Polymer Free Amphilimus Drug Eluting Stent for Infrapopliteal Arterial Disease in Patients with Critical Limb Ischemia: A New Device in the Armamentarium

Background and Objectives: Endovascular technologies have significantly improved the outcome of patients with critical limb ischemia (CLI). Drug eluting stents (DES) have documented their efficacy against percutaneous transluminal angioplasty (PTA) and bare metal stents (BMS) in infrapopliteal arterial occlusive disease. However, late in-stent neoatherosclerosis may lead to vascular lumen loss and eventually thrombosis. Polymer free DES constitute a new technology aiming to improve long term patency which their action is still under investigation. The purpose of this study is to report the mechanism of action and to provide a literature review of a novel polymer free amphilimus eluting stent (Cre8, Alvimedica, Instabul, Turkey) in infrapopliteal arterial disease. Methods: Publications listed in electronic databases, European Union Drug Regulating Authorities Clinical Trials Database, as well as scientific programmes of recent interventional vascular conferences were searched. Three studies were included. We analyzed primary and secondary patency, major amputation rate, freedom from CD-TLR, and mortality. Results: Cre8 was implanted in 79 patients with CLI. Most of the patients (n = 65) were Rutherford class 5-6 (82.3%), and diabetes mellitus (DM) was present in 66 patients (83.5%). Mean primary patency was 82.5% at 12 months. Mean lesion stented length was 20 mm and 35 mm in two studies. Mean limb salvage was 91.3% at 12 months. Freedom from CD-TLR was reported in two out of the three studies and was 96% and 83.8%. Mortality was 15% and 23.8% in the same studies, whilst it was not reported in one study. Conclusion: Stenting of infrapopliteal arteries with Cre8 is safe and feasible in patients with CLI and diabetes. All studies have shown very good primary patency and freedom from CD-TLR at 12 and 24 months. Larger observational prospective studies and randomized trials are necessary to establish long term effectiveness and clinical outcomes using the non-polymer Cre8 DES.

Co-axial fibrous scaffolds integrating with carbon fiber promote cardiac tissue regeneration post myocardial infarction

Myocardium is an excitable tissue with electrical conductivity and mechanical strength. In this work, carbon fibers (CFs) and co-axial fibrous mesh were integrated which combined the high modulus and excellent electrical conductivity of CFs and the fibrous and porous structures of the electrospun fibers. The scaffold was fabricated by simply integrating coaxial electrospun fibers and carbon fibers through a freeze-drying procedure. It was shown that the integration of carbon fibers have the conductivity and Young's modulus of the fibrous mesh increased significantly, meanwhile, upregulated the expression of CX43, α-actinin, RhoA of the neonatal rat primary cardiomyocytes and primary human umbilical vein endothelial cells (HUVECs), and promoted the secretion of VEGF of HUVECs. Moreover, the cardiomyocytes grown on the scaffolds increased the ability of HUVECs migration. When implanted to the injury area post myocardial infraction, the scaffolds were able to effectively enhance the tissue regeneration and new vessel formation, which rescued the heart dysfunction induced by the myocardial infraction, evidenced by the results of echocardiography and histochemical analysis. In conclusion, the composite scaffolds could promote the myocardium regeneration and function's recovery by enhancing cardiomyocytes maturation and angiogenesis and establishing the crosstalk between the cardiomyocytes and the vascular endothelial cells.

Plasma Modification of Carbon Coating Produced by RF CVD on Oxidized NiTi Shape Memory Alloy under Glow-Discharge Conditions

Our previous work has shown that for cardiac applications, combining low-temperature plasma oxidation with an amorphous carbon coating (a-C:N:H type) constitutes a prospective solution. In this study, a short-term modification by low-temperature oxygen plasma is proposed as an example and a method for shaping the topography and surface energy of the outer amorphous carbon coating, produced via the Radio-Frequency Chemical Vapour Deposition (RFCVD) method on NiTi alloy oxidized under glow-discharge conditions. This treatment alters the chemical composition of the outer zone of the surface layer. A slight increase is also noted in the surface roughness at the nanoscale. The contact angles were shown to increase by about 20% for water and 30% for diiodomethane, while the surface free energy decreased by ca. 11%. The obtained results indicate that even short-term contact with low-temperature plasma can shape the surface properties of the carbon coating, an outcome which shows potential in terms of its use in medical applications.

