Effect of fibroin sponge coating on in vivo performance of knitted silk small diameter vascular grafts

Abstract

ABSTRACT. Vascular grafts under 5 mm or less in diameter are not developed due to a problem caused by early thrombus formation, neointimal hyperplasia, etc. Bombyx mori silk fibroin (SF) which has biodegradability and tissue infiltration is focused as tube and coating material of vascular grafts. Coating is an important factor to maintain the strength of the anastomotic region of vascular grafts, and to prevent the blood leak from the vascular grafts after implantation. Therefore, in this research, we focused on the SF concentration of the coating solution, and tissue infiltration and remodeling were compared among each SF concentration. Silk poly (-ethylene) glycol diglycidyl ether (PGDE) coating with concentrations of 1.0%, 2.5%, 5.0%, and 7.5% SF were applied for the double-raschel knitted small-sized vessel with 1.5 mm diameter and 1cm in length. The grafts were implanted in the rat abdominal aorta and removed after 3 weeks or 3 months. Vascular grafts patency was monitored by ultrasound, and morphological evaluation was performed by histopathological examination. SF concentration had no significant effects on the patency rate. However, tissue infiltration was significantly higher in the sample of 2.5% SF in 3 weeks, and 1.0% and 2.5% SF in 3 months. Also, in comparison of length inside of the graft, stenosis were not found in 3 weeks, however, found with 5.0% and 7.5% in 3 months. From these results, it is clear that 2.5% SF coating is the most suitable concentration, based on the characteristics of less stenosis, early tissue infiltration, and less neointimal hyperplasia.

Three-Layered Silk Fibroin Tubular Scaffold for the Repair and Regeneration of Small Caliber Blood Vessels: From Design to in vivo Pilot Tests

“…The simplest technical approach to create at least an additional layer is to coat the textile tubular scaffold with a film-forming biocompatible polymer (SF or gelatin) (Fukayama et al, 2015; Yamamoto et al, 2016). The use of SF microfibers as scaffold material and of SF aqueous solution as coating showed advantages in terms of enhanced in vivo endothelialization, which corresponded to improved graft performance (e.g., medium-to-long term patency).…”

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

“…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.…”

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

“…ECs and SMCs were observed onto the luminal area of the graft for proximal and distal parts, but contrarily to the rat models no ECs were visible in the middle portion even after 1 year. In 2015, PGDE was used again by Fukayama et al, 83 who made double-raschel knitted silk scaffolds coated with silk and PGDE sponges for studying the impact of silk concentration in the sponges. After implanting the grafts (1.5 mm in diameter, 1 cm long) for up to 3 months in rat models, they showed that the ideal concentration was 1.5% of silk, regarding stenosis, tissue infiltration, and intimal hyperplasia.…”