Fabrication and Characterization of Electrospun Poly-Caprolactone-Gelatin Composite Cuffs for Tissue Engineered Blood Vessels

Strong, durable terminal regions that can be easily handled by researchers and surgeons are a key factor in the successful fabrication of tissue engineered blood vessels (TEBV). The goal of this study was to fabricate and characterize electrospun cuffs made of poly-caprolactone (PCL) combined with gelatin that reinforce and strengthen each end of cell-derived vascular tissue tubes. PCL is ideal for vascular tissue engineering applications due to its mechanical properties; however, PCL alone does not support cell attachment. Therefore, we introduced gelatin, a natural matrix-derived protein, into the electrospun material to promote cell adhesion. This work compared the effects of two different methods for introducing gelatin into the PCL materials: gelatin coating and gelatin co-electrospinning. Porosity, pore size, fiber diameter, and mechanical properties of the electrospun materials were measured in order to compare the features of gelatin PCL composites that have the greatest impact on cellular infiltration. Porosity was quantified by liquid intrusion, fiber diameter and pore size were measured using scanning electron microscopy, and tensile mechanical testing was used to evaluate strength, elastic modulus, and extensibility. Attachment and outgrowth of smooth muscle cells onto cuff materials was measured to evaluate differences in cellular interactions between materials by using a metabolic attachment assay and a cellular outgrowth assay. Finally, cuffs were fused with totally cell-derived TEBV and the integration of cuffs with tissue was evaluated by longitudinal pull to failure testing and histological analysis. Overall, these cuffs were shown to be able to add length and increase strength to the ends of TEBV for tube cannulation and manipulation during in vitro culture. In particular, PCL:gelatin cospun cuffs were shown to improve cellular attachment and cuff fusion compared to pure PCL cuffs, while still increasing the strength of the TEBV terminal ends