Engineered small diameter vascular grafts by combining cell sheet engineering and electrospinning technology.

Tissue engineering offers an attractive approach to creating functional small-diameter (<5mm) blood vessels by combining autologous cells with a natural and/or synthetic scaffold under suitable culture conditions, which results in a tubular construct that can be implanted in vivo. We have previously developed a vascular scaffold fabricated by electrospinning poly(ε-caprolactone) (PCL) and type I collagen that mimics the structural and biomechanical properties of native vessels. In this study, we investigated whether a smooth muscle cell (SMC) sheet could be combined with the electrospun vascular scaffolds to produce a more mature smooth muscle layer as compared to the conventional cell seeding method. The pre-fabricated SMC sheet, wrapped around the vascular scaffold, provided high cell seeding efficiency (approx. 100%) and a mature smooth muscle layer that expressed strong cell-to-cell junction, connexin 43 (CX43), and contractile proteins, α smooth muscle actin (α-SMA) and myosin light chain kinase (MLCK). Moreover, bioreactor-associated preconditioning of the SMC sheet-combined vascular scaffold maintained high cell viability (95.9 ± 2.7%) and phenotypes and improved cellular infiltration and mechanical properties (35.7% of tensile strength, 47.5% of elasticity, and 113.2% of elongation at break).