Approach for Fabricating Tissue Engineered Vascular Grafts with Stable Endothelialization

A major roadblock in the development of tissue engineered vascular grafts (TEVGs) is achieving construct endothelialization that is stable under physiological stresses. The aim of the current study was to validate an approach for generating a mechanically stable layer of endothelial cells (ECs) in the lumen of TEVGs. To accomplish this goal, a unique method was developed to fabricate a thin EC layer using poly(ethylene glycol) diacrylate (PEGDA) as an intercellular cementing agent. This EC layer was subsequently bonded to the lumen of a tubular scaffold to generate a bi-layered construct. The viability of bovine aortic endothelial cells (BAECs) through the cementing process was assessed. Cemented EC layer expression of desired phenotypic markers (AcLDL uptake, VE-cadherin, eNOS, PECAM-1) as well as of injury-associated markers (E-selectin, SM22 alpha) was also examined. These studies indicated that the cementing process allowed ECs to maintain high viability and expression of mature EC markers while not significantly stimulating primary injury pathways. Finally, the stability of the cemented EC layers under abrupt application of high shear pulsatile flow (similar to 11 dyn/cm(2), P (avg) similar to 95 mmHg, Delta P similar to 20 mmHg) was evaluated and compared to that of conventionally seeded EC layers. Whereas the cemented ECs remained fully intact following 48 h of pulsatile flow, the seeded EC layers delaminated after less than 1 h of flow. Furthermore, the ability to extend this approach to degradable PEGDA cements permissive of cell elongation was demonstrated. Combined, these results validate an approach for fabricating bi-layered TEVGs with stable endothelialization.