In Vitro Toxicity of Fine Particles of Hydroxyapatite

Abstract

Although experimental and clinical studies have indicated that hydroxyapatite is a well tolerated material, in vitro studies using cultured fibroblastic cells and fine powders of hydroxyapatite have shown toxicity with both cell death and an inhibition of mitosis. The cell damage occurs with fine particles of different makes of hydroxyapatite and requires direct contact between cells and particles. Damage does not occur if the particles are separated from the cells by a microporous membrane. The damaged cells release LDH suggesting some form of membrane damage and microscopy shows particles adhering to the cell membrane. There is no evidence to suggest toxicity of larger granules of hydroxyapatite intended for clinical use, nor is anything yet known of the importance of this mechanism of cell damage in vivo.