Bioresorbable Scaffolds in Percutaneous Coronary Intervention: Facing Old Problems, Raising New Hopes

Hybrid interpenetrating network of polyester coronary stent with tunable biodegradation and mechanical properties

Poly(l-lactide) (PLLA) is an important candidate raw material of the next-generation biodegradable stent for percutaneous coronary intervention, yet how to make a polyester stent with sufficient mechanical strength and relatively fast biodegradation gets to be a dilemma. Herein, we put forward a hybrid interpenetrating network (H-IPN) strategy to resolve this dilemma. As such, we synthesize a multi-functional biodegradable macromer of star-like poly(d,l-lactide-co-ɛ-caprolactone) with six acrylate end groups, and photoinitiate it, after mixing with linear PLLA homopolymer, to trigger the free radical polymerization. The resultant crosslinked polymer blend is different from the classic semi-interpenetrating network, and partial chemical crosslinking occurs between the linear polymer and the macromer network. Combined with the tube blow molding and the postprocessing laser cutting, we fabricate a semi-crosslinked-polyester biodegradable coronary stent composed of H-IPN, which includes a physical network of polyester spherulites and a chemical crosslinking network of copolyester macromers and a part of homopolymers. Compared with the currently main-stream PLLA stent in research, this H-IPN stent realizes a higher and more appropriate biodegradation rate while maintaining sufficient radial strength. A series of polymer chemistry, polymer physics, polymer processing, and in vitro and in vivo biological assessments of medical devices have been made to examine the H-IPN material. The interventional implanting of the H-IPN stent into aorta abdominalis of rabbits and the follow-ups to 12 months have confirmed the safety and effectiveness.

Development of Innovative Biomaterials and Devices for the Treatment of Cardiovascular Diseases

Cardiovascular diseases have become the leading cause of death worldwide. The increasing burden of cardiovascular diseases has become a major public health problem and how to carry out efficient and reliable treatment of cardiovascular diseases has become an urgent global problem to be solved. Recently, implantable biomaterials and devices, especially minimally invasive interventional ones, such as vascular stents, artificial heart valves, bioprosthetic cardiac occluders, artificial graft cardiac patches, atrial shunts, and injectable hydrogels against heart failure, have become the most effective means in the treatment of cardiovascular diseases. Herein, an overview of the challenges and research frontier of innovative biomaterials and devices for the treatment of cardiovascular diseases is provided, and their future development directions are discussed.

Current perspectives on bioresorbable scaffolds in coronary intervention and other fields

Introduction: The first-generation bioresorbable scaffolds (BRSs) had a large strut profile to compensate for the insufficient radial strength of bioresorbable polymer materials, resulting in higher scaffold thrombosis rates than conventional drug-eluting stents. To improve the clinical safety and efficacy, the new generation BRSs have been improved by optimal structure design, post-processing of bioresorbable polymer materials, or altering bioresorbable metallic alloys.Areas covered: This review summarizes the lessons learned from the first-generation BRS, updates the clinical outcomes of trials evaluating ABSORB bioresorbable vascular scaffold at long-term and bioresorbable metallic alloy-based devices, and examines recent outcomes of BRS treated in STEMI patients. This review also provides an overview of the current clinical data of seven BRSs manufactured in Asia, and of the BRSs extended application in other clinical arenas.Expert opinion: Drawbacks of the first-generation BRSs need to be addressed by the next generation of these stents with novel materials and technologies. Clinical research, including randomized controlled trials, are required to further evaluate BRSs application in coronary artery disease. The encouraging results of BRSs innovation applied in the peripheral arteries and gastrointestinal tracts support other potential clinical applications of BRS technology.