The First-Generation Drug-Eluting Stents and Coronary Endothelial Dysfunction

Novel laser-textured grooves extended to the sidewall edges of CoCr surfaces for rapid and selective endothelialization following coronary artery stenting

The long-term performance of coronary stents is often compromised by delayed endothelialization and late thrombosis, particularly in drug-eluting stents (DES) that impair vascular healing. To address these challenges, we report a novel micro-hierarchical surface modification that integrates sidewall edge structuring into grid patterns on cobalt-chromium (CoCr) stents, enhancing endothelial cell (EC) interactions without compromising mechanical integrity. Laser fabrication was used to create microgrooves (5-30 μm) with extended sidewall edges, designed to promote rapid EC adhesion and proliferation. Comprehensive in vitro evaluations, including EC viability, adhesion, and platelet aggregation assays, demonstrated that stents with grid pattern and sidewall edge structuring on an already fabricated stent enhanced EC viability approximately six-fold compared to the non-patterned controls, reaching 2276 ± 220 cells/ml by day three of culture. The sidewall edges provided possible promising stable anchoring sites and gateway channels, improving EC attachment and selective alignment, while also substantially reducing platelet deposition in grooved regions. To ensure these surface modifications did not affect mechanical performance, comprehensive three-point bending and radial compression tests were conducted. No significant differences were observed compared to coronary stents, confirming that the micro-hierarchical texture with sidewall edges maintains essential mechanical properties. Together, these findings highlight the potential of sidewall edge-integrated grid patterns to accelerate endothelialization and reduce thrombogenic risks, offering a promising strategy for improving the design and long-term performance of next-generation coronary stents.

A comparison of endothelial cell growth on commercial coronary stents with and without laser surface texturing

Complete endothelialisation of coronary stents is an important determinant of future thrombotic complications following coronary stenting. Stent surface texture is an important factor that influences endothelial cell growth. With the emergence of second and third generation coronary stents, is limited comparative data describing endothelial cell growth in contemporary stent platforms, and limited data available on approaches used to rapidly modify the surfaces of commercial coronary stents to improve endothelialisation. In this study we have determined the in vitro proliferation of the primary human coronary artery endothelial cells on the commonly used 4 types of commercial coronary stents and found that the inner surface of BioMatrix drug-eluting stents (DES), after eliminating of the polymer and drug coating, had significantly higher endothelial cell proliferation compared to that of other bare metal stents (BMS): Multi-Link8, Integrity and Omega. The surfaces of the 3 types of BMS which are smooth, displayed similar endothelial cell proliferation, suggesting the importance of surface features in manipulating endothelial cell growth. Laser surface texturing was used to create micro/nano patterns on the stents. The laser treatment has significantly increased endothelial proliferation on the inner surfaces of all 4 types of stents, and Multi-Link8 stents displayed the highest (>100%) improvement. The laser textured BioMatrix stents had the highest absolute number of endothelial cells growth. Our results provided useful information in the endothelialisation potential for the commonly used commercial coronary stents and suggested a potential future application of laser surface bioengineering to coronary stents for better biocompatibility of the device.

mTOR contributes to endothelium-dependent vasorelaxation by promoting eNOS expression and preventing eNOS uncoupling

Clinically used inhibitors of mammalian target of rapamycin (mTOR) negatively impacts endothelial-dependent vasodilatation (EDD) through unidentified mechanisms. Here we show that either the endothelium-specific deletion of Mtor to inhibit both mTOR complexes, or depletion of Raptor or Rictor to disrupt mTORC1 or mTORC2, causes impaired EDD, accompanied by reduced NO in the serum of mice. Consistently, inhibition of mTOR decreases NO production by human and mouse EC. Specifically, inhibition of mTORC1 suppresses eNOS gene expression, due to impairment in p70S6K-mediated posttranscriptional regulation of the transcription factor KLF2 expression. In contrast to mTORC1 inhibition, a positive-feedback between MAPK (p38 and JNK) activation and Nox2 upregulation contributes to the excessive generation of reactive oxygen species (ROS), which causes eNOS uncoupling and decreased NO bioavailability in mTORC2-inhibited EC. Adeno-associated virus-mediated EC-specific overexpression of KLF2 or suppression of Nox2 restores EDD function in endothelial mTORC1- or mTORC2-inhibited mice.

The endothelium-specific inhibition of either of mammalian target of rapamycin (mTOR) complexes impairs endothelial-dependent vasodilatation (EDD), accompanied by decreased nitric oxide bioavailability in both human and mice endothelial cells.

Coronary vasomotion after treatment with drug-coated balloons or drug-eluting stents: a prospective, open-label, single-centre randomised trial

BACKGROUND

Although recent studies have reported that drug-coated balloons (DCB) are non-inferior to drug-eluting stents (DES) for the treatment of native coronary arteries in a specific population, there is no available information concerning vasomotion after treatment with DCB.

AIMS

The aim of this study was to prospectively compare coronary vasomotion in patients with small coronary artery disease treated with DCB versus DES.

METHODS

Forty-two native lesions (2.0-3.0 mm) treated in our institution were randomly assigned to the DCB arm (n=19) or the bioabsorbable polymer everolimus-eluting stents arm (n=23) after successful predilation. At eight months after treatment, endothelium-dependent and -independent vasomotion was evaluated with intracoronary infusions in incremental doses of acetylcholine (right coronary artery: low dose 5 μg, high dose 50 μg; left coronary artery: low dose 10 μg, high dose 100 μg) and nitroglycerine (200 μg). The mean lumen diameter of the distal segment, beginning 5 mm and ending 15 mm distal to the edge of the treated segment, was quantitatively measured by angiography.

RESULTS

The luminal dimension in the treated segment did not differ between groups at the follow-up angiography. The vasoconstriction after acetylcholine infusion was less pronounced in the DCB arm than in the DES arm (low-dose: 6±13% vs -3±18%, p=0.060; high-dose: -4±17% vs -21±29%, p=0.035). The response to nitroglycerine did not differ between groups (17±13% vs 17±22%, p=0.929).

CONCLUSIONS

Vasoconstriction after acetylcholine infusion in the peri-treated region was less pronounced in the DCB arm than in the DES arm, suggesting that endothelial function in treated coronary vessels could be better preserved by DCB than by new-generation DES.

