Effects of ibandronate-hydroxyapatite on resorptive activity of osteoclasts

INTRODUCTION Bisphosphonates (BPs) can be locally used to improve the osteogenesis around hydroxyapatite (HA) implants. However, there are almost no reports discussing the effects of BPs in the bound state with HA on osteoclasts. Ibandronate is a BP widely used in clinical practice. This study was designed to evaluate the effects of ibandronate combined with HA on the morphology and resorptive activity of osteoclasts. MATERIAL AND METHODS The HA and ibandronate-HA were prepared. Osteoclasts were isolated from Sprague-Dawley rats and then the cells were cultured with both HA and ibandronate-HA. Then the cell morphology was inspected by inverted phase contrast microscope and transmission electron microscopy observation. The resorptive activity was tested using the dyeing agent seminaphthofluorescein and bone resorption assay. RESULTS Compared with the control group, the osteoclasts demonstrated morphological alterations, and the hydrogen ion concentration was significantly lower in the ibandronate-HA group. Areas of the resorption pits formed by the osteoclasts were significantly smaller, the trabecula thickness appeared thicker, and concentration of CTx was also significantly lower in the experimental group. CONCLUSIONS Resorptive activity of osteoclasts cultured with ibandronate-HA was weaker than that of the control group. Ibandronate on HA in the bound state could maintain its action as an inhibitor to osteoclasts.