The role of proliferation and migration in endothelial cell monolayer formation on a tissue-engineered blood vessel wall model

The formation of an endothelial cell (EC) monolayer is one critical factor in the development of a tissue engineered vascular graft. One potential method for endothelialization is the migration of native ECs from the surrounding blood vessel onto the newly implanted graft. Therefore, experiments were performed to investigate the potential of ECs to migrate on a tissue engineered blood vessel wall model (TEWM) and form a new monolayer. Although new EC monolayer was formed on glass coated with collagen, monolayer formation was inhibited on the TEWM. An inhibition of proliferation was associated with the lack of monolayer formation on the TEWM. The addition of bFGF to the culture media stimulated EC movement but not monolayer formation or proliferation on the TEWM. By investigating single cell migration characteristics, ECs were shown to have higher persistence times but lower cell speeds on the TEWM versus glass coated with collagen. Even though the EC displayed different migration characteristics, EC dispersion on the two surfaces was similar. Studying the clustering of receptors crosslinked to the extracellular matrix of ECs indicated that the ECs adhere differently to the TEWM versus glass coated with collagen. These findings demonstrate that ECs need to both migrate and proliferate to form new monolayer and that the inability of ECs to proliferate on the TEWM is one limiting factor in monolayer formation. Continued investigation into the mechanism and stimulation of EC proliferation on the TEWM may lead to developing a tissue engineered vascular graft that has the potential to be endothelialized after implantation.