Evaluation of an in vitro endothelialized vascular graft under pulsatile shear stress with a novel radiolabeling procedure

Objective: To improve the hemocompatibility of vascular grafts, endothelial cell (EC) seeding of biomaterials prior to implantation is critical. The current in vitro study was designed to investigate such a feasibility on a collagen-coated heparin-bonded graft and to evaluate cell detachment upon pulsatile shear stress.Materials and methods: Endothelial cells (EA-hy-926) were seeded onto grafts. The endothelialization of the grafts was evaluated by the [3H]-thymidine incorporation, scanning electron microscopy (SEM) and histological examinations. After in situ EC radiolabeling with a novel 99mTc technique, the prostheses were exposed to pulsatile shear stress (0.27 N/m2), mimicking the shear rate occurring in a superficial femoral artery, for 3 h in a flow circuit and EC loss quantified by gamma camera detection. Results: Complete EC coverage was achieved after 5 days. Three hours of artificial perfusion resulted in a low EC loss (12.9±0.8%, n=7). SEM shows EC withstanding shear stress in valleys of prosthesis circumvolutions. Conclusions: These satisfactory results could be explained by the high affinity of EC for heparinized surfaces in addition to cell surface receptors involved in adhesion to collagen.