骨補填材リン酸八カルシウムの結晶性状多様性と骨形成活性

抄録

  Octacalcium bis (hydrogenphosphate) tetrakis (phosphate), having a chemical composition Ca₈(HPO₄)₂(PO₄)₄·5H₂O, frequently expressed as Ca₈H₂(PO₄)₆·5H₂O and abbreviated to octacalcium phosphate (OCP), have become recognized to show a highly osteoconductive performance in comparison with other calcium phosphate materials. Such a bioactive property has been found to be induced while OCP is mineralized to a poorly crystallized calcium-deficient hydroxyapatite (Ca-deficient HA) involving inorganic ion incorporation or release and serum protein adsorption under physiological condition. OCP displays non-stoichiometric composition and distinct morphological feature in the crystals. These physicochemical characteristics are acquired depending on the synthesis condition. OCP is capable of stimulating osteoblastic differentiation and osteoclast formation from their precursor cells in vitro therefore may activate these cells directly or indirectly under an environment induced by its mineralizing process to Ca-deficient HA if implanted in bone defects. These osteoconductive properties can be modified by the crystals stoichiometry through distinct biological responses.