Inhibition of VRK1 suppresses proliferation and migration of vascular smooth muscle cells and intima hyperplasia after injury via mTORC1/β-catenin axis

Characterized by abnormal proliferation and migration of vascular smooth muscle cells (VSMCs), neointima hyperplasia is a hallmark of vascular restenosis after percutaneous vascular interventions. Vaccinia-related kinase 1 (VRK1) is a stress adaption-associated ser/thr protein kinase that can induce the proliferation of various types of cells. However, the role of VRK1 in the proliferation and migration of VSMCs and neointima hyperplasia after vascular injury remains unknown. We observed increased expression of VRK1 in VSMCs subjected to platelet-derived growth factor (PDGF)-BB by western blotting. Silencing VRK1 by shVrk1 reduced the number of Ki-67-positive VSMCs and attenuated the migration of VSMCs. Mechanistically, we found that relative expression levels of β-catenin and effectors of mTOR complex 1 (mTORC1) such as phospho (p)-mammalian target of rapamycin (mTOR), p-S6, and p-4EBP1 were decreased after silencing VRK1. Restoration of β-catenin expression by SKL2001 and re-activation of mTORC1 by Tuberous sclerosis 1 siRNA (siTsc1) both abolished shVrk1-mediated inhibitory effect on VSMC proliferation and migration. siTsc1 also rescued the reduced expression of β-catenin caused by VRK1 inhibition. Furthermore, mTORC1 re-activation failed to recover the attenuated proliferation and migration of VSMC resulting from shVrk1 after silencing β-catenin. We also found that the vascular expression of VRK1 was increased after injury. VRK1 inactivation in vivo inhibited vascular injury-induced neointima hyperplasia in a β-catenindependent manner. These results demonstrate that inhibition of VRK1 can suppress the proliferation and migration of VSMC and neointima hyperplasia after vascular injury via mTORC1/β-catenin pathway.

Cardiovascular Stents: A Review of Past, Current, and Emerging Devices

One of the leading causes of morbidity and mortality worldwide is coronary artery disease, a condition characterized by the narrowing of the artery due to plaque deposits. The standard of care for treating this disease is the introduction of a stent at the lesion site. This life-saving tubular device ensures vessel support, keeping the blood-flow path open so that the cardiac muscle receives its vital nutrients and oxygen supply. Several generations of stents have been iteratively developed towards improving patient outcomes and diminishing adverse side effects following the implanting procedure. Moving from bare-metal stents to drug-eluting stents, and recently reaching bioresorbable stents, this research field is under continuous development. To keep up with how stent technology has advanced in the past few decades, this paper reviews the evolution of these devices, focusing on how they can be further optimized towards creating an ideal vascular scaffold.

Coronary artery bypass graft surgery versus stenting for patients with chronic kidney disease and complex coronary artery disease: a systematic review and meta-analysis

BACKGROUND

The relative role of coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) with stent implantation in patients with chronic kidney disease (CKD) and complex coronary artery disease (CAD) remains debatable due to the lack of randomized controlled trials (RCTs). We therefore performed this meta-analysis to compare the outcomes of the two strategies in CKD patients with multivessel and/or left main disease.

METHODS

Electronic databases including PubMed, EMBASE and Cochrane Library were comprehensively searched to identify the eligible subgroup analysis of RCTs and propensity-matched registries. The primary endpoint was all-cause mortality during the longest follow-up.

RESULTS

Five subgroup analyses of RCTs and six propensity-matched registries involving 26,441 patients were analyzed. Overall, the strategy of CABG was associated with lower risks of long-term mortality [odds ratio (OR) 0.83, 95% confidence interval (CI) 0.74-0.93], myocardial infarction (OR, 0.41; 95% CI, 0.27-0.62), and repeat revascularization (OR, 0.25; 95% CI, 0.16-0.39) compared with PCI in CKD patients with complex CAD. However, CABG was slightly associated with higher risk of stroke than PCI (OR, 1.33; 95% CI, 1.00-1.77). Nonetheless, the higher stroke risk in the CABG group no longer existed during long-term follow-up (OR, 0.92; 95% CI, 0.37-2.25) (>3 years).

CONCLUSION

This meta-analysis supports the current guideline advising CABG for patients with CKD and complex CAD. At the expense of slightly increased risk of stroke, CABG reduces the incidences of long-term all-cause death, myocardial infarction and repeat revascularization compared with PCI.

Fractional Flow Reserve following Percutaneous Coronary Intervention

Fractional flow reserve (FFR) is routinely used to determine lesion severity prior to percutaneous coronary intervention (PCI). However, there is an increasing recognition that FFR may also be useful following PCI to identify mechanisms leading to restenosis and the need for repeat revascularization. Post-PCI FFR is associated with the presence and severity of stent under-expansion and may help identify peri-stent-related complications. FFR pullback may also unmask other functionally significant lesions within the target vessel that were not appreciable on angiography. Recent studies have confirmed the prognostic utility of performing routine post-PCI FFR and suggest possible interventional targets that would improve stent durability. In this review, we detail the theoretical basis underlying post-PCI FFR, provide practical tips to facilitate measurement, and discuss the growing evidence supporting its use.

Assessment of the healing process after percutaneous implantation of a cardiovascular device: a systematic review

The healing process, occurring after intra-cardiac and intra-vascular device implantation, starts with fibrin condensation and attraction of inflammatory cells, followed by the formation of fibrous tissue that slowly covers the device. The duration of this process is variable and may be incomplete, which can lead to thrombus formation, dislodgement of the device or stenosis. To better understand this process and the neotissue formation, animal models were developed: small (rats and rabbits) and large (sheep, pigs, dogs and baboons) animal models for intra-vascular device implantation; sheep and pigs for intra-cardiac device implantation. After intra-vascular and intra-cardiac device implantation in these animal models, in vitro techniques, i.e. histology, which is the gold standard and scanning electron microscopy, were used to assess the device coverage, characterize the cell constitution and detect complications such as thrombosis. In humans, optical coherence tomography and intra-vascular ultrasounds are both invasive modalities used after stent implantation to assess the structure of the vessels, atheroma plaque and complications. Non-invasive techniques (computed tomography and magnetic resonance imaging) are in development in humans and animal models for tissue characterization (fibrosis), device remodeling evaluation and device implantation complications (thrombosis and stenosis). This review aims to (1) present the experimental models used to study this process on cardiac devices; (2) focus on the in vitro techniques and invasive modalities used currently in humans for intra-vascular and intra-cardiac devices and (3) assess the future developments of non-invasive techniques in animal models and humans for intra-cardiac devices.

