Hybrid Co-Spinning and Melt Electrowriting Approach Enables Fabrication of Heterotypic Tubular Scaffolds Resembling the Non-Linear Mechanical Properties of Human Blood Vessels

The current barrier to clinical translation of small-caliber tissue-engineered vascular grafts (TEVGs) is the long-term patency upon implantation in vivo. Key contributors are thrombosis and stenosis caused by inadequate mechanical graft properties and mismatch of hemodynamic conditions. Herein, the authors report on an approach for the fabrication of a mechanically tunable bilayered composite TEVGs. Using a combination of solution electrospinning (SES) and melt electrowriting (MEW), it is shown that the mechanical properties can be tailored and the natural J-shape of the stress–strain relationship can be recapitulated. Upon cell seeding, the luminal surface of the composite SES layers permits the formation of a confluent mature endothelium. MEW fibers provide structural support to promote stacking and orientation of MSCs in a near-circumferential native vessel like direction. By adjusting the ratios of poly(ε-caprolactone) and poly(ester-urethane) during the SES process, TEVGs with a range of tunable mechanical properties can be manufactured. Notably, this hybrid approach permits modulation of the radial tensile properties of TEVGs to approximate different native vessels. Overall, a strategy for the fabrication of TEVGs with mechanical properties resembling those of native vessels which can help to accommodate long-term patency of TEVGs at various treatment sites in future applications is demonstrated.