A review on biodegradable biliary stents: materials and future trends

Biliary stricture is defined as the reduction and narrowing of the bile duct lumen, which can be caused by many factors such as cancer and inflammation. Biliary stent placement can effectively alleviate benign and malignant biliary strictures. However, the commonly used plastic or metallic biliary stents are far from ideal and do not satisfy all clinical requirements,although several types of biodegradable biliary stents have been developed and used clinically. In this review, we summarized current development status of biodegradable stents with the emphasis on the stent materials. We also presented the future development trends based on the published literature.

Two-stage degradation and novel functional endothelium characteristics of a 3-D printed bioresorbable scaffold

Bioresorbable scaffolds have emerged as a new generation of vascular implants for the treatment of atherosclerosis,and designed to provide a temporary scaffold that is subsequently absorbed by blood vessels over time.Presently,there is insufficient data on the biological and mechanical responses of blood vessels accompanied by bioresorbable scaffolds(BRS)degradation.Therefore,it is necessary to investigate the inflexion point of degradation,the response of blood vessels,and the pathophysiological process of vascular,as results of such studies will be of great value for the design of next generation of BRS.In this study,abdominal aortas of SD rats were received 3-D printed poly-l-actide vascular scaffolds(PLS)for various durations up to 12 months.The response of PLS implanted aorta went through two distinct processes:(1)the neointima with desirable barrier function was obtained in 1 month,accompanied with slow degradation,inflammation,and intimal hyperplasia;(2)significant degradation occurred from 6 months,accompanied with decreasing inflammation and intimal hyperplasia,while the extracellular matrix recovered to normal vessels which indicate the positive remodeling.These in vivo results indicate that 6 months is a key turning point.This“two-stage degradation and vascular characteristics”is proposed to elucidate the long-term effects of PLS on vascular repair and demonstrated the potential of PLS in promoting endothelium function and positive remodeling,which highlights the benefits of PLS and shed some light in the future researches,such as drug combination coatings design.

利用多轴3D打印系统制造锥形生物可吸收支架

Coronary artery disease(CAD)is the leading cause of death worldwide.Implantation of traditional cylindrical stents into the stenotic coronary arteries is widely used in patients with CAD.However,because most coronary arteries taper in diameter by at least 0.5 mm over a length of 20 mm[1],natural size mismatch is common between a cylindrical stent and a tapered coronary artery.This stent-vessel mismatch may directly cause either increased stress on both stent and vessel or incomplete stent apposition,followed by vessel injury,in-stent restenosis,or stent thrombosis[2,3].