Thrombotic responses to coronary stents, bioresorbable scaffolds and the Kounis hypersensitivity-associated acute thrombotic syndrome

Recurrent subacute stent thrombosis after drug-eluting stent implantation: a case report

BACKGROUND

While drug-eluting stents (DESs) have revolutionized percutaneous coronary intervention (PCI), early stent-related complications remain challenging. We present a rare case of recurrent subacute stent thrombosis (ST) following DES implantation.

CASE PRESENTATION

A 51-year-old female with acute inferior-posterior myocardial infarction underwent primary PCI with everolimus-eluting stent deployment in the left circumflex artery (LCX). Despite dual antiplatelet therapy, she developed recurrent LCX occlusion at 8 days (subacute ST confirmed by intravascular ultrasound) and 25 days post-PCI. Serial interventions included additional stenting and drug-coated balloon angioplasty. Elevated platelet counts and negative autoimmune marker results suggest potential inadequate platelet inhibition or hypersensitivity reactions.

CONCLUSIONS

This case highlights the diagnostic challenges in differentiating ST from restenosis, emphasizes the role of intravascular imaging, and underscores the need for personalized antiplatelet regimens. Hypersensitivity reactions to stent components and Kounis syndrome should be considered in refractory cases.

Nanotechnology in development of next generation of stent and related medical devices: Current and future aspects

Coronary stents have saved millions of lives in the last three decades by treating atherosclerosis especially, by preventing plaque protrusion and subsequent aneurysms. They attenuate the vascular SMC proliferation and promote reconstruction of the endothelial bed to ensure superior revascularization. With the evolution of modern stent types, nanotechnology has become an integral part of stent technology. Nanocoating and nanosurface fabrication on metallic and polymeric stents have improved their drug loading capacity as well as other mechanical, physico-chemical, and biological properties. Nanofeatures can mimic the natural nanofeatures of vascular tissue and control drug-delivery. This review will highlight the role of nanotechnology in addressing the challenges of coronary stents and the recent advancements in the field of related medical devices. Different generations of stents carrying nanoparticle-based formulations like liposomes, lipid-polymer hybrid NPs, polymeric micelles, and dendrimers are discussed highlighting their roles in local drug delivery and anti-restenotic properties. Drug nanoparticles like Paclitaxel embedded in metal stents are discussed as a feature of first-generation drug-eluting stents. Customized precision stents ensure safe delivery of nanoparticle-mediated genes or concerted transfer of gene, drug, and/or bioactive molecules like antibodies, gene mimics via nanofabricated stents. Nanotechnology can aid such therapies for drug delivery successfully due to its easy scale-up possibilities. However, limitations of this technology such as their potential cytotoxic effects associated with nanoparticle delivery that can trigger hypersensitivity reactions have also been discussed in this review. This article is categorized under: Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Hemocompatibility of all-trans retinoic acid-loaded citrate polymer coatings for vascular stents

Purpose

Current strategies implementing drug-eluting polymer stent coatings fail to fully address the lasting effects of endothelial suppression which ultimately result in delayed reendothelialization and thrombogenic complications. The present study investigates the in vitro hemocompatibility of all-trans retinoic acid loaded poly (1,8-octanediol-co-citrate) coatings (AtRA-POC coatings) for advanced intravascular stent technology. The ability of these materials in supporting endothelial restoration via migration and proliferation while inhibiting smooth muscle cell growth is also explored.

Methods

Using in vitro models, the hemocompatibility of AtRA-loaded POC-coated cobalt chromium (CoCr) vascular stents was evaluated in terms of platelet and inflammatory activity. Platelet activity was quantified by platelet adhesion and platelet activation, further supported by SEM visualization. Inflammatory activity was quantified by the production of proinflammatory cytokines by THP1 monocytes. Lastly, in vitro wound healing and an 5-Ethynyl-2'deoxyuridine (EdU) and pico green DNA assays were used in quantitating endothelial and smooth muscle cell migration and proliferation.

Results

Experimental examinations of platelet adhesion and activation demonstrate significant reductions in the platelet response to POC coated AtRA loaded stents when compared to bare CoCr stents. Such findings reveal AtRA-POC coatings to have significantly improved hemocompatibility compared to that of bare metal stents and at least as good as POC alone. Similarly, in reference to LPS-stimulated controls, Human monocyte-like THP1 cells in culture with AtRA-POC-CoCr stents for 24 hours showed reduced detection of proinflammatory cytokines, comparable to that of bare CoCr and untreated controls. This result supports AtRA-POC coatings as possessing limited immunological potential. Observations from in vitro endothelial and smooth muscle cell investigations demonstrate the ability of the drug AtRA to allow cell processes involved in restoration of the endothelium while inhibiting smooth muscle cell processes.

