Blood-compatible and biodegradable polymer-coated drug-eluting stent

A drug-eluting stent (DES) is a metal stent that has been coated with a drug known to suppress restenosis. To prepare a novel DES, a bare metal stent (BMS) was coated with sirolimus (SRL) in a blood-compatible, biodegradable polymer, poly lactic-glycolic acid, grafted with poly ethylene glycol (PLGA-PEG), by an ultrasonic spray method. The PLGA-PEG-coated DES was designed to control the drug release-rate by varying the PEG content in the polymer. The release behavior of SRL from the DES showed a burst-release pattern in 7 days and then sustained-release over 21 days. The amount of SRL released increased with increasing PEG content in the polymer up to 15%. The PLGA-PEG copolymer coated on the stent showed the potential to act as a bio-degradable drug reservoir. In an in vitro platelet adhesion test, the PLGA-PEG15-coated DES showed significantly reduced platelet deposition versus the BMS. The DES revealed anti-thrombotic activity and blood-compatibility presumably due to the increased hydrophilicity of the surface of the stent and the amount of SRL loading corresponding to the high PEG content in the polymer. In an animal study, the restenosis rate was reduced in the PLGA-PEG15-coated DES group (20.2±11.02%) versus the BMS group (44.2±12.11%). The PLGA-PEG15-coated DES inhibited smooth muscle cell (SMC) proliferation and prevented in-stent restenosis (ISR) in in vivo test. We successfully obtained the PLGA-PEG15-coated DES with smooth surface and sustained drug-release properties.