In vivo biocompatibility and hemocompatibility of a polytetrafluoroethylene small diameter vascular graft modified with sulfonated silk fibroin.

Objective: To evaluate the biocompatibility and hemocompatibility of an enhanced polytetrafluoroethylene (ePTFE) graft modified with sulfonated silk fibroin (SF) and to compare the patency rate of the modified graft to that of the commercially available unmodified ePTFE graft in a rabbit model.

Methods: Twelve SF-modified grafts were used to replace a section of the lower abdominal aortic artery in rabbits, and 10 unmodified ePTFE grafts were used as controls. The patency rates of these grafts were examined according to physical findings, ultrasonic examination, and scanning electron microscopy (SEM).

Results: The patency rates of SF-modified ePTFE grafts on day 3, from day 4 to 3 months, and at 3 months were 100%, 91.7%, and 91.7%, respectively, and these values were higher than those for the unmodified grafts (60.0%, 33.3%, and 20.0%, respectively, with P = 0.029, 0.022, and 0.002, respectively). SEM images of grafts harvested 3 months postoperatively showed that approximately 84% of the inner surface of the SF-modified grafts was covered with endothelial cells growing longitudinally with extensive cell-cell connections. In comparison, endothelial cells covered only approximately 11% of the inner lumen of the unmodified grafts, and the inner surface of these grafts was covered with activated platelets, erythrocytes, and newly formed extracellular matrix. We also have developed a rabbit model to evaluate the patency rate of small diameter vessel graft by replacing the lower abdominal aortic artery with graft.

Conclusion: The SF-modified ePTFE graft had a higher patency rate than the unmodified PTFE graft in vivo. In addition, replacement of the rabbit abdominal aortic artery represents a feasible and convenient model for evaluating the patency of small diameter vascular grafts.