# Angioplasty Using 4-Hexylresorcinol-Incorporated Silk Vascular Patch in Rat Carotid Defect Model
###### Abstract  
The aim of this study was to evaluate and compare the efficacy of 4-hexylresorcinol (4-HR)-incorporated silk as a vascular patch scaffold to that of the commercial polytetrafluoroethylene (PTFE) vascular patch (GORE\({}^{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{ \text  
Several patch materials were implemented in carotid artery angioplasty, such as autogenous vein, xenogeneic, and synthetic patches [8; 9; 10]. The saphenous vein has the advantages of an autogenous tissue surface, a sufficient length for grafting, and a resistance to infection [11]. However, an additional operation is required to harvest the vein, and there is a risk of wound complication at the recipient site [11]. In contrast, the synthetic patch can be made immediately available and does not require any additional surgery for harvesting. In addition, the synthetic patch has a lower risk of postoperative patch rupture and aneurysm dilatation [3]. Commonly used synthetic patch materials include polytetrafluoroethylene (PTFE) and textile Dacron patches [9; 12]. Although the synthetic patch has many advantages, it carries a higher risk of infection and foreign-body reaction that can lead to graft failure [13; 14]. The ideal non-autogenous patch material should have biocompatibility, allowance for endothelial cell migration, broad availability, and favorable handling [8; 15; 16]. Although the synthetic patch yielded favorable results in many clinical trials, a more biocompatible and economical biomaterial patch should be developed to reduce the risks associated with artery repair in the oral and maxillofacial region. Silk derived from the silkworm _Bombyx mori_ is a natural biopolymer, and is used as a biomaterial scaffold [17]. Owing to its good biocompatibility and mechanical properties, silk was also used as a suture material for decades [18]. More recently, silk was used in the tissue engineering of scaffolds such as bone, cartilage, artificial tympan membrane, and vessels [19; 20; 21]. A silk cocoon is mainly composed of the two proteins, silk fibroin (SF) and sericin [18]. SF constitutes the core of the silk filament, and is generally used as the post-sericin-removal biomaterial in a process known as degumming [22]. SF has excellent biocompatibility and biodegradability properties, and is used as a vascular tissue scaffold [23]. Furthermore, SF is used as the main component of the small-diameter vascular graft material and vascular patch purposed for vessel repair [23]. However, unlike SF, silk mat derived from cocoons is yet to be employed as a vascular tissue scaffold. Silk mat can be easily separated from the cocoon to obtain different membrane thicknesses [24]. This separated silk membrane has excellent osteogenic and physical properties, which make it well suited for use as the barrier membrane in guided bone regeneration (GBR) [24; 25]. Silk membrane demonstrated good bone regeneration ability in bone defect studies, and has the potential to be employed as a GBR membrane that does not initiate a foreign-body reaction [26]. Silk mat also has mechanical and biological properties that make it well suited for use as a vascular patch material. As an example, silk mat can be processed into thin layers through the process of silk cocoon separation [24]. Additionally, this silk mat demonstrated excellent tensile strength in wet conditions [27]. Considering the qualities of silk mat, we implemented the inner layer of silk mat as a vascular patch scaffold in this study. The 4-hexylresorcinol (4-HR) natural phenolic compound has antiseptic and antimicrobial activities [28]. This compound was used as a food additive to prevent the melanosis of seafood and fruit, and as antisetics for skin and oral mucosa [29; 30]. It was recently employed as a component in silk-based biomaterials because of its antiseptic and anti-inflammatory activities [31].