Implications of coronary artery bypass grafting and percutaneous coronary intervention on disease progression and the resulting changes to the physiology and pathology of the native coronary arteries

Myocardial revascularization can be achieved through 2 different methods: coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI). Clinical trials comparing PCI and CABG generally use the composite end points of death, stroke, myocardial infarction and target vessel revascularization to determine superiority. Other effects of these interventions, including the preservation of normal coronary physiology, the response of the coronary tree to stressors and the response of the vessel wall to the revascularization intervention, are not routinely considered, but these may have significant implications for patients in the medium and long term. For PCI, relatively small differences in clinical outcomes have been reported between bare metal and drug-eluting stents, and the latter seems to have inconsistent and somewhat unpredictable effects on the vascular biology of the coronary arteries. In coronary bypass, the use of arterial conduits is associated with superior clinical outcomes, better long-term patency and the preservation of essentially normal coronary function after intervention. This review assembles the clinical, physiological, angiographic and pathological literature currently available and attempts to provide a more complete picture of the effects of CABG and PCI on coronary arteries.

Development of Dual Drug Eluting Cardiovascular Stent with Ultrathin Flexible Poly(l-lactide-co-caprolactone) Coating

The pleiotropic effects of the atorvastatin-fenofibrate combination can be effectively harnessed for site-specific therapy to minimize stent-related complications. The present study aims to utilize the pleiotropic effects of these two drugs entrapped in a uniform and defect-free coating of poly(l-lactide-co-caprolactone) (PLCL) on a stainless steel stent to overcome stent-associated limitations. The stent coating parameters were optimized using ultrasonic spray coating technique to achieve a thin, smooth, and defect-free dual drug-loaded polymer coating on the stent. The dual drug-loaded polymer coated stent was characterized for surface morphology, thickness and coating integrity. In vitro drug release kinetics of the fabricated stent reveals a sustained release of both drugs for more than 60 days. Significant reduction of thrombus formation and adhesion of lipopolysaccharide-stimulated macrophages on the dual drug containing polymer-coated stent indicates that the drug combination possesses antithrombotic and anti-inflammatory effects. The combination did not adversely influence endothelialization but significantly retarded smooth muscle cell proliferation indicating its potential to overcome restenosis. No bacterial biofilm formation was observed on the stent due to the antibacterial activity of atorvastatin. A rat subcutaneous model was used to evaluate the biocompatibility of the coated stent and compared with the commercial stent. MicroCT, scanning electron microscopy, and morphometric analyses revealed that the coated stents exhibited excellent histocompatibility with no inflammatory response as evidenced from the cytokine levels measured 28 days postimplantation. Our data demonstrates for the first time that the combination of atorvastatin and fenofibrate can be successfully employed in cardiovascular stents to overcome the current limitations of conventional drug-eluting stents.

Non-Inferiority of Resolute Integrity Drug-Eluting Stent to Benchmark Xience Drug-Eluting Stent

BACKGROUND

The Resolute Integrity coronary drug-eluting stent (DES), the next evolution of the Resolute DES, is designed with thinner stent struts and continuous sinusoidal technology to further enhance performance. This study evaluated the performance of the Resolute Integrity DES compared with the historical performance of Xience V.

METHODS AND RESULTS

We assessed the safety, efficacy, and deliverability of Resolute Integrity compared with the Xience DES, the prespecified historical control, in PROPEL, a large, real-world prospective, single-arm, open-label study. A total of 1,204 subjects were enrolled in PROPEL and treated with the Resolute Integrity DES at 76 sites in Japan. Lesion and procedural success rates were 100% and 99%, respectively. Patients were equally complex in the Resolute Integrity and Xience cohorts. At 1 year in the clinical-only cohort, the primary endpoint target lesion failure was 4.3% (34/800) in the Resolute Integrity cohort compared with 8.5% (97/1,142) in the Xience historical controls (P<0.001 for non-inferiority). Target vessel failure, major adverse cardiac events, target vessel myocardial infarction, and the composite cardiac death and target vessel myocardial infarction were all lower with Resolute Integrity compared with Xience, including in "high risk" patients.

CONCLUSIONS

In the large, prospective, multicenter PROPEL trial, the performance of the Resolute Integrity DES was non-inferior to that of the benchmark Xience DES used as a historical comparator.

Analysis of Combined Transcriptomes Identifies Gene Modules that Differentially Respond to Pathogenic Stimulation of Vascular Smooth Muscle and Endothelial Cells

Smooth muscle cells (SMCs) and endothelial cells (ECs) are vital cell types composing the vascular medial wall and the atheroprotective inner lining, respectively. Current treatments for cardiovascular disease inhibit SMC hyperplasia but compromise EC integrity, predisposing patients to thrombosis. Therapeutics targeting SMCs without collateral damage to ECs are highly desirable. However, differential (SMC versus EC) disease-associated regulations remain poorly defined. We conducted RNA-seq experiments to investigate SMC-versus-EC differential transcriptomic dynamics, following treatment of human primary SMCs and ECs with TNFα or IL-1β, both established inducers of SMC hyperplasia and EC dysfunction. As revealed by combined SMC/EC transcriptomes, after TNFα or IL-1β induction, 174 and 213 genes respectively showed greater up-regulation in SMCs than in ECs (SMC-enriched), while 117 and 138 genes showed greater up-regulation in ECs over SMCs (EC-enriched). Analysis of gene interaction networks identified central genes shared in the two SMC-enriched gene sets, and a distinct group of central genes common in the two EC-enriched gene sets. Significantly, four gene modules (subnetworks) were identified from these central genes, including SMC-enriched JUN and FYN modules and EC-enriched SMAD3 and XPO1 modules. These modules may inform potential intervention targets for selective blockage of SMC hyperplasia without endothelial damage.

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.

Advances in Clinical Cardiology 2016: A Summary of the Key Clinical Trials

INTRODUCTION

The findings of many new cardiology clinical trials over the last year have been published or presented at major international meetings. This paper aims to describe and place in context a summary of the key clinical trials in cardiology presented between January and December 2016.

METHODS

The authors reviewed clinical trials presented at major cardiology conferences during 2016 including the American College of Cardiology (ACC), European Association for Percutaneous Cardiovascular Interventions (EuroPCR), European Society of Cardiology (ESC), European Association for the Study of Diabetes (EASD), Transcatheter Cardiovascular Therapeutics (TCT), and the American Heart Association (AHA). Selection criteria were trials with a broad relevance to the cardiology community and those with potential to change current practice.

RESULTS

A total of 57 key cardiology clinical trials were identified for inclusion. Here we describe and place in clinical context the key findings of new data relating to interventional and structural cardiology including delayed stenting following primary angioplasty, contrast-induced nephropathy, management of jailed wires, optimal duration of dual antiplatelet therapy (DAPT), stenting vs bypass for left main disease, new generation stents (BioFreedom, Orsiro, Absorb), transcatheter aortic valve implantation (Edwards Sapien XT, transcatheter embolic protection), and closure devices (Watchman, Amplatzer). New preventative cardiology data include trials of bariatric surgery, empagliflozin, liraglutide, semaglutide, PCSK9 inhibitors (evolocumab and alirocumab), and inclisiran. Antiplatelet therapy trials include platelet function monitoring and ticagrelor vs clopidogrel for peripheral vascular disease. New data are also presented in fields of heart failure (sacubitril/valsartan, aliskiren, spironolactone), atrial fibrillation (rivaroxaban in patients undergoing coronary intervention, edoxaban in DC cardioversion), cardiac devices (implantable cardioverter defibrillator in non-ischemic cardiomyopathy), and electrophysiology (cryoballoon vs radiofrequency ablation).

