A bilayered elastomeric scaffold for tissue engineering of small diameter vascular grafts

A major barrier to the development of a clinically useful small diameter tissue engineered vascular graft (TEVG) is the scaffold component. Scaffold requirements include matching the mechanical and structural properties with those of native vessels and optimizing the microenvironment to foster cell integration, adhesion and growth. We have developed a small diameter, bilayered, biodegradable, elastomeric scaffold based on a synthetic, biodegradable elastomer. The scaffold incorporates a highly porous inner layer, allowing cell integration and growth, and an external, fibrous reinforcing layer deposited by electrospinning. Scaffold morphology and mechanical properties were assessed, quantified and compared with those of native vessels. Scaffolds were then seeded with adult stem cells using a rotational vacuum seeding device to obtain a TEVG, cultured under dynamic conditions for 7days and evaluated for cellularity. The scaffold showed firm integration of the two polymeric layers with no delamination. Mechanical properties were physiologically consistent, showing anisotropy, an elastic modulus (1.4±0.4MPa) and an ultimate tensile stress (8.3±1.7MPa) comparable with native vessels. The compliance and suture retention forces were 4.6±0.5×10−4mmHg−1 and 3.4±0.3N, respectively. Seeding resulted in a rapid, uniform, bulk integration of cells, with a seeding efficiency of 92±1%. The scaffolds maintained a high level of cellular density throughout dynamic culture. This approach, combining artery-like mechanical properties and a rapid and efficient cellularization, might contribute to the future clinical translation of TEVGs.