Histological characteristics of Platelet-Rich Fibrin clots obtained under various modes of blood centrifugation

Autologous products of the first and second generation, namely platelet-rich plasma and platelet-rich fibrin, are considered promising for regenerative medicine. They differ from each other in physical properties, as well as in the way they are obtained. The key procedure of all techniques is centrifugation; changing its parameters affects the biological properties of these biomaterials. The aim of the work is to determine and histologically characterize the area of concentration cells of autologous fibrin enriched with platelets, depending on the change in centrifugation parameters. The studies were carried out on rabbits. Blood was collected and platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) were obtained using different values of relative centrifugal force: 100 g, 400 g, 735 g, 906 g, 1843 g. Due to the fact that it is impossible to determine the number of platelets in PRF clots, the counting was performed in platelet-rich plasma obtained by a single centrifugation with the corresponding parameters that were used to obtain PRF. The length of the formed clots was compared and a histological assessment of the cell composition in different layers (lower, middle and upper) was carried out. The highest platelet concentrations were observed in PRP obtained at 100 g and 400 g. Application of different values of centrifugal force showed obvious differences in the formation of platelet-rich fibrin clots. After preparation of I-PRF, its volume was significantly less than that of standard PRF, and the border between erythrocytes was less distinct. During the histological examination of fibrin clots, a change in the distribution of cellular elements in different parts was found with a change in the centrifugation parameters. With an increase in the parameter of relative centrifugal force, the length of the fibrin clot significantly increases, but the concentration of platelets in it significantly decreases. That is, it was found that the most optimal value of the relative centrifugal force for obtaining platelet mass is 100 g, which makes it possible to achieve the number of platelets greater than 800×109/L.