Drug-eluting stents signify a major achievement in reducing the incidence of coronary restenosis after percutaneous transluminal coronary angioplasty. However, where drug-eluting stents have been unsuccessful, endoluminal gel-paving strategies offer renewed optimism, mainly in a variety of vascular procedures requiring catheter-based sustained, localized delivery of therapeutic drugs, and biological factors. Despite promising results in animals, endoluminal paving has met with very limited clinical success because of the technical difficulties and stringent safety demands. The current study presents an alternative to gel paving using 40-mum-thick biodegradable polymeric films for deployment onto the artery wall during balloon angioplasty and stenting. The films are made from a durable yet compliant network of alginate and polyethylene glycol (PEG), and are securely held affixed to the vessel wall by the expanded stent struts. The alginate-based films are characterized by measuring their strength, elasticity, degree of swelling, degradability in water and saline, and drug release properties. The combination of alginate and PEG afforded the films sufficient strength and compliance for endoluminal deployment using an in vitro organ culture system. In characterizing the film degradability, it was discovered that the ionic concentration of the buffered saline was the main determinant in regulating the degradation kinetics and the release kinetics of the drug molecule Paclitaxel. These results suggest that the use of alginate-based, PEG-containing polymeric films for endoluminal coverage offers an alternative solution to conventional drug-eluting stents, with the added advantage of uniform endoluminal coverage of the treated segment and homogeneous endoluminal application of the active substance.

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Alginate‐based biomaterials can form naturally derived polymeric hydrogels with sufficient structural integrity to readily be used in many clinical applications. However, ionically cross‐linked alginate gels do not always possess structural properties suitable for application as erodable polymeric films for controlled release of drugs and growth factors. In this study, semi‐rigid polymeric films were constructed of sodium alginate and polyethylene glycol (PEG) by means of a rehydration cross‐linking technique. The films were assembled by dehydrating a solution of alginate and PEG and cross‐linking the alginate during its rehydration with a solution of calcium chloride. The product is a highly dense polymeric network that prevents in vivo cellular infiltration and disassembles primarily by surface erosion. By implanting the PEG‐alginate films into the subcutis of rats, the mechanism of polymer degradation was demonstrated to occur via inflammation‐mediated erosion of the material rather than by means of cellular infiltration. There were extensive areas of foamy macrophages at the site of the implant, indicating a likely mechanism of removal and disposal of the disassembled PEG and alginate polymer. The eroded fragments of the film that remained after six weeks did not exhibit signs of a cellular infiltrate but rather stayed intact, appearing as small, dense fragments of polymer. Our observations that nearly all the PEG‐alginate material was cleared from the implantation site by the sixth postoperative week highlight the potential exploitation of these films as bioresorbable wound dressings with prospective utilization as a drug delivery device. Moreover, the employment of polymeric films made of functionalized PEG, which enables covalent attachment of biological molecules, potentiates their use for growth factor delivery applications.