Rapid endothelialization and thin luminal layers in vascular grafts using silk fibroin

The histological effects of silk fibroin (SF) in vascular grafts have not been clarified comprehensively in a large-animal model. This study aimed to observe the histological changes in vascular grafts by using Bombyx mori SF in a dog model. A splice graft consisting of SF and control grafts were implanted in the abdominal aorta of dogs, and the histological characteristics of the 2 types of grafts in each splice graft were compared. Five splice grafts consisted of one graft made of polyester (PE) fibers coated with SF and another coated with gelatin, 4 splice grafts consisted of one graft made of SF fibers coated with gelatin and another made of PE fibers coated with gelatin, and 2 splice grafts consisted of one graft made of SF fibers coated with SF and another made of PE fibers coated with SF. The graft made of PE fibers coated with SF showed more endothelial cells than the graft made of PE fibers coated with gelatin. The grafts using SF as a coating material or graft fibers showed a thinner luminal layer than the grafts made of PE fibers coated with gelatin. This study suggests that SF use for vascular grafts has advantages of rapid endothelialization and tendency to form thin luminal layers.