Affiliations: Division of Inorganic Materials, Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, 2-3-10, Surugadai-Kanda, Chiyoda-ku, Tokyo 101, Japan | Department of Biomaterials Science, Faculty of Dentistry, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyou-ku, Tokyo 113, Japan
Abstract: Hydroxyapatite (HAp) microcrystals were synthesized by a neutralization reaction of Ca(OH)2 suspension and H3PO4 solution using an ultrasonic homogenizer. The in vitro interaction of HAp microcrystals with rat peritoneal macrophages was investigated by measuring the viability, acid phosphatase (ACP) activity, lactate dehydrogenase (LDH) activity and intracellular calcium content. HAp calcined at 800°C and α-alumina particles (alumina) were used as comparative materials. Macrophages actively phagocytosed HAp microcrystals by dissolving them. However, no damage in macrophages exposed to HAp microcrystals was observed by transmission electron microscopy. Macrophages in the presence of HAp microcrystals showed less ACP and LDH activity and higher intracellular calcium content than those in the presence of calcined HAp and alumina. HAp microcrystals had excellent biocompatibility to macrophages as well as sintered HAp.
Keywords: hydroxyapatite microcrystals, macrophage, viability, acid phosphatase, intracellular Ca content