Conclusion

This study demonstrates AtRA loaded POC coatings are hemocompatible, noninflammatory, and provide a promising strategy in enhancing vascular stent techniques and clinical integration. Possessing hemocompatibility and immunological compatibility that is at least as good as bare metal stents as clinical standards support the use of AtRA-POC coatings for vascular applications. Additionally, selectively reducing smooth muscle cell proliferation while supporting endothelial cell proliferation and migration further demonstrates the potential of these materials in significantly improving the state of vascular stent technology in the area of stent thrombosis and neointimal hyperplasia.

Stentless percutaneous coronary intervention with directional coronary atherectomy and drug-coated balloon angioplasty in worsening angina patients with metal allergies

Metal allergy is a concern in percutaneous coronary intervention (PCI) with stent implantation because of its potential association with poor cardiovascular outcomes, such as stent thrombosis and recurrent in-stent restenosis requiring revascularization. Although stentless PCI with drug-coated balloon (DCB) angioplasty is theoretically useful for patients with metal allergies, DCB angioplasty alone for huge plaques in large vessels may yield inadequate luminal enlargement and coronary deep dissection, leading to insufficient results. Directional coronary atherectomy (DCA) is effective to reduce plaque volume. However, the efficacy of DCA followed by DCB (DCA/DCB) angioplasty in patients with metal allergies has never been described. We present two cases wherein stentless PCI with DCA/DCB angioplasty was an alternative revascularization strategy for patients with metal allergy and concomitant worsening angina pectoris involving proximal left anterior descending artery stenoses. Preoperative evaluation using coronary computed tomography angiography in Case 1 and intravascular ultrasound in Case 2 was useful to determine the possible use of the DCA/DCB procedure for huge plaques in large vessels.

Learning objective

Revascularization for patients with metal allergy with worsening angina pectoris due to stenoses of the proximal main arteries is often challenging because of the necessity to avoid stent implantation. As stentless percutaneous coronary intervention (PCI) is theoretically useful in such settings, PCI with directional coronary atherectomy (DCA)/drug-coated balloon angioplasty can be one of the treatable strategies. Preoperative evaluation of plaque morphology for the suitability of DCA procedure is important.

Cases of allergic coronary syndrome (Kounis syndrome) : what we should know

Kounis syndrome (KS) is an acute coronary syndrome that occurs with allergic, hypersensitivity, anaphylactic, or anaphylactoid reactions associated with mast cell activation, and entails significant morbidity and mortality risks. We present four cases of acute coronary syndrome developing after insect bites, chemotherapy, and coronary stent implantation. Two patients were lost due to anaphylactic shock-related multiorgan failures and sudden cardiac death. Since a wide range of drugs, foods, environmental conditions, and disease states may be associated with KS, all physicians must be aware of the syndrome.

Association of Circulating IgE and CML Levels with In-Stent Restenosis in Type 2 Diabetic Patients with Stable Coronary Artery Disease

Background: We investigated whether serum levels of immunoglobin (Ig) E and Nε-carboxymethyl-lysine (CML) are related to in-stent restenosis (ISR) in patients with stable coronary artery disease and type 2 diabetes mellitus (T2DM). Methods: Serum levels of IgE and CML were measured in 196 ISR patients and 220 non-ISR patients with stable angina and T2DM who received angiographic follow-up 12 months after percutaneous coronary intervention (PCI) with third-generation drug-eluting stent (DES) implantation for de novo lesions. Multivariate logistic regression analysis was performed to assess the association between IgE or CML and ISR. Results: Both IgE and CML levels were higher in patients with ISR compared with non-ISR patients (IgE: 187.10 (63.75−489.65) vs. 80.25 (30.65−202.50), p < 0.001; CML: 203.26 (164.50−266.84) vs. 174.26 (130.85−215.56), p < 0.001). The rate of ISR increased stepwise with increasing tertiles of IgE and CML levels (p for all trends < 0.001), and IgE correlated significantly with CML. After adjusting for potential confounders, IgE and CML levels remained independently associated with ISR. Moreover, IgE and CML levels improved the predictive capability of traditional risk factors for ISR, and there existed an interaction between IgE and CML in relation to ISR (p for interaction < 0.01). Conclusion: Elevated circulating IgE and CML levels confer an increased risk for ISR after DES-based PCI in type 2 diabetic patients with stable coronary artery disease.

