The first results of obtaining a hybrid hydrogel based on fibrin and polyvinyl alcohol: comparison with monocomponent hydrogels

Fibrin displays promising characteristics for tissue engineering. However, it has suboptimal physical and mechanical properties when used as a material for cardiovascular applications. Obtaining an interpenetrating polymer network (IPN) hydrogel based on fibrin and polyvinyl alcohol (PVA) can improve the physical and mechanical characteristics and shrink behavior of fibrin. Aim: To perform sequential polymerization of fibrin and PVA to obtain IPN hydrogel and analyze its properties in comparison with monocomponent hydrogels. Material and Methods. Fibrinogen was isolated from the peripheral blood of patients using ethanol precipitation, then polyvinyl alcohol dissolved in saline was added to it. First, fibrin polymerization was initiated by adding calcium chloride to the solution. Then, it was followed by polyvinyl alcohol undergoing freeze–thaw cycles. Thus, a hydrogel based on fibrin and PVA, samples from pure fibrin and pure polyvinyl alcohol were prepared. We studied the structure of hydrogels, their physical and mechanical properties, shrink behavior and biological activity. Statistical data processing was carried out using the GraphPad Prism 6 software. Results. 3D structure of the hydrogel is presented by polyvinyl alcohol polygonal cavities with a network of thin fibrin fibers. The distribution of components was equal in the inside of the samples, while polyvinyl alcohol prevails on the surface. Elongation (247 (220.0; 293.2)%; p = 0.0005) and Young’s modulus (0.09 (0.11; 0.13) mPa; p = 0.0001) of the hydrogel were statistically significantly higher compared to fibrin values. The hydrogel did not shrink, unlike fibrin that shrunk (11-fold decrease in volume). The number of adherent endothelial cells on the hydrogel matrices was 8 times higher than on polyvinyl alcohol, but 10 times lower than on fibrin. There was no proliferative activity of cells on polyvinyl alcohol, but 13.6% of proliferating cells were noted on the IPN hydrogel, and 59.52% on fibrin Conclusion. Using sequential polymerization to obtain the IPN hydrogel based on fibrin and polyvinyl alcohol provides an equal distribution of fibers in the thickness of the material, making it possible to obtain hydrogels with improved mechanical properties and shrink behavior. However, the components on the surface of the IPN hydrogel need to be redistributed - more polyvinyl alcohol should be added still maintaining a relatively low adhesiveness of the material. Therefore further research is necessary to create the most optimal conditions for cell activity.