Porous bioactive scaffolds: characterization and biological performance in a model of tibial bone defect in rats

The aim of this study was to evaluate the effects of highly porous Biosilicate (R) scaffolds on bone healing in a tibial bone defect model in rats by means of histological evaluation (histopathological and immunohistochemistry analysis) of the bone callus and the systemic inflammatory response (immunoenzymatic assay). Eighty Wistar rats (12 weeks-old, weighing +/-300 g) were randomly divided into 2 groups (n = 10 per experimental group, per time point): control group and Biosilicate (R) group (BG). Each group was euthanized 3, 7, 14 and 21 days post-surgery. Histological findings revealed a similar inflammatory response in both experimental groups, 3 and 7 days post-surgery. During the experimental periods (3-21 days post-surgery), it was observed that the biomaterial degradation, mainly in the periphery region, provided the development of the newly formed bone into the scaffolds. Immunohistochemistry analysis demonstrated that the Biosilicate (R) scaffolds stimulated cyclooxygenase-2, vascular endothelial growth factor and runtrelated transcription factor 2 expression. Furthermore, in the immunoenzymatic assay, BG presented no difference in the level of tumor necrosis factor alpha in all experimental periods. Still, BG showed a higher level of interleukin 4 after 14 days post-implantation and a lower level of interleukin 10 in 21 days post-surgery. Our results demonstrated that Biosilicate (R) scaffolds can contribute for bone formation through a suitable architecture and by stimulating the synthesis of markers related to the bone repair.