Kounis syndrome: from an unexpected case in the Emergency Room to a review of the literature

Kounis syndrome (KS) is a coronary syndrome in the setting of allergic/anaphylactic reactions and can be classified in three variants: vasospastic allergic angina (type I), allergic myocardial infarction (type II) and stent thrombosis (type III). The early diagnosis is of paramount importance for the correct management and the prognosis, being KS a life-threatening emergency condition. KS is not uncommon, but it is frequently unrecognized or undiagnosed in virtue of its broad clinical manifestations. The diagnosis should be based on the combination of cardiovascular and allergic/anaphylactic clinical symptoms and signs, as well as on laboratory, electrocardiographic, echocardiographic, and angiographic evidence. ECG monitoring, cardiac enzymes and troponin are mandatory to confirm or exclude KS in a patient with subclinical or clinical, acute or chronic allergic reactions. Nevertheless, the treatment is a real challenge for the emergency clinicians because guidelines have not been established yet, and the therapy is based on the variant type. We herein report the case of type I KS in a woman with no prior history of allergy, admitted to our emergency department for abdominal pain, nausea and hematochezia. Starting from this case we conducted a systematic search of the following databases: PubMed, Google Scholar, Science Direct, Medline, using the keywords of "Kounis syndrome", "coronary spams", "cardiac arrest", "sudden death", "allergy", and "anaphylaxis". The main purpose of this review is to remind emergency clinicians to keep a high index of suspicion regarding KS when dealing with patients with allergic reactions or anaphylaxis to promptly identify and correctly manage KS.

Comparison of biodegradable and newer generation durable polymer drug-eluting stents with short-term dual antiplatelet therapy: a systematic review and Bayesian network meta-analysis of randomized trials comprising of 43,875 patients

Newer generation durable polymer drug-eluting stents (DP-DES) and biodegradable polymer DES (BP-DES) have similar efficacy with dual-antiplatelet therapy (DAPT) duration of > 6 months. However, this difference in outcomes have not been well studied in shorter DAPT regime. This study compares the safety and efficacy profiles of DP-DES and BP-DES based on short-term (1-3 months), intermediate-term (4-6 months) and standard DAPT (6-12 months) durations. A search was conducted on Embase and Medline for Randomized Controlled Trials (RCTs) comparing stent types, and DAPT durations. Primary endpoints include cardiac death, myocardial infarction (MI), definite stent thrombosis, stroke, target vessel revascularization (TVR) and major bleeding. Network analysis was conducted to summarize the evidence. A total of 15 RCTs involving 43,875 patients were included. DP-DES was associated with significantly lower major bleeding rates compared to BP-DES (RR 0.44, Crl 0.22-0.83) in short-term DAPT. Among DP-DES patients, short-term DAPT was associated with lower major bleeding risk compared to standard DAPT (RR 0.47, CrI 0.32-0.69). This favorable bleeding profile with short DAPT was not found in BP-DES patients. Cardiac death, MI, definite stent thrombosis, stroke and TVR rates were similar across the various DAPT durations and stent types. Our preliminary findings demonstrated comparable efficacy and safety outcomes between BP-DES and newer generation BP-DES across various DAPT durations. In patients requiring short DAPT, DP-DES had more favourable major bleeding profile compared to BP-DES, without compromising anti-thrombotic efficacy.

Jujuboside B Inhibits Neointimal Hyperplasia and Prevents Vascular Smooth Muscle Cell Dedifferentiation, Proliferation, and Migration via Activation of AMPK/PPAR-γ Signaling

The uncontrolled proliferation and migration of vascular smooth muscle cells is a critical step in the pathological process of restenosis caused by vascular intimal hyperplasia. Jujuboside B (JB) is one of the main biologically active ingredients extracted from the seeds of Zizyphus jujuba (SZJ), which has the properties of anti-platelet aggregation and reducing vascular tension. However, its effects on restenosis after vascular intervention caused by VSMCs proliferation and migration remain still unknown. Herein, we present novel data showing that JB treatment could significantly reduce the neointimal hyperplasia of balloon-damaged blood vessels in Sprague-Dawley (SD) rats. In cultured VSMCs, JB pretreatment significantly reduced cell dedifferentiation, proliferation, and migration induced by platelet-derived growth factor-BB (PDGF-BB). JB attenuated autophagy and reactive oxygen species (ROS) production stimulated by PDGF-BB. Besides, JB promoted the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ). Notably, inhibition of AMPK and PPAR-γ partially reversed the ability of JB to resist the proliferation and migration of VSMCs. Taken as a whole, our findings reveal for the first time the anti-restenosis properties of JB in vivo and in vitro after the endovascular intervention. JB antagonizes PDGF-BB-induced phenotypic switch, proliferation, and migration of vascular smooth muscle cells partly through AMPK/PPAR-γ pathway. These results indicate that JB might be a promising clinical candidate drug against in-stent restenosis, which provides a reference for further research on the prevention and treatment of vascular-related diseases.