CONCLUSION

This paper presents a summary of key clinical cardiology trials during the past year and should be of practical value to both clinicians and cardiology researchers.

Unimolecular Micelle-Based Hybrid System for Perivascular Drug Delivery Produces Long-Term Efficacy for Neointima Attenuation in Rats

At present, there are no clinical options for preventing neointima-caused (re)stenosis after open surgery such as bypass surgery for treating flow-limiting vascular disease. Perivascular drug delivery is a promising strategy, but in translational research, it remains a major challenge to achieve long-term (e.g., > 3 months) anti(re)stenotic efficacy. In this study, we engineered a unique drug delivery system consisting of durable unimolecular micelles, formed by single multiarm star amphiphilic block copolymers with only covalent bonds, and a thermosensitive hydrogel formed by a poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide) triblock copolymer (abbreviated as triblock gel) that is stable for about 4 weeks in vitro. The drug-containing unimolecular micelles (UMs) suspended in Triblock gel were able to sustain rapamycin release for over 4 months. Remarkably, even 3 months after perivascular application of the rapamycin-loaded micelles in Triblock gel in the rat model, the intimal/medial area ratio (a restenosis measure) was still 80% inhibited compared to the control treated with empty micelle/gel (no drug). This could not be achieved by applying rapamycin in Triblock gel alone, which reduced the intimal/medial ratio only by 27%. In summary, we created a new UM/Triblock gel hybrid system for perivascular drug delivery, which produced a rare feat of 3-month restenosis inhibition in animal tests. This system exhibits a real potential for further translation into an anti(re)stenotic application with open surgery.

Interleukin-1β is associated with coronary endothelial dysfunction in patients with mTOR-inhibitor-eluting stent implantation

Implantation of mammalian target of rapamycin (mTOR)-inhibitor drug-eluting stents (DESs) impairs coronary endothelial function. There are no known non-invasive biomarkers of coronary endothelial dysfunction. We aimed to assess the association between serum interleukin-1beta (IL-1β) and coronary endothelial dysfunction in patients with mTOR-inhibitor DES implantation and to investigate the association between the mTOR pathway and IL-1β. We enrolled 35 patients who had implanted DESs for coronary artery disease. At a 10-month follow-up, peripheral venous blood samples were collected to measure IL-1β levels. Coronary endothelial dysfunction was evaluated by intracoronary infusion of incremental doses of acetylcholine. Serum IL-1β levels were significantly associated with the magnitude of vasoconstriction to acetylcholine at the segment distal (P < 0.05) but not proximal to the stent. Serum IL-1β levels were positively correlated with stent length (P < 0.05). To examine the direct effects of mTOR inhibition on IL-1β release, sirolimus was incubated in cultured human umbilical vein endothelial cells (HUVECs) or coronary artery smooth muscle cells (CASMCs). Sirolimus directly increased IL-1β mRNA expression (P < 0.01) and enhanced IL-1β release into the culture media (P < 0.01) in CASMCs, but not in HUVECs. Inhibition of mTOR triggers IL-1β release through transcriptional activation in CASMCs. Serum IL-1β levels are a potential biomarker for mTOR-inhibitor DES-associated coronary endothelial dysfunction.

Beneficial Effects of a Novel Bioabsorbable Polymer Coating on Enhanced Coronary Vasoconstricting Responses After Drug-Eluting Stent Implantation in Pigs in Vivo

OBJECTIVES

The aim of this study was to examine which component of drug-eluting stents (DES) plays a major role in enhanced coronary vasoconstricting responses after DES implantation in pigs.

BACKGROUND

Recent studies have reported unremitting angina due to vasomotion abnormalities even after successful DES implantation. However, it remains to be elucidated which component of DES (metal stent, polymer coating, or antiproliferative drug) is responsible for DES-induced coronary hyperconstricting responses.

METHODS

We developed poly-dl-lactic acid and polycaprolactone (PDLLA-PCL) copolymer technology with higher biocompatibility that is resorbed within 3 months. Four types of coronary stents were made: 1) a stent with polylactic acid (PLA) polymer coating containing antiproliferative drug (P1+D+); 2) a stent with PLA polymer coating alone without any drug (P1+D-); 3) a stent with novel PDLLA-PCL polymer coating alone (P2+D-); and 4) a bare metal stent (P-D-). The 4 stents were randomly deployed in the left anterior descending and left circumflex coronary arteries in 12 pigs.

RESULTS

After 1 month, coronary vasoconstriction by intracoronary serotonin was enhanced at P1+D+ and P1+D- stent edges compared with P2+D- and P-D- stent edges and was prevented by a specific Rho-kinase (a central molecule of coronary spasm) inhibitor, hydroxyfasudil. Immunostainings showed that inflammatory changes and Rho-kinase activation were significantly enhanced at P1+D+ and P1+D- sites compared with P2+D- and P-D- sites. There were significant positive correlations between the extent of inflammation or Rho-kinase expression/activation and that of coronary vasoconstriction.

CONCLUSIONS

These results indicate the important roles of PLA polymer coating in DES-induced coronary vasoconstricting responses through inflammatory changes and Rho-kinase activation in pigs in vivo, which are ameliorated by PDLLA-PCL copolymers.

Preserved endothelial vasomotor function after everolimus-eluting stent implantation

AIMS

To compare the degree of endothelial dysfunction (ED) in patients treated with everolimus-eluting stent (EES) versus bare metal stent (BMS) implantation.

METHODS AND RESULTS

This is an observational study. A total of 30 elective patients (15 treated with EES and 15 with BMS) were recruited. All patients underwent coronary angiography and intracoronary acetylcholine (Ach) test at different doses at six months after stent implantation. Quantitative coronary angiography analysis was performed to evaluate the changes in mean luminal diameter (MLD) of the segments distal to the distal stent edge after increasing doses of Ach. Both EES and BMS groups had similar baseline characteristics except for stent length (18.6±2.5 vs. 16.5±2.5 mm; p=0.033) and diameter (3.1±0.2 vs. 3.4±0.3 mm; p=0.007). The vasomotion test showed that EES had 3.14% of MLD decrease after Ach infusion and BMS had 2.35% of vasoconstriction (p=0.62). After adjustment for baseline characteristics, no statistical difference was observed between groups.

