The Effects of Electrically Polarized Hydroxyapatite on Osteogenic Cell Activity and Bone Formation

摘要

Exclusively large surface charges are inducible on hydroxyapatite (HAp) ceramics by proton transport polarization. In the present study, we examined osteogenic cell responses and new bone formation on electrically polarized HAp plates that were implanted into calvarial bone defects in rats. In the first group of rats, test pieces were placed with their positively charged surfaces face down on the dura mater. In a second group, test pieces were placed with their negatively charged surfaces face down on the dura mater. A third group received non-charged test pieces. Bone mineral density was measured and histological examination was carried out to characterize the newly formed bone as well as quantification. Furthermore, enzyme histochemistry involving the detection of alkaline phosphatase and tartrate-resistant acid phosphatase was performed to quantify osteogenic cell activity. No bone formation was observed at the pericranium, suggesting that the pericranium is a poor osteoinducer. Bone growth was enhanced in the groups that received polarized HAp plates, both at the negatively and positively charged surfaces. In addition to the electrostatic force that attracts Ca{sup}(2+) to the negatively charged surfaces, the suppressive effects on osteoclasts proliferation on the positively charged surfaces may enhance bone formation in vivo.