Effect of degradation products of iron-bioresorbable implants on the physiological behavior of macrophages in vitro

The degradation of bioresorbable metals in vivo changes the physicochemical properties in the environment of an implant, such as a stent in the artery wall, and may induce the alteration of the functions of the surrounding cells. The Fe-degradation, from bioresorbable stents, is a particularly intricate process because it leads to the release of soluble (SDP) and insoluble degradation products (IDP) of varied composition. Macrophages are involved in the resorption of the exogenous agents coming from degradation of these materials. In the present work an Fe⁰ ring, made with a pure Fe wire, in contact with macrophage cell cultures was used to simulate the behaviour of a biodegradable Fe-based implant in a biological environment. Non-invasive time-lapse optical microscopy was applied to obtain images of macrophages exposed to Fe-degradation products, without using staining to avoid distortions and artefacts. It was noticed that as metal degraded, the IDP formed in situ accumulated close to the Fe⁰ ring. In this zone, the macrophages showed a dynamic process of uptake of dark Fe-containing products, confirmed by SEM-EDX. These macrophages showed alterations in the morphology and decrease in the motility and viability. The inability of the macrophages to move and to degrade the engulfed products caused a long persistence of IDP in the zone closest to the metal. The deleterious effects of IDP accumulated close to the ring, were significantly worse than those observed in the experiments made with (1) concentrated salt solutions (Fe³⁺ salt 3 mM), with the same amount of precipitates but uniformly distributed in the well, and (2) diluted salt solutions (Fe³⁺ salt 1 mM) with mainly soluble species. The results were confirmed by standard staining protocols that revealed dead cells close to the Fe⁰ ring and oxidative stress in cells exposed to both soluble and insoluble species.

Interactions at engineered graft-tissue interfaces: A review

The interactions at the graft-tissue interfaces are critical for the results of engraftments post-implantation. To improve the success rate of the implantations, as well as the quality of the patients' life, understanding the possible reactions between artificial materials and the host tissues is helpful in designing new generations of material-based grafts aiming at inducing specific responses from surrounding tissues for their own reparation and regeneration. To help researchers understand the complicated interactions that occur after implantations and to promote the development of better-designed grafts with improved biocompatibility and patient responses, in this review, the topics will be discussed from the basic reactions that occur chronologically at the graft-tissue interfaces after implantations to the existing and potential applications of the mechanisms of such reactions in designing of grafts. It offers a chance to bring up-to-date advances in the field and new strategies of controlling the graft-tissue interfaces.

Insight into the Time Course of Type III Kounis Syndrome: A Case Report

BACKGROUND

Kounis syndrome is a rare condition that is characterized by the coexistence of acute coronary syndrome and allergic reactions; however, its time course remains unclear. We report a case of anaphylactic shock with subsequent development of ST-segment elevation myocardial infarction.

CASE REPORT

A 47-year-old man with food allergies presented to the emergency department of our hospital with breathing difficulties after eating bread. He had a history of angina and underwent stent implantation 3 years earlier. On examination, he was lethargic, disoriented, and in shock. He had a rash on his face and anterior chest wall, as well as severe itching and sweating. Anaphylaxis was diagnosed and, 3 min after presentation, 0.5 mg epinephrine was injected intramuscularly into the right thigh. Electrocardiography, which was recorded 2 min after the administration of epinephrine, was normal; however, chest pain developed suddenly 18 min later. Repeat electrocardiography showed ST-segment elevations, and emergency coronary angiography revealed total occlusion of the left anterior descending coronary artery (i.e., the previous stenting site). Recanalization of the left anterior descending coronary artery was achieved after repeated thrombus aspiration with difficulty, followed by stent implantation inside of the stent under the support of intra-aortic balloon pumping. The clinical course was uneventful. He was discharged and advised to avoid eating wheat and carry an epinephrine self-injection kit for anaphylaxis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The present case highlights the importance of recognizing Kounis syndrome in the management of anaphylactic shock because treatment may be difficult, particularly in patients with type III Kounis syndrome.

