Role of precoating in artificial vessel endothelialization

As the progress of vascular surgery, artificial vessels have become the substitute for large and middle diameter vessels but have not for small diameter ones owing to thrombogenesis and occlusion within a short period of time after being applied. Artificial vessel endothelialization is one of the ideal methods to resolve such issue and has been improved continuously since Herring in 1978 put forward this term in the first time and utilized vascular endothelial cells (ECs) harvested from living animals to perform the test of artificial vessel endothelialization. However, human endothelial cells show little adhesion to the currently available vascular graft materials and some expanded polytetrafluoroethylene (ePTFE) grafts have shown only 10%+/-7% endothelial cell attachment rate (ECA, ie, attachment of ECs when incubated in vitro). Moreover, when the graft is exposed to pulsatile blood flow, a high proportion of cells are washed off from the lumen. Maximum cell loss occurs in the first 30-45 min after exposure to pulsatile flow, with up to 70% of cells lost. After that, a slower exponential loss occurs over the next 24 h. The lack of retention of cells could be partly overcome by sodding, but other techniques, involving engineering the lumen to improve ECA and endothelial cell retention rate (ECR, ie, retention of ECs when the grafts are exposed to pulsatile flow) have been developed. These include shear stress preconditioning, electrostatic charging and, above all, most successfully to date, precoating with EC specific adhesive glues that are mostly found in the extracellular basement membrane of blood vessels. The commonest are chemical coatings, preclotting, chemical bonding, and surface modifications.