Compositions Including Synthetic and Natural Blends for Integration and Structural Integrity: Engineered for Different Vascular Graft Applications.

Tissue engineering approaches for small-diameter arteries require a scaffold that simultaneously maintains patency by preventing thrombosis and intimal hyperplasia, maintains its structural integrity after grafting, and allows integration. While synthetic and extracellular matrix-derived materials can provide some of these properties individually, developing a scaffold that provides the balanced properties needed for vascular graft survival in the clinic has been particularly challenging. After 30 years of research, there are now several scaffolds currently in clinical trials. However, these products are either being investigated for large-diameter applications or they require pre-seeding of endothelial cells. This progress report identifies important challenges unique to engineering vascular grafts for high pressure arteries less than 4 mm in diameter (e.g., coronary artery), and discusses limitations with the current usage of the term "small-diameter." Next, the composition and processing techniques used for generating tissue engineered vascular grafts (TEVGs) are discussed, with a focus on the benefits of blended materials. Other scaffolds for non-tissue engineering approaches and stents are also briefly mentioned for comparison. Overall, this progress report discusses the importance of defining the most critical challenges for small diameter TEVGs, developing new scaffolds to provide these properties, and determining acceptable benchmarks for scaffold responses in the body.