Abstract
Artificial vascular grafts with low thrombogenicity are generally required to avoid blood platelet adhesion and to minimize intimal hyperplasia, thus retaining vascular patency. In this study, we aimed to determine the acute and subacute hemocompatibility of silk fibroin (SF) grafts by in vitro and in vivo evaluation. Blood contact reaction with SF grafts was examined by thrombin-anti-thrombin III complex (TAT) formation, platelet activation level by beta-thromboglobulin (beta-TG), complement system response (C3a and SC5b-9), platelet and fibrin deposition and compared with commercially available polyethylene terephthalate (PET) artificial grafts in vitro. The biocompatibility and coagulation-inducing effect of coating materials were evaluated by in vivo implantation in rats. Two weeks after implantation, SF grafts showed low subacute coagulation. All blood parameters evaluated for animals implanted with SF-coated grafts showed almost the same values as those for sham-operated animals. Our results support the suggestion that SF will be a suitable material for vascular regeneration in future.
Highlights
The increasing morbidity in modern society due to cardiovascular disease has made it an urgent necessity to develop blood vessel substitutes, especially those with an internal diameter of less than 6 mm, to replace diseased coronary and below-the-knee vessels
To examine the hemocompatibility of an silk fibroin (SF)-based artificial vascular graft, thrombogenicity, coagulation activation, platelet and complement system activation were evaluated by human blood contact in vitro with scanning electron microscopy (SEM) observation and measurements of thrombin-anti-thrombin III complex (TAT), β-TG, C3a and SC5b-9
SEM observation of platelet adhesion and aggregation on a material surface after blood contact is a reliable method of assessing thrombogenicity
Summary
The increasing morbidity in modern society due to cardiovascular disease has made it an urgent necessity to develop blood vessel substitutes, especially those with an internal diameter of less than 6 mm, to replace diseased coronary and below-the-knee vessels. For the last 50 years, therapies for such diseases have involved surgical replacement of the damaged vessels with autologous vessels or synthetic materials. Limited supply and metabolic diseases are problems for autologous vessel replacement, while acute thrombosis, infection and lack of biocompatibility are problems associated with the current synthetic materials (Murugesan et al, 2008). Laboratory models have shown that synthetic grafts are substantially more thrombogenic compared to autologous veins. Polyester synthetic materials such as polyethylene terephthalate (PET) have been used routinely for surgical replacement of the large arteries with high blood flow velocity for the past half century (Devine et al, 2004). In order to design small-diameter arterial prosthesis, the complete design specifications should be determined based on the features of successful large diameter vascular prosthesis (How et al, 1992)
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