Controlled release of granulocyte colony-stimulating factor enhances osteoconductive and biodegradable properties of Beta-tricalcium phosphate in a rat calvarial defect model

Autologous bone grafts remain the gold standard for the treatment of congenital craniofacial disorders; however, there are potential problems including donor site morbidity and limitations to the amount of bone that can be harvested. Recent studies suggest that granulocyte colony-stimulating factor (G-CSF) promotes fracture healing or osteogenesis. The purpose of the present study was to investigate whether topically applied G-CSF can stimulate the osteoconductive properties of beta-tricalcium phosphate ( β -TCP) in a rat calvarial defect model. A total of 27 calvarial defects 5 mm in diameter were randomly divided into nine groups, which were treated with various combinations of a β -TCP disc and G-CSF in solution form or controlled release system using gelatin hydrogel. Histologic and histomorphometric analyses were performed at eight weeks postoperatively. The controlled release of low-dose (1  μ g and 5  μ g) G-CSF significantly enhanced new bone formation when combined with a β -TCP disc. Moreover, administration of 5  μ g G-CSF using a controlled release system significantly promoted the biodegradable properties of β -TCP. In conclusion, the controlled release of 5  μ g G-CSF significantly enhanced the osteoconductive and biodegradable properties of β -TCP. The combination of G-CSF slow-release and β -TCP is a novel and promising approach for treating pediatric craniofacial bone defects.