Bio-based covered stents: the potential of biologically-derived membranes.

Endovascular treatment using bare metal stents or drug eluting stents is routinely performed to restore the blood flow in the coronary and peripheral arteries; however, intimal hyperplasia and late stent thrombosis are still major issues leading to stent failure and often to the need for re-intervention. Covered stents have emerged as an alternative approach to avoid intimal hyperplasia. They are characterized by the presence of a membrane that spans the struts of the stent and acts as a physical barrier to block the ingrowth of the neointimal tissue into the lumen. Currently used membrane-materials include mainly synthetic polymers. Their main limitation is their lack of hemocompatibility, which can induce thrombosis and ultimately reocclusion, thus impairing the long-term performance of these devices. To overcome this issue, the use of biologically-derived materials has been proposed with the aim of enhancing the biocompatibility and the capability of this type of stents to support endothelialization. The aim of this review is to give a comprehensive overview of the applications of bio-based covered stents as well as the different strategies followed for their development from the perspective of the material selection, fabrication approaches and validation of the different concepts in animal and clinical trials.