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

Abstract

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.

Current Strategies for the Manufacture of Small Size Tissue Engineering Vascular Grafts

“…So far, decellularized native tissues are the most successful in vivo approach, although post-implantation thrombus events are the main limitation for low long-term patency. Moreover, decellularization is still a topic of debate because the incompleteness of the process may lead to an immunogenic reaction by the recipient, whereas an excessive chemical treatment can provoke the loss of mechanical properties and aneurysmal dilatation (Shojaee and Bashur, 2017 ).…”

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

“…898 In contrast to the case of large-diameter arteries, where there are already practical non-tissue-engineered grafts, there is an urgent need to develop biomimetic scaffolds for clinically regenerating blood vessels of small sizes (typically, <6 mm). 899 The currently used grafts are plagued by thrombosis and unsatisfactory long-term patency because of the poor blood compatibility, mismatch in biodegradability between the implanted graft and the progressively regenerating tissue, and poor mechanical strength incapable of supporting the dynamics of blood flow.…”

Two Sides of Electrospun Fiber in Promoting and Inhibiting Biomedical Processes

“…The risk of thrombosis increased due to lumen narrowing and the corresponding hemodynamic change caused by mechanical properties, indicating that applying materials like elastin to mimic the strength and elasticity of native vessels can effectively prevent thrombosis. [ 258 ] Wise et al. produced a conduit‐like scaffold that mimicked the mechanical properties of the internal mammary artery through an electrospun mixture composed of recombinant human tropoelastin (rhTE) and PCL.…”