Histological Evaluation of Erythropoietin Application on Bone Healing in Rat Calvaria

Introduction: Erythropoietin (ЕPО) is a glycoprotein hormone whose primary physiological functions is regulation of erythropoiesis. During the last decade, its additional, so-called pleiotropic functions, have become also important. As skeletal regeneration is concerned, EPO successfully combines haemopoiesis with bone formation. Due to its osteogenic and angiogenic potential, EPO promotes endochondral ossification, formation of osteoblasts and blood vessels. Aim of the Work: The purpose of the present study was to perform histological evaluation of effects from either local (independent and combined with bone substitute) or systemic administration of EPO using critical-size calvarial bone defect model in rats. Materials and Methods: Thirty-six male Wistar albino rats, 6 months of age, weighing 250-300 g were used in the experiments. Experimental animals were randomly assigned to three groups. Two symmetrical defects were created in the calvaria of each of rats. Thirty and ninety days after the surgical procedure, rats from each group were euthanised to obtain material for histological examination after staining with haematoxylin-eosin and Schmorl's stain. Results: The results showed that EPO was successful in coupling haemopoiesis and bone formation. Due to its osteogenic and angiogenic potential, EPO stimulated the formation of osteoblasts and blood vessels at the site of defect. Conclusion: Local erythropoietin application resulted in bone formation and could be successfully used for bone regeneration. Combined with bone substitute, EPO potentiated its effect and improved bone healing. Contrary to expectations, the effect of EPO systemic application was found to be unsatisfactory.