Are seeded endothelial cells the origin of neointima on prosthetic vascular grafts?

Although endothelial cell seeding has been demonstrated to be effective in producing uniform endothelial coverage on prosthetic grafts, no one has demonstrated that the seeded cells are the genetic precursors of the endothelial cells that ultimately line the graft. This study was performed to determine whether seeded endothelial cells were the source of the neoendothelial surface on Dacron vascular grafts implanted in the pig. Eight pairs of littermate male and female pigs were selected at birth and allowed to grow until their weight reached 20 to 25 kg. Endothelial cells were enzymatically harvested from the jugular vein of the female siblings and seeded onto 8 mm diameter grafts, 25 cm in length. The grafts were then implanted as a thoracoabdominal bypass into the male siblings. Seven other randomly selected pigs of similar size (four males and three females) had thoracoabdominal bypass with similar grafts, which were preclotted with autologous blood only, but not seeded. After 4 weeks, grafts in both groups were covered with a neointima that was more than 90% thrombus-free. The graft surface cells were grown in culture and were documented to be endothelium. Chromosome analysis demonstrated that the surface cells on the seeded grafts were from the male host and did not originate from the donor female cells. We conclude that seeded endothelial cells are not the source for the neointima on Dacron grafts in the porcine model. In addition, we have again documented that spontaneous endothelial coverage of grafts does occur without endothelial seeding.