Apolipoprotein E Stimulates Bone Formation on Titanium in Vitro

Objective: To examine the effects of apolipoprotein E2, a strongly expressed molecule during titanium implant healing, on bone formation by rat primary osteoblasts over titanium.Materials and Methods: Primary rat osteoblasts were cultured on titanium in the presence of 0.011.0 μg/mL apolipoprotein E2. After 2 or 3 weeks of culture, bone formation was analysed by staining the bone-like nodules with calcein blue. The mRNAs of the osteogenic genes type I collagen, osteopontin, and osteocalcin, were analysed using semi-quantitative reverse transcriptase polymerase chain reaction.Results: Apolipoprotein E2 enhanced bone-like nodule formation on titanium in a dose-dependent manner. Apolipoprotein E2 strongly upregulated osteopontin and osteocalcin mRNA expression, but had only a small effect on type I collagen mRNA expression.Conclusion: Apolipoprotein E2 stimulated bone formation on titanium disks in vitro. This may lead to a new approach to accelerating implant healing.