Acceleration of new bone formation by an electrically polarized hydroxyapatite microgranule/platelet-rich plasma composite

We have developed a technology for the electrical polarization and electrical characterization of hydroxyapatite (HA) microgranules. In order to improve handling of ceramic powders to fulfill complex geometrical demands, platelet-rich plasma (PRP) containing many growth factors was chosen as a carrier of HA microgranules. In this study, the effects of this electrically polarized HA microgranule/PRP composite on new bone formation were examined. To compare osteoconductivity, HA microgranules with or without electrical polarization/PRP composite gel, HA microgranules alone with or without electrical polarization, or PRP gel were implanted into holes in the medial femoral condyles of rabbits. As a control, some of the bone holes were left empty (n=6 in each group). Histological examination was performed 3 and 6weeks after the surgical operation. It was suggested that PRP alone could not induce new bone formation until 6weeks after implantation. HA microgranules with or without electrical polarization/PRP composite, especially the former, activated osteogenic cells, resulting in enhanced bone formation. It was confirmed that electrical polarization treatment of HA microgranules can accelerate new bone formation, and that this effect is enhanced by forming a complex within the PRP.