Evaluation of endothelialization in the center part of graft using 3 cm vascular grafts implanted in the abdominal aortae of the rat

Abstract

In order to develop small-diameter vascular grafts, it is necessary to evaluate endothelialization, especially, in the center part at early stage. For implantation of vascular grafts of 1 cm in length to abdominal aortae of rat, endothelial cells can be formed easily by stretching anastomosis. We evaluated the endothelialization in the center part of vascular grafts by implanting vascular grafts using transgenic (TG) silk fibroin (SF) of 3 cm in length. Vascular grafts were prepared 1.5 mm in diameter and 1 and 3 cm in length using wild type (WT) SF and TG SF by braiding structure, respectively. The grafts were removed after 2 weeks or 3 months and evaluated pathologically. Endothelialization was not confirmed totally after 3 months of implantation. However, endothelialization in the center part of grafts was significantly higher in TG SF than in WT SF. No significant difference was found regarding tissue infiltration and internal diameter. The TG SF revealed migration of the endothelial cells into the center part of the vessels at the early stage. Also, tissue infiltration and remodeling is expected using SF. The 3 cm length vascular grafts can be evaluated as a new experimental system.

Comparison of the knitted silk vascular grafts coated with fibroin sponges prepared using glycerin, poly(ethylene glycol diglycidyl ether) and poly(ethylene glycol) as porogens

“…This result was also better than reported in previous studies using transgenic silk. 22 Endothelialization at the center of the artificial blood vessel is formed by extension from the anastomotic portion and capillary invasion from the outside to the inside of the graft. 51 Because invasion of the self-tissue including capillary vessels are quite important for endothelialization in this way, it is thought that the coating which is degraded early and accelerates remodeling functions advantageously for endothelialization.…”

“…10 Recently, it has been used as an excellent biomaterial because of the ability to fabricate silk into a wide range of materials with tunable mechanical and degradation properties. 11,12 In the last decade, our group [13][14][15][16][17][18][19][20][21][22] and other groups [23][24][25][26] have shown that SF is an excellent candidate for vascular grafts on the basis of in vivo implant data with rats and/or dogs. SF vascular grafts prepared in our studies [15][16][17][18][19][20][21][22] consist of the SF fiber base coated with the SF sponge.…”

“…A similar double-raschel knitted SF vascular graft coated with SF sponge using EtOH for insolubilization was prepared for comparison. 19,22 Here, we call these four kinds of SF grafts as PEG-, PGDE-, Glyc-, and EtOH-SF grafts, respectively. Using rat implantation experiments, patency and biological reactions of hydrated porous SF grafts were evaluated and compared with each other.…”

“…11,12 In the last decade, our group 13–22 and other groups 23–26 have shown that SF is an excellent candidate for vascular grafts on the basis of in vivo implant data with rats and/or dogs. SF vascular grafts prepared in our studies 15–22 consist of the SF fiber base coated with the SF sponge. Before coating, the graft base was prepared using the SF fiber because of its high strength, toughness, and moderate elasticity.…”

Insight on the endothelialization of small silk-based tissue-engineered vascular grafts

“…However, the experiment would have to be repeated for results to be confirmed. The use of transgenic silk was reported again in 2017: Fukayama et al 86 created braided scaffolds using silk fibroin incorporating a vascular endothelial growth factor (VEGF) gene. The interest in VEGF is due to its properties mediating ECs growth and migration.…”