Fabrication of a low-kink-radius bilayer vascular scaffold incorporating a TPU stent fabricated via melt electrowriting and an electrospun PCL/PU/gelatin layer

This study investigates the fabrication of a small-diameter bilayer vascular graft, which is an inner layer fabricated from melt-electrowriting (MEW) thermoplastic polyurethane (TPU) scaffold and an outer co-electrospun layer made of heparinized polycaprolactone (PCL)/polyurethane (PU)/gelatin, aimed at mimicking the extracellular matrix (ECM). The bilayer structure exhibited good flexibility, mechanical stability, and anti-thrombogenic properties, overcoming the drawbacks of vascular grafts, such as high kink radius and tendency toward thrombosis. MTT assays proved cytocompatibility, showing an increase in cell proliferation over 7 days, the optical density of the bilayer vascular graft increased from [Formula: see text] on day [Formula: see text] to [Formula: see text] on day [Formula: see text], respectively, due to its fibrous structure and hydrophilic properties. Live/dead and SEM assays confirmed cell viability, attachment, and endothelial layer formation on the scaffold, which provides long-term graft patency. The bilayer graft with integrated MEW structure provided the balanced mechanical and kink-radius properties (ultimate tensile strength [Formula: see text], Young's modulus [Formula: see text], suture retention [Formula: see text]) with a low kink radius ([Formula: see text]), surpassing the mechanical properties of coronary artery. A heparin release profile of 70% after 4 weeks was obtained, thus increasing anticoagulant effects. This combination of synthetic (TPU, PCL, PU) and natural (gelatin) polymers yields a biocompatible, structurally stable vascular graft, which efficiently supports endothelialization, and thus has good potential for clinical vascular applications.