The effect of implantation materials based on equine and bovine xenogenic bone extracellular matrix on the formation of extracellular neutrophilic traps (experimental study)

Abstract

Purpose To study the effect of osteoplastic materials based on the extracellular xenomatrix of bovine and equine bone tissue on the formation of neutrophil extracellular traps (NETs) in the peripheral blood of rabbits in the early post-operative period after implantation. Materials and methods The study was carried out on 18 male rabbits of the Soviet Chinchilla breed, aged from 8 months to 1.2 years, weighing from 3.0 to 4.5 kg. A perforated bone defect of a cylindrical shape measuring 2 x 6 mm in the distal metaphysis of the right and left femurs was modeled in the animals. The rabbits were divided into three groups, six animals each. In group I, the bone defect was left unfilled; in group II, the defect was filled with a bovine bone tissue xenomatrix, and an equine bone tissue xenomatrix was implanted in group III animals. The implantation material had the appearance of a yellowish crumb with a particle size of 0.5– 1 mm. Blood smears stained according to Romanovsky-Giemsa were used for counting extracellular neutrophil traps (NETs). The percentage of neutrophils that passed the stages of nuclear transformation and emitted free chromatin into the extracellular space in the form of network-like structures was calculated. Results On days 3–7 of the experiment, the number of NETs increased in the early stages of NETosis in all groups. There were no significant differences between the groups. In group I, on days 7 and 14, the number of early forms of NETs (stages 1a and 1b) returned to the values of the preoperative period. In groups II and III, normalization of NETs (stage 1a) did not occur, and the content of NETs (stage 1b) returned to the initial level only by day 30 of the experiment. On days 3, 7, 14, the number of mature NETs increased in all groups. The highest values were noted in group II, where the bovine xenogeneic matrix was implanted. Conclusion Implantation materials based on the extracellular matrix of equine and bovine xenogeneic bone stimulate excessive formation of early NETs on days 14–30 of the experimental period in response to xenotransplantation. Xenomaterials of bovine bone tissue, in comparison with xenomaterials of equine bone tissue, induce a more pronounced inflammatory reaction in the nearest time after defect filling, which is manifested by higher production of mature NETs on days 3–14 of the experiment.