A Rat Carotid Artery Pressure-Controlled Segmental Balloon Injury with Periadventitial Therapeutic Application

Cardiovascular disease remains the leading cause of death and disability worldwide, in part due to atherosclerosis. Atherosclerotic plaque narrows the luminal surface area in arteries thereby reducing adequate blood flow to organs and distal tissues. Clinically, revascularization procedures such as balloon angioplasty with or without stent placement aim to restore blood flow. Although these procedures reestablish blood flow by reducing plaque burden, they damage the vessel wall, which initiates the arterial healing response. The prolonged healing response causes arterial restenosis, or re-narrowing, ultimately limiting the long-term success of these revascularization procedures. Therefore, preclinical animal models are integral for analyzing the pathophysiological mechanisms driving restenosis, and provide the opportunity to test novel therapeutic strategies. Murine models are cheaper and easier to operate on than large animal models. Balloon or wire injury are the two commonly accepted injury modalities used in murine models. Balloon injury models in particular mimic the clinical angioplasty procedure and cause adequate damage to the artery for the development of restenosis. Herein we describe the surgical details for performing and histologically analyzing the modified, pressure-controlled rat carotid artery balloon injury model. Additionally, this protocol highlights how local periadventitial application of therapeutics can be used to inhibit neointimal hyperplasia. Lastly, we present light sheet fluorescence microscopy as a novel approach for imaging and visualizing the arterial injury in three-dimensions.

Plaque Rupture-Induced Myocardial Infarction and Mechanical Circulatory Support in Alpha-Gal Allergy

Alpha-gal (AG) allergy is an IgE-mediated allergic reaction to galactose-alpha-1,3-galactose found in mammalian meat. Heparin, being derived from porcine intestinal tissue, may have a degree of cross-reactivity with AG antigen and thus place patients at risk for allergic and even anaphylactic reactions. This is especially important in patients with myocardial infarction (MI) and mechanical circulatory support, such as a left ventricular assist device (LVAD), since anticoagulation is immediately required. Therefore, individualized assessment and preoperative planning is needed regarding the use of heparin vs. nonheparinoid products in such a population.

A case report of Kounis syndrome presenting with a rash, very late stent thrombosis and coronary evaginations

BACKGROUND

Very late stent thrombosis (ST) is a concern in the era of drug-eluting stents (DESs), and ST is associated with peri-DES coronary artery aneurysmal lesions or coronary evaginations. An increasing number of cases of concurrent systemic allergic reaction and ST have been reported as Kounis syndrome (KS) in the literature. The number of patients with very late ST caused by KS is small, and further investigation of the potential pathophysiology is required.

CASE SUMMARY

We report a case of KS that manifested as systemic urticaria followed by very late ST 14 years after placement of two sirolimus-eluting stents (SESs). Three months after the event of ST, coronary evaginations at the stented segments were detected on intravascular optical coherence tomography.

DISCUSSION

Coronary evaginations are associated with local hypersensitivity, stent malapposition, uncovered strut, and flow disturbance that may predispose to ST. Systemic allergic reactions are known to promote platelet adhesion and aggregation. This case of KS suggests a pathophysiology in which the synergic effects between the coronary evaginations and a systemic allergic reaction may contribute to very late ST. For patients with Type 3 KS, performing follow-up intracoronary imaging tests may be important to confirm potential coronary evaginations, especially in patients with SESs.

Total Panax notoginseng saponin inhibits balloon injury-induced neointimal hyperplasia in rat carotid artery models by suppressing pERK/p38 MAPK pathways

Total Panax notoginseng saponin (TPNS) is the main bioactivity compound derived from the roots and rhizomes of Panax notoginseng (Burk.) F.H. Chen. The aim of this study was to investigate the effectiveness of TPNS in treating vascular neointimal hyperplasia in rats and its mechanisms. Male Sprague-Dawley rats were randomly divided into five groups, sham (control), injury, and low, medium, and high dose TPNS (5, 10, and 20 mg/kg). An in vivo 2F Fogarty balloon-induced carotid artery injury model was established in rats. TPNS significantly and dose-dependently reduced balloon injury-induced neointimal area (NIA) (P<0.001, for all doses) and NIA/media area (MA) (P<0.030, for all doses) in the carotid artery of rats, and PCNA expression (P<0.001, all). The mRNA expression of smooth muscle (SM) α-actin was significantly increased in all TPNS groups (P<0.005, for all doses) and the protein expression was significantly increased in the medium (P=0.006) and high dose TPNS (P=0.002) groups compared to the injury group. All the TPNS doses significantly decreased the mRNA expression of c-fos (P<0.001). The medium and high dose TPNS groups significantly suppressed the upregulation of pERK1/2 protein in the NIA (P<0.025) and MA (P<0.004). TPNS dose-dependently inhibited balloon injury-induced activation of pERK/p38MAPK signaling in the carotid artery. TPNS could be a promising agent in inhibiting cell proliferation following vascular injuries.

