This project has been funded by the University of Applied Sciences and Arts Western Switzerland and was initiated thanks to a collaboration with the department of Cardiology of the University of Fribourg. Acute coronary syndromes are associated with high morbidity and mortality rates of utmost clinical importance. The resulting high social and economic impact calls for novel therapeutic strategies. The current standard of care is the balloon-expandable, drug-eluting metallic stent. More than 5 million implantations of coronary stents are performed worldwide each year.

However, late stent thrombosis represents an aggravating bane of coronary stenting. The medical and industrial communities have started developing new temporary stents with increased biocompatibility.

Consequently, the first fully-bioresorbable drug-eluting stent (BRS) was introduced into clinical practice in 2012. The most currently developed BRS are based on polylactide (PLA). Although PLA permits sufficient artery support, hydrolysis of PLA is associated in vivo with vascular inflammation. Recent data shows increased vascular fragility and questions on PLA security in light of an increased risk of late thrombosis.

The search for the next generation of stents focuses on (i) new materials and designs presenting optimal mechanical, biocompatibility and bioresorbable properties and (ii) innovative methods    to   foster    rapid    healing   or re-reendothelialization of injured vessels. 

We aimed to provide a proof of concept that manufacturing    stents   by   3D   printing    with melt-extrusion (also called fused deposition modelling or FDM) using bioresorbable polymers is possible for the required small dimensions of a stent (coronary scaffold).

This funding allowed us to develop and construct a lab-built 3D printing platform for scaffold printing.

We gained experience with this technology, performed first printing tests and manufactured first stent prototypes with polycaprolactone (PCL) as biomaterial.

In addition, different innovative instruments for the fabrication and characterization of the printed scaffolds have been developed and successfully used: a screw melt-micro extruder that can work under protective gas / vacuum, a rotational axis for tubular coronary scaffold printing, a strain-stress measurement unit for thin polymers fibers and an Iris radial force measurement unit. Our 3D printing platform is located in a biosafety cabinet class II for printing under sterile conditions (clean-room environment).

 

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