Diagnostic Imaging Studies on Local and Systemic Erythropoietin Application for Promoting Bone Regeneration in Rat Calvarial Defects

SIMPLE SUMMARY: Erythropoietin (ЕPО) is a glycoprotein hormone which, apart from its physiological function in the regulation of erythropoiesis, has additional functions in the animal and human body. In orthopaedic patients EPO treatment induces regeneration of bone defects, proliferation of osteoblasts and new blood vessel formation, improvement of early endochondral ossification and bone mechanical strength, thus resulting in enhanced bone healing. The purpose of this study was to compare the effects of local and systemic application of recombinant human erythropoietin (rhEPO) on the healing of rat calvarial defects. The systemic effect of EPO treatment was monitored by haematological analyses on days 0, 30 and 90. Bone healing was monitored via radiography and computed tomography on the same time intervals. The results demonstrated that intraperitoneally-injected rhEpo did not result in bone formation. Simultaneously, it affects the erythropoiesis by increasing the erythrocyte counts, haemoglobin and haematocrit. At the same time, single local dose rhEpo applied on collagen carrier could be used for enhancing bone healing without systemic effect. ABSTRACT: The purpose of this study was to compare the effects of local and systemic application of recombinant human erythropoietin (rhEPO) on the healing of rat calvarial defects. Twenty-four male skeletally-mature Wistar rats were used. Two bone 5 mm critical size defects were created in calvarial bones of each rat. In rats from experimental group I (n = 12), EPO was applied locally on a collagen cone in left defects, whereas a collagen cone soaked with physiological saline was placed in right defects. The rats from experimental group II were injected once intraperitoneally with 4900 IU/kg EPO; a collagen cone was only placed in left defects, whereas the right defects were left empty. The systemic effect of EPO treatment was monitored by haematological analyses on days 0, 30 and 90. Bone healing was monitored via radiography and computed tomography on the same time intervals. The results demonstrated that local EPO application had no significant effect on haemopoiesis, unlike the systemic application. At the same time, it resulted in new bone formation and therefore, could be successfully used as a means of promoting bone regeneration.