CONCLUSIONS

In our study EES implantation was associated with a low degree of ED and had a similar vasomotion response as compared to BMS. Prospective randomised investigations are warranted to confirm these findings.

Prevalence of coronary macro- and micro-vascular dysfunctions after drug-eluting stent implantation without in-stent restenosis

BACKGROUND

The aim was to examine the prevalence and characteristics of epicardial vasomotor abnormality (EVA) and coronary microvascular dysfunction (CMD) including endothelium-dependent (EDCMD) or -independent (EICMD) in patients following a second-generation drug-eluting stent (second DES) implantation without in-stent restenosis.

METHODS AND RESULTS

In 105 patients who underwent second DES implantation in the left anterior descending coronary artery (74 men; mean age, 67.9±9.6years), and in 105 suspected angina patients without stenting (65 men; mean age 66.4±9.1years), we evaluated EVA using the acetylcholine provocation test, EDCMD and EICMD by measuring the coronary flow reserve and the relationship between myocardial ischemia (intracoronary lactate production between aorta and coronary sinus and ST-T changes) or recurrent angina and vascular function. There was no difference in the incidence of EVA between DES and control (49.5% versus 55.2%; P=0.41). Given that the prevalence of CMD was higher in DES than in control (59.0% versus 29.5%; P<0.001), CMD may be associated with stent placement. Of the CMD patients, EDCMD alone, EICMD alone, and both CMDs were found in 40.3%, 22.6%, and 37.1%, respectively. Myocardial ischemia was detected in 42.4% of patients, and recurrent angina was more common in the presence of both EDCMD and EICMD in patients with EVA or CMD compared to patients with normal vascular function (EVA, 42.9% versus 7.7%, P=0.015: CMD, 39.1% versus 7.7%, P=0.007).

CONCLUSIONS

Myocardial ischemia and recurrent angina may be caused by the presence of both EDCMD and EICMD after a second DES implantation without ISR.

Outcomes of DES in Diabetic and Nondiabetic Patients with Complex Coronary Artery Disease after Risk Stratification by the SYNTAX Score

Diabetes mellitus (DM) increases the risk of adverse outcomes after coronary revascularization. Controversy persists regarding the optimal revascularization strategy for diabetic patients with multivessel coronary artery disease (MVD).

Cyclic nucleotide phosphodiesterases in heart and vessels: A therapeutic perspective

Cyclic nucleotide phosphodiesterases (PDEs) degrade the second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), thereby regulating multiple aspects of cardiac and vascular muscle functions. This highly diverse class of enzymes encoded by 21 genes encompasses 11 families that are not only responsible for the termination of cyclic nucleotide signalling, but are also involved in the generation of dynamic microdomains of cAMP and cGMP, controlling specific cell functions in response to various neurohormonal stimuli. In the myocardium and vascular smooth muscle, the PDE3 and PDE4 families predominate, degrading cAMP and thereby regulating cardiac excitation-contraction coupling and smooth muscle contractile tone. PDE3 inhibitors are positive inotropes and vasodilators in humans, but their use is limited to acute heart failure and intermittent claudication. PDE5 is particularly important for the degradation of cGMP in vascular smooth muscle, and PDE5 inhibitors are used to treat erectile dysfunction and pulmonary hypertension. There is experimental evidence that these PDEs, as well as other PDE families, including PDE1, PDE2 and PDE9, may play important roles in cardiac diseases, such as hypertrophy and heart failure, as well as several vascular diseases. After a brief presentation of the cyclic nucleotide pathways in cardiac and vascular cells, and the major characteristics of the PDE superfamily, this review will focus on the current use of PDE inhibitors in cardiovascular diseases, and the recent research developments that could lead to better exploitation of the therapeutic potential of these enzymes in the future.

The effects of plasma electrolytically oxidized NiTi on in vitro endothelialization

The role of biomaterials surface in controlling the interfacial biological events leading to implant integration is of key importance. In this study, the effects of NiTi surfaces treated by plasma electrolytic oxidation (PEO) on human umbilical vein endothelial cells (HUVECs) have been investigated. The changes in NiTi surface morphology and chemistry were assessed by SEM, XPS and cross-section TEM/EDX analyzes whereas the effects of the resultant surfaces on in vitro endothelialization and cell junction proteins have been evaluated by life/dead staining, SEM, cells counting, qPCR and immunofluorescence. The findings indicated that the PEO-treated NiTi, with a microporous morphology and oxide dominated surface chemistry, supports viability and proliferation of HUVECs. Numerous thin filopodia probing the microporous surface assisted cells attachment. In addition, claudin-5 and occludin have been upregulated and expression of vascular endothelial-cadherin was not suppressed on PEO-treated NiTi relative to the reference electropolished surfaces. The results of this study suggest that novel NiTi surfaces may be developed using the PEO process, which can be of benefit to atherosclerosis treatment.

Comparison of Resolute zotarolimus-eluting stents versus everolimus-eluting stents in patients with metabolic syndrome and acute myocardial infarction: propensity score-matched analysis

BACKGROUND

Despite common use of second-generation drug-eluting stents in treating patients with coronary artery disease, there is lack of data comparing these stents exclusively in patients with acute myocardial infarction (AMI), especially with metabolic syndrome (MetS), which is highly prevalent in AMI and potential to worsen clinical outcomes. The aim of this study was to compare clinical outcomes of everolimus-eluting stent (EES) and Resolute-zotarolimus-eluting stent (R-ZES) in AMI patients with MetS, in terms of stent-related and patient-related outcomes.

METHODS

A total of 3942 AMI patients in the KAMIR (Korea Acute Myocardial Infarction Registry) were grouped according to the presence of MetS and stent type: EES (N=1582) and R-ZES (N=255) in MetS (1837). Target lesion failure (TLF) and patient-oriented composite events (POCE) at 1 year were evaluated.

RESULTS

In MetS patients, TLF (3.7% vs. 2.7%, p=0.592) and POCE (7.9% vs. 6.7%, p=0.764) were similar between EES and R-ZES. Also in Non-MetS patients, TLF (3.9% vs. 3.1%, p=0.307) and POCE (6.4% vs. 7.3%, p=0.866) were similar between 2 groups. TLF was similar between MetS and Non-MetS patients (3.6% vs. 3.8%), while POCEs (7.7% vs. 6.6%) were higher in MetS. Propensity-score matching analysis showed similar results between stent groups in MetS and Non-MetS. In multivariate analysis, left ventricular ejection fraction and symptom-to-door time were independent predictors of TLF and POCE in MetS patients with AMI.

