Steady-State Behavior and Endothelialization of a Silk-Based Small-Caliber Scaffold In Vivo Transplantation

Abstract

A silk-based small-caliber tubular scaffold (SFTS), which is fabricated using a regenerated silk fibroin porous scaffold embedding a silk fabric core layer, has been proved to possess good cell compatibility and mechanical properties in vitro. In this study, the endothelialization ability and the steady-state blood flow of SFTSs were evaluated in vivo by implanting and replacing a common carotid artery in a rabbit. The results of the color doppler ultrasound and angiographies showed that the blood flow was circulated in the grafts without aneurysmal dilations or significant stenoses at any time point, and ran stronger and close to the autologous blood vessel from one month after implantation. The SFTSs presented an initial tridimensionality without being distorted or squashed. SEM and immunohistochemistry results showed that a clear and discontinuous endodermis appeared after one month of implantation; when implanted for three months, an endothelial layer fully covered the inner surface of SFTSs. RT-PCR results indicated that the gene expression level of CD31 in SFTSs was 45.8% and 75.3% by that of autologous blood vessels at 3 months and 12 months, respectively. The VEGF gene showed a high expression level that continued to increase after implantation.

In-vivo evaluation of silk fibroin small-diameter vascular grafts: state of art of preclinical studies and animal models

“…A study employed a 3 mm diameter tubular scaffold, produced by braiding SF yarns and coating with a SF-PGDE aqueous solution, to evaluate endothelialization and steady-state blood flow in vivo by implanting and replacing a common carotid artery in rabbits (30). Doppler ultrasound and angiography demonstrated graft patency without aneurysmal dilations or significant stenoses at any time point, with waveforms comparable to the native contralateral artery.…”

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

“…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. More recently, Li et al 84 designed tubular braided scaffolds coated with silk fibroin then freeze-dried and cross-linked with PGDE. They implanted the grafts (15 mm long and 3 mm inner diameter) for 1 year in rabbits and observed that an endothelial layer had formed after 1 month and that by 3 months endothelialization was complete.…”

Evaluation of new robust silk fibroin hydrogels for posterior scleral reinforcement in rabbits

“…Previous research has demonstrated that in vivo , only very mild inflammatory responses to SF occur ( Wang Y et al, 2008 ). Regenerated silk fibroin (RSF) has been widely utilized as an excellent biomaterial for various biomedical applications, such as cartilage regeneration ( Wang et al, 2006 ; Hong et al, 2020 ), artificial blood vessels ( Lovett et al, 2007 ; Zhang et al, 2008 ; Li et al, 2019 ), drug delivery scaffolds ( Wang X et al, 2008 ; Maity et al, 2020 ), ligament reconstruction ( Bi et al, 2021 ; Yan et al, 2021 ), bone tissue engineering ( Hofmann et al, 2007 ; Gambari et al, 2019 ), and skin tissue engineering ( Bhardwaj et al, 2015 ). RSF can be fabricated into various forms of materials, including fibers, films, porous sponges, hydrogels, scaffolds, and nanomicrospheres ( Kundu et al, 2013 ; Lu et al, 2015 ; Yan et al, 2015 ; Kapoor and Kundu, 2016 ; Choi et al, 2018 ).…”