Potential of bone scaffolds containing vancomycin and bone morphogenetic protein-2 in a rat model of osteomyelitis

Background: Infected bone is often intractable. An ideal approach is to simultaneously eradicate infection and repair the bone defect. The development of osteoinductive bone graft composites to control antibiotic drug release would be useful for the treatment of intractable bone infections.

Objectives: To develop a rat model of osteomyelitis for assessing osteoinductive bone graft scaffolds containing antibiotics and a bone morphogenetic protein.

Methods: Si-imprinted calcium phosphate is a new hydroxyapatite derivative used in fabricating bone scaffolds. Vancomycin and bone morphogenetic protein-2 (BMP-2) were loaded onto scaffolds of Si-imprinted calcium phosphate using an established method. The efficiency of the scaffold as a drug carrier system was assessed in vivo. Osteomyelitis was induced in rats by infection of the tibial epiphysis with Staphylococcus aureus (BAA 1680). The success of inducing disease was checked after 4 weeks using bacterial culture and radiography. A 10 mm metaphysis bone was surgically removed and replaced with a drug-loaded scaffold. Histology and X-ray imaging were used to evaluate the implants at 8 weeks post implantation.

Results: We successfully established a rat model of osteomyelitis. The causative bacteria were effectively eradicated by vancomycin released from the implants. Enhanced bone formation was observed for the implant samples containing vancomycin and BMP-2 compared with those containing either vancomycin or BMP2 alone.

Conclusions: The newly developed bone scaffold has potential as a vehicle for therapeutic agents to treat bone diseases.