CONCLUSIONS

In MetS patients with AMI, EES and R-ZES showed excellent performance and safety. However, patient-oriented composite events were relatively high, suggesting more efforts to improve them.

Effect of a novel peptide, WKYMVm- and sirolimus-coated stent on re-endothelialization and anti-restenosis

The drug-eluting stent still has limitations such as thrombosis and inflammation. These limitations often occur in the absence of endothelialization. This study investigated the effects of WKYMVm- and sirolimus-coated stents on re-endothelialization and anti-restenosis. The WKYMVm peptide, specially synthesized for homing endothelial colony-forming cells, was coated onto a bare-metal stent with hyaluronic acid through a simple dip-coating method (designated HA-Pep). Thereafter, sirolimus was consecutively coated to onto the HA-Pep (designated Pep/SRL). The cellular response to stents by human umbilical-vein endothelial cells and vascular smooth-muscle cells was examined by XTT assay. Stents were implanted into rabbit iliac arteries, isolated 6 weeks post-implantation, and then subjected to histological analysis. The peptide was well attached to the surface of the stents and the sirolimus coating made the surface smooth. The release pattern for sirolimus was similar to that of commercial sirolimus-coated stents (57.2% within 7 days, with further release for up to 28 days). Endothelial-cell proliferation was enhanced in the HA-Pep group after 7 days of culture (38.2 ± 7.62%, compared with controls). On the other hand, the proliferation of smooth-muscle cells was inhibited in the Pep/SRL group after 7 days of culture (40.7 ± 6.71%, compared with controls). In an animal study, the restenosis rates for the Pep/SRL group (13.5 ± 4.50%) and commercial drug-eluting stents (Xience Prime™; 9.2 ± 7.20%) were lower than those for bare-metal stents (25.2 ± 4.52%) and HA-Pep stents (26.9 ± 3.88%). CD31 staining was incomplete for the bare-metal and Xience Prime™ groups. On the other hand, CD31 staining showed a consecutive linear pattern in the HA-Pep and Pep/SRL groups, suggesting that WKYMVm promotes endothelialization. These results indicate that the WKYMVm coating could promote endothelial healing, and consecutive coatings of WKYMVm and sirolimus onto bare-metal stents have a potential role in re-endothelialization and neointimal suppression.

Long-Term Safety of Drug-Eluting and Bare-Metal Stents: Evidence From a Comprehensive Network Meta-Analysis

BACKGROUND

Previous meta-analyses have investigated the relative safety and efficacy profiles of different types of drug-eluting stents (DES) and bare-metal stents (BMS); however, most prior trials in these meta-analyses reported follow-up to only 1 year, and as such, the relative long-term safety and efficacy of these devices are unknown. Many recent studies have now reported extended follow-up data.

OBJECTIVES

This study sought to investigate the long-term safety and efficacy of durable polymer-based DES, bioabsorbable polymer-based biolimus-eluting stents (BES), and BMS by means of network meta-analysis.

METHODS

Randomized controlled trials comparing DES to each other or to BMS were searched through MEDLINE, EMBASE, and Cochrane databases and proceedings of international meetings. Information on study design, inclusion and exclusion criteria, sample characteristics, and clinical outcomes was extracted.

RESULTS

Fifty-one trials that included a total of 52,158 randomized patients with follow-up duration ≥3 years were analyzed. At a median follow-up of 3.8 years, cobalt-chromium everolimus-eluting stents (EES) were associated with lower rates of mortality, definite stent thrombosis (ST), and myocardial infarction than BMS, paclitaxel-eluting stents (PES), and sirolimus-eluting stents (SES) and less ST than BES. Phosphorylcholine-based zotarolimus-eluting stents had lower rates of definite ST than SES and lower rates of myocardial infarction than BMS and PES. The late rates of target-vessel revascularization were reduced with all DES compared with BMS, with cobalt-chromium EES, platinum chromium-EES, SES, and BES also having lower target-vessel revascularization rates than PES.

CONCLUSIONS

After a median follow-up of 3.8 years, all DES demonstrated superior efficacy compared with BMS. Among DES, second-generation devices have substantially improved long-term safety and efficacy outcomes compared with first-generation devices.

Role of cAMP-phosphodiesterase 1C signaling in regulating growth factor receptor stability, vascular smooth muscle cell growth, migration, and neointimal hyperplasia

RATIONALE

Neointimal hyperplasia characterized by abnormal accumulation of vascular smooth muscle cells (SMCs) is a hallmark of occlusive disorders such as atherosclerosis, postangioplasty restenosis, vein graft stenosis, and allograft vasculopathy. Cyclic nucleotides are vital in SMC proliferation and migration, which are regulated by cyclic nucleotide phosphodiesterases (PDEs).

OBJECTIVE

Our goal is to understand the regulation and function of PDEs in SMC pathogenesis of vascular diseases.

METHODS AND RESULTS

We performed screening for genes differentially expressed in normal contractile versus proliferating synthetic SMCs. We observed that PDE1C expression was low in contractile SMCs but drastically elevated in synthetic SMCs in vitro and in various mouse vascular injury models in vivo. In addition, PDE1C was highly induced in neointimal SMCs of human coronary arteries. More importantly, injury-induced neointimal formation was significantly attenuated by PDE1C deficiency or PDE1 inhibition in vivo. PDE1 inhibition suppressed vascular remodeling of human saphenous vein explants ex vivo. In cultured SMCs, PDE1C deficiency or PDE1 inhibition attenuated SMC proliferation and migration. Mechanistic studies revealed that PDE1C plays a critical role in regulating the stability of growth factor receptors, such as PDGF receptor β (PDGFRβ) known to be important in pathological vascular remodeling. PDE1C interacts with low-density lipoprotein receptor-related protein-1 and PDGFRβ, thus regulating PDGFRβ endocytosis and lysosome-dependent degradation in an low-density lipoprotein receptor-related protein-1-dependent manner. A transmembrane adenylyl cyclase cAMP-dependent protein kinase cascade modulated by PDE1C is critical in regulating PDGFRβ degradation.

CONCLUSIONS

These findings demonstrated that PDE1C is an important regulator of SMC proliferation, migration, and neointimal hyperplasia, in part through modulating endosome/lysosome-dependent PDGFRβ protein degradation via low-density lipoprotein receptor-related protein-1.

Bioresorbable scaffolds for percutaneous coronary interventions

Innovations in drug-eluting stents (DES) have substantially reduced rates of in-segment restenosis and early stent thrombosis, improving clinical outcomes following percutaneous coronary interventions (PCI). However a fixed metallic implant in a vessel wall with restored patency and residual disease remains a precipitating factor for sustained local inflammation, in-stent neo-atherosclerosis and impaired vasomotor function increasing the risk for late complications attributed to late or very late stent thrombosis and late target lesion revascularization (TLR) (late catch-up).