Atomic Layer Deposition Coating of TiO2 Nano-Thin Films on Magnesium-Zinc Alloys to Enhance Cytocompatibility for Bioresorbable Vascular Stents

Background and purpose

A coronary stent is a well-known cardiovascular medical device implanted to resolve disorders of the circulatory system due to bloodstream narrowing. Since the implanted device interacts with surrounding biological environments, the surface properties of a typical implantable stent play a critical role in its success or failure. Endothelial cell adhesion and proliferation are fundamental criteria needed for the success of a medical device. Metallic coronary stents are commonly used as biomaterial platforms in cardiovascular implants. As a new generation of coronary stents, bioresorbable vascular scaffolds have attracted a great deal of attention among researchers and studies on bioresorbable materials (such as magnesium and zinc) remain a target for further optimization. However, additional surface modification is needed to control the biodegradation of the implant material while promoting biological reactions without the use of drug elution.

Methods

Herein, precise temperature and thickness controlled atomic layer deposition (ALD) was utilized to provide a unique and conformal nanoscale TiO₂ coating on a customized magnesium-zinc stent alloy.

Results

Impressively, results indicated that this TiO₂ nano-thin film coating stimulated coronary arterial endothelial cell adhesion and proliferation with additional features acting as a protective barrier. Data revealed that both surface morphology and surface hydrophilicity contributed to the success of the ALD nanoscale coating, which further acted as a protection layer inhibiting the release of harmful degradation products from the magnesium-zinc stent.

Conclusion

Overall, the outcome of this in vitro study provided a promising ALD stent coating with unique nano-structural surface properties for increased endothelialization, and as a result, ALD should be further studied for numerous biomedical applications.

Recurrent Type III Kounis Syndrome: Will Anti-Immunoglobulin E Drug Be Another Option?

Kounis syndrome was recognized as the concurrence of acute cardiovascular events with hypersensitivity reactions. We report a case of Kounis syndrome type III (coronary thrombosis) variant in a 48-year-old man who had experienced recurrent acute myocardial infarctions after scallion-induced hypersensitivity reactions. After appropriate antithrombotic, antihistamine, and reperfusion strategies, the patient was found to have elevated levels of immunoglobulin E and chronic urticaria. Upon administration of omalizumab, there was an improvement of chronic urticaria, a decrease in immunoglobulin E levels, and resolution of the ischemic attacks.

Anti-CD34-Grafted Magnetic Nanoparticles Promote Endothelial Progenitor Cell Adhesion on an Iron Stent for Rapid Endothelialization

Iron stents, with superior mechanical properties and controllable degradation behavior, have potential for use as feasible substitutes for nondegradable stents in the treatment of coronary artery occlusion. However, corrosion renders the iron surface hard to modify with biological molecules to accelerate endothelialization and solve restenosis. The objective of this study is to demonstrate the feasibility of using endothelial progenitor cells (EPCs) to rapidly adhere onto iron surfaces with the assistance of anti-CD34-modified magnetic nanoparticles. Transmission electron microscopy, Fourier transform infrared spectroscopy, Thermogravimetric analysis, XRD, and anti-CD34 immunofluorescence suggested that anti-CD34 and citric acid were successfully modified onto Fe3O4, and Prussian blue staining demonstrated the selectivity of the as-prepared nanoparticles for EPCs. Under an external magnetic field (EMF), numerous nanoparticles or EPCs attached onto the surface of iron pieces, particularly the side of the iron pieces exposed to flow conditions, because iron could be magnetized under the EMF, and the magnetized iron has an edge effect. However, the uniform adhesion of EPCs on the iron stent was completed because of the weakening edge effect, and the sum of adherent EPCs was closely linked with the magnetic field (MF) intensity, which was validated by the complete covering of EPCs on the iron stent upon exposure to a 300 mT EMF within 3 h, whereas almost no cells were observed on the iron stent without an EMF. These results verify that this method can efficiently promote EPC capture and endothelialization of iron stents.

Kounis Syndrome—not a Single-organ Arterial Disorder but a Multisystem and Multidisciplinary Disease

