Early restenosis after drug-eluting stent implantation: A putative role for platelet activation

microRNAs Distinctively Regulate Vascular Smooth Muscle and Endothelial Cells: Functional Implications in Angiogenesis, Atherosclerosis, and In-Stent Restenosis

Endothelial cells (EC) and vascular smooth muscle cells (VSMC) are the main cell types within the vasculature. We describe here how microRNAs (miRs)--noncoding RNAs that can regulate gene expression via translational repression and/or post-transcriptional degradation--distinctively modulate EC and VSMC function in physiology and disease. In particular, the specific roles of miR-126 and miR-143/145, master regulators of EC and VSMC function, respectively, are deeply explored. We also describe the mechanistic role of miRs in the regulation of the pathophysiology of key cardiovascular processes including angiogenesis, atherosclerosis, and in-stent restenosis post-angioplasty. Drawbacks of currently available therapeutic options are discussed, pointing at the challenges and potential clinical opportunities provided by miR-based treatments.

Plasma-induced nanopillars on bare metal coronary stent surface for enhanced endothelialization

An increased risk of late stent thrombosis associated with polymer carriers on the surface of drug-eluting stents remains one of the challenges in cardiovascular stent technology, which has instigated a renewed interest in the polymer-less, bare metal stent approach. As thrombus formation is most likely augmented by the lack of endothelial cell coverage at the exposed stented site, an improved stent surface that enhances cell coverage is essential for viable polymer-less all metal stents. We demonstrate superior endothelial cell growth, more continuous monolayer formation and overall improved endothelialization with nanopillar arrays created via radio frequency plasma surface texturing on our all metallic stent surface of MP35N stent alloy. It is shown that the nanotextured surface significantly up-regulates primary bovine aortic endothelial cell (BAEC) functionality when compared with unprocessed, smooth MP35N surfaces without a nanopillar topography. The desirable presence of transmembrane tight junctions and highly organized monolayer formation was induced by the presence of the nanopillar surface texture. The nanopillar structure also produced a reduced level of oxidative stress in the BAECs. These findings may contribute to new nanotechnology-based surface design concepts for bare metal stents producing advanced cardiovascular implants which mitigate late stent thrombosis.

Rationale and study design of the OISTER trial: optical coherence tomography evaluation of stent struts re-endothelialization in patients with non-ST-elevation acute coronary syndromes--a comparison of the intrEpide tRapidil eluting stent vs. taxus drug-eluting stent implantation

BACKGROUND

Drug-eluting stents (DES) have been designed to prevent restenosis, but long-term clinical outcome may be offset by an increased risk of stent thrombosis, which is associated with suboptimal stent implantation or delayed re-endothelialization. DES implantation has also been associated with local persistent endothelial dysfunction. Conversely, Trapidil is a potent anti-inflammatory, vasodilatator and antiproliferative drug and several studies have shown anti-restenotic effects, suggesting substantial clinical benefits through the use of Trapidil-eluting DES.

STUDY DESIGN

This is a longitudinal, single-blind, double-arm, randomized multicenter study. Forty patients with non-ST-elevation acute coronary syndromes who present at the index procedure with multivessel coronary disease in the major epicardial coronary arteries will be enrolled. Patients should present a culprit lesion with stenosis 70% or more associated with another stenosis 70% or more in another coronary artery. Patients will be randomized in a 1: 1 fashion to receive either an Intrepide trapidil-eluting stent or a Taxus paclitaxel-eluting stent on the culprit lesion. After 90 days, the nonculprit lesion will be treated with the stent of the opposite randomization arm and optical coherence tomography (OCT) analysis of the index stented segment will be performed. Follow-up angiography, combined with vasomotor analysis of endothelial function by rapid atrial pacing, will be done at 12 months after the index procedure on both stents. To further characterize the status of the endothelium, serum measurement of vascular endothelial growth factor gradient between the aorta and 15 mm distal to the implanted stent will be performed at 12 months. The primary endpoint of the study is to compare stent struts re-endothelialization at 90 days by OCT. The secondary endpoint is to compare angiographic outcome and coronary endothelial function 12 months after the index procedure and to compare clinical outcome at 1 and 2 years between trapidil-eluting DES versus paclitaxel-eluting DES.

CONCLUSION

We hypothesize that the utilization of trapidil-eluting DES in the setting of acute coronary syndromes will be characterized by a greater early re-endothelialization associated with an antiproliferative effect offering a similar efficacy with a better safety profile compared with first-generation DES.