Use of electron microscopy to study platelets and thrombi

Electron microscopy has been a valuable tool for the study of platelet biology and thrombosis for more than 70 years. Early studies using conventional transmission and scanning electron microscopy (EM) provided a foundation for our initial understanding of platelet structure and how it changes upon platelet activation. EM approaches have since been utilized to study platelets and thrombi in the context of basic, translational and clinical research, and they are instrumental in the diagnosis of multiple platelet function disorders. In this brief review, we provide a sampling of the many contributions EM based studies have made to the field, including both historical highlights and contemporary applications. We will also discuss exciting new imaging modalities based on EM and their utility for the study of platelets, hemostasis and thrombosis into the future.

The Cre8 amphilimus-eluting stent for the treatment of coronary artery disease: safety and efficacy profile

Introduction: Polymer-free drug-eluting stents are designed with stent surface modifications and drug-matrix formulations in order to release antiproliferative agents without the need of a polymer coating. Polymer-free technologies have the potential to overcome complications due to polymer persistence over time, such as local inflammatory reactions, delayed arterial healing, neoatherosclerosis, and subsequent ischemic adverse events.Areas covered: The Cre8 polymer-free amphilimus-eluting stent received CE mark in 2011 and was conceived with the aim of addressing the safety and efficacy limitations of early generation drug-eluting stents based on permanent polymer coatings. Besides the absence of polymer, the main features of the Cre8 stent include the abluminal reservoirs, the passive carbon film coating, and the antiproliferative agent formulation based on sirolimus mixed with free-fatty acid chain - namely amphilimus. This review will focus on the Cre8 development, technical characteristics, preclinical evidence, clinical efficacy and safety, and future perspectives.Expert opinion: The Cre8 stent has shown favorable angiographic and clinical outcomes at short and medium-term follow-up. This technology might provide a benefit in patients with diabetes. Further randomized evidence is required to provide an adequate clinical evaluation of this promising technology in patients with and without diabetes.

Carbon-Coated Stent and the Role of the Kallikrein-Kinin System in Peripheral Angioplasty

OBJECTIVE

The purpose of this study was to investigate the clinical evolution of patients treated with carbon-coated stent, as well as its patency and the inflammatory response triggered by this process through the quantification of serum elements of the kallikrein-kinin system (KKS).

METHODS

This was a single-center prospective study with 27 patients with peripheral artery disease (PAD) who required percutaneous transluminal angioplasty and stenting of the iliacofemoropopliteal segment using carbon-coated stent grafts (carbostents). The blood concentrations of the total and kininogen fractions were evaluated using immunoenzymatic methods. Plasma kallikrein levels were assessed by the colorimetric method and tissue kallikrein levels were evaluated by the spectrophotometric method. The activity of kininase II was measured by -fluorometric analysis.

RESULTS

Of the 27 patients who completed the 6 months of the study (11 iliac territory, 16 femoropopliteal territory), only one experienced restenosis (3.7%) (femoropopliteal segment) and no patient had occlusion (96.3% of patency). In 1 year, four patients were lost to follow-up and all 23 patients evaluated maintained stent patency, except for the patient who had restenosis throughout the first 6 months. We report complete (100%) member salvage in 12 months of follow-up. The activity levels of high- and low-molecular-weight kininogens decreased significantly over time (before vs. 24 h, p < 0.01; before vs. 6 months, p < 0.001, and before vs. 24 h, p < 0.01; before vs. 6 months, p < 0.001; 24 h vs. 6 months, p < 0.001, respectively). Patients also had significantly lower levels of plasma and tissue kallikrein (before vs. 24 h, p < 0.001; before vs. 6 months, p < 0.001, and before vs. 24 h, p < 0.01; before vs. 6 months, p < 0.05, respectively). There was a significant increase in the enzymatic activity of kininase II at 24 h and after 6 months compared to the pre-treatment control (p < 0.001).

