PROMUS^™ stent (EES type) and the BioMatrix^™ stent (BES type). Methods: From March 2008 to September 2011, all patients treated with the PROMUS™ stent or the BioMatrix™ stent for coronary artery stenosis at Tehran Heart Center were enrolled. The primary end points were 1-year adverse events, comprising death, myocardial infarction, target vessel revascularization, and target lesion revascularization. The secondary end point was stent thrombosis. The Cox proportional hazard model was used to assess the adjusted association between the stent type and the follow-up outcome. Results: From 949 patients (66.3% male, mean age =59.48 ± 10.46 y) with 1,018 treated lesions, 591 patients (630 lesions, 65.1% male, mean age = 59.24 ± 10.23 y) received the PROMUS^™ stent and 358 patients (388 lesions, 68.2% male, mean age = 59.88 ± 10.83 y) were treated with the BioMatrix^™ stent. Before adjustment, the rate of the primary end points was 3.2% and 3.4% in the EES and BES, respectively (p value = 0.925, HR _{(EES to BES)} = 1.035, 95% CI: 0.50 to 2.13). The rate of stent thrombosis was 2% and 1.7% in the EES and BES, respectively (p value = 0.698). After adjustment on confounder variables, there was no statistically significant difference in major adverse cardiac events between the PROMUS^™ stent and the BioMatrix^™ stent (p value = 0.598, HR _{(EES to BES)} = 0.817, 95% CI: 0.39 to 1.73). Conclusion: At 1 year's follow-up, the BES and EES showed similar safety and efficacy rates in the patients undergoing percutaneous coronary intervention with a relatively low rate of adverse events in the 2 groups.

Potential therapeutic effects of mTOR inhibition in atherosclerosis

Despite significant improvement in the management of atherosclerosis, this slowly progressing disease continues to affect countless patients around the world. Recently, the mechanistic target of rapamycin (mTOR) has been identified as a pre-eminent factor in the development of atherosclerosis. mTOR is a constitutively active kinase found in two different multiprotein complexes, mTORC1 and mTORC2. Pharmacological interventions with a class of macrolide immunosuppressive drugs, called rapalogs, have shown undeniable evidence of the value of mTORC1 inhibition to prevent the development of atherosclerotic plaques in several animal models. Rapalog-eluting stents have also shown extraordinary results in humans, even though the exact mechanism for this anti-atherosclerotic effect remains elusive. Unfortunately, rapalogs are known to trigger diverse undesirable effects owing to mTORC1 resistance or mTORC2 inhibition. These adverse effects include dyslipidaemia and insulin resistance, both known triggers of atherosclerosis. Several strategies, such as combination therapy with statins and metformin, have been suggested to oppose rapalog-mediated adverse effects. Statins and metformin are known to inhibit mTORC1 indirectly via 5' adenosine monophosphate-activated protein kinase (AMPK) activation and may hold the key to exploit the full potential of mTORC1 inhibition in the treatment of atherosclerosis. Intermittent regimens and dose reduction have also been proposed to improve rapalog's mTORC1 selectivity, thereby reducing mTORC2-related side effects.

MTOR regulates the pro-tumorigenic senescence-associated secretory phenotype by promoting IL1A translation

The TOR (target of rapamycin) kinase limits longevity by poorly understood mechanisms. Rapamycin suppresses the mammalian TORC1 complex, which regulates translation, and extends lifespan in diverse species, including mice. We show that rapamycin selectively blunts the pro-inflammatory phenotype of senescent cells. Cellular senescence suppresses cancer by preventing cell proliferation. However, as senescent cells accumulate with age, the senescence-associated secretory phenotype (SASP) can disrupt tissues and contribute to age-related pathologies, including cancer. MTOR inhibition suppressed the secretion of inflammatory cytokines by senescent cells. Rapamycin reduced IL6 and other cytokine mRNA levels, but selectively suppressed translation of the membrane-bound cytokine IL1A. Reduced IL1A diminished NF-κB transcriptional activity, which controls much of the SASP; exogenous IL1A restored IL6 secretion to rapamycin-treated cells. Importantly, rapamycin suppressed the ability of senescent fibroblasts to stimulate prostate tumour growth in mice. Thus, rapamycin might ameliorate age-related pathologies, including late-life cancer, by suppressing senescence-associated inflammation.

Controlled Slow-Release Drug-Eluting Stents for the Prevention of Coronary Restenosis: Recent Progress and Future Prospects

Drug-eluting stents (DES) have become more widely used by cardiologists than bare metal stents (BMS) because of their better ability to control restenosis. However, recognized negative events, particularly including delayed or incomplete endothelialization and late stent thrombosis, have caused concerns over the long-term safety of DES. Although stent-based drug delivery can facilitate a drug's release directly to the restenosis site, a burst of drug release can seriously affect the pharmacological action and is a major factor accounting for adverse effects. Therefore, the drug release rate has become an important criterion in evaluating DES. The factors affecting the drug release rate include the drug carrier, drug, coating methods, drug storage, elution direction, coating thickness, pore size in the coating, release conditions (release medium, pH value, temperature), and hemodynamics after the stent implantation. A better understanding of how these factors influence drug release is particularly important for the reasonable use of efficient control strategies for drug release. This review summarizes the factors influencing the drug release from DES and presents strategies for enhancing the control of the drug's release, including the stent design, the application of absorbable stents, the development of new polymers, and the application of nanocarriers and improvements in the coating technology. Therefore, this paper provides a reference for the preparation of novel controlled slow-release DES.

A propensity score matched analysis to determine if second-generation drug-eluting stents outperform first-generation drug-eluting stents in a complex patient population

BACKGROUND

Drug-eluting stents (DES) are routinely used in complex patients, but the impact of 1st- versus 2nd-generation DES on clinical outcomes has not been well described. This study aimed to assess the efficacy and safety of 2nd-generation (everolimus-eluting) DES compared to 1st-generation (sirolimus- and paclitaxel-eluting) DES in a selected, higher-risk population with complex clinical and angiographic features.

METHODS

The study included 5693 consecutive patients with the presence of ≥ 1 predefined complex clinical and angiographic characteristic treated with either generation DES. Using propensity score matching, the clinical outcomes of 1076 patients treated with 2nd-generation DES were compared with the outcomes of a matched population treated with 1st-generation DES over 1-year follow-up.

RESULTS

After matching, baseline clinical and angiographic characteristics were similar between groups. At 1-year follow-up, the rate of major adverse cardiac events was 9.4% with 2nd-generation DES and 11.3% with 1st-generation DES (p=0.16). There were no significant differences in the rates of death (3.2 vs. 4.0%, p=0.30), myocardial infarction (1.6 vs. 1.3%, p=0.57), target vessel revascularization (5.9 vs. 7.3%, p=0.17) or target lesion revascularization (4.4 vs. 5.0%, p=0.50). Definite stent thrombosis was less frequent with 2nd-generation DES (0.1 vs. 0.8%, p=0.011), as was definite or probable stent thrombosis (0.7 vs. 1.6%, p=0.040).

CONCLUSION

In this propensity score matched patient population with complex features undergoing percutaneous coronary intervention, the use of 2nd-generation DES was associated with lower rates of stent thrombosis, and similar 1-year major adverse cardiac events compared to 1st-generation DES.