Synthesis of Hydroxyapatite Contining Manganese and Its Evaluation of Biocompatibility

Biomaterials made using hydroxyapatite (HAp) and calcium phosphates, which are inorganic components of hard tissues, have been developed to fill bone defects caused by various diseases. A biomaterial of HAp containing collagen, an organic component of bone, has also been developed. However, the physical and biological functions of these bone biomaterials remain inadequate. Focusing on Zinc(Zn) and Manganese(Mn) ions out of the divalent cations involved in the activity of integrins, which are molecules existing in cell membranes, we synthesized three kinds of inorganic biomaterials—pure HAp, Zn-containing HAp (Zn-HAp), and Mn-containing HAp (Mn-HAp)—by a wet process. These three kinds of HAp powders were formed into pellets of 6mm diameter and 1mm thickness and their bio-adaptability was investigated. In vitro experiments using osteoblast-like cells (MC3T3E1) demonstrated that Mn-HAp showed higher cell adhesion potential than pure HAp, indicating that Mn addition improves bioresponses. This may be because Mn ions eluted from Mn-HAp pellets activated integrins, which are closely related to the cell adhesion potential of MC3T3E1 cells to the surface of the pellets.