Coronary symptoms associated with conditions related to mast cell activation and inflammatory cell interactions, such as those involving T-lymphocytes and macrophages, further inducing allergic, hypersensitivity, anaphylactic, or anaphylactic insults, are currently referred to as the Kounis syndrome. Kounis syndrome is caused by inflammatory mediators released during allergic insults, post-inflammatory cell activation, and interactions via multidirectional stimuli. A platelet subset of 20% with high- and low-affinity IgE surface receptors is also involved in this process. Kounis syndrome is not just a single-organ but also a complex multisystem and multi-organ arterial clinical condition; it affects the coronary, mesenteric, and cerebral arteries and is accompanied by allergy–hypersensitivity–anaphylaxis involving the skin, respiratory, and vascular systems in the context of anesthesia, surgery, radiology, oncology, or even dental and psychiatric medicine; further, it has significantly influences both morbidity and mortality. Kounis syndrome might be caused by numerous and continuously increasing causes, with broad clinical symptoms and signs, via multi-organ arterial system involvement, in patients of any age, thereby demonstrating predominant anaphylactic features in terms of a wide spectrum of mast cell-association disorders. Cardiac symptoms, such as chest pain, coronary vasospasm, angina pectoris, myocardial infarction, stent thrombosis, acute cardiac failure, and sudden cardiac death associated with subclinical, clinical, acute, or chronic allergic reactions, constitute the clinical manifestations of this syndrome. Since its first description, a common pathway between allergic and non-allergic coronary events has been demonstrated. The hypothesis is based on the existence of a much higher degree of mast cell degranulation at plaque erosion or rupture sites compared with at the adjacent areas or even more distant segments in post-acute myocardial infarction of non-allergic etiology. Although mast cell activation, differentiation, and mediator release takes days or weeks, the mast cell degranulation may occur just before any acute coronary event, further resulting in coronary artery vasoconstriction and atheromatous plaque rupture. It seems that medications and natural molecules stabilizing the mast cell membrane as well as monoclonal antibodies protecting the mast cell surface can emerge as novel therapeutic modalities for acute coronary and cerebrovascular event prevention.

Microgrooves Encourage Endothelial Cell Adhesion and Organization on Shape-Memory Polymer Surfaces

Cardiovascular stents have become the mainstay for treating coronary and other vascular diseases; however, the need for long-term anti-platelet therapies continues to drive research on novel materials and strategies to promote in situ endothelialization of these devices, which should decrease local thrombotic response. Shape-memory polymers (SMPs) have shown promise as polymer stents due to their self-deployment capabilities and vascular biocompatibility. We previously demonstrated isotropic endothelial cell adhesion on the unmodified surfaces of a family of SMPs previously developed by our group. Here, we evaluate whether endothelial cells align preferentially along microgrooved versus unpatterned surfaces of these SMPs. Results show that micropatterning SMP surfaces enhances natural surface hydrophobicity, which helps promote endothelial cell attachment and alignment along the grooves. With the addition of microgrooves to the SMP surface, this class of SMPs may provide an improved surface and material for next-generation blood-contacting devices.

Postmortem IgE determination in coronary artery disease

Allergic, IgE-mediated inflammation is thought to play a role in atherogenesis and atherosclerotic disease progression. In this study, total IgE and mast cell tryptase were measured in a series of forensic autopsy cases including non-allergic cardiac deaths (14 cases with minimal or no coronary atherosclerosis, 14 cases with significant coronary artery atherosclerosis without acute coronary thrombosis, and 14 cases with significant coronary artery atherosclerosis and acute coronary thrombosis or myocardial infarction) and non-allergic non-cardiac deaths (21 cases with death due to hanging and 21 cases with death due to intracranial gunshot wounds), in order to correlate laboratory results with morphological findings and compare them to conclusions reported in the clinical setting. In cardiac death cases, postmortem serum total IgE levels were increased in 7 out of 42 cases and mast cell tryptase levels were increased in 3 out of 42 cases. In non-cardiac death cases, postmortem serum total IgE levels were not increased in 39 out of 42 cases and mast cell tryptase levels were not increased in any of these cases. These preliminary findings seem to indicate that a portion of coronary deaths characterized by coronary artery atherosclerosis of various severities are also characterized by increased total IgE and mast cell tryptase levels, thus corroborating the data previously reported in both clinical and forensic literature on this topic as well as the necessity of combining morphological investigations focusing on the heart and coronary arteries with biochemical analyses.

Erratum to thrombotic responses to coronary stents, bioresorbable scaffolds and the Kounis hypersensitivity-associated acute thrombotic syndrome

[This corrects the article DOI: 10.21037/jtd.2017.03.134.].

Anaphylactic cardiovascular collapse and Kounis syndrome: systemic vasodilation or coronary vasoconstriction?

