Tri-layered silk fibroin and poly-E⟩-caprolactone small diameter vascular grafts tested in vitro and in vivo

A silk fibroin (SF) and poly-epsilon-caprolactone (PCL) tri-layered nano-fibrous scaffold composed of an inner, middle, and outer layer is fabricated via sequential electrospinning. The middle layer of the SF/PCL blend nano-fiber is introduced to minimize delamination of each layer of the scaffold. The inner layer is composed of SF with Spirulina maxima extract (SP), and the outer is composed of PCL. The anti-thrombic effects of SP are tested first. The structure, mechanical properties, and cytocompatibility of the scaffold are evaluated. The tri-layered nano-fiber scaffold is implanted into a rat carotid artery, and the sample after 3 weeks of implantation is evaluated histologically. The SP exerts anti-thrombic activity, and the SF with SP inhibits platelet adhesion. The tri-layered scaffold with the middle layer composed of SF/PCL blend exhibits excellent tensile strengths, burst pressure strength, and suture retention strength. The fabricated material does not induce any cytotoxicity. The cells are well spread on the scaffold. Recipient vessel maintains patency 3 weeks after implantation. The inner lumen of the scaffold reveals regenerated endothelial cells. The results indicate that the tri-layered tubular SF/PCL vascular grafts can be used in vascular tissue engineering due to their excellent mechanical properties and good tissue regeneration capability.