The formation of an endothelial cell lining on the inner surface of polymeric grafts may reduce the inherent thrombogenicity of synthetic implants. Endothelial cell transplantation onto the luminal surface of grafts has been suggested as one method of creating new endothelial cell linings on grafts. The purpose of this study was to morphologically evaluate the very early events of healing (between 4 and 14 days) of 1-mm-internal-diameter expanded polytetrafluoroethylene (ePTFE) grafts that were treated with autologous microvessel endothelial cells at the time of graft implantation. We evaluated the development of new intimal linings in microvascular endothelial cell-sodded 1-mm ePTFE vascular grafts and compared their healing characteristics with non-cell-treated grafts by using a rat aortic graft model. Endothelial cells were isolated from intraperitoneal fat pads of female rats and transplanted onto the grafts by using a pressure sodding method. One-centimeter-long grafts were immediately implanted as interpositional grafts in the aorta. Non-cell-treated grafts were also implanted. Grafts were explanted 4, 7, and 14 days after implantation and were evaluated by light and scanning electron microscopy. Morphometric analysis of the graft surfaces revealed the cellular coverage in sodded grafts to be 93.7 +/- 8.7% and in nonsodded grafts, 1.1 +/- 1.9%. Areas not covered by cells exhibited thrombus and bare graft. The luminal lining of cells exhibited morphological characteristics, indicating they were antithrombogenic, based on morphological criteria, and exhibited characteristics of endothelium.(ABSTRACT TRUNCATED AT 250 WORDS)