The first reported human anaphylactic death is considered to be the Pharaoh Menes death, caused by a wasp sting. Currently, anaphylactic cardiovascular events represent one of most frequent medical emergencies. Rapid diagnosis, prompt and appropriate treatment can be life saving. The main concept beyond anaphylaxis lies to myocardial damage and ventricular dysfunction, thus resulting in cardiovascular collapse. Cardiac output depression due to coronary hypoperfusion from systemic vasodilation, leakage of plasma and volume loss due to increased vascular permeability, as well as reduced venous return, are regarded as the main causes of cardiovascular collapse. Clinical reports and experiments indicate that the human heart, in general, and the coronary arteries, in particular, could be the primary target of the released anaphylactic mediators. Coronary vasoconstriction and thrombosis induced by the released mediators namely histamine, chymase, tryptase, cathepsin D, leukotrienes, thromboxane and platelet activating factor (PAF) can result to further myocardial damage and anaphylaxis associated acute coronary syndrome, the so-called Kounis syndrome. Kounis syndrome with increase of cardiac troponin and other cardiac biomarkers, can progress to heart failure and cardiovascular collapse. In experimental anaphylaxis, cardiac reactions caused by the intracardiac histamine and release of other anaphylactic mediators are followed by secondary cardiovascular reactions, such as cardiac arrhythmias, atrioventricular block, acute myocardial ischemia, decrease in coronary blood flow and cardiac output, cerebral blood flow, left ventricular developed pressure (LVdp/dtmax) as well as increase in portal venous and coronary vascular resistance denoting vascular spasm. Clinically, some patients with anaphylactic myocardial infarction respond satisfactorily to appropriate interventional and medical therapy, while anti-allergic treatment with antihistamines, corticosteroids and fluid replacement might be ineffective. Therefore, differentiating the decrease of cardiac output due to myocardial tissue hypoperfusion from systemic vasodilation and leakage of plasma, from myocardial tissue due to coronary vasoconstriction and thrombosis might be challenging during anaphylactic cardiac collapse. Combined antiallergic, anti-ischemic and antithrombotic treatment seems currently beneficial. Simultaneous measurements of peripheral arterial resistance and coronary blood flow with newer diagnostic techniques including cardiac magnetic resonance imaging (MRI) and myocardial scintigraphy may help elucidating the pathophysiology of anaphylactic cardiovascular collapse, thus rendering treatment more rapid and effective.

Cinnamic aldehyde inhibits vascular smooth muscle cell proliferation and neointimal hyperplasia in Zucker Diabetic Fatty rats

Atherosclerosis remains the number one cause of death and disability worldwide. Atherosclerosis is treated by revascularization procedures to restore blood flow to distal tissue, but these procedures often fail due to restenosis secondary to neointimal hyperplasia. Diabetes mellitus is a metabolic disorder that accelerates both atherosclerosis development and onset of restenosis. Strategies to inhibit restenosis aim at reducing neointimal hyperplasia by inhibiting vascular smooth muscle cell (VSMC) proliferation and migration. Since increased production of reactive oxygen species promotes VSMC proliferation and migration, redox intervention to maintain vascular wall redox homeostasis holds the potential to inhibit arterial restenosis. Cinnamic aldehyde (CA) is an electrophilic Nrf2 activator that has shown therapeutic promise in diabetic rodent models. Nrf2 is a transcription factor that regulates the antioxidant response. Therefore, we hypothesized that CA would activate Nrf2 and would inhibit neointimal hyperplasia after carotid artery balloon injury in the Zucker Diabetic Fatty (ZDF) rat. In primary ZDF VSMC, CA inhibited cell growth by MTT with an EC₅₀ of 118 ± 7 μM. At a therapeutic dose of 100 μM, CA inhibited proliferation of ZDF VSMC in vitro and reduced the proliferative index within the injured artery in vivo, as well as migration of ZDF VSMC in vitro. CA activated the Nrf2 pathway in both ZDF VSMC and injured carotid arteries while also increasing antioxidant defenses and reducing markers of redox dysfunction. Additionally, we noted a significant reduction of neutrophils (69%) and macrophages (78%) within the injured carotid arteries after CA treatment. Lastly, CA inhibited neointimal hyperplasia evidenced by a 53% reduction in the intima:media ratio and a 61% reduction in vessel occlusion compared to arteries treated with vehicle alone. Overall CA was capable of activating Nrf2, and inhibiting neointimal hyperplasia after balloon injury in a rat model of diabetic restenosis.

Allergic recurrent coronary stent thrombosis: A mini-review of Kounis syndrome

Kounis syndrome (KS) consists of an association between hypersensitivity reactions triggered by various environmental and pharmacological factors and acute coronary syndromes. Blood supply may be compromised by either vasospasm (type I), native plaque destabilization (type II) or stent thrombosis (type III). Although the prognosis is generally favorable, treatment should include aggressive anti-thrombotic and anti-allergic therapies. A case compatible with type III KS, manifested as a macular rash followed by two episodes of stent thrombosis after primary angioplasty (PCI) of the right coronary artery is presented, and complemented by a review on the topic.

Insights on Localized and Systemic Delivery of Redox-Based Therapeutics

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