The quest for optimal coronary stenting continues by further innovations in stent design and by using biocompatible materials other than cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding, local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics have been recently developed. These devices have been utilized in selected clinical applications so far providing preliminary evidence of safety showing comparable performance with current generation drug-eluting stents (DES).

Herein we provide a comprehensive overview of the current status of these technologies, we elaborate on the potential benefits of transient coronary scaffolds over permanent stents in the context of vascular reparation therapy, and we further focus on the evolving challenges these devices have to overcome to compete with current generation DES. Condensed Abstract:: The quest for optimizing percutaneous coronary interventions continues by iterative innovations in device materials beyond cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding; local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics were recently developed. These devices have been utilized in selected clinical applications providing preliminary evidence of safety showing comparable intermediate term clinical outcomes with current generation drug-eluting stents.

Prognostic value of VEGF in patients submitted to percutaneous coronary intervention

We examined the longitudinal changes of VEGF levels after percutaneous coronary intervention for predicting major adverse cardiac events (MACE) in coronary artery disease (CAD) patients. VEGF was measured in 94 CAD patients' serum before revascularization, 1-month and 1-year after. Independently of clinical presentation, patients had lower VEGF concentration than a cohort of healthy subjects (median, IQ: 15.9, 9.0–264 pg/mL versus 419, 212–758 pg/mL; P < 0.001) at baseline. VEGF increased to 1-month (median, IQ: 276, 167–498 pg/mL; P < 0.001) and remained steady to 1-year (median, IQ: 320, 173–497 pg/mL; P < 0.001) approaching control levels. Drug eluting stent apposition and previous medication intake produced a less steep VEGF evolution after intervention (P < 0.05). Baseline VEGF concentration <40.8 pg/mL conveyed increased risk for MACE in a 5-year follow-up. Results reflect a positive role of VEGF in recovery and support its importance in CAD prognosis.

Current and future perspectives on drug-eluting bioresorbable coronary scaffolds

Despite improvements in stent platform, polymer and drug elution, the permanent metallic stents have significant limitations as they distort vessel physiology, predispose to late thrombosis and may preclude surgical revascularization. Bioresorbable scaffold (BRS) technology has evolved over the last few years to overcome these drawbacks. Actually, different BRS are either available or under clinical and preclinical investigation. However, the use of BRS has largely been restricted to patients recruited into clinical trials with a relatively small number of 'real world' patients treated with these devices. Here, we highlight the potentialities of these devices, describe the evidence from the recent clinical trials and discuss the potential advantages, as well as challenges, that this novel technology may face in routine clinical practice.

An activator of mTOR inhibits oxLDL-induced autophagy and apoptosis in vascular endothelial cells and restricts atherosclerosis in apolipoprotein E⁻/⁻ mice

Oxidized low-density lipoprotein (oxLDL) inhibits mammalian target of rapamycin (mTOR) and induces autophagy and apoptosis in vascular endothelial cells (VECs) that play very critical roles for the cardiovascular homostasis. We recently defined 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO) as a new activator of mTOR. Therefore, we hypothesized that 3BDO had a protective role in VECs and thus stabilized atherosclerotic lesions in apolipoprotein E^-/- (apoE^-/-) mice. Our results showed that oxLDL inhibited the activity of mTOR and increased the protein level of autophagy-related 13 (ATG13) and its dephosphorylation, thus inducing autophagy in human umbilical vein endothelial cells (HUVECs). All of these effects were strongly inhibited by 3BDO. In vivo experiments confirmed that 3BDO activated mTOR and decreased the protein level of ATG13 in the plaque endothelium of apoE^-/- mice. Importantly, 3BDO did not affect the activity of mTOR and autophagy in macrophage cell line RAW246.7 and vascular smooth muscle cells of apoE^-/- mice, but suppressed plaque endothelial cell death and restricted atherosclerosis development in the mice. 3BDO protected VECs by activating mTOR and thus stabilized atherosclerotic lesions in apoE^-/- mice.

Effect of olmesartan on the levels of circulating endothelial progenitor cell after drug-eluting stent implantation in patients receiving statin therapy

BACKGROUND

The endothelial progenitor cell (EPC) plays an important role in repairing vascular injury. Statins and angiotensin II receptor blockers increase the level of circulating EPCs. However, it is unknown whether the angiotensin II receptor blocker olmesartan synergistically acts with statins to increase the levels of circulating EPCs. Moreover, the association between the levels of circulating EPCs and endothelial dysfunction after implantation of drug-eluting stents (DESs) has not been evaluated.

METHODS

Nine patients with stable coronary artery disease underwent percutaneous coronary intervention (PCI) and received DES implantation. All patients received olmesartan in addition to statin therapy after PCI. The dose of olmesartan was based on the physician's discretion as per the patients' blood pressure. The levels of circulating EPCs were analyzed at baseline, post-PCI, and 1, 2, 3, and 8 months after PCI. Coronary angiography and the acetylcholine provocation test were performed on all patients at 8 months.

RESULTS

Although the angiotensin II level significantly changed, the levels of circulating EPCs did not change during 8 months of olmesartan treatment (3.1±0.6cells/ml, 2.5±0.8cells/ml, 2.0±0.6cells/ml, 2.9±0.9cells/ml, 3.0±0.4cells/ml, 3.4±0.8cells/ml, p=0.64). The patients were subsequently divided into two groups based on whether the level of circulating EPCs was less or greater than 4cells/ml at 8 months. There were no significant differences in the mean vessel diameter of each segment (proximal, proximal edge, distal edge, and distal) after the acetylcholine provocation test between the two groups.

CONCLUSIONS

Low-to-moderate doses of olmesartan might not increase the level of circulating EPCs in patients receiving statin therapy. There might be no association between the levels of circulating EPCs and the degree of coronary vasospasm in the acetylcholine provocation test 8 months after DES implantation.

A novel coating of type IV collagen and hyaluronic acid on stent material-titanium for promoting smooth muscle cell contractile phenotype

The method of stent implantation is currently considered an effective means of treating atherosclerosis. However, implanting of cardiovascular stent often leads to intimal breakage and hyperplasia. The phenomenon that vascular smooth muscle cells (SMCs) transform from contractile to synthetic phenotype becomes a serious obstacle to intimal recovery. To improve how SMCs transform from a synthetic to contractile phenotype, a technique of coimmobilization was used to form type IV collagen (CoIV) and hyaluronic acid (HA) coating on the widely used stent material, titanium (Ti). In this work, several bio-functional coatings made of CoIV/HA mixtures in different ratios were fabricated on the Ti surface. The quantitative characterization of CoIV showed that introducing HA could enhance the amount of the immobilized CoIV on the alkali activated Ti (TiOH) surface. The immunofluorescence staining results of myosin heavy chain (MHC) and DAPI showed that the coating of CoIV/HA in ratios of 200 μg/ml (M200) and 500 μg/ml (M500) also could promote SMCs expressing more contractile phenotype compared with TiOH/CoIV control samples, while the AO/PI staining results indicated that SMCs on the M200 and M500 samples showed less apoptosis ratio. Thus, we hope that this study can provide more helpful exploration and application for promoting the SMC contractile phenotype on the cardiovascular stents.

