Controlling drug delivery from coronary stents: are we aiming for the right targets?

Multimodal effects of asymmetric coating of coronary stents by electrospinning and electrophoretic deposition

Drug-eluting stents (DESs) are drug-coated vascular implants that inhibit smooth muscle cell proliferation and limit in-stent re-stenosis. However, traditional DESs release a single drug into the blood and cannot cope with complex mechanisms in atherosclerosis and body responses. The present study aimed to develop a novel multimodal stent by fabricating asymmetric coating with electrophoretic deposition and electrospinning. Herein, we use heparin-loaded alginate (Hep/Alg) and atorvastatin calcium-loaded polyurethane (AtvCa/PU) coatings on the stent luminal and abluminal surfaces, respectively. Scanning electron microscopy (SEM) micrographs showed that the alginate coatings had uniformity and thin thickness. Meanwhile, the PU fibers were formed without beads, with an acceptable diameter and suitable mechanical properties. PU nanofiber revealed minimal degradation in a 1-month study. The release of AtvCa and Hep continued for 8 days without a significant initial burst release. None of the stent coatings were cytotoxic or hemolytic, and PU nanofibers supported the survival of human umbilical endothelial cells (HUVEC) with high adhesion and flattened morphologies. The results indicate that electrophoretic deposition and electrospinning have significant potential for achieving asymmetric coating on stents and a promising approach for dual drug release for multimodal effects in vascular stent applications.

Bioresorbable drug-eluting scaffolds for treatment of vascular disease

INTRODUCTION

Theoretical advantages of fully bioresorbable scaffold (BRS) stem from transient vessel support without rigid caging. Therefore, it could reduce long-term adverse events associated with the presence of foreign materials.

AREAS COVERED

This article will provide an overview of: drug-eluting BRS for various applications in the treatment of vascular disease; The mechanisms of active agent release from such scaffolds; currently available drug-eluting BRS and their future applications are also discussed.

EXPERT OPINION

The current BRS have been developed in order to achieve optimal vascular patency while providing long-term safety. The clinical efficacy and safety of BRS in coronary treatment have been reported as equal to that of the current metallic drug eluting stents in simple lesions. The application of BRS can potentially be expanded to other vascular beds. The research in bioengineering for the appropriate materials should not only focus on biocompatibility but also should be tailored according to the sites of implantation, which may require different strength and supporting period. The ultimate goal in this field is to develop a biocompatible device that provides equivalent and complementary therapy to other devices, and is able to disappear when the mechanical support and drug delivery are no longer required.