111Indium labeling of endothelial cells: Potential problems when applied to studies of vascular graft seeding

Abstract 111 Indium labeling of endothelial cells has been widely used to study the kinetics of endothelial cell seeding of vascular grafts. In the current study two potential areas of inaccuracy of the technique were investigated, namely, the rate of spontaneous loss of 111 indium from the labeled cells and the degree to which the free 111 indium attaches to the surface of vascular graft material. It was found that a significant amount of spontaneous leakage of 111 indium occurred from both human umbilical vein (HUVECs) and omental microvascular (HOTMECs) endothelial cells such that by 4 h only 50.6% of the original tracer remained in the HOTMECs and 72.4% in the HUVECs (p < 0.05). With regard to the attachment of free 111 indium-oxine to polytetrafluoroethylene (PTFE) or compliant polyurethane (CPU) vascular graft material, there were significant (P < 0.01) differences between the two materials treated with a range of surface coatings (fibronectin, collagen, and blood preclot). It is concluded that if the technique is used to quantify endothelial cell attachment in graft-seeding experiments, then separate validations for cell type, experimental and culture conditions, and graft surface studied are required.