STUDY OF DEGRADATION, BIOCOMPATIBILITY AND CALCIFICATION CHARACTERISTICS OF BIOMATERIALS FOR VASCULAR SURGERY

Highlights Silk fibroin is resistant to early degradation, focal calcification, adsorbs albumin, and does not cause pronounced local and systemic inflammation during subcutaneous implantation in rats, which is comparable and even superior in properties to bovine pericardium used in vascular surgery. Aim . To study the hydrolytic degradation of silk fibroin (SF), to evaluate in a comparative aspect the surface adsorption of proteins by matrices from SF and bovine pericardium (BP), calcification of biomaterials, as well as their biocompatibility, the dynamics of biodegradation and systemic inflammation after subcutaneous implantation in rats. Methods . Matrices from SF were made by electrospinning. The BP flap was used as a comparison material. The loss of SF mass and the change in pH of the incubation solution during its hydrolytic degradation in vitro were studied at periods of 1, 3, 6, and 12 months. The surface adsorption of albumin and fibrinogen by matrices was assessed in vitro. Samples of SF and BP were implanted subcutaneously in rats for periods of 7, 14, 30, and 60 days. After explantation of the matrices, a histological examination of the samples was performed and their calcification was assessed. The levels of interleukins 6 and 8, tumor necrosis factor-α, and monocyte chemotactic protein-1 were studied in the blood serum of rats using the enzyme immunoassay method. Results . Hydrolytic degradation of SF in vitro resulted in a 6% loss of the matrix mass and was accompanied by a decrease in the pH of the incubation solution to 6.56. Twice as much albumin and six times as much fibrinogen were adsorbed on the SF surface than on the BP surface. Signs of SF biodegradation and a thin connective tissue capsule around the matrix appeared after 30 days of subcutaneous implantation in rats. No pronounced inflammation or calcification of SF were detected. Subcutaneous implantation of BP was accompanied by the formation of a pronounced connective tissue capsule around the sample after 60 days, fraying, and degradation of the material. Localized foci of calcification were not detected at any time point of subcutaneous implantation. The content of proinflammatory cytokines in the blood serum of rats after subcutaneous implantation of SF and BP decreased by day 60 of the study without statistically significant intergroup differences. Conclusion . Due to its resistance to premature degradation and calcification, increased surface adsorption of albumin, optimal biocompatibility and the absence of pronounced peri-implantation and systemic inflammation, SF is comparable and also has a number of advantages compared to BP used in vascular surgery.