Development of silk vascular graft coated with silk sponge

Purpose: Changes in diet and lifestyle have increased the number of patients with vascular diseases. Synthetic grafts yield unacceptable outcomes in very small vessels, such as coronary arteries, causing the exclusive use of native vessels despite their limited availability and sometimes suboptimal quality. Therefore, a small-diameter vascular graft that achieves outcomes comparable to native vessels is clinically needed. Methods: In this paper, porous silk fibroin vascular grafts (PSVG) were prepared using a double-raschel knitting machine to create vascular grafts from silk fibers, followed by coating with a silk sponge using poly(ethylene glycol diglycidyl ether) as a porogen. Gelatin-sealed polyethylene terephthalate vascular grafts and non-porous silk vascular grafts were prepared as controls. Results: When this PSVG was implanted into rats, positive results were observed 4 weeks post-implantation. Specifically, endothelial-like cells were confirmed in the central part of the patent PSVG, indicating that endothelialization had progressed within a relatively short period of 4 weeks. However, gelatin-sealed polyethylene terephthalate vascular grafts and non-porous silk vascular grafts showed no indication of the presence of the endothelial-like cells. Conclusions: These results indicate that PSVG is promising as small-diameter grafts for implantation.