Enhancement of endothelialisation of coronary stents by laser surface engineering

BACKGROUND AND OBJECTIVE

Coronary stents have been widely used in the treatment of coronary heart disease. However, complications have hampered the long-term success of the device. Bare-metal stents (BMS) have a high rate of restenosis and poor endothelialisation. The drug-eluting stents (DES), although dramatically reduce restenosis, significantly prevent endothelialisation leading to late thrombosis and behave the same way as BMS after drug releasing. Rapid adhesion and growth of endothelial cells on the stent surface is a key process for early vascular healing after coronary stenting which contributes to the reduction of major complications. Surface properties manipulate cell growth and directly determine the success and life-span of the implants. However, the ideal surface properties of coronary stents are not yet fully understood. The objective of this research is to understand how surface micro/nano textures and associated material chemistry changes generated by a laser beam affect the behavior of endothelial cells on bare metal 316L stents.

MATERIALS AND METHODS

A high power laser beam was applied to modifying the surface properties of 316L coronary stent material and the commercial coronary stents, followed by examination of the adhesion and proliferation of human coronary endothelial cells that were growing on the surfaces. Surface properties were examined by scanning electron microscopy, contact angle measurement, and X-ray photoelectron spectroscopy.

RESULTS

A novel surface with combined micro/nano features was created on stent material 316L and coronary stent with a specific surface chemistry. This surface gives rise to a threefold increase in the adhesion and eightfold increase in the proliferation of endothelial cells. Interestingly, such effects were only observed when the surface texture was produced in the nitrogen atmosphere suggesting the importance of the surface chemistry, including the dramatic increase of chromium nitride, for the interaction of endothelial cells with the material surface. This novel surface is also super-hydrophilic with close to zero water/cell culture fluid contact angles and low cytotoxicity.

CONCLUSIONS

A novel surface created by laser surface-engineering with a combination of defined surface texture and surface chemistry was found beneficial for the improvement of coronary stent endothelialisation. The technology presented here could work with both DES and BMS with added benefit for the improvement of the biocompatibility of current coronary stents.

Effects of stem cell mobilization by granulocyte colony-stimulating factor on endothelial function after sirolimus-eluting stent implantation: a double-blind, randomized, placebo-controlled clinical trial

BACKGROUND

Stem cell mobilization by granulocyte colony-stimulating factor (G-CSF) has been shown to enhance endothelial healing after spontaneous or iatrogenic arterial disruption. Granulocyte colony-stimulating factor treatment might attenuate endothelial dysfunction after sirolimus-eluting stent (SES) implantation that may be associated with adverse cardiac events during follow-up. This prospective, double-blind, randomized, placebo-controlled study investigated whether G-CSF improved endothelial dysfunction after SES implantation.

METHODS

One hundred patients who underwent SES implantation were randomly assigned to the G-CSF (n = 50) or the placebo group (n = 50). They received daily subcutaneous injection of 300 μg G-CSF or saline for 5 days. Endothelial function was estimated by measuring the coronary vasoreactivity in the segments 15 mm proximal and distal to SES in response to intracoronary infusion of acetylcholine (10(-8) and 10(-7) mol/L) at 9-month follow-up.

RESULTS

Follow-up angiography was performed in 41 G-CSF patients (82%) and 46 placebo patients (92%) (P = .14). Changes in coronary diameter in response to acetylcholine infusion in the proximal segment were not significantly different between the 2 groups. However, vasoconstriction in the distal segment in response to 10(-8) mol/L (-3.9% ± 6.4% vs -7.0% ± 8.1%, P < .05) and 10(-7) mol/L (-8.8% ± 11.0% vs -15.2% ± 7.6%, P < .01) acetylcholine infusion was attenuated in the G-CSF group. Endothelium-independent vasodilatation after nitrate infusion did not differ between the 2 groups.

CONCLUSION

Granulocyte colony-stimulating factor attenuates endothelial dysfunction after SES implantation.

Time course of endothelium-dependent and -independent coronary vasomotor response to coronary balloons and stents. Comparison of plain and drug-eluting balloons and stents

OBJECTIVES

This study sought to determine the time dependency of the endothelium-dependent and -independent vascular responses after percutaneous coronary intervention (PCI) with drug-eluting (DEB) or plain balloons, bare-metal (BMS), and drug-eluting (DES) stents, or controls.

BACKGROUND

Long-term endothelial dysfunction after DES implantation is associated with delayed healing and late thrombosis.

METHODS

Domestic pigs underwent PCI using DEB or plain balloon, BMS, or DES. The dilated and stented segments, and the proximal reference segments of stents and control arteries were explanted at 5-h, 24-h, 1-week, and 1-month follow-up (FUP). Endothelin-induced vasoconstriction and endothelium-dependent and -independent vasodilation of the arterial segments were determined in vitro and were related to histological results.

RESULTS

DES- and BMS-treated arteries showed proneness to vasoconstriction 5 h post-PCI. The endothelium-dependent vasodilation was profoundly (p < 0.05) impaired early after PCI (9.8 ± 3.7%, 13.4 ± 9.2%, 5.7 ± 5.3%, and 7.6 ± 4.7% using plain balloon, DEB, BMS, and DES, respectively), as compared with controls (49.6 ± 9.5%), with slow recovery. In contrast to DES, the endothelium-related vasodilation of vessels treated with plain balloon, DEB, and BMS was increased at 1 month, suggesting enhanced endogenous nitric oxide production of the neointima. The endothelium-independent (vascular smooth muscle-related) vasodilation decreased significantly at 1 day, with slow normalization during FUP. All PCI-treated vessels exhibited imbalance between vasoconstriction-vasodilation, which was more pronounced in DES- and BMS-treated vessels. No correlation between histological parameters and vasomotor function was found, indicating complex interactions between the healing neoendothelium and smooth muscle post-PCI.

CONCLUSIONS

Coronary arteries treated with plain balloon, DEB, BMS, and DES showed time-dependent loss of endothelial-dependent and -independent vasomotor function, with imbalanced contraction/dilation capacity.