CONCLUSION

Our early experience shows that the use of carbon-coated stents in PAD appears to be safe, with low rates of early restenosis (3.7% in the first 6 months and 5% in the 12 months of follow-up). We concluded that KKS was involved in the inflammatory response caused by the placement of carbon-coated stents.

One-year clinical outcomes of patients treated with polymer-free amphilimus-eluting stents or zotarolimus-eluting stents: A propensity-score adjusted analysis

Background

Polymer‐free amphilimus‐eluting stents (PF‐AES) represent a novel elution‐technology in coronary stenting. We aimed to assess 1‐year clinical outcomes of PF‐AES as compared to latest‐generation permanent polymer zotarolimus‐eluting stents (PP‐ZES) in a real‐world all‐comers setting.

Methods

A prospective registry of patients treated with either PF‐AES or PP‐ZES between 2014 and 2016 was conducted. The primary outcome was defined as major adverse cardiac and cerebrovascular events (MACCE), and the secondary outcome was defined as target‐lesion failure (TLF) at 1 year. To account for measured confounders, a propensity‐score adjusted Cox proportional‐hazard model was built to evaluate clinical outcomes.

Results

A total of 734 consecutive patients with 1,269 DES implantations were enrolled. The population was characterized by 28% diabetes, 24% ST‐segment elevation myocardial infarction, and a high number of complex lesions (69%). The rate of MACCE was 11.5% for PF‐AES and 13.6% for PP‐ZES, p_log‐rank = 0.11. TLF was numerically lower in PF‐AES as compared to PP‐ZES (5.4 vs. 6.1%, p_log‐rank = 0.68). After propensity‐score adjustment, PF‐AES showed a trend toward a lower rate of MACCE and a favorable rate of TLF as compared to PP‐ZES (HR 0.70; 95%CI 0.45 to 1.10, P = 0.12; and HR 0.88; 95%CI 0.47 to 1.65, P = 0.68, respectively). Rates of definite ST were low (0.8 vs. 0.3%, p_log‐rank = 0.62).

Conclusions

Our study suggests that implantation of PF‐AES was safe and effective in real‐world patients, with low‐rates of MACCE and TLF at 1 year. Our data needs to be confirmed by a large trial to evaluate the clinical outcomes of this novel polymer‐free, eluting‐technology used in PF‐AES.

A facile synthesis of label-free carbon dots with unique selectivity-tunable characteristics for ferric ion detection and cellular imaging applications

The application of a pH-tuning concept to create specific analytical responses of carbon dots towards a specific targeted metal ion.

Hybrid a-CNH+TiO2+TiN-type surface layers produced on NiTi shape memory alloy for cardiovascular applications

AIM

The goal was to improve the properties of NiTi shape memory alloy to make it suitable for cardiac applications. For this purpose, a hybrid a-CNH+TiO₂+TiN-type surface layer was produced on NiTi alloy and characterized.

MATERIALS & METHODS

The NiTi alloy subjected to hybrid process combining low-temperature oxynitriding under glow discharge conditions and radio frequency chemical vapor deposition process was examined for microstructure, surface topography, corrosion resistance, wettability and surface-free energy, Ni ion release and platelets adhesion, aggregation and activation.

RESULTS

The hybrid surface layers showed slightly increased surface roughness, better corrosion resistance, a more hydrophobic nature, decreased surface free energy, smaller release of nickel ions and reduced platelets activation.

CONCLUSION

The produced layers could expand the range of NiTi medical applications.

Midterm and one-year outcome of amphilimus polymer free drug eluting stent in patients needing short dual antiplatelet therapy. Insight from the ASTUTE registry (AmphilimuS iTalian mUlticenTer rEgistry)

BACKGROUND

To assess clinical outcomes of patients needing short dual antiplatelet therapy (S-DAPT) after PCI with Cre8 polymer-free amphilimus eluting-stent (AES). The Cre8-AES with pure i-Carbofilm coating was supposed to induce faster stent endothelialization and reduce device thrombogenicity.

METHODS

We performed a sub-analysis of unrestricted consecutive patients treated with Cre8-AES between August 2011 and January 2015. Two groups were formed: 1) patients discharged with S-DAPT (≤3-month), because of high bleeding risk or attending urgent non-cardiac surgery; and 2) patients discharged with Recommended DAPT duration (R-DAPT; ≥6-month). The primary ischemic- and bleeding-safety endpoints were Target Vessel Failure (TVF, composite endpoint of cardiac-death, target vessel-myocardial infarction and target vessel-revascularization), and major-bleeding (BARC ≥type-3a) at 6-month and 1-year.

RESULTS

106 patients (8.7%) were discharged with ≤3-month DAPT (83±19days; S-DAPT group) and 1102 patients (90.6%) with ≥6-month DAPT (342±62days; R-DAPT group). Between S-DAPT and R-DAPT groups no significant differences were observed in TVF at 1-year (5.7% vs 5.1%); 1-year BARC major bleeding rate was higher in S-DAPT group (3.4% vs 0.2%, p=0.007) with all bleeding events occurred within 3months. The landmark analysis (started at 90days, ended at 1year) showed no differences in BARC major bleedings between groups (0% vs. 0.3%).

CONCLUSIONS

The results of this multicenter registry show that the use of Cre8 AES in patients needing short DAPT (≤3-month) was safe regarding ischemic events and could favor a reduction of bleeding events related to the recommended DAPT. A large randomized trial is necessary to support these preliminary findings.

Formation of Nanocones on Highly Oriented Pyrolytic Graphite by Oxygen Plasma

Improvement in hemocompatibility of highly oriented pyrolytic graphite (HOPG) by formation of nanostructured surface by oxygen plasma treatment is reported. We have showed that by appropriate fine tuning of plasma and discharge parameters we are able to create nanostructured surface which is densely covered with nanocones. The size of the nanocones strongly depended on treatment time. The optimal results in terms of material hemocompatibility were obtained after treatment with oxygen plasma for 15 s, when both the nanotopography and wettability were the most favorable, since marked reduction in adhesion and activation of platelets was observed on this surface. At prolonged treatment times, the rich surface topography was lost and thus also its antithrombogenic properties. Chemical composition of the surface was always more or less the same, regardless of its morphology and height of the nanocones. Namely, on all plasma treated samples, only a few atomic percent of oxygen was found, meaning that plasma caused mostly etching, leading to changes in the surface morphology. This indicates that the main preventing mechanism against platelets adhesion was the right surface morphology.

Chemico-physical characterisation and in vivo biocompatibility assessment of DLC-coated coronary stents

The vast majority of stent thrombosis occurs in the acute and sub-acute phases and is more common in patients with acute coronary syndromes, due to the thrombotic milieu where stent struts are positioned. Stent thrombosis is likely due to incomplete tissue coverage of metallic stents as the contact between metallic stents and blood elements may lead to platelet adhesion and trigger vessel thrombosis. If a stent is covered after 7 days, the risk that it will be found uncovered at later stages is very low (<1%). In this article, we demonstrate that diamond-like carbon (DLC) coatings, deposited by physical vapour deposition, promote rapid endothelisation of coronary stent devices, with very low platelets activation, reducing thrombotic clots. We relate these behaviours to the surface and bulk material properties of the DLC films, subjected to a comprehensive chemico-physical characterisation using several techniques (X-ray photoelectron spectroscopy, atomic force microscopy, field-emission scanning electron microscope, transmission electron microscopy combined with electron energy loss spectroscopy, Raman and dispersive X-ray spectroscopy). In vivo studies, conducted on 24 pigs, have shown complete endothelisation after 7 days, with no fibrin mesh and with only rare monocytes scattered on the endothelial layer while 30 and 180 days tests have shown reduced inflammatory activation and a complete stabilisation of the vessel healing, with a minimal neointimal proliferation. The integral and permanent DLC film coating improves haemo- and bio-compatibility and leads to an excellent early vessel healing of the stent whilst the extremely thin strut thickness reduces the amount of late neointima and consequently the risk of late restenosis. These data should translate into a reduced acute and sub-acute stent thrombosis.