[Stimulative and regulative functions of osteoblasts loaded under the titanium particles on osteoclasts]

Our previous studies on the function of the osteoblasts (OBs) have shown that worn titanium particles decrease osteoblast function and promot secretion of bone resorption cytokines of OBs surrounding the synovium-like interface membrane of loosening implants. The current study was aimed to test the hypothesis that osteoclasts (OCs) bone absorption function is induced by conditioned media (CM) prepared from OBs loaded in the presence or absence of titanium particles (with three mean diameters 6.9 microm, 2.7 microm, and 0.9 microm, respectively). The effects of CM on OCs function were examined using a combination of the morphological characteristics tests, i.e., TRAP dyeing, scanning electron microscopy, F-actin immunofluorescence protocol for confocal microscopy, bone resorption lacunae assay, osteoclastic calcium tracking, with biochemical evaluation, i.e., C-terminal cross-linked telopeptides of type I collagen evaluated with ABC-ELISA method. The results showed that CM from 0.9 microm titanium particles could induce osteoclastic differentiation and formation, could partially influence the survival of the OCs; while CM of 2.7 microm and 6.9 microm titanium particles, especially the latter, could obviously augmented osteoclastic activity, survival, or differentiation. The stimulation of osteoclast function may be due to a parallel increase in the intracellular free calcium concentration. The present study provides strong support for the hypothesis that osteoclastic activity, survival, or differentiation are very important in the development of aseptic loosening. The development of therapeutic interventions to reduce osteoclastic function and optimization of biomaterials may be useful approaches for improving the performance of orthopaedic implants.