Morphological aspects of orbital defect reconstruction in rats with elastin-based biomaterial

The objective of the study was to identify morphological aspects of replacement of xenogeneic decellularized elastin matrix (ХDEM) transplanted into a bone defect of the upper orbital wall in rats. Materials and methods. The experiment was performed on 60 Wistar rats with artificially created 7×4 mm defect in the upper edge of their orbit. In the experimental group (n=30), DХEM was placed in the defect area. Its size matched the size of the defect, and it was attached with a suture material (50 μm silk). Soft tissues were sutured layer by layer in the control group (n=30). Tissue excision was performed after 1, 3 and 12 months. Histological, immunohistochemical and electron microscopic methods were employed. Results. We were gradually replacing DХEM with bone tissue against the background of a pronounced reaction of CD68+/MMP-9+ macrophages, which implied its resorption and lysis. Osteogenesis occurred via intramembranous ossification and endochondral ossification, which was preceded by centripetal migration of endothelial kidneys with subsequent differentiation into capillaries and overgrowth of loose fibrous connective tissue containing progenitor cells. The microenvironment, represented by reticulin fibers, TGF-β1, and sulfated glycosaminoglycans, could contribute to the differentiation of progenitor cells in the osteogenic direction and to osteogenesis per se. In the control group, the defect remained open throughout the experiment. Conclusion. Decellularized biomaterial, based on elastin matrix, has osteoconductive and osteoinductive properties and can serve an adequate biomimetic